Showing 1–50 of 283 results for author: Zhou, S

Integration-by-parts identities in the presence of measurement delta functions

Authors: Saimeng Zhou

Abstract: We derive a convenient form of integration-by-parts (IBP) identities for dimensionally regulated loop integrals that include a measurement constraint imposed by a delta distribution $δ(φ(\ell))$, where $φ$ is a regular and generally non-linear function of the loop momentum. Non-trivial IBP relations can be generated directly by vectors tangent to the hypersurface $φ=0$, leaving the measurement del… ▽ More We derive a convenient form of integration-by-parts (IBP) identities for dimensionally regulated loop integrals that include a measurement constraint imposed by a delta distribution $δ(φ(\ell))$, where $φ$ is a regular and generally non-linear function of the loop momentum. Non-trivial IBP relations can be generated directly by vectors tangent to the hypersurface $φ=0$, leaving the measurement delta as an overall factor and avoiding derivatives of distributions. This construction provides a systematic route to differential distributions within reverse unitarity for non-linear measurement functions, in particular, for transverse-momentum distributions. We implement the construction and validate it for transverse-momentum distributions in $t\bar tH$ production at leading order and $t\bar t$ production at next-to-leading order in QCD. △ Less

Submitted 24 August, 2026; originally announced August 2026.

Comments: 19 pages, 2 figures

Report number: TTK-26-28

Heating Up the Black Hole X-ray Binary Accretion Disk by Superradiance

Authors: Antonios Kyriazis, Fengwei Yang, Siyu Zhou

Abstract: A superradiant cloud of ultralight axions around a black hole, that is part of an X-ray binary system, can heat up its accretion disk and be detected by the thermal X-ray spectrum emitted by the disk. We consider a derivative coupling of the axions to the plasma fermions and calculate the emissivity of the inverse bremsstrahlung process that results in a temperature fluctuation of the disk. Based… ▽ More A superradiant cloud of ultralight axions around a black hole, that is part of an X-ray binary system, can heat up its accretion disk and be detected by the thermal X-ray spectrum emitted by the disk. We consider a derivative coupling of the axions to the plasma fermions and calculate the emissivity of the inverse bremsstrahlung process that results in a temperature fluctuation of the disk. Based on the thin-disk model and the multicolor disk model, we derive the thermal spectrum with axion heating, which shows an enhanced thermal photon flux and a red-/blue- shifted peak spectral frequency. A single bump hunting search of the axion heating signature in the thermal spectrum of a $10M_\odot$ black hole X-ray binary with a spectral measurement sensitivity of 10\% (1\%) can derive the constraint on axion-electron coupling $|g_{ae}|\gtrsim7.5\times 10^{-12} ~(2.4 \times 10^{-12})$ for axion mass $m_a=5.2\times 10^{-12}\,$eV in a saturated $|211\rangle$ state, and $|g_{ae}|\gtrsim4.5\times 10^{-12} ~(1.4 \times 10^{-12})$ for axion mass $m_a=1.0\times10^{-11}\,$eV in a saturated $|322\rangle$ state. The projected sensitivities are competitive with those from XENONnT. A detailed continuum fitting can further improve the detectability and provide a complementary bound to the black hole spin-down measurement. △ Less

Submitted 18 August, 2026; originally announced August 2026.

S-matrix bootstrap bounds on self-interacting dark matter

Authors: Qing Chen, Zhuo-Hui Wang, Shuang-Yong Zhou

Abstract: Self-interacting dark matter turns the structure of galactic halos into a direct requirement on a low-energy scattering amplitude. We show that, for weakly coupled scalar dark matter, this requirement implies a much stronger mass bound on the dark matter particle than partial-wave unitarity alone. Using analyticity, crossing symmetry, locality and partial-wave unitarity, we compute the maximal all… ▽ More Self-interacting dark matter turns the structure of galactic halos into a direct requirement on a low-energy scattering amplitude. We show that, for weakly coupled scalar dark matter, this requirement implies a much stronger mass bound on the dark matter particle than partial-wave unitarity alone. Using analyticity, crossing symmetry, locality and partial-wave unitarity, we compute the maximal allowed threshold amplitude with a dispersive primal S-matrix bootstrap, assuming only a weakly coupled EFT below a scale $Λ$ and allowing arbitrary UV particle content above $Λ$. For the benchmark self-interaction cross section $σ_{\rm self}=10^{-24}(M/\mathrm{GeV})\mathrm{cm}^2$, the mass of a generic weakly coupled scalar satisfies $M\lesssim 0.3\,\mathrm{GeV}$ in the controlled EFT regime. If dark matter is a derivative-dominated pseudo-Nambu-Goldstone boson, the mass bound is lowered to the MeV scale or below, depending on the hierarchy $M/Λ$. △ Less

Submitted 14 July, 2026; originally announced July 2026.

Comments: 6 pages, 3 figures

Report number: USTC-ICTS/PCFT-26-43

First measurement of the masses of the $Υ_1(1D)$ and $Υ_3(1D)$ states and the energy dependence of the cross sections for $e^+e^-\toΥ_J(1D)η$ and $e^+e^-\toΥ_J(1D)π^+π^-$

Authors: Belle, Belle II Collaborations, :, M. Abumusabh, I. Adachi, K. Adamczyk, A. Aggarwal, H. Ahmed, Y. Ahn, M. Akdag, N. Akopov, S. Alghamdi, M. Alhakami, N. Althubiti, K. Amos, M. Angelsmark, N. Anh Ky, C. Antonioli, K. Arai, H. Atmacan, T. Aushev, V. Aushev, R. Ayad, V. Babu, H. Bae , et al. (376 additional authors not shown)

Abstract: We study the processes $e^+e^-\toΥ_J(1D)η$ and $e^+e^-\toΥ_J(1D)π^+π^-$ at center-of-mass energies $\sqrt{s}$=(10.73 -- 11.02) GeV using a $142.5\,\mathrm{fb}^{-1}$ data sample, including 122~fb$^{-1}$ near the $Υ$(10860) peak ($\sqrt{s}$ = 10.866 GeV), collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. From the peak sample, the products of Born cross section times… ▽ More We study the processes $e^+e^-\toΥ_J(1D)η$ and $e^+e^-\toΥ_J(1D)π^+π^-$ at center-of-mass energies $\sqrt{s}$=(10.73 -- 11.02) GeV using a $142.5\,\mathrm{fb}^{-1}$ data sample, including 122~fb$^{-1}$ near the $Υ$(10860) peak ($\sqrt{s}$ = 10.866 GeV), collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. From the peak sample, the products of Born cross section times branching fraction are obtained for $σ_{\rm Born}(e^+e^-\toΥ_J(1D)η)$ or $σ_{\rm Born}(e^+e^-\toΥ_J(1D)π^+π^-)$ and ${\cal B}(Υ_J(1D)\toχ_{b1}γ)$ or ${\cal B}(Υ_J(1D)\toχ_{b2}γ)$ for each $Υ_J(1D)$ state. The corresponding branching fractions for $Υ(10860)$ decays are also obtained. The significances of the $Υ_1(1D)$, $Υ_2(1D)$, and $Υ_3(1D)$ signals are 4.8$σ$, ${>}10σ$, and 3.0$σ$, respectively, including systematic uncertainties. The mass for $Υ_2(1D)$ is measured to be $(10167.0\pm 1.0\pm 0.2)$ MeV/$c^2$, where the first and second uncertainties are statistical and systematic. The mass splittings $Δm_{12}=m(Υ_2(1D))-m(Υ_1(1D))$ and $Δm_{23}=m(Υ_3(1D))-m(Υ_2(1D))$ are $(11.8\pm1.5\pm0.4)$ MeV/$c^2$ and $(7.6\pm2.4\pm0.6)$ MeV/$c^2$, respectively.~We determine the energy dependence of the cross sections for $e^+e^-\toΥ_J(1D)η$ and $e^+e^-\toΥ_J(1D)π^+π^-$ for the $Υ_1(1D)$, $Υ_2(1D)$, and $Υ_3(1D)$ states, combined. △ Less

Submitted 5 July, 2026; originally announced July 2026.

Comments: 12 pages, 7 figures

Report number: Belle II Preprint 2026-014; KEK Preprint 2026-10

Neutrino mass constraints in the Schwarzschild-de Sitter black-hole dark energy model with ACT DR6 and DESI DR2 data

Authors: Sheng-Han Zhou, Tian-Nuo Li, Guo-Hong Du, Yi-Min Zhang, Zhao-Yu Li, Jing-Fei Zhang, Xin Zhang

Abstract: Recent DESI observations have posed new challenges to $Λ$CDM, showing a preference for dynamical dark energy and yielding neutrino mass constraints within $Λ$CDM that approach the lower bound allowed by neutrino oscillation experiments. In this work, we investigate cosmological constraints on the key neutrino parameters, $\sum m_ν$ and $N_{\rm eff}$, within the Schwarzschild-de Sitter black-hole d… ▽ More Recent DESI observations have posed new challenges to $Λ$CDM, showing a preference for dynamical dark energy and yielding neutrino mass constraints within $Λ$CDM that approach the lower bound allowed by neutrino oscillation experiments. In this work, we investigate cosmological constraints on the key neutrino parameters, $\sum m_ν$ and $N_{\rm eff}$, within the Schwarzschild-de Sitter black-hole dark energy (SdSDE) framework. We use cosmic microwave background (CMB) data from Planck and ACT DR6, baryon acoustic oscillation data from DESI DR2, and type Ia supernova data from DES-Dovekie and PantheonPlus. We find that SdSDE scenarios prefer a positive neutrino mass whenever $\sum m_ν$ is allowed to vary. Using CMB+DESI+DES-Dovekie data, we obtain $\sum m_ν=0.207^{+0.047}_{-0.052}~{\rm eV}$ for SdSDE+$\sum m_ν$, reduced to $\sum m_ν=0.162^{+0.055}_{-0.056}~{\rm eV}$ when $N_{\rm eff}$ is also varied. This arises from the positive correlation between $N_{\rm eff}$ and $\sum m_ν$, together with the systematic preference of SdSDE for values of $N_{\rm eff}$ below the standard value. Furthermore, the best-fit $χ^2$ comparison shows that $Λ$CDM with extended neutrino parameters is strongly preferred over the corresponding SdSDE extension. Overall, the positive neutrino mass preference induced by SdSDE may reflect parameter compensation rather than an improved global fit, a possibility that should be further tested with future high-precision observational data. △ Less

Submitted 3 July, 2026; originally announced July 2026.

Comments: 13 pages, 5 figures

Revealing precision bounds on neutrino oscillation parameters with quantum estimation theory

Authors: Jihong Huang, Tommy Ohlsson, Sampsa Vihonen, Shun Zhou

Abstract: Quantum estimation theory provides ultimate precision bounds on parameter estimation, independent of experimental setups. In this article, we apply this theoretical framework to neutrino oscillations, aiming to clarify some subtle issues and reveal the maximum achievable precision of oscillation parameters. First, taking the example of two-flavor oscillations, we clarify how the quantum Fisher inf… ▽ More Quantum estimation theory provides ultimate precision bounds on parameter estimation, independent of experimental setups. In this article, we apply this theoretical framework to neutrino oscillations, aiming to clarify some subtle issues and reveal the maximum achievable precision of oscillation parameters. First, taking the example of two-flavor oscillations, we clarify how the quantum Fisher information (QFI) depends on the choice of bases when the basis transformation itself involves the parameters in question. Then, for three-flavor oscillations, we compute the QFI matrix for electron and muon neutrino states in the flavor basis and derive analytical expressions and numerical results for both diagonal and off-diagonal elements. The implications of off-diagonal correlations for multiparameter estimation are discussed, and the quantum Cramér-Rao bounds on the precision of oscillation parameters for typical reactor and long-baseline accelerator neutrino experiments are obtained. Our results establish a theoretical benchmark for the ultimate precision achievable in future neutrino oscillation experiments. △ Less

Submitted 26 June, 2026; originally announced June 2026.

Comments: 20 pages, 4 figures

Resolving the Hubble Tension in the Early Dark Energy Framework with JWST and DESI Data

Authors: Guo-Hong Du, Tian-Nuo Li, Lu Yin, Sheng-Han Zhou, Hao Wang, Jing-Fei Zhang, Xin Zhang

Abstract: In the JWST and DESI era, the JWST high-redshift galaxy observations and DESI baryon acoustic oscillation (BAO) measurements severely challenge the standard $Λ$CDM model, while the $H_0$ tension becomes increasingly prominent. In this work, we investigate the capability of the early dark energy (EDE) model to alleviate the $H_0$ tension utilizing cosmic microwave background data from Planck, ACT,… ▽ More In the JWST and DESI era, the JWST high-redshift galaxy observations and DESI baryon acoustic oscillation (BAO) measurements severely challenge the standard $Λ$CDM model, while the $H_0$ tension becomes increasingly prominent. In this work, we investigate the capability of the early dark energy (EDE) model to alleviate the $H_0$ tension utilizing cosmic microwave background data from Planck, ACT, and SPT, BAO data from DESI, and ultraviolet luminosity function observations from the JWST. Within the canonical axion EDE framework, the CMB+DESI+JWST data significantly increase the $H_0$ value to $71.58\pm1.05\,\mathrm{km\,s^{-1}\,Mpc^{-1}}$, alleviating the $H_0$ tension to the $1.0σ$ level. Simultaneously, this model improves the fit to the JWST data and exhibits statistical performance significantly better than the $Λ$CDM model, with $Δχ^2_{\mathrm{tot}} = -18.26$ and $Δ\mathrm{DIC} = -11.89$. Our results highlight the complementary advantages of JWST high-redshift galaxy data alongside early- and late-time observations in testing EDE and alleviating the $H_0$ tension. △ Less

Submitted 17 June, 2026; originally announced June 2026.

Comments: 10 pages, 3 figures

Quantum-Corrected Q-balls in the Friedberg-Lee-Sirlin Model

Authors: Yong-Xiang Su, Qi-Xin Xie, Shuang-Yong Zhou

Abstract: We study the real-time quantum dynamics of Q-balls in the Friedberg-Lee-Sirlin model within the inhomogeneous Hartree approximation. The mean fields are evolved self-consistently with the leading quantum two-point functions, which are implemented numerically through a stochastic ensemble representation. After introducing a renormalized formulation and a classical-limit scaling, we simulate single-… ▽ More We study the real-time quantum dynamics of Q-balls in the Friedberg-Lee-Sirlin model within the inhomogeneous Hartree approximation. The mean fields are evolved self-consistently with the leading quantum two-point functions, which are implemented numerically through a stochastic ensemble representation. After introducing a renormalized formulation and a classical-limit scaling, we simulate single-Q-ball configurations in $3+1$ dimensions and compare their quantum-corrected evolution with the corresponding classical dynamics. We find a clear separation between a classical regime, where quantum fluctuations remain small and the evolution closely follows the classical solution, and a quantum regime, where the fluctuation sector carries a sizable fraction of the Noether charge. We also observe a periodic exchange of Noether charge between the mean fields and the fluctuation modes within the Hartree approximation. We further investigate the stability of quantum-corrected Q-balls and find an intermediate window in which configurations that are classically stable become unstable once Hartree fluctuations are included. Our results provide a first step toward real-time quantum simulations of Q-balls in renormalizable two-field soliton models. △ Less

Submitted 24 May, 2026; originally announced May 2026.

Comments: 36 pages, 16 figures

Precise theoretical prediction on branching fractions and polarizations of $D \to V V$ decays

Authors: Jing Ou-Yang, Hui Zheng, Run-Hui Li, Si-Hong Zhou

Abstract: We present a precise and systematic analysis of $D \to V V$ decays within the factorization-assisted topological-amplitude approach, where $D$ denotes the set $\{D^0, \, D^+,\, D^+_s\}$ and $V$ represents the vector mesons $ρ, K^*, ω$, and $φ$. Given the limited current experimental data, the factorization-assisted topological-amplitude approach serves as a available phenomenological framework for… ▽ More We present a precise and systematic analysis of $D \to V V$ decays within the factorization-assisted topological-amplitude approach, where $D$ denotes the set $\{D^0, \, D^+,\, D^+_s\}$ and $V$ represents the vector mesons $ρ, K^*, ω$, and $φ$. Given the limited current experimental data, the factorization-assisted topological-amplitude approach serves as a available phenomenological framework for predicting charmed meson decays to both vector mesons. In this framework, incorporating flavor SU(3) symmetry breaking effects, we can express nonfactorizable contributions of different modes as a minimal set of universal parameters globally fitted to experimental data. Utilizing 36 experimental data points for $D \to VV$ decays, we precisely extract ten nonfactorizable parameters associated with the $C$ and $E$ topological diagrams with $χ^2/\mathrm{d.o.f.}=8.43$. We find that a large strong phase in the longitude $E$ amplitude cause strong destructive interference with the $C$ longitudinal component, yielding $f_\parallel >f_L $, contrary to the naive factorization predictions. Additionally, for modes processing exclusively by the $E$ diagram, the amplitude hierarchy $|S|<|D|$ leads to a $D$-wave branching fraction larger than that of the $S$-wave. This explains recent observations that contradict $S$-wave dominance predictions. The predicted branching fractions and polarizations for 28 decay modes are consistent with existing experimental data. Unobserved modes, especially those with branching fractions of order $10^{-3}\sim10^{-2}$, the $D$-wave dominated modes, and modes exhibiting $f_\parallel >f_L $, await measurement by BESIII, STCF, Belle II, and LHCb. △ Less

Submitted 28 July, 2026; v1 submitted 1 April, 2026; originally announced April 2026.

Comments: 25 pages, 1 figures

Full positivity bounds for anomalous quartic gauge couplings in SMEFT

Authors: Fu-Ming Chang, Zhuo-Yan Chen, Shuang-Yong Zhou

Abstract: Electroweak boson scattering at the LHC provides a crucial avenue for probing physics beyond the Standard Model, particularly regarding deviations in quartic gauge couplings. We derive the complete set of positivity bounds for the $22$ dimension-$8$ anomalous quartic gauge coupling (aQGC) coefficients within the Standard Model Effective Field Theory (SMEFT). Moving beyond previous studies limited… ▽ More Electroweak boson scattering at the LHC provides a crucial avenue for probing physics beyond the Standard Model, particularly regarding deviations in quartic gauge couplings. We derive the complete set of positivity bounds for the $22$ dimension-$8$ anomalous quartic gauge coupling (aQGC) coefficients within the Standard Model Effective Field Theory (SMEFT). Moving beyond previous studies limited to transverse vector bosons, our analysis incorporates all electroweak boson modes, explicitly constructing the extremal rays (ERs) of the positivity cone through a group theoretic framework. We utilize two independent methods--direct construction and Casimir operator analysis--to determine these rays, addressing complexities such as parity-violating operators and continuous parameter degeneracies. Our results indicate that the positivity bounds impose severe constraints, restricting the physically viable parameter space to approximately $0.0313\%$ of the naive total space. Furthermore, we derive linear analytical bounds for various operator combinations and provide an easy-to-use Python package, {\tt SMEFTaQGC}, which implements algorithms to numerically verify positivity and compute the optimized positivity bounds for general aQGC configurations. △ Less

Submitted 13 April, 2026; v1 submitted 31 March, 2026; originally announced April 2026.

Comments: 47 pages, 5 figures, 5 tables, ancillary Python package; added Appendix D on potential effects of dim-6 aQGCs

Report number: USTC-ICTS/PCFT-26-11

Observation of $Λ^+_c\to nπ^+η$ and search for $Λ^+_c\to na_0(980)^+$

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, C. S. Akondi, R. Aliberti, A. Amoroso, Q. An, Y. H. An, Y. Bai, O. Bakina, Y. Ban, H. -R. Bao, X. L. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. B. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko , et al. (722 additional authors not shown)

Abstract: By analysing 6.1 ${\rm fb}^{-1}$ of data collected at center-of-mass energies between $\sqrt{s}=4.600$ and 4.843 $\rm GeV$ with the BESIII detector at the BEPCII collider, we observe the decay $Λ_c^+\to nπ^+η$ for the first time with a statistical significance of $9.5σ$. The ratio of branching fractions $\mathcal{B}(Λ_c^+\to nπ^+η)/\mathcal{B}(Λ_c^+\to Λπ^+η)$ is measured to be… ▽ More By analysing 6.1 ${\rm fb}^{-1}$ of data collected at center-of-mass energies between $\sqrt{s}=4.600$ and 4.843 $\rm GeV$ with the BESIII detector at the BEPCII collider, we observe the decay $Λ_c^+\to nπ^+η$ for the first time with a statistical significance of $9.5σ$. The ratio of branching fractions $\mathcal{B}(Λ_c^+\to nπ^+η)/\mathcal{B}(Λ_c^+\to Λπ^+η)$ is measured to be $0.155\pm0.031_{\rm stat.}\pm0.012_{\rm syst.}$ Taking the world average of $\mathcal{B}(Λ_c^+\to Λπ^+η)$ as reference, the absolute branching fraction is calculated to be $\mathcal{B}(Λ_c^+\to nπ^+η)=(2.94\pm0.59_{\rm stat.}\pm0.23_{\rm syst.}\pm0.13_{\rm ref.})\times10^{-3}$. The intermediate process $Λ_c^+\to na_0(980)^+$ is also searched for in the $π^+η$ invariant mass spectrum. Since no significant signal is found, the upper limit on $\mathcal{B}(Λ_c^+\to na_0(980)^+)\times\mathcal{B}(a_0(980)^+\toπ^+η)$ is set to $8.4\times10^{-4}$ at 90\% confidence level. A sophisticated deep learning approach using a Transformer-based architecture is employed to distinguish signals from prevalent hadronic backgrounds, complemented by thorough validation and systematic uncertainty quantification. △ Less

Submitted 7 August, 2026; v1 submitted 30 March, 2026; originally announced March 2026.

Comments: 26 pages, 6 figures

Journal ref: JHEP 08 (2026), 009

Investigation of the $D^{0} \rightarrow K_S^{0} π^{0} η,\ K_S^{0} π^{0} π^0$ decays

Authors: Wei Liang, Chu-Wen Xiao, Guo-Mei Gan, Shi-Qi Zhou

Abstract: Inspired by the invariant mass distributions for the decays $D^{0} \rightarrow K_S^{0} π^{0} η$ and $D^{0} \rightarrow K_S^{0} π^{0} π^{0}$ reported by the BESIII Collaboration, we investigate these processes with an unified final state interaction formalism by incorporating both the $S$-wave pseudoscalar meson-pseudoscalar meson interactions within a chiral unitary approach and the $P$-wave contr… ▽ More Inspired by the invariant mass distributions for the decays $D^{0} \rightarrow K_S^{0} π^{0} η$ and $D^{0} \rightarrow K_S^{0} π^{0} π^{0}$ reported by the BESIII Collaboration, we investigate these processes with an unified final state interaction formalism by incorporating both the $S$-wave pseudoscalar meson-pseudoscalar meson interactions within a chiral unitary approach and the $P$-wave contribution from the intermediate resonance $\bar{K}^*(892)$. By performing a combined fit to the invariant mass spectra and taking into account the coherence between the $S$- and $P$-waves, our results are in agreement with the experimental data. For the decay $D^{0} \rightarrow K_S^{0} π^{0} η$, the structure near 1.0 GeV in the $π^0 η$ invariant mass distribution corresponds to the signal of the $a_{0}(980)$, which is dynamically generated from the $S$-wave interactions. In the case of $D^{0} \rightarrow K_S^{0} π^{0} π^{0}$, the near-threshold enhancement in the $π^0π^0$ mass distribution arises from the combined contributions of the $f_0(500)$ and the intermediate $\bar{K}^*(892)$, while the cusp-like structure around 1 GeV$^2$ is associated with the $f_0(980)$. △ Less

Submitted 16 March, 2026; originally announced March 2026.

Comments: 15 pages,6 figures

Observation of $\barΛp\to K^{+}π^{+}π^{-}π^{0}$ and $\barΛp\to K^{+}π^{+}π^{-}2π^{0}$

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, C. S. Akondi, R. Aliberti, A. Amoroso, Q. An, Y. H. An, Y. Bai, O. Bakina, Y. Ban, H. -R. Bao, X. L. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. B. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko , et al. (728 additional authors not shown)

Abstract: Using $(10087 \pm 44) \times 10^6$ $J/ψ$ events collected with the BESIII detector at a center-of-mass energy of $\sqrt{s}=3.097$ GeV, the antihyperon-nucleon annihilation processes $\barΛ p \to K^+ π^+ π^- + kπ^0$ ($k=1,2,3$) are studied at an incident $\barΛ$ momentum of approximately 1.074 GeV/$c$. The reactions $\barΛ p \to K^+ π^+ π^- π^0$ and $\barΛ p \to K^+ π^+ π^- 2π^0$ are observed for t… ▽ More Using $(10087 \pm 44) \times 10^6$ $J/ψ$ events collected with the BESIII detector at a center-of-mass energy of $\sqrt{s}=3.097$ GeV, the antihyperon-nucleon annihilation processes $\barΛ p \to K^+ π^+ π^- + kπ^0$ ($k=1,2,3$) are studied at an incident $\barΛ$ momentum of approximately 1.074 GeV/$c$. The reactions $\barΛ p \to K^+ π^+ π^- π^0$ and $\barΛ p \to K^+ π^+ π^- 2π^0$ are observed for the first time, with corresponding cross sections $σ_{\barΛ p \to K^+ π^+ π^- π^0} = 8.5^{+1.2}_{-1.1} (\rm{stat.}) \pm 0.4 (\rm {syst.})$ mb and $σ_{\barΛ p \to K^+ π^+ π^- 2π^0} = 7.9^{+1.9}_{-1.7} \pm 0.4$ mb. No significant signal is found for $\barΛ p \to K^+ π^+ π^- 3π^0$, and an upper limit of 7.2 mb is set at a 90\% confidence level. An evidence for the $K^{*}(892)^+$ resonance is seen in the $K^+π^0$ invariant mass spectrum $M_{K^+π^0}$ for $k=1$, and the corresponding cross section for $\barΛ p \to K^{*}(892)^+ π^+ π^-$ is measured to be $σ_{\barΛ p \to K^{*}(892)^+ π^+ π^-} = 12.5^{+3.8}_{-3.4} \pm 1.2$ mb. Owing to the limited statistics, possible interference effects are not considered. These findings offer crucial input to deepen our understanding of the antihyperon-nucleon interactions. △ Less

Submitted 15 April, 2026; v1 submitted 1 February, 2026; originally announced February 2026.

Journal ref: Phys. Rev. Lett. 136, 171904 (2026)

Precision Higgs Boson Probe of Type-II Seesaw Models

Authors: Saiyad Ashanujjaman, P. S. Bhupal Dev, Jihong Huang, Shun Zhou

Abstract: Despite direct searches at the LHC excluding tripletlike Higgs bosons up to several hundred GeV over much of the type-II seesaw model parameter space, parts of it -- most notably those featuring ``cascade decays'' of the charged Higgs bosons into their neutral partners and off-shell $W$ bosons -- still remain unconstrained. Meanwhile, measurements of the diphoton signal strength of the Standard Mo… ▽ More Despite direct searches at the LHC excluding tripletlike Higgs bosons up to several hundred GeV over much of the type-II seesaw model parameter space, parts of it -- most notably those featuring ``cascade decays'' of the charged Higgs bosons into their neutral partners and off-shell $W$ bosons -- still remain unconstrained. Meanwhile, measurements of the diphoton signal strength of the Standard Model (SM) Higgs boson -- potentially modified by loop contributions from tripletlike Higgs states -- are in good agreement with the SM expectation, with combined experimental uncertainties currently at approximately 8%. Given the trend in previous measurements, it is expected that future precision Higgs measurements at the HL-LHC and a future lepton collider such as the Circular Electron Positron Collider, Future Circular Collider, or Muon Collider will be consistent the standard diphoton signal strength, albeit with significantly reduced uncertainties, down to about 0.7%. Presuming this and considering all relevant constraints, we explore whether such increasingly precise diphoton measurements can indirectly probe the parameter space that currently evades direct searches. We find that subpercent-level determinations of the diphoton rate will decisively probe a substantial fraction of this otherwise elusive region. △ Less

Submitted 9 March, 2026; v1 submitted 8 December, 2025; originally announced December 2025.

Comments: Version to appear in Phys. Rev. D (as a Letter)

Report number: TTP25-055, P3H-25-108

Journal ref: Phys. Rev. D 113, L051704 (2026)

Identified charged hadron production in Au+Au collisions at $\sqrt{s_\mathrm{NN}}$ = 54.4 GeV with the STAR detector

Authors: STAR Collaboration, B. E. Aboona, J. Adam, G. Agakishiev, I. Aggarwal, M. M. Aggarwal, Z. Ahammed, A. Aitbayev, I. Alekseev, E. Alpatov, A. K. Alshammri, A. Aparin, S. Aslam, J. Atchison, G. S. Averichev, V. Bairathi, X. Bao, P. Barik, K. Barish, S. Behera, P. Bhagat, A. Bhasin, S. Bhatta, I. G. Bordyuzhin, J. D. Brandenburg , et al. (363 additional authors not shown)

Abstract: We present results on the production of $π^{\pm}$, $K^{\pm}$, $p$, and $\bar{p}$ in Au+Au collisions at $\sqrt{s_\mathrm{NN}}$ = 54.4~GeV using the STAR detector at RHIC, at midrapidity ($|y| <$ 0.1). Invariant yields of these particles as a function of transverse momentum are shown. We determine bulk properties such as integrated particle yields ($dN/dy$), mean transverse momentum (… ▽ More We present results on the production of $π^{\pm}$, $K^{\pm}$, $p$, and $\bar{p}$ in Au+Au collisions at $\sqrt{s_\mathrm{NN}}$ = 54.4~GeV using the STAR detector at RHIC, at midrapidity ($|y| <$ 0.1). Invariant yields of these particles as a function of transverse momentum are shown. We determine bulk properties such as integrated particle yields ($dN/dy$), mean transverse momentum ($\langle p_{T} \rangle$), particle ratios, which provide insight into the particle production mechanisms. Additionally, the kinetic freezeout parameters ($T_\text{kin}$ and $\langle β_{T} \rangle$), which provide information about the dynamics of the system at the time of freezeout, are obtained. The Bjorken energy density ($ε_{\rm{BJ}}$), which gives an estimate of the energy density in the central rapidity region of the collision zone at the formation time $τ$, is calculated and presented as a function of multiplicity for various energies. The results are compared with those from the models such as A Multi-Phase Transport (AMPT) and Heavy Ion Jet INteraction Generator (HIJING) for further insights. △ Less

Submitted 21 May, 2026; v1 submitted 6 December, 2025; originally announced December 2025.

Comments: 14 pages, 16 figures

Journal ref: Physical Review C 113, 054907 (2026)

Robust evidence for dynamical dark energy in light of DESI DR2 and joint ACT, SPT, and Planck data

Authors: Tian-Nuo Li, Guo-Hong Du, Sheng-Han Zhou, Yun-He Li, Jing-Fei Zhang, Xin Zhang

Abstract: Recent baryon acoustic oscillation (BAO) measurements released by DESI, when combined with cosmic microwave background (CMB) data and type Ia supernova (SN) data, suggest a significant preference for dynamical dark energy (DDE) that exhibits the phantom-like behavior in the past and has transitioned into quintessence-like behavior today. In this work, we conduct a comprehensive analysis of six rep… ▽ More Recent baryon acoustic oscillation (BAO) measurements released by DESI, when combined with cosmic microwave background (CMB) data and type Ia supernova (SN) data, suggest a significant preference for dynamical dark energy (DDE) that exhibits the phantom-like behavior in the past and has transitioned into quintessence-like behavior today. In this work, we conduct a comprehensive analysis of six representative DDE parametrization models by utilizing the latest and most precise CMB data jointly from ACT, SPT, and Planck, in conjunction with BAO data from DESI DR2 and SN data from DESY5, PantheonPlus, and Union3. Our overall analysis indicates that the preference for DDE in the Quintom-B regime remains robust, regardless of the DDE parameterization model and the data combination employed. The trend of this preference is significantly strengthened with the support of DESY5 SN data. Specifically, when using the CMB+DESI+DESY5 data, for the Barboza-Alcaniz (BA) model, we obtain $w_0 = -0.785 \pm 0.047$ and $w_a = -0.43^{+0.10}_{-0.09}$, which significantly deviate from the $Λ$CDM values and provide evidence for DDE at the $4.2σ$ level. By the reconstruction of the dark energy equation of state $w(z)$, normalized dark energy density $f_{\mathrm{DE}}(z)$, and the deceleration parameter $q(z)$, we also observe clear departures from $Λ$CDM, further reinforcing the case for DDE. Furthermore, the Bayesian evidence analysis indicates that the Chevallier-Polarski-Linder, BA and Exponential models are moderately favored relative to $Λ$CDM based on the CMB+DESI+DESY5 data. △ Less

Submitted 27 February, 2026; v1 submitted 27 November, 2025; originally announced November 2025.

Comments: 13 pages, 4 figures

Journal ref: Physics of the Dark Universe 52 (2026) 102254

Probing unitarity violation of lepton flavor mixing matrix with reactor antineutrinos at JUNO and TAO

Authors: Jihong Huang, Shun Zhou

Abstract: Motivated by the precise measurements of neutrino oscillation parameters at Jiangmen Underground Neutrino Observatory (JUNO), we investigate the possibility of probing the unitarity violation of lepton flavor mixing matrix solely with reactor antineutrinos. First, we stress that it is necessary to reconsider the production and detection of neutrinos in a self-consistent way, apart from neutrino pr… ▽ More Motivated by the precise measurements of neutrino oscillation parameters at Jiangmen Underground Neutrino Observatory (JUNO), we investigate the possibility of probing the unitarity violation of lepton flavor mixing matrix solely with reactor antineutrinos. First, we stress that it is necessary to reconsider the production and detection of neutrinos in a self-consistent way, apart from neutrino propagation, when analyzing experimental sensitivities to unitarity violation. Then, concentrating on JUNO and its satellite experiment Taishan Antineutrino Observatory (TAO), we demonstrate how the event rates of inverse beta decays (i.e., $\overlineν^{}_e + p \to e^+ + n$) for observing $\overlineν^{}_e \to \overlineν^{}_e$ oscillations, and those of elastic antineutrino-electron scattering (i.e., $\overlineν^{}_α+ e^- \to \overlineν^{}_α+ e^-$ with $α= e, μ, τ$) for $\overlineν^{}_e \to \overlineν^{}_μ$ and $\overlineν^{}_e \to \overlineν^{}_τ$ oscillations, depend on the parameters characterizing unitarity violation. Our investigation will be useful for JUNO and TAO to place independent constraints with more data in the near future. △ Less

Submitted 19 January, 2026; v1 submitted 19 November, 2025; originally announced November 2025.

Comments: 21 pages, 1 figure, more discussions and references added, version accepted by PLB

Journal ref: Phys. Lett. B 873 (2026) 140160

Updated branching ratios and $CP$ asymmetries in $D \to PV$ decays

Authors: Hui Zheng, Jia-Rui Dong, Si-Hong Zhou

Abstract: Motivated by extensive new high-precision experimental data, we present an updated analysis of the two-body charm decays $D \to PV$ (with $P =π,K, η^{(\prime)}$ and $V =ρ, K^*, ω, φ$) within the factorization-assisted topological-amplitude (FAT) approach. In the framework, flavor SU(3) symmetry breaking effect is incorporated into the topological amplitudes, allowing the nonfactorizable contri… ▽ More Motivated by extensive new high-precision experimental data, we present an updated analysis of the two-body charm decays $D \to PV$ (with $P =π,K, η^{(\prime)}$ and $V =ρ, K^*, ω, φ$) within the factorization-assisted topological-amplitude (FAT) approach. In the framework, flavor SU(3) symmetry breaking effect is incorporated into the topological amplitudes, allowing the nonfactorizable contributions from topological diagrams to be expressed as a minimal set of universal parameters determined through a global fit to experimental data. Thanks to the sufficient data with high precision, we are now able to quantify the nonfactorizable contribution of so-called ``factorization" $T$ diagram, which is essential for explaining the observed branching ratios. The parameters for the $C$, $E$, and $A$ diagrams are also updated with significant improved precision, and notably, the resulting strong phases differ substantially from those in the earlier FAT analysis. We find that the $C$ topological amplitude features substantial nonfactorizable effects in the charm sector. These refined parameters enable predictions of significantly improved accuracy, yielding branching ratios in good agreement with current data and the latest results in topological diagram approach, and the predicted direct $\mathit{CP}$ asymmetries differ distinctly form previous FAT results due to updated strong phases. In several modes, the $\mathit{CP}$ asymmetries are predicted to reach $\mathcal{O}(10^{-3})$, thereby making them promising observables for future high-precision experiments at LHCb, BESIII and Belle II. Predictions for unobserved decay modes, especially those with branching fractions of order $10^{-4}\sim10^{-3}$, are also provided for forthcoming experimental tests. △ Less

Submitted 13 November, 2025; originally announced November 2025.

Comments: 22 pages, 2 figures

Pseudo-Hermitian QFT: relativistic scattering and symmetry structure

Authors: Ruifeng Leng, Cheng-Yang Lee, Siyi Zhou

Abstract: Unitarity is a cornerstone of quantum theory, ensuring the conservation of probability and information. Although non-Hermitian Hamiltonians are typically associated with open or dissipative systems, pseudo-Hermitian quantum mechanics shows that real spectra and unitary evolution can still emerge through a suitably defined inner product. Motivated by this insight, we extend the pseudo-Hermitian fra… ▽ More Unitarity is a cornerstone of quantum theory, ensuring the conservation of probability and information. Although non-Hermitian Hamiltonians are typically associated with open or dissipative systems, pseudo-Hermitian quantum mechanics shows that real spectra and unitary evolution can still emerge through a suitably defined inner product. Motivated by this insight, we extend the pseudo-Hermitian framework to relativistic quantum field theory and construct a consistent formulation of scattering processes. A novel structural feature of this theory is the presence of distinct metric operators for the in and out sectors, connected through a nontrivial metric projector that guarantees global probability conservation under pseudo-unitary time evolution. We further develop a general symmetry formalism, showing that each symmetry generally corresponds to two pseudo-unitary operators associated with the in and out metrics, respectively. Within this framework, the scattering matrix admits a perturbative expansion through the Dyson series and remains Lorentz invariant and unitary, remarkably in complete agreement with the conventional Hermitian case. The fundamental CPT theorem is also shown to hold. Our results provide a rigorous foundation for interacting pseudo-Hermitian quantum field theories and open new directions for exploring their possible physical implications beyond the standard Hermitian paradigm. △ Less

Submitted 31 October, 2025; originally announced October 2025.

Comments: 37 pages, no figures

$Q$-ball superradiance: Analytical approach

Authors: Guo-Dong Zhang, Shuang-Yong Zhou, Meng-Fan Zhu

Abstract: It was recently discovered that waves scattering off a $Q$-ball can extract energy from it. We present an analytical treatment of this process by adopting a multi-step function approximation for the background field, which yields perturbative solutions expressed in terms of Bessel functions. For thin-wall $Q$-balls, the amplification factors reduce to simple sinusoidal functions, which explains th… ▽ More It was recently discovered that waves scattering off a $Q$-ball can extract energy from it. We present an analytical treatment of this process by adopting a multi-step function approximation for the background field, which yields perturbative solutions expressed in terms of Bessel functions. For thin-wall $Q$-balls, the amplification factors reduce to simple sinusoidal functions, which explains the multi-peak structure of the spectrum and identifies the physical quantities that determine it. For instance, at high frequencies, the peak spacing is simply the inverse of the $Q$-ball size. The analytical solution further enables us to delineate the full range of possible amplification factors. For general $Q$-balls, this analytical framework also substantially improves the efficiency of evaluating the amplification factors. △ Less

Submitted 30 October, 2025; originally announced October 2025.

Comments: 21 pages, 8 figures

Effective Theory for Light Portal Dark Matter Detection

Authors: Qing Chen, Shuang-Yong Zhou

Abstract: We develop a general framework for the computation of light portal dark matter direct detection, incorporating a consistent treatment of finite momentum transfer. In this framework, dark matter interacts with Standard Model matter through a light mediator, which simultaneously serves as the force carrier for dark matter self-interaction, potentially with a distinct coupling strength. The correspon… ▽ More We develop a general framework for the computation of light portal dark matter direct detection, incorporating a consistent treatment of finite momentum transfer. In this framework, dark matter interacts with Standard Model matter through a light mediator, which simultaneously serves as the force carrier for dark matter self-interaction, potentially with a distinct coupling strength. The corresponding effective theory relevant for detecting this class of dark matter is systematically constructed. Our analysis focuses on light (semi)relativistic dark matter, which may originate from cosmic-ray boosting and can be probed in high threshold experiments such as large-volume neutrino detectors. In this context, the nucleon matrix elements of the effective operators at finite momentum transfer are required, made available through recent advances in lattice QCD and related nonperturbative methods. The relativistic Fermi gas model is used to convert the nucleon-level momentum transfer to the nuclear level, thereby incorporating nuclear effects pertinent to heavy target experiments. To demonstrate the utility of the framework, we present ultraviolet-complete examples featuring spin-1 and spin-2 portal dark matter. For these models, we compute the differential cross sections with respect to momentum transfer, adopting parameter choices that address the so-called core-cusp problem in astrophysical observations via dark matter self-interactions. △ Less

Submitted 26 October, 2025; originally announced October 2025.

Comments: 35 pages, 4 figures

Report number: USTC-ICTS/PCFT-25-50

The anomalous spin-statistics connection arising from pseudo-Hermiticity

Authors: Yao Bai, Cheng-Yang Lee, Ruifeng Leng, Siyi Zhou

Abstract: We establish a new spin-statistics theorem for a class of free pseudo-Hermitian quantum field theories whose particles furnish unitary irreducible representations of the Poincaré group. In this framework, free pseudo-Hermitian fields with integer spin exhibit fermionic statistics, whereas those with half-integer spin exhibit bosonic statistics, opposite to the conventional case. This reversal aris… ▽ More We establish a new spin-statistics theorem for a class of free pseudo-Hermitian quantum field theories whose particles furnish unitary irreducible representations of the Poincaré group. In this framework, free pseudo-Hermitian fields with integer spin exhibit fermionic statistics, whereas those with half-integer spin exhibit bosonic statistics, opposite to the conventional case. This reversal arises from defining canonical field operators using pseudo-Hermitian conjugation rather than Hermitian conjugation, thereby circumventing the conventional spin-statistics theorem. The free fields retain locality, Lorentz covariance, and unitary evolution. However, interactions may violate unitarity due to the intrinsically non-Hermitian nature of the full Hamiltonian. We discuss potential resolutions to restore unitarity in interacting theories. △ Less

Submitted 26 October, 2025; originally announced October 2025.

Comments: 20 pages

Search for a hypothetical gauge boson and dark photons in charmonium transitions

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. B. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai , et al. (677 additional authors not shown)

Abstract: We report a direct search for a new gauge boson, $X$, with a mass of $17~\text{MeV}/c^2$, which could explain the anomalous excess of $e^+e^-$ pairs observed in the $^8\text{Be}$ nuclear transitions. The search is conducted in the charmonium decays $χ_{cJ}\to X J/ψ~(J=0,1,2)$ via the radiative transition $ψ(3686)\toγχ_{cJ}$ using $\left(2712.4\pm 14.3 \right)\times 10^6$ $ψ(3686)$ events collected… ▽ More We report a direct search for a new gauge boson, $X$, with a mass of $17~\text{MeV}/c^2$, which could explain the anomalous excess of $e^+e^-$ pairs observed in the $^8\text{Be}$ nuclear transitions. The search is conducted in the charmonium decays $χ_{cJ}\to X J/ψ~(J=0,1,2)$ via the radiative transition $ψ(3686)\toγχ_{cJ}$ using $\left(2712.4\pm 14.3 \right)\times 10^6$ $ψ(3686)$ events collected with the BESIII detector at the BEPCII collider. No significant signal is observed, and the updated upper limit on the coupling strength of charm quark and the new gauge boson, $ε_c$, is set to be $|ε_c|<1.2\times 10^{-2}$ at $90\%$ confidence level. We also report new constraints on the mixing strength $ε$ between the Standard Model photon and dark photon $γ^\prime$ in the mass range from $5~\text{MeV}/c^2$ to $300~\text{MeV}/c^2$. The upper limits at $90\%$ confidence level vary within $(2.5-17.5)\times 10^{-3}$ depending on the $γ^\prime $ mass. △ Less

Submitted 5 February, 2026; v1 submitted 18 October, 2025; originally announced October 2025.

Comments: 12 pages, 4 figures

Journal ref: Phys. Rev. D 113, 032009 (2026)

The detection of cosmic neutrino background with helicity-changing decays

Authors: Jihong Huang, Shun Zhou

Abstract: In this talk, we present the investigation of the invisible decays of a heavy massive neutrino into a lighter neutrino and a massless Nambu-Goldstone boson, i.e., $ν_i^{} \to ν_j^{} + φ$. The total decay rates are calculated in the most general case, where the individual helicities of both parent and daughter neutrinos are specified. We then examine the evolution of the number densities of cosmolo… ▽ More In this talk, we present the investigation of the invisible decays of a heavy massive neutrino into a lighter neutrino and a massless Nambu-Goldstone boson, i.e., $ν_i^{} \to ν_j^{} + φ$. The total decay rates are calculated in the most general case, where the individual helicities of both parent and daughter neutrinos are specified. We then examine the evolution of the number densities of cosmological relic neutrinos throughout the expansion of the Universe, and explore the consequent impacts on the capture rates in PTOLEMY-like experiments. The total event rates can be significantly modified compared to those in the scenario of stable neutrinos, with helicity-changing decays playing an especially important role in the Dirac neutrino case. △ Less

Submitted 17 October, 2025; originally announced October 2025.

Comments: 5 pages, 1 figure; Contribution to the Proceedings of the 19th International Conference on Topics in Astroparticle and Underground Physics (TAUP2025)

Alleviating the $H_0$ tension through the interacting dark energy model from quantum gravitational field theory in light of DESI DR2

Authors: Yi-Min Zhang, Tian-Nuo Li, Guo-Hong Du, Sheng-Han Zhou, Li-Yang Gao, Jing-Fei Zhang, Xin Zhang

Abstract: Recent DESI DR2 data has shown a significant preference for dynamical dark energy, yet this has further exacerbated the $H_0$ tension. In this work, we explore the potential of interacting dark energy models ($\widetildeΛ$CDM and $e\widetildeΛ$CDM) within the asymptotic-safety framework of quantum gravitational field theory to alleviate the $H_0$ tension. We perform observational constraints using… ▽ More Recent DESI DR2 data has shown a significant preference for dynamical dark energy, yet this has further exacerbated the $H_0$ tension. In this work, we explore the potential of interacting dark energy models ($\widetildeΛ$CDM and $e\widetildeΛ$CDM) within the asymptotic-safety framework of quantum gravitational field theory to alleviate the $H_0$ tension. We perform observational constraints using the latest baryon acoustic oscillation data from DESI DR2, cosmic microwave background (CMB) data from Planck and ACT, and type Ia supernova data from DESY5 and PantheonPlus, as well as the SH0ES data. From our analysis, we observe the dynamical scale parameter of the cosmological constant, $δ_Λ = -0.270\pm 0.100$, in the $e\widetildeΛ$CDM model using the CMB+DESI+SH0ES data, which deviates from $Λ$CDM at the $2.7σ$ level. Simultaneously, we find $H_0 = 70.84\pm 0.74~\mathrm{km\,s^{-1}\,Mpc^{-1}}$, reducing the $H_0$ tension to $1.7σ$. This increase in the inferred $H_0$ is due to the anti-correlation between $δ_Λ$ and $H_0$, whereby a negative $δ_Λ$ leads to a higher $H_0$ value. Furthermore, for the CMB+DESI+SH0ES combination, we obtain $Δχ^2_{\min}=-14.14$ and $Δ\mathrm{DIC}=-9.18$, favoring the $e\widetildeΛ$CDM model over $Λ$CDM. Overall, the $e\widetildeΛ$CDM model can improve the fit and ease the $H_0$ tension, especially for the data combinations that provide the strongest statistical support. △ Less

Submitted 20 June, 2026; v1 submitted 14 October, 2025; originally announced October 2025.

Comments: 13 pages, 4 figures

One-Loop Effects in the Neutrino Matter Potential and Implications for Non-Standard Interactions

Authors: Jihong Huang, Tommy Ohlsson, Sampsa Vihonen, Shun Zhou

Abstract: In this work, we emphasize that it is necessary to take into account one-loop corrections of $2.0\%$ to the neutrino matter potential in the precision measurements of neutrino oscillation parameters and in the experimental searches for new physics beyond the Standard Model. With the numerical simulation of the DUNE experiment, we study how radiative corrections to the matter potential affect neutr… ▽ More In this work, we emphasize that it is necessary to take into account one-loop corrections of $2.0\%$ to the neutrino matter potential in the precision measurements of neutrino oscillation parameters and in the experimental searches for new physics beyond the Standard Model. With the numerical simulation of the DUNE experiment, we study how radiative corrections to the matter potential affect neutrino oscillation probabilities, and thus, the event rates in the presence of neutrino non-standard interactions (NSIs). We find that neglecting one-loop corrections may lead to wrong conclusions for the discovery of NSIs. The implications for the determination of neutrino mass ordering and constraints on the NSI parameters in future long-baseline accelerator neutrino experiments are explored in a quantitative way. △ Less

Submitted 17 December, 2025; v1 submitted 6 October, 2025; originally announced October 2025.

Comments: 17 pages, 7 figures, 1 table

Journal ref: Phys.Rev.D 112 (2025) 11, 116014

One-loop Renormalization of the Type-I Seesaw Model in the On-shell Scheme

Authors: Jihong Huang, Shun Zhou

Abstract: In this paper, we continue to carry out the one-loop renormalization of the type-I seesaw model in the on-shell scheme. Different from the modified minimal-subtraction ($\overline{\rm MS}$) scheme, such an investigation is mainly motivated by the fact that the on-shell scheme has been widely adopted in the renormalization of the standard electroweak theory and implemented for its precision tests.… ▽ More In this paper, we continue to carry out the one-loop renormalization of the type-I seesaw model in the on-shell scheme. Different from the modified minimal-subtraction ($\overline{\rm MS}$) scheme, such an investigation is mainly motivated by the fact that the on-shell scheme has been widely adopted in the renormalization of the standard electroweak theory and implemented for its precision tests. We first specify the physical parameters in the on-shell scheme, and then fix the corresponding counterterms through on-shell renormalization conditions. In the presence of massive Majorana neutrinos, we propose a practical method to determine gauge-independent counterterms for the lepton flavor mixing matrix. With the explicit counterterms in both the $\overline{\rm MS}$ and on-shell schemes, we establish the matching relations of the electric charge, physical masses and flavor mixing matrix elements between these two schemes. Our results in the present and previous papers lay the foundation for precision calculations in the type-I seesaw model. △ Less

Submitted 3 January, 2026; v1 submitted 16 September, 2025; originally announced September 2025.

Comments: 27 pages, version accepted by Nucl. Phys. B

Journal ref: Nucl. Phys. B 1022 (2026) 117271

Measuring neutrino masses with joint JWST and DESI DR2 data

Authors: Sheng-Han Zhou, Tian-Nuo Li, Guo-Hong Du, Jun-Qian Jiang, Jing-Fei Zhang, Xin Zhang

Abstract: Early JWST observations reveal an unexpectedly abundant population of high-redshift candidate massive galaxies at $z \gtrsim 7$, and recent DESI measurements show a preference for dynamical dark energy, which together present a significant challenge to the standard $Λ$CDM cosmology. In this work, we jointly analyze high-redshift galaxy data from JWST, baryon acoustic oscillations data from DESI DR… ▽ More Early JWST observations reveal an unexpectedly abundant population of high-redshift candidate massive galaxies at $z \gtrsim 7$, and recent DESI measurements show a preference for dynamical dark energy, which together present a significant challenge to the standard $Λ$CDM cosmology. In this work, we jointly analyze high-redshift galaxy data from JWST, baryon acoustic oscillations data from DESI DR2, and cosmic microwave background (CMB) data from Planck and ACT, measuring the total neutrino mass $\sum m_ν$. We consider three dark energy models ($Λ$CDM, $w$CDM, and $w_0w_a$CDM) and three mass hierarchies. Our results indicate that in the $w_0w_a$CDM model, adding JWST data to CMB+DESI tightens the upper limit of $\sum m_ν$ by about $5.8\%-10.2\%$, and we obtain $\sum m_ν < 0.167~\mathrm{eV}$ ($2σ$) in the normal hierarchy (NH) case. Furthermore, JWST also offers indicative lower limits on star formation efficiency parameter of $f_{*,10} \gtrsim 0.146-0.161$. Bayesian evidence weakly favors the $w_0w_a$CDM+$\sum m_ν$(NH) model relative to the $Λ$CDM+$\sum m_ν$(NH) model using CMB+DESI+JWST data. These results suggest that the joint analysis of high-redshift JWST data and low-redshift DESI data provides compelling constraints on neutrino mass and merits further investigation. △ Less

Submitted 17 December, 2025; v1 submitted 13 September, 2025; originally announced September 2025.

Comments: 11 pages, 3 figures

Journal ref: Physical Review D 112, 123532 (2025)

Determination of CKM matrix element and axial vector form factors from weak decays of quantum-entangled strange baryons

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai , et al. (705 additional authors not shown)

Abstract: The electromagnetic structure of the nucleon can be determined from the scattering of electrons off a nucleon target. However, to study its axial structure, neutrino beams are required. The results from these experiments should be extrapolated to zero energy-momentum transfers to access the static properties of the nucleon. For baryons with strange quarks, hyperons, the static limit can instead be… ▽ More The electromagnetic structure of the nucleon can be determined from the scattering of electrons off a nucleon target. However, to study its axial structure, neutrino beams are required. The results from these experiments should be extrapolated to zero energy-momentum transfers to access the static properties of the nucleon. For baryons with strange quarks, hyperons, the static limit can instead be approached in semi-leptonic decays, which give direct access to the weak magnetism and axial-vector coupling strengths that are inaccessible in electromagnetic interactions. The axial-vector coupling as while weak magnetism coupling and the overall normalization, given by form factor $f_1$, are being determined with increased precision from the theory of strong interactions using a first principles formulation on the space--time lattice. Furthermore, the probability of the semi-leptonic hyperon decay is approximately proportional to $|V_{us}|^2\cdot (f_1^2+3g_1^2)$, where $V_{us}$ is the CKM matrix element responsible for the transition between an $s$ and a $u$ quark. Current determinations of $|V_{us}|$ come from kaon decays, but the results are not consistent and could indicate a deviation from CKM matrix unitarity, a tell-tale sign of physics beyond the Standard Model (SM) of elementary particles. Here we determine the absolute branching fraction and weak coupling strengths for $Λ\to p e^-\barν_e$, and $\bar Λ\to \bar p e^+ν_e$. These observables combined with form factors determined from first-principle lattice QCD calculations allow for the extraction of the $|V_{us}|$ value. We demonstrate how $|V_{us}|$ can be extracted with increasing sensitivity using polarized hyperons from entangled, baryon-antibaryon pairs, thus enabling a complementary road to that of meson decays. In addition, the presented experimental method can be used for other semileptonic decays of baryons. △ Less

Submitted 12 September, 2025; v1 submitted 11 September, 2025; originally announced September 2025.

Comments: 24 pages, 4 figures

Towards a detection of reactor $\overlineν^{}_e \to \overlineν^{}_μ$ and $\overlineν^{}_e \to \overlineν^{}_τ$ oscillations with possible CP violation

Authors: Yifang Wang, Zhi-zhong Xing, Shun Zhou

Abstract: We propose an unprecedented detection of reactor $\overlineν^{}_e \to \overlineν^{}_μ$ and $\overlineν^{}_e \to \overlineν^{}_τ$ oscillations by using elastic antineutrino-electron scattering processes $\overlineν^{}_α+ e^- \to \overlineν^{}_α+ e^-$ (for $α= e, μ, τ$), among which the $\overlineν^{}_e$ events can be singled out by accurately measuring the $\overlineν^{}_e$ flux via the inverse bet… ▽ More We propose an unprecedented detection of reactor $\overlineν^{}_e \to \overlineν^{}_μ$ and $\overlineν^{}_e \to \overlineν^{}_τ$ oscillations by using elastic antineutrino-electron scattering processes $\overlineν^{}_α+ e^- \to \overlineν^{}_α+ e^-$ (for $α= e, μ, τ$), among which the $\overlineν^{}_e$ events can be singled out by accurately measuring the $\overlineν^{}_e$ flux via the inverse beta decay $\overlineν^{}_e + p \to e^+ + n$. A proof-of-concept study shows that such measurements will not only be able to test the conservation of probability for reactor antineutrino oscillations, but also offer a new possibility to probe leptonic CP violation at the one-loop level. △ Less

Submitted 30 August, 2025; originally announced September 2025.

Comments: 12 pages, 3 figures

One-loop Renormalization of the Type-I Seesaw Model in the Modified Minimal-subtraction Scheme

Authors: Jihong Huang, Shun Zhou

Abstract: Extending the Standard Model (SM) with three right-handed neutrinos, the type-I seesaw model serves as the simplest and most natural scenario to successfully explain both tiny neutrino masses and the baryon number asymmetry in the Universe. In this paper, we perform a complete one-loop renormalization of the type-I seesaw model in the modified minimal-subtraction ($\overline{\rm MS}$) scheme. The… ▽ More Extending the Standard Model (SM) with three right-handed neutrinos, the type-I seesaw model serves as the simplest and most natural scenario to successfully explain both tiny neutrino masses and the baryon number asymmetry in the Universe. In this paper, we perform a complete one-loop renormalization of the type-I seesaw model in the modified minimal-subtraction ($\overline{\rm MS}$) scheme. The one-loop self-energy corrections of charged leptons and Majorana neutrinos are calculated in the $R_ξ^{}$ gauge, and the explicit expressions of all the counterterms for wave functions, fermion masses and the leptonic flavor mixing matrix are given. Furthermore, adopting the Euler-like parametrization of the $6\times 6$ unitary leptonic flavor mixing matrix, we derive one-loop renormalization-group equations for all the physical parameters in the $\overline{\rm MS}$ scheme, including neutrino masses, mixing angles and CP-violating phases. The modification of the one-loop renormalization of the original SM parameters due to the presence of heavy Majorana neutrinos is investigated as well. In this way, we provide a self-consistent theoretical framework to thoroughly test the type-I seesaw model at the one-loop level with future precision data. △ Less

Submitted 3 January, 2026; v1 submitted 29 July, 2025; originally announced July 2025.

Comments: 31 pages, 3 figures, more discussions and references added, version accepted by Nucl. Phys. B

Journal ref: Nucl. Phys. B 1022 (2026) 117270

Probing Cosmic Neutrino Background through Parametric Fluorescence

Authors: Guo-yuan Huang, Shun Zhou

Abstract: We point out that relic neutrinos from the Big Bang may induce the parametric fluorescence in atomic or molecular systems, which offers a novel way to discover cosmic neutrino background. By coherently scattering with molecular energy levels, a massive neutrino can spontaneously ``decay" into a lighter neutrino and an infrared signal photon, i.e., $ν^{}_{i} + M \to ν^{}_{j} + γ^{}_{\rm S} + M$, wh… ▽ More We point out that relic neutrinos from the Big Bang may induce the parametric fluorescence in atomic or molecular systems, which offers a novel way to discover cosmic neutrino background. By coherently scattering with molecular energy levels, a massive neutrino can spontaneously ``decay" into a lighter neutrino and an infrared signal photon, i.e., $ν^{}_{i} + M \to ν^{}_{j} + γ^{}_{\rm S} + M$, where the molecular state $M$ remains unchanged after the scattering. Because the amplitudes of different radiants are matched in phase, the rate is coherently enhanced and proportional to the squared density of ambient dipoles. When the energy transfer from neutrinos coincides with the energy-level difference, the fluorescence will be on resonance. Near the resonance, the rate is proportional to the square of the coherence time $T^{}_{\rm c}$ of the ensemble. For a nominal target volume of $5~{\rm m^3}$ (or $5~{\rm cm^3}$), the signal rate can reach $1~{\rm yr}^{-1}$ for $T^{}_{\rm c} = 10~{\rm ns}$ (or $T^{}_{\rm c} = 10~{\rm μs}$). This event rate appears to be very promising in consideration of an even longer coherence time that is achievable in solid systems. △ Less

Submitted 27 February, 2026; v1 submitted 14 July, 2025; originally announced July 2025.

Comments: 5 pages, 3 figures plus supplemental material; matches the published version; minor typos corrected

Journal ref: Phys. Rev. Lett. 136 (2026) 081003

Precise Measurement of the $Λ$ Electric Dipole Moment through the Entangled Strange Baryon-Antibaryon System

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai , et al. (696 additional authors not shown)

Abstract: The dominance of matter over antimatter in the universe has consistently driven the pursuit of new physics beyond the Standard Model that violates charge-parity symmetry. Unlike the well-constrained electrons and neutrons, strange baryons (hyperons) remain a largely unexplored territory, in which interactions between hyperons and particles from new physics could induce a non-trivial electric dipol… ▽ More The dominance of matter over antimatter in the universe has consistently driven the pursuit of new physics beyond the Standard Model that violates charge-parity symmetry. Unlike the well-constrained electrons and neutrons, strange baryons (hyperons) remain a largely unexplored territory, in which interactions between hyperons and particles from new physics could induce a non-trivial electric dipole moment (EDM). However, direct measurements of hyperon EDMs through spin precession are highly challenging due to their short lifetimes. In this paper, we present a novel method to extract the EDM of the lightest hyperon, $Λ$, using the entangled $Λ$$\overlineΛ$ system. Our result is consistent with zero, achieving a three-order-of-magnitude improvement over the previous upper limit established in the 1980s with comparable statistics, providing stringent constraints on potential new physics. △ Less

Submitted 28 June, 2025; v1 submitted 23 June, 2025; originally announced June 2025.

Analysis of three-body charmed $B$ meson decays $B \to {D}(V^* \to){V P}$

Authors: Jing Ou-Yang, Run-Hui Li, Si-Hong Zhou

Abstract: We systematically analyze the decays $B_{(s)} \to D_{(s)} (V^* \to)\, V\, P$, where $V^*$ represents a vector resonance ($ρ, \, ω$ or $K^*$), and $V P$ denotes the final-state meson pairs $ ω\, π$, $ ρ\, π$ and $ ρ\, K$. The intermediate subprocesses $B_{(s)} \to D_{(s)} V^*$ are calculated in the factorization-assisted topological-amplitude approach, while the intermediate resonant states $V^*$ a… ▽ More We systematically analyze the decays $B_{(s)} \to D_{(s)} (V^* \to)\, V\, P$, where $V^*$ represents a vector resonance ($ρ, \, ω$ or $K^*$), and $V P$ denotes the final-state meson pairs $ ω\, π$, $ ρ\, π$ and $ ρ\, K$. The intermediate subprocesses $B_{(s)} \to D_{(s)} V^*$ are calculated in the factorization-assisted topological-amplitude approach, while the intermediate resonant states $V^*$ are modeled using a relativistic Breit-Wigner distribution, subsequently decaying into $VP$ through strong interactions. We predict the off-shell effects of the ground-state resonances ($ρ,\, ω, \, K^*$) in $B_{(s)} \to D_{(s)} (V^* \to )V P$. Our results show that the virtual contributions from $ρ\to ω\, π$, $ω\to ρ\, π$, and $K^* \to ρ\, K$ are crucial for these three-body decays, $B_{(s)} \to D_{(s)} V\, P$. In particular, the branching fractions arising from the $ρ$ and $ω$ virtual effects can be comparable to the total decay rates of $B_{(s)} \to D_{(s)} ω\, π$ and $B_{(s)} \to D_{(s)} ρ\, π$, respectively. Decays with branching fractions of order $10^{-6}-10^{-4}$ are expected to be measurable at Belle II and LHCb. Compared with previous perturbative QCD predictions for $B_{(s)} \to D_{(s)} (ρ\to)\, ω\, π$, our results are consistent but exhibit higher precision. △ Less

Submitted 21 September, 2025; v1 submitted 17 June, 2025; originally announced June 2025.

Comments: 25 pages, 2 figures

Dense Matter in Neutron Stars with eXTP

Authors: Ang Li, Anna L. Watts, Guobao Zhang, Sebastien Guillot, Yanjun Xu, Andrea Santangelo, Silvia Zane, Hua Feng, Shuang-Nan Zhang, Mingyu Ge, Liqiang Qi, Tuomo Salmi, Bas Dorsman, Zhiqiang Miao, Zhonghao Tu, Yuri Cavecchi, Xia Zhou, Xiaoping Zheng, Weihua Wang, Quan Cheng, Xuezhi Liu, Yining Wei, Wei Wang, Yujing Xu, Shanshan Weng , et al. (60 additional authors not shown)

Abstract: In this White Paper, we present the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission to constrain the equation of state of dense matter in neutron stars, exploring regimes not directly accessible to terrestrial experiments. By observing a diverse population of neutron stars - including isolated objects, X-ray bursters, and accreting systems - eXTP's unique combination of timin… ▽ More In this White Paper, we present the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission to constrain the equation of state of dense matter in neutron stars, exploring regimes not directly accessible to terrestrial experiments. By observing a diverse population of neutron stars - including isolated objects, X-ray bursters, and accreting systems - eXTP's unique combination of timing, spectroscopy, and polarimetry enables high-precision measurements of compactness, spin, surface temperature, polarimetric signals, and timing irregularity. These multifaceted observations, combined with advances in theoretical modeling, pave the way toward a comprehensive description of the properties and phases of dense matter from the crust to the core of neutron stars. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is planned to be launched in early 2030. △ Less

Submitted 8 September, 2025; v1 submitted 9 June, 2025; originally announced June 2025.

Comments: accepted for publication in the SCIENCE CHINA Physics, Mechanics & Astronomy

Journal ref: SCIENCE CHINA Physics, Mechanics & Astronomy 68, 119503 (2025)

Effects of the Matter Potential at One-Loop Level on Neutrino Oscillations in Long-Baseline Experiments

Authors: Jihong Huang, Tommy Ohlsson, Sampsa Vihonen, Shun Zhou

Abstract: In this work, we investigate in a quantitative way how much radiative corrections to the matter potential for neutrino oscillations can impact the sensitivity to neutrino mass ordering in long-baseline accelerator experiments. Using numerical simulations for the future experiment DUNE, we find that the statistical significance for excluding the incorrect mass ordering can be enhanced by about… ▽ More In this work, we investigate in a quantitative way how much radiative corrections to the matter potential for neutrino oscillations can impact the sensitivity to neutrino mass ordering in long-baseline accelerator experiments. Using numerical simulations for the future experiment DUNE, we find that the statistical significance for excluding the incorrect mass ordering can be enhanced by about $0.4σ$ if a one-loop correction of $2.0\%$ -- based on the Fermi coupling constant $G^{}_μ$ derived from measurements of muon lifetime -- is included. The radiative corrections at one-loop level lead to resolving the neutrino mass ordering at $5σ$ confidence level 4-9 days earlier than at tree level. In contrast, the sensitivity to leptonic CP violation in DUNE is essentially unchanged. Finally, we emphasize that one-loop corrections should be incorporated into analyses of future neutrino oscillation data in a consistent and systematic manner. △ Less

Submitted 28 June, 2025; v1 submitted 22 April, 2025; originally announced April 2025.

Comments: 15 pages, 4 figures, 1 table

Journal ref: Phys.Rev.D 111 (2025) 11, 116024

Wigner multiplets in QFT: from Wigner degeneracy to Elko fields

Authors: Cheng-Yang Lee, Ruifeng Leng, Siyi Zhou

Abstract: We establish the theoretical foundation of the Wigner superposition field, a quantum field framework for spin-1/2 fermions that exhibit a Wigner doublet -- a discrete quantum number arising from nontrivial representations of the extended Poincaré group. In contrast to the previously developed doublet formalism, which treats the Wigner degeneracy as a superficial label, the superposition formalism… ▽ More We establish the theoretical foundation of the Wigner superposition field, a quantum field framework for spin-1/2 fermions that exhibit a Wigner doublet -- a discrete quantum number arising from nontrivial representations of the extended Poincaré group. In contrast to the previously developed doublet formalism, which treats the Wigner degeneracy as a superficial label, the superposition formalism encodes it directly into the structure of a unified field via a coherent superposition of degenerate spinor fields. By imposing the Lorentz covariance, causality, and canonical quantization, we derive nontrivial constraints on the field configuration, which uniquely identify the Elko field as the consistent realization of the Wigner superposition field. Our analysis further clarifies that although the Elko field is a spinor field, it possesses mass dimension one and obeys the Klein-Gordon rather than the Dirac kinematics. Moreover, we explore the general Elko representation through basis redefinitions, showing that certain traditional properties, such as being eigenspinors of charge conjugation, are artifacts of specific basis choices rather than intrinsic features. Finally, we discuss the physical implications of Elko as a dark matter (DM) candidate. This work lays the foundation for a systematic reformulation of Elko interactions and its phenomenology as a viable component of DM. △ Less

Submitted 13 June, 2025; v1 submitted 21 April, 2025; originally announced April 2025.

Comments: 33 pages, no figures

Journal ref: JHEP06(2025)127

Axion forces in axion backgrounds

Authors: Yuval Grossman, Bingrong Yu, Siyu Zhou

Abstract: Axions can naturally be very light due to the protection of an (approximate) shift symmetry. Because of their pseudoscalar nature, the long-range force mediated by the axion at tree level is spin dependent, which cannot lead to observable effects between two unpolarized macroscopic objects. At the one-loop level, however, the exchange of two axions does mediate a spin-independent force. This force… ▽ More Axions can naturally be very light due to the protection of an (approximate) shift symmetry. Because of their pseudoscalar nature, the long-range force mediated by the axion at tree level is spin dependent, which cannot lead to observable effects between two unpolarized macroscopic objects. At the one-loop level, however, the exchange of two axions does mediate a spin-independent force. This force is coherently enhanced in the presence of an axion background. In this work, we study the two-axion exchange force in a generic axion background. We find that the breaking of the axion shift symmetry plays a crucial role in determining this force. The background-induced axion force $V_{\rm bkg}$ vanishes in the shift-symmetry restoration limit. The shift symmetry can be broken either explicitly by non-perturbative effects or effectively by the axion background. When the shift symmetry is broken, $V_{\rm bkg}$ scales as $1/r$ and could be further enhanced by a large occupation number of the background axions. We investigate possible experimental probes of this effect in two distinct scenarios: an axion dark matter background and a solar axion flux, using fifth-force searches and atomic spectroscopy experiments. In the axion dark matter case, we find that the background-induced axion force can place strong constraints on axion couplings and masses, comparable to existing astrophysical bounds. △ Less

Submitted 8 December, 2025; v1 submitted 31 March, 2025; originally announced April 2025.

Comments: 60 pages, 13 figures, 2 tables; v2: astrophysical bounds updated in Figs. 7 and 8, references updated, version accepted by JHEP

Neutrino Theory in the Precision Era

Authors: Asmaa Abada, Gabriela Barenboim, Toni Bertólez-Martínez, Sandipan Bhattacherjee, Sara Bolognesi, Patrick D. Bolton, Nilay Bostan, Gustavo C. Branco, Sabya Sachi Chatterjee, Adriano Cherchiglia, Marco Chianese, B. A. Couto e Silva, Peter B. Denton, Stephen Dolan, Marco Drewes, Ilham El Atmani, Miguel Escudero, Ivan Esteban, Manuel Ettengruber, Enrique Fernández-Martínez, Julien Froustey, Raj Gandhi, Julia Gehrlein, Srubabati Goswami, André de Gouvêa , et al. (54 additional authors not shown)

Abstract: This document summarises discussions on future directions in theoretical neutrino physics, which are the outcome of a neutrino theory workshop held at CERN in February 2025. The starting point is the realisation that neutrino physics offers unique opportunities to address some of the most fundamental questions in physics. This motivates a vigorous experimental programme which the theory community… ▽ More This document summarises discussions on future directions in theoretical neutrino physics, which are the outcome of a neutrino theory workshop held at CERN in February 2025. The starting point is the realisation that neutrino physics offers unique opportunities to address some of the most fundamental questions in physics. This motivates a vigorous experimental programme which the theory community fully supports. \textbf{A strong effort in theoretical neutrino physics is paramount to optimally take advantage of upcoming neutrino experiments and to explore the synergies with other areas of particle, astroparticle, and nuclear physics, as well as cosmology.} Progress on the theory side has the potential to significantly boost the physics reach of experiments, as well as go well beyond their original scope. Strong collaboration between theory and experiment is essential in the precision era. To foster such collaboration, \textbf{we propose to establish a CERN Neutrino Physics Centre.} Taking inspiration from the highly successful LHC Physics Center at Fermilab, the CERN Neutrino Physics Centre would be the European hub of the neutrino community, covering experimental and theoretical activities. △ Less

Submitted 27 March, 2025; originally announced April 2025.

Comments: summary document of the CERN Neutrino Platform Pheno Week 2025 as input to the European Strategy for Particle Physics 2025 update; 13 pages

Analysis of three-body hadronic $D$-meson decays

Authors: Xu-Da Zhou, Si-Hong Zhou

Abstract: Motivated by recent experimental advances in three-body hadronic $D$ decays from BESIII, we present a systematic analysis of $D_{(s)} \to P_1 (V \to) P_2 P_3 $ decay processes, where $V$ denotes vector resonances ($ρ, K^*, ω$, $φ$) and $P_{1,2,3}$ are light pseudoscalar mesons ($π,K, η^{(\prime)}$). Using the factorization-assisted topological-amplitude (FAT) approach we calculate the intermediate… ▽ More Motivated by recent experimental advances in three-body hadronic $D$ decays from BESIII, we present a systematic analysis of $D_{(s)} \to P_1 (V \to) P_2 P_3 $ decay processes, where $V$ denotes vector resonances ($ρ, K^*, ω$, $φ$) and $P_{1,2,3}$ are light pseudoscalar mesons ($π,K, η^{(\prime)}$). Using the factorization-assisted topological-amplitude (FAT) approach we calculate the intermediate subprocesses $D_{(s)} \to P_1 V$, incorporating relativistic Breit-Wigner distributions to model the subsequent $V \to P_2 P_3$ strong decays. By comprehensively including all relevant resonances ($ρ, K^*, ω, φ$), we calculate branching fractions for these decay modes as well as the Breit-Wigner-tail effects in $D_{(s)} \to P_1 (ω\to) KK$ processes. Our framework comprehensively incorporates both factorizable and nonfactorizable contributions, significantly improving theoretical predictions in the nonperturbative regime where conventional methods face challenges due to the limited mass scale of charm mesons. The FAT approach yields results in good agreement with experimental data, demonstrating its effectiveness in capturing nonfactorizable contributions with improved precision. Our predictions for yet-unobserved decay modes, particularly those with branching fractions in the order of $10^{-4}$ to $10^{-3}$, are expected to be tested in future high-precision experiments at BESIII and LHCb. △ Less

Submitted 30 June, 2025; v1 submitted 24 March, 2025; originally announced March 2025.

Comments: 27 pages, 1 figures

Measurements of the branching fractions of $Ξ_{c}^{+}\to Σ^{+}K_{S}^{0}$, $Ξ_{c}^{+}\to Ξ^{0}π^{+}$, and $Ξ_{c}^{+}\to Ξ^{0}K^{+}$ at Belle and Belle II

Authors: Belle, Belle II Collaborations, :, I. Adachi, J. K. Ahn, Y. Ahn, N. Akopov, S. Alghamdi, M. Alhakami, N. Althubiti, K. Amos, N. Anh Ky, C. Antonioli, D. M. Asner, M. Aversano, R. Ayad, V. Babu, N. K. Baghel, P. Bambade, Sw. Banerjee, M. Barrett, M. Bartl, J. Baudot, A. Beaubien, F. Becherer , et al. (335 additional authors not shown)

Abstract: Using 983.0 $\rm{fb}^{-1}$ and 427.9 $\rm{fb}^{-1}$ data samples collected with the Belle and Belle II detectors at the KEKB and SuperKEKB asymmetric energy $e^+e^-$ colliders, respectively, we present studies of the Cabibbo-favored $Ξ_c^+$ decays ${Ξ_{c}^{+}\to Σ^{+}K_{S}^{0}}$ and $Ξ_{c}^{+}\to Ξ^{0}π^{+}$, and the singly Cabibbo-suppressed decay $Ξ_{c}^{+}\to Ξ^{0}K^{+}$. The ratios of branchin… ▽ More Using 983.0 $\rm{fb}^{-1}$ and 427.9 $\rm{fb}^{-1}$ data samples collected with the Belle and Belle II detectors at the KEKB and SuperKEKB asymmetric energy $e^+e^-$ colliders, respectively, we present studies of the Cabibbo-favored $Ξ_c^+$ decays ${Ξ_{c}^{+}\to Σ^{+}K_{S}^{0}}$ and $Ξ_{c}^{+}\to Ξ^{0}π^{+}$, and the singly Cabibbo-suppressed decay $Ξ_{c}^{+}\to Ξ^{0}K^{+}$. The ratios of branching fractions of ${Ξ_{c}^{+}\to Σ^{+}K_{S}^{0}}$ and $Ξ_{c}^{+}\to Ξ^{0}K^{+}$ relative to that of $Ξ_{c}^{+}\toΞ^{-}π^{+}π^{+}$ are measured for the first time, while the ratio ${\cal B}(Ξ_{c}^{+}\toΞ^{0}π^{+})/{\cal B}(Ξ_{c}^{+}\toΞ^{-}π^{+}π^{+}) $ is also determined and improved by an order of magnitude in precision. The measured branching fraction ratios are $\frac{\cal{B}(Ξ_{c}^{+} \to Σ^{+}K_{S}^{0})}{\cal{B}(Ξ_{c}^{+}\to Ξ^{-}π^{+}π^+)}= 0.067 \pm 0.007 \pm 0.003$, $\frac{\cal{B}(Ξ_c^{+} \to Ξ^{0}π^{+})}{\cal{B}(Ξ_{c}^{+}\to Ξ^{-}π^{+}π^+)} = 0.251 \pm 0.005 \pm 0.010$, $\frac{\cal{B}(Ξ_c^{+} \to Ξ^{0}K^{+})}{\cal{B}(Ξ_{c}^{+}\to Ξ^{-}π^{+}π^+)} = 0.017 \pm 0.003 \pm 0.001$. Additionally, the ratio ${\cal B}(Ξ_{c}^{+}\toΞ^{0}K^{+})/{\cal B}(Ξ_{c}^{+}\toΞ^{0}π^{+})$ is measured to be $ 0.068 \pm 0.010 \pm 0.004$. Here, the first and second uncertainties are statistical and systematic, respectively. Multiplying the ratios by the branching fraction of the normalization mode, ${\mathcal B}(Ξ_{c}^{+}\toΞ^{-}π^{+}π^+)= (2.9\pm 1.3)\%$, we obtain the following absolute branching fractions ${\cal B}(Ξ_{c}^{+}\toΣ^{+}K^{0}_{S}) = (0.194 \pm 0.021 \pm 0.009 \pm 0.087 )%$, ${\cal B}(Ξ_{c}^{+}\toΞ^{0}π^{+}) = (0.728 \pm 0.014 \pm 0.027 \pm 0.326 )%$, ${\cal B}(Ξ_{c}^{+}\toΞ^{0}K^{+}) = (0.049 \pm 0.007 \pm 0.003 \pm 0.022 )%$. △ Less

Submitted 29 July, 2025; v1 submitted 22 March, 2025; originally announced March 2025.

Comments: 20 pages, 4 figures, 3 Tables; accepted for publication in JHEP

Report number: Belle II Preprint 2025-005; KEK Preprint 2025-2

Journal ref: JHEP08(2025)195

Search for the radiative leptonic decay $D^+\toγe^+ν_e$ using Deep Learning

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai , et al. (680 additional authors not shown)

Abstract: Using 20.3$~\rm fb^{-1}$ of $e^+e^-$ annihilation data collected at a center-of-mass energy of 3.773$~\rm GeV$ with the BESIII detector, we report an improved search for the radiative leptonic decay $D^+\toγe^+ν_e$. An upper limit on its partial branching fraction for photon energies $E_γ>10~\rm MeV$ was determined to be $1.2\times10^{-5}$ at 90\% confidence level; this excludes most current theor… ▽ More Using 20.3$~\rm fb^{-1}$ of $e^+e^-$ annihilation data collected at a center-of-mass energy of 3.773$~\rm GeV$ with the BESIII detector, we report an improved search for the radiative leptonic decay $D^+\toγe^+ν_e$. An upper limit on its partial branching fraction for photon energies $E_γ>10~\rm MeV$ was determined to be $1.2\times10^{-5}$ at 90\% confidence level; this excludes most current theoretical predictions. A sophisticated deep learning approach, which includes thorough validation and is based on the Transformer architecture, was implemented to efficiently distinguish the signal from massive backgrounds. △ Less

Submitted 22 September, 2025; v1 submitted 20 March, 2025; originally announced March 2025.

Comments: 16 pages, 6 figures

Journal ref: Chinese Phys. C 49, 083001 (2025)

Superradiance of Friedberg-Lee-Sirlin Solitons

Authors: Guo-Dong Zhang, Cheng-Hao Li, Qi-Xin Xie, Shuang-Yong Zhou

Abstract: It has recently been pointed out that rotation in internal space can induce superradiance. We explore this effect in non-topological solitons of the two-field Friedberg-Lee-Sirlin model. This renormalizable model admits very large solitons, making the perturbative scattering equations highly sensitive to boundary conditions and requiring a relaxation method for their solution. We find that the ene… ▽ More It has recently been pointed out that rotation in internal space can induce superradiance. We explore this effect in non-topological solitons of the two-field Friedberg-Lee-Sirlin model. This renormalizable model admits very large solitons, making the perturbative scattering equations highly sensitive to boundary conditions and requiring a relaxation method for their solution. We find that the energy extraction rate is strongly influenced by the mass hierarchy of the two scalars, and solitons with lower internal frequencies lead to more peaks in the spectra of the amplification factors. Additionally, we derive absolute bounds on the amplification factors for general ingoing modes using a linear fractional optimization algorithm and establish analytical bounds near the mass gap. △ Less

Submitted 19 March, 2025; v1 submitted 6 March, 2025; originally announced March 2025.

Comments: 21 pages,12 figures; v2: refs added

Contributions of $ρ(770,1450)\to ωπ$ for the Cabibbo-favored $D \to hωπ$ decays

Authors: Wen-Fei Wang, Jiao-Yuan Xu, Si-Hong Zhou, Pan-Pan Shi

Abstract: Recently, the BESIII Collaboration has observed the three-body decays $D_s^+\to ηωπ^+$, $D^+\to K^0_Sπ^+ω$ and $D^0\to K^-π^+ω$. In this work, we investigate the contributions of the subprocesses $ρ^+\to ωπ^+$ in these Cabibbo-favored decays $D \to hωπ$, with $ρ^+= \{ρ(770)^+, ρ(1450)^+, ρ(770)^+\&ρ(1450)^+\}$ and $h=\{ η, K^0_S, K^-\}$, by introducing these subprocesses into the decay amplitudes… ▽ More Recently, the BESIII Collaboration has observed the three-body decays $D_s^+\to ηωπ^+$, $D^+\to K^0_Sπ^+ω$ and $D^0\to K^-π^+ω$. In this work, we investigate the contributions of the subprocesses $ρ^+\to ωπ^+$ in these Cabibbo-favored decays $D \to hωπ$, with $ρ^+= \{ρ(770)^+, ρ(1450)^+, ρ(770)^+\&ρ(1450)^+\}$ and $h=\{ η, K^0_S, K^-\}$, by introducing these subprocesses into the decay amplitudes of relevant decay processes via the vector form factor $F_{ωπ}$ which has measured in the related $τ$ and $e^+e^-$ processes; we provide the first theoretical predictions for the branching fractions of the quasi-two-body decays $D_s^+\toη[ρ^+\to]ωπ^+$, $D^+\to K^0_S[ρ^+\to]ωπ^+$ and $D^0\to K^-[ρ^+\to]ωπ^+$. Our findings reveal that the contributions from the subprocess $ρ(770)^+\toωπ^+$ are significant in these observed three-body decays $D_s^+\toηωπ^+$, $D^+\to K^0_S ωπ^+$ and $D^0\to K^- ωπ^+$, notwithstanding the contributions originating from the Breit-Wigner tail effect of $ρ(770)^+$. The numerical results of this study suggest that the dominant resonance contributions for the three-body decays $D_s^+\toηωπ^+$ and $D^+\to K^0_S ωπ^+$ are originated from the $P$-wave intermediate states $ρ(770)^+$, $ρ(1450)^+$ and their interference effects. △ Less

Submitted 5 October, 2025; v1 submitted 16 February, 2025; originally announced February 2025.

Comments: 10 pages, 3 figures, accepted for publication in Chinese Physics C

Journal ref: Chinese Physics C Vol. 50, No. 2 (2026) 023111

Wigner multiplets in QFT: dark sector and CPT-violating scenarios

Authors: Cheng-Yang Lee, Ruifeng Leng, Siyi Zhou

Abstract: The classification of elementary particles based on unitary irreducible representations of the Poincare group has been a cornerstone of modern Quantum Field Theory (QFT). While the Standard Model (SM) does not inherently include Dark Matter (DM), any fundamental DM candidate should still conform to this classification or its extensions. Beyond the standard representations, Wigner introduced a clas… ▽ More The classification of elementary particles based on unitary irreducible representations of the Poincare group has been a cornerstone of modern Quantum Field Theory (QFT). While the Standard Model (SM) does not inherently include Dark Matter (DM), any fundamental DM candidate should still conform to this classification or its extensions. Beyond the standard representations, Wigner introduced a class of nontrivial states characterized by an additional discrete degree of freedom, known as the Wigner degeneracy. We systematically investigate the QFT of such Wigner degenerate multiplets, particularly focusing on the massive spin-1/2 case. We construct a theoretical framework where the two-fold Wigner spinor fields, $ψ_{\pm\frac{1}{2}}(x)$, form a doublet representation. We analyze their transformation properties under discrete symmetries (C, P, and T), revealing novel mixing effects due to Wigner degeneracy and an emergent accidental U(2) global symmetry. Furthermore, we explore their Yukawa and gauge interactions, demonstrating that such interactions generally break the CPT symmetry. However, we derive conditions for the CPT conservation and discuss potential phenomenological consequences beyond the SM. These results provide new insights into the possible role of Wigner-degenerate states in fundamental physics, particularly in the dark sector. △ Less

Submitted 5 June, 2025; v1 submitted 13 February, 2025; originally announced February 2025.

Comments: 38 pages, no figures

Journal ref: JHEP06(2025)054

Wigner-like Parametrization of Canonical Seesaw Models

Authors: Shun Zhou

Abstract: In this paper, we introduce the Wigner parametrization of unitary matrices and then apply it to the full description of canonical seesaw models, which extend the Standard Model with three right-handed neutrino singlets and account simultaneously for tiny Majorana neutrino masses and the baryon number asymmetry in the Universe. In the Wigner parametrization, the strong hierarchy between the electro… ▽ More In this paper, we introduce the Wigner parametrization of unitary matrices and then apply it to the full description of canonical seesaw models, which extend the Standard Model with three right-handed neutrino singlets and account simultaneously for tiny Majorana neutrino masses and the baryon number asymmetry in the Universe. In the Wigner parametrization, the strong hierarchy between the electroweak scale $Λ^{}_{\rm EW} \approx 10^2~{\rm GeV}$ and the seesaw scale $Λ^{}_{\rm SS} \approx 10^{14}~{\rm GeV}$ is generally captured by three small rotation angles $\{\vartheta^{}_1, \vartheta^{}_2, \vartheta^{}_3\} \approx {\cal O}(Λ^{}_{\rm EW}/Λ^{}_{\rm SS})$, and all the remaining parameters reside in four $3\times 3$ unitary matrices. The connection between the Wigner parametrization and those in the literature is also established. △ Less

Submitted 11 February, 2025; originally announced February 2025.

Comments: 14 pages, no figures

Cosmological search for sterile neutrinos after DESI 2024

Authors: Guo-Hong Du, Tian-Nuo Li, Peng-Ju Wu, Lu Feng, Sheng-Han Zhou, Jing-Fei Zhang, Xin Zhang

Abstract: The question of whether the massive sterile neutrinos exist remains a crucial unresolved issue in both particle physics and cosmology. We explore the cosmological constraints on the massive sterile neutrinos using the latest observational data, including the baryon acoustic oscillations data from DESI, the cosmic microwave background data from Planck satellite and ACT, and the 5-year Type Ia super… ▽ More The question of whether the massive sterile neutrinos exist remains a crucial unresolved issue in both particle physics and cosmology. We explore the cosmological constraints on the massive sterile neutrinos using the latest observational data, including the baryon acoustic oscillations data from DESI, the cosmic microwave background data from Planck satellite and ACT, and the 5-year Type Ia supernova data and the 3-year weak-lensing data from DES. We search for the massive sterile neutrinos within the $Λ$CDM, $w$CDM, and $w_0w_a$CDM models. Our analysis shows that when considering massive sterile neutrinos within the $w_0w_a\rm CDM$ model, the combined datasets allow us to infer a non-zero sterile neutrino mass at approximately $2σ$ confidence level. Specifically, in the $w_0w_a$CDM+Sterile model, the effective mass of sterile neutrinos and the effective number of relativistic species are constrained to be $m_{ν,\ \mathrm{sterile}}^{\mathrm{eff}} = 0.50^{+0.33}_{-0.27} \, \mathrm{eV}$ and $N_\mathrm{eff} = 3.076^{+0.011}_{-0.017}$, respectively. However, the $Λ$CDM+Sterile and $w$CDM+Sterile models could not provide evidence supporting the existence of massive sterile neutrinos. △ Less

Submitted 20 December, 2025; v1 submitted 18 January, 2025; originally announced January 2025.

Comments: 11 pages, 5 figures; accepted for publication in the European Physical Journal C

Journal ref: Eur. Phys. J. C (2026) 86: 110

Elastic Neutrino-electron Scattering at the One-loop Level in the Standard Model

Authors: Jihong Huang, Shun Zhou

Abstract: In this paper, we perform a complete calculation of the differential cross section for elastic neutrino-electron scattering at the one-loop level in the Standard Model (SM), by using up-to-date values of relevant input parameters in the on-shell renormalization scheme. A careful comparison with the calculation done by Sarantakos, Sirlin and Marciano more than forty years ago in the same scheme is… ▽ More In this paper, we perform a complete calculation of the differential cross section for elastic neutrino-electron scattering at the one-loop level in the Standard Model (SM), by using up-to-date values of relevant input parameters in the on-shell renormalization scheme. A careful comparison with the calculation done by Sarantakos, Sirlin and Marciano more than forty years ago in the same scheme is carried out, and an excellent agreement is found if the same values of input parameters are taken. Then we apply our results to compute the event rates for the detection of reactor antineutrinos in both JUNO and TAO experiments, which are now under construction and will soon be in operation. It should be emphasized that one-loop radiative corrections in the SM must be taken into account in the first place when searching for possible new-physics effects in the coming era of precision neutrino physics. △ Less

Submitted 8 September, 2025; v1 submitted 22 December, 2024; originally announced December 2024.

Comments: 28 pages, 8 figures, 1 table, more discussions and references added, correct the total numbers of target electrons and accordingly the event rates, version accepted by PRD

Journal ref: Phys.Rev.D 111 (2025) 3, 033005

Observations of the singly Cabibbo-suppressed decays $Ξ_c^{+} \to pK_{S}^{0}$, $Ξ_c^+ \to Λπ^+$, and $Ξ_c^+ \to Σ^{0} π^+$ at Belle and Belle II

Authors: Belle, Belle II Collaborations, :, I. Adachi, L. Aggarwal, N. Akopov, M. Alhakami, A. Aloisio, N. Althubiti, N. Anh Ky, D. M. Asner, H. Atmacan, T. Aushev, V. Aushev, M. Aversano, R. Ayad, V. Babu, N. K. Baghel, S. Bahinipati, P. Bambade, Sw. Banerjee, M. Barrett, J. Baudot, A. Baur, A. Beaubien , et al. (323 additional authors not shown)

Abstract: Using data samples of 983.0~$\rm fb^{-1}$ and 427.9~$\rm fb^{-1}$ accumulated with the Belle and Belle~II detectors operating at the KEKB and SuperKEKB asymmetric-energy $e^+e^-$ colliders, singly Cabibbo-suppressed decays $Ξ_c^{+} \to pK_{S}^{0}$, $Ξ_c^+ \to Λπ^+$, and $Ξ_c^+ \to Σ^{0} π^+$ are observed for the first time. The ratios of branching fractions of $Ξ_{c}^{+}\to p K_{S}^{0}$,… ▽ More Using data samples of 983.0~$\rm fb^{-1}$ and 427.9~$\rm fb^{-1}$ accumulated with the Belle and Belle~II detectors operating at the KEKB and SuperKEKB asymmetric-energy $e^+e^-$ colliders, singly Cabibbo-suppressed decays $Ξ_c^{+} \to pK_{S}^{0}$, $Ξ_c^+ \to Λπ^+$, and $Ξ_c^+ \to Σ^{0} π^+$ are observed for the first time. The ratios of branching fractions of $Ξ_{c}^{+}\to p K_{S}^{0}$, $Ξ_{c}^{+}\to Λπ^{+}$, and $Ξ_{c}^{+}\to Σ^{0} π^{+}$ relative to that of $Ξ_c^+ \to Ξ^- π^{+} π^{+}$ are measured to be \begin{equation} \frac{{\cal B}(Ξ_c^+ \to pK_S^0)}{{\cal B}(Ξ_c^{+} \to Ξ^{-} π^+ π^+)} = (2.47 \pm 0.16 \pm 0.07)\% \notag, \end{equation} \begin{equation} \frac{{\cal B}(Ξ_c^+ \to Λπ^+)}{{\cal B}(Ξ_c^{+} \to Ξ^{-} π^+ π^+)} = (1.56 \pm 0.14 \pm 0.09)\% \notag, \end{equation} \begin{equation} \frac{{\cal B}(Ξ_c^+ \to Σ^0 π^+)}{{\cal B}(Ξ_c^{+} \to Ξ^{-} π^+ π^+)} = (4.13 \pm 0.26 \pm 0.22)\% \notag. \end{equation} Multiplying these values by the branching fraction of the normalization channel, ${\cal B}(Ξ_c^{+} \to Ξ^{-} π^+π^+) = (2.9 \pm 1.3)\%$, the absolute branching fractions are determined to be \begin{equation} {\cal B}(Ξ_c^{+} \to p K_{S}^{0}) = (7.16 \pm 0.46 \pm 0.20 \pm 3.21) \times 10^{-4} \notag, \end{equation} \begin{equation} {\cal B}(Ξ_c^{+} \to Λπ^+) = (4.52 \pm 0.41 \pm 0.26 \pm 2.03) \times 10^{-4} \notag, \end{equation} \begin{equation} {\cal B}(Ξ_c^{+} \to Σ^0 π^+) = (1.20 \pm 0.08 \pm 0.07 \pm 0.54) \times 10^{-3} \notag. \end{equation} The first and second uncertainties above are statistical and systematic, respectively, while the third ones arise from the uncertainty in ${\cal B}(Ξ_c^{+} \to Ξ^{-} π^{+} π^{+})$. △ Less

Submitted 13 December, 2024; originally announced December 2024.

Comments: 21 pages, 5 pages

Report number: Belle II Preprint 2024-028; KEK Preprint 2024-29

Journal ref: JHEP03(2025)061

Non-topological solitons and quasi-solitons

Authors: Shuang-Yong Zhou

Abstract: Solitons in relativistic field theories are not necessarily topologically charged. In particular, non-topological solitons -- known as Q-balls -- arise naturally in nonlinear field theories endowed with attractive interactions and internal symmetries. Even without stabilizing internal symmetries, quasi-solitons known as oscillons, which are long-lived, can also exist. Both Q-balls and oscillons ha… ▽ More Solitons in relativistic field theories are not necessarily topologically charged. In particular, non-topological solitons -- known as Q-balls -- arise naturally in nonlinear field theories endowed with attractive interactions and internal symmetries. Even without stabilizing internal symmetries, quasi-solitons known as oscillons, which are long-lived, can also exist. Both Q-balls and oscillons have significant applications in cosmology and particle physics. This review is an updated account of the intriguing properties and dynamics of these non-topological solitons and quasi-solitons, as well as their important roles in early-universe scenarios and particle physics models. △ Less

Submitted 25 November, 2024; originally announced November 2024.

Comments: 53 pages, invited review for Reports on Progress in Physics; comments welcome

Journal ref: Rept.Prog.Phys. 88 (2025) 4, 046901