Showing 1–50 of 73 results for author: Kim, M

Constraints on ultralight bosons from merging binary and remnant black holes observed during the second and third parts of the fourth LIGO-Virgo-KAGRA observing run

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, A. Abe, I. Abouelfettouh, F. Acernese, K. Ackley, A. Adam, S. Adhicary, D. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1786 additional authors not shown)

Abstract: We present constraints on ultralight bosons using binary black hole mergers observed in the second and third parts of the fourth LIGO-Virgo-KAGRA observing run. Directed searches are conducted for long-transient gravitational waves from ultralight vector boson clouds around merger remnants, using a hidden-Markov-model (HMM) tracking scheme. We target the remnant black holes formed in the binary co… ▽ More We present constraints on ultralight bosons using binary black hole mergers observed in the second and third parts of the fourth LIGO-Virgo-KAGRA observing run. Directed searches are conducted for long-transient gravitational waves from ultralight vector boson clouds around merger remnants, using a hidden-Markov-model (HMM) tracking scheme. We target the remnant black holes formed in the binary coalescences that produced GW250114 and GW250207. We find no evidence for such signals from either target. Estimating our search sensitivity at a threshold corresponding to a 1% false alarm probability, we thus disfavor vector boson masses in the range of $[2.80, 3.95]\times 10^{-13}$ eV with greater than 90% confidence. In addition, we derive constraints on ultralight scalar and vector bosons from the inferred high spins of the constituent black holes in three binaries, using events GW240515, GW241113, and GW241225_08. The excluded mass ranges in this approach depend on the assumed black-hole ages. At $10^5$ years, corresponding to typical dynamically formed binaries, we exclude scalar and vector bosons in the ranges $[1.39, 6.94]\times 10^{-13}$ eV and $[0.32, 14.4]\times 10^{-13}$ eV at 90% confidence, respectively. △ Less

Submitted 11 August, 2026; originally announced August 2026.

Comments: 27 pages (12 pages author list, 15 pages main paper), 5 figures

Report number: LIGO-P2600218

A Bayesian approach to the long-baseline neutrino oscillation sensitivity of DUNE

Authors: DUNE Collaboration, S. Abbaslu, F. Abd Alrahman, A. Abed Abud, R. Acciarri, M. A. Acero, M. R. Adames, G. Adamov, M. Adamowski, K. Adhikari, C. Adriano, K. Agudelo-Jaramillo, F. Akbar, F. Alemanno, N. S. Alex, L. Aliaga Soplin, A. Alqaisi, O. Alterkait, A. Alton, R. Alvarez, T. Alves, A. Aman, H. Amar, R. M. Amarinei, P. Amedo , et al. (1262 additional authors not shown)

Abstract: The sensitivity of the Deep Underground Neutrino Experiment (DUNE) to neutrino oscillation is evaluated using a Bayesian Markov Chain Monte Carlo (MCMC) approach. This analysis uses the same underlying sensitivity inputs as previous DUNE studies [Eur. Phys. J. C 80, 978 (2020)], and therefore does not present updated DUNE sensitivities, but instead explores the additional inferences accessible usi… ▽ More The sensitivity of the Deep Underground Neutrino Experiment (DUNE) to neutrino oscillation is evaluated using a Bayesian Markov Chain Monte Carlo (MCMC) approach. This analysis uses the same underlying sensitivity inputs as previous DUNE studies [Eur. Phys. J. C 80, 978 (2020)], and therefore does not present updated DUNE sensitivities, but instead explores the additional inferences accessible using a Bayesian approach. We present four-dimensional posterior probability distributions of the oscillation parameters, highlighting the breadth of correlation in the parameter space of interest, especially between $\sin^2 θ_{23}$ and $\sin^2 θ_{13}$. We exploit the flexibility of the Bayesian framework to incorporate parameter constraints post hoc and assess the impact of applying a reactor short-baseline $θ_{13}$ constraint. A significant increase in the sensitivity to the $θ_{23}$ octant is found when including the constraint. Posterior distributions of derived quantities can be easily constructed from MCMC results. This work presents the first study of DUNE's sensitivity to the Jarlskog invariant, $J$, a quantity that provides a parametrisation-independent measure of charge-parity violation in the leptonic sector. △ Less

Submitted 4 August, 2026; originally announced August 2026.

Comments: 20 pages, 5 figures

Report number: FERMILAB-PUB-26-0548-LBNF

The QCD Scale Parameter from the Photon Structure Function

Authors: Hun Jang, Eun Bok, Hyeunwoo Kim, Byeongjun Yoon, Sun Myong Kim

Abstract: Photon structure function has been a solid platform in testing strong interaction along with nucleon structure function. Strong Interaction has the property that it is perturbatively calculable at high energy but becomes non-perturbative at low energy. This nature makes QCD hard to handle theoretically in factorizing these two regions. The fundamental dimensional parameter, so called the QCD scale… ▽ More Photon structure function has been a solid platform in testing strong interaction along with nucleon structure function. Strong Interaction has the property that it is perturbatively calculable at high energy but becomes non-perturbative at low energy. This nature makes QCD hard to handle theoretically in factorizing these two regions. The fundamental dimensional parameter, so called the QCD scale parameter, $Λ_{\overline{\textrm{MS}}}$, is one of key players to factorize two energy regions. In this work, we extract the QCD scale parameter from the photon structure function by separating the perturbative QCD and non-perturbative QCD. In the process we use the vector dominance model for the non-perturbative energy region of the photon structure function. △ Less

Submitted 3 April, 2026; v1 submitted 30 November, 2025; originally announced December 2025.

Comments: 19 pages, 5 figures. A minor revision has been made. This version of the paper was published in JKPS

Journal ref: J. Korean Phys. Soc. (2026)

Directed searches for gravitational waves from ultralight vector boson clouds around merger remnant and galactic black holes during the first part of the fourth LIGO-Virgo-KAGRA observing run

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu , et al. (1747 additional authors not shown)

Abstract: We present the first directed searches for long-transient and continuous gravitational waves from ultralight vector boson clouds around known black holes (BHs). We use LIGO data from the first part of the fourth LIGO-Virgo-KAGRA observing run. The searches target two distinct types of BHs and use two new semicoherent methods: hidden Markov model (HMM) tracking for the remnant BHs of the mergers GW… ▽ More We present the first directed searches for long-transient and continuous gravitational waves from ultralight vector boson clouds around known black holes (BHs). We use LIGO data from the first part of the fourth LIGO-Virgo-KAGRA observing run. The searches target two distinct types of BHs and use two new semicoherent methods: hidden Markov model (HMM) tracking for the remnant BHs of the mergers GW230814_230901 and GW231123_135430 (referred to as GW230814 and GW231123 in this study), and a dedicated method using the Band Sampled Data (BSD) framework for the galactic BH in the Cygnus X-1 binary system. Without finding evidence of a signal from vector bosons in the data, we estimate the mass range that can be constrained. For the HMM searches targeting the remnants from GW231123 and GW230814, we disfavor vector boson masses in the ranges $[0.94, 1.08]$ and $[2.75, 3.28] \times 10^{-13}$ eV, respectively, at 30% confidence, assuming a 1% false alarm probability. Although these searches are only marginally sensitive to signals from merger remnants at relatively large distances, future observations are expected to yield more stringent constraints with high confidence. For the BSD search targeting the BH in Cygnus X-1, we exclude vector boson masses in the range $[0.85, 1.59] \times 10^{-13}$ eV at 95% confidence, assuming an initial BH spin larger than 0.5. △ Less

Submitted 9 June, 2026; v1 submitted 8 September, 2025; originally announced September 2025.

Comments: 34 pages, 4 figures

Report number: LIGO-P2500256

Photoproduction and detection of $ρ'\rightarrowπ^+π^-π^+π^-$ decays in ultra-peripheral collisions and at an electron-ion collider

Authors: Neha Devi, Minjung Kim, Spencer R. Klein, Janet Seger

Abstract: Vector meson photoproduction is an important probe of nuclear structure. Light vector mesons are most sensitive to low$-x$ structure, as long as they are not too light for perturbative QCD calculations. The $ρ'$ is of interest as an intermediate mass state (between the $ρ$ and $J/ψ$) that is easier to detect than the $φ$. Using HERA data on proton targets, we make projections for lead/gold targe… ▽ More Vector meson photoproduction is an important probe of nuclear structure. Light vector mesons are most sensitive to low$-x$ structure, as long as they are not too light for perturbative QCD calculations. The $ρ'$ is of interest as an intermediate mass state (between the $ρ$ and $J/ψ$) that is easier to detect than the $φ$. Using HERA data on proton targets, we make projections for lead/gold targets in UPCs at the Large Hadron Collider and RHIC, and for $ep$ and $eA$ collisions at a future Electron-Ion Collider (EIC). We compare the UPC projections with ALICE data, and constrain the branching ratio divided by the square of the photon-$ρ'$ coupling. The data prefer large couplings and small branching ratio, probably less than 25\%. The photon-meson coupling predicted by generalized vector meson dominance does not fit the data. The HERA $ep$ and ALICE UPC $e$Pb data exhibit very similar $4π$ mass spectra, indicating that, if the system is composed of two resonances, the products of their photon couplings with their four-pion branching ratios are similar. The predicted rates are high for both UPCs and the EIC. The $ρ'\rightarrowπ^+π^-π^+π^-$ decay can be observed at the EIC with high efficiency. In $ep$ collisions at the highest energy, the forward B0 detector is needed to observe this channel down to the lowest achievable Bjorken$-x$ values. △ Less

Submitted 1 December, 2025; v1 submitted 1 May, 2025; originally announced May 2025.

Comments: 8 pages; version to appear in Phys. Rev. C

Ab Initio Calculations of the Carbon and Oxygen Isotopes: Energies, Correlations, and Superfluid Pairing

Authors: Young-Ho Song, Myungkuk Kim, Youngman Kim, Kihyeon Cho, Serdar Elhatisari, Dean Lee, Yuan-Zhuo Ma, Ulf-G. Meißner

Abstract: We perform \textit{ab initio} nuclear lattice calculations of the neutron-rich carbon and oxygen isotopes using high-fidelity chiral interactions. We find good agreement with the observed binding energies and compute correlations associated with each two-nucleon interaction channel. For the isospin $T=1$ channels, we show that the dependence on $T_z$ provides a measure of the correlations among th… ▽ More We perform \textit{ab initio} nuclear lattice calculations of the neutron-rich carbon and oxygen isotopes using high-fidelity chiral interactions. We find good agreement with the observed binding energies and compute correlations associated with each two-nucleon interaction channel. For the isospin $T=1$ channels, we show that the dependence on $T_z$ provides a measure of the correlations among the extra neutrons in the neutron-rich nuclei. For the spin-singlet S-wave channel, we observe that any paired neutron interacts with the nuclear core as well as its neutron pair partner, while any unpaired neutron interacts primarily with only the nuclear core. For the other partial waves, the correlations among the extra neutrons grow more slowly and smoothly with the number of neutrons. These general patterns are observed in both the carbon and oxygen isotopes and may be universal features that appear in many neutron-rich nuclei. △ Less

Submitted 3 December, 2025; v1 submitted 25 February, 2025; originally announced February 2025.

Comments: 25 pages, 18 figures, to be published in Phyiscs Letters B

Studying the Strangeness $D$-Term in Hall C via Exclusive $φ$ Electroproduction

Authors: H. T. Klest, S. Joosten, H. Szumila-Vance, W. Armstrong, F. A. Flor, B. Kim, M. H. Kim, V. Klimenko, S. Lee, Z. -E. Meziani, C. Peng, N. Pilleux, P. E. Reimer, J. Xie, Z. Xu, M. Żurek, A. Hoghmrtsyan, A. Mkrtchyan, H. Mkrtchyan, V. Tadevosyan, Y. Hatta, P. Markowitz, G. Niculescu, I. Niculescu, A. Camsonne , et al. (34 additional authors not shown)

Abstract: We propose a measurement of exclusive electroproduction of $φ$ mesons near threshold in Hall C. We will measure the |t|-dependence of the exclusive $φ$ electroproduction cross section, which has recently been proposed as an observable sensitive to the strangeness $D$-term. The contribution of strangeness to the total $D$-term is presently unknown, with different arguments favoring $D_s$ being larg… ▽ More We propose a measurement of exclusive electroproduction of $φ$ mesons near threshold in Hall C. We will measure the |t|-dependence of the exclusive $φ$ electroproduction cross section, which has recently been proposed as an observable sensitive to the strangeness $D$-term. The contribution of strangeness to the total $D$-term is presently unknown, with different arguments favoring $D_s$ being large, being small, or even having opposite sign from the total $D$-term. Our exploratory measurement is designed to distinguish between these hypotheses. If $D_s$ turns out to be small, $φ$ electroproduction can be used to study the gluon $D$-term. In addition, this dataset will allow us to perform measurements of other exclusive meson final states, including the first measurement of $η'$ electroproduction and multi-differential measurements of $η$ and $ω$ electroproduction. △ Less

Submitted 17 December, 2025; v1 submitted 2 January, 2025; originally announced January 2025.

Comments: Proposal submitted to Jefferson Lab PAC 53 On ArXiv, v1 is the letter-of-intent, v2 is the approved proposal

Report number: E12-25-007

Ultralight vector dark matter search using data from the KAGRA O3GK run

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, R. Abbott, H. Abe, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, N. Adhikari, R. X. Adhikari, V. K. Adkins, V. B. Adya, C. Affeldt, D. Agarwal, M. Agathos, O. D. Aguiar, I. Aguilar, L. Aiello, A. Ain, P. Ajith, T. Akutsu, S. Albanesi , et al. (1778 additional authors not shown)

Abstract: Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we prese… ▽ More Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for $U(1)_{B-L}$ gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the $U(1)_{B-L}$ gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM. △ Less

Submitted 5 March, 2024; originally announced March 2024.

Comments: 20 pages, 5 figures

Report number: LIGO-P2300250

Schwinger Pair Production and Vacuum Birefringence around High Magnetized Neutron Stars

Authors: Chul Min Kim, Sang Pyo Kim

Abstract: Highly magnetized neutron stars have magnetic fields of order of the critical field and can lead to measurable QED effects. We consider the Goldreich-Julian pulsar model with supercritical magnetic fields, induced subcritical electric fields, and a period of milliseconds. We then study the strong field physics, such as Schwinger pair production and the vacuum birefringence including the wrench eff… ▽ More Highly magnetized neutron stars have magnetic fields of order of the critical field and can lead to measurable QED effects. We consider the Goldreich-Julian pulsar model with supercritical magnetic fields, induced subcritical electric fields, and a period of milliseconds. We then study the strong field physics, such as Schwinger pair production and the vacuum birefringence including the wrench effect, whose X-ray polarimetry will be observed in future space missions. △ Less

Submitted 30 August, 2023; originally announced August 2023.

Comments: 13 pages, 6 figures; Talk at the Fifth Zeldovich meeting, an international conference in honor of Ya. B. Zeldovich held in Yerevan, Armenia on June 12--16, 2023

Modeling Backward-Angle ($u$-channel) Virtual Compton Scattering at an Electron-Ion Collider

Authors: Zachary Sweger, Spencer R. Klein, Yuanjing Ji, Minjung Kim, Saeahram Yoo, Ziyuan Zeng, Daniel Cebra, Xin Dong

Abstract: High-energy backward ($u$-channel) reactions can involve very large momentum transfers to the target baryons, shifting them by many units of rapidity. These reactions are difficult to understand in conventional models in which baryon number is carried by the valence quarks. Backward Compton scattering is an especially attractive experimental target, because of its simple final state. There is curr… ▽ More High-energy backward ($u$-channel) reactions can involve very large momentum transfers to the target baryons, shifting them by many units of rapidity. These reactions are difficult to understand in conventional models in which baryon number is carried by the valence quarks. Backward Compton scattering is an especially attractive experimental target, because of its simple final state. There is currently limited data on this process, and that data is at low center-of-mass energies. In this paper, we examine the prospects for studying backward Compton scattering at the future Electron-Ion Collider (EIC). We model the cross-section and kinematics using the limited data on backward Compton scattering and backward meson production, and then simulate Compton scattering at EIC energies, in a simple model of the ePIC detector. Generally, the proton is scattered toward mid-rapidity, while the produced photon is in the far-forward region, visible in a Zero Degree Calorimeter (ZDC). We show that the background from backward $π^0$ production can be rejected using a high-resolution, well-segmented ZDC. △ Less

Submitted 21 August, 2023; originally announced August 2023.

Comments: 12 pages, 9 figures

Hot QCD White Paper

Authors: M. Arslandok, S. A. Bass, A. A. Baty, I. Bautista, C. Beattie, F. Becattini, R. Bellwied, Y. Berdnikov, A. Berdnikov, J. Bielcik, J. T. Blair, F. Bock, B. Boimska, H. Bossi, H. Caines, Y. Chen, Y. -T. Chien, M. Chiu, M. E. Connors, M. Csanád, C. L. da Silva, A. P. Dash, G. David, K. Dehmelt, V. Dexheimer , et al. (149 additional authors not shown)

Abstract: Hot QCD physics studies the nuclear strong force under extreme temperature and densities. Experimentally these conditions are achieved via high-energy collisions of heavy ions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). In the past decade, a unique and substantial suite of data was collected at RHIC and the LHC, probing hydrodynamics at the nucleon scale, the… ▽ More Hot QCD physics studies the nuclear strong force under extreme temperature and densities. Experimentally these conditions are achieved via high-energy collisions of heavy ions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). In the past decade, a unique and substantial suite of data was collected at RHIC and the LHC, probing hydrodynamics at the nucleon scale, the temperature dependence of the transport properties of quark-gluon plasma, the phase diagram of nuclear matter, the interaction of quarks and gluons at different scales and much more. This document, as part of the 2023 nuclear science long range planning process, was written to review the progress in hot QCD since the 2015 Long Range Plan for Nuclear Science, as well as highlight the realization of previous recommendations, and present opportunities for the next decade, building on the accomplishments and investments made in theoretical developments and the construction of new detectors. Furthermore, this document provides additional context to support the recommendations voted on at the Joint Hot and Cold QCD Town Hall Meeting, which are reported in a separate document. △ Less

Submitted 30 March, 2023; originally announced March 2023.

Comments: 190 pages, 69 figures

The Present and Future of QCD

Authors: P. Achenbach, D. Adhikari, A. Afanasev, F. Afzal, C. A. Aidala, A. Al-bataineh, D. K. Almaalol, M. Amaryan, D. Androić, W. R. Armstrong, M. Arratia, J. Arrington, A. Asaturyan, E. C. Aschenauer, H. Atac, H. Avakian, T. Averett, C. Ayerbe Gayoso, X. Bai, K. N. Barish, N. Barnea, G. Basar, M. Battaglieri, A. A. Baty, I. Bautista , et al. (378 additional authors not shown)

Abstract: This White Paper presents the community inputs and scientific conclusions from the Hot and Cold QCD Town Meeting that took place September 23-25, 2022 at MIT, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 424 physicists registered for the meeting. The meeting highlighted progress in Quantum Chromodynamics (QCD) nuclear physics since the 2015… ▽ More This White Paper presents the community inputs and scientific conclusions from the Hot and Cold QCD Town Meeting that took place September 23-25, 2022 at MIT, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 424 physicists registered for the meeting. The meeting highlighted progress in Quantum Chromodynamics (QCD) nuclear physics since the 2015 LRP (LRP15) and identified key questions and plausible paths to obtaining answers to those questions, defining priorities for our research over the coming decade. In defining the priority of outstanding physics opportunities for the future, both prospects for the short (~ 5 years) and longer term (5-10 years and beyond) are identified together with the facilities, personnel and other resources needed to maximize the discovery potential and maintain United States leadership in QCD physics worldwide. This White Paper is organized as follows: In the Executive Summary, we detail the Recommendations and Initiatives that were presented and discussed at the Town Meeting, and their supporting rationales. Section 2 highlights major progress and accomplishments of the past seven years. It is followed, in Section 3, by an overview of the physics opportunities for the immediate future, and in relation with the next QCD frontier: the EIC. Section 4 provides an overview of the physics motivations and goals associated with the EIC. Section 5 is devoted to the workforce development and support of diversity, equity and inclusion. This is followed by a dedicated section on computing in Section 6. Section 7 describes the national need for nuclear data science and the relevance to QCD research. △ Less

Submitted 4 March, 2023; originally announced March 2023.

Comments: QCD Town Meeting White Paper, as submitted to 2023 NSAC LRP committee on Feb. 28, 2023

Journal ref: Nucl.Phys.A 1047 (2024) 122874

Search for $e\toτ$ Charged Lepton Flavor Violation at the EIC with the ECCE Detector

Authors: J. -L. Zhang, S. Mantry, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann, M. H. S. Bukhari , et al. (262 additional authors not shown)

Abstract: The recently approved Electron-Ion Collider (EIC) will provide a unique new opportunity for searches of charged lepton flavor violation (CLFV) and other new physics scenarios. In contrast to the $e \leftrightarrow μ$ CLFV transition for which very stringent limits exist, there is still a relatively large discovery space for the $e \to τ$ CLFV transition, potentially to be explored by the EIC. With… ▽ More The recently approved Electron-Ion Collider (EIC) will provide a unique new opportunity for searches of charged lepton flavor violation (CLFV) and other new physics scenarios. In contrast to the $e \leftrightarrow μ$ CLFV transition for which very stringent limits exist, there is still a relatively large discovery space for the $e \to τ$ CLFV transition, potentially to be explored by the EIC. With the latest detector design of ECCE (EIC Comprehensive Chromodynamics Experiment) and projected integral luminosity of the EIC, we find the $τ$-leptons created in the DIS process $ep\to τX$ are expected to be identified with high efficiency. A first ECCE simulation study, restricted to the 3-prong $τ$-decay mode and with limited statistics for the Standard Model backgrounds, estimates that the EIC will be able to improve the current exclusion limit on $e\to τ$ CLFV by an order of magnitude. △ Less

Submitted 20 July, 2022; originally announced July 2022.

Comments: 11 pages, 8 figures, to be submitted to NIM

Vacuum Birefringence in a Supercritical Magnetic Field and a Subcritical Electric Field

Authors: Chul Min Kim, Sang Pyo Kim

Abstract: Recent ultra-intense lasers of subcritical fields and proposed observations of the x-rays polarization from highly magnetized neutron stars of supercritical fields have attracted attention to vacuum birefringence, a unique feature of nonlinear electrodynamics. We propose a formulation of vacuum birefringence that incorporates the effects of the weaker electric field added to the extremely strong m… ▽ More Recent ultra-intense lasers of subcritical fields and proposed observations of the x-rays polarization from highly magnetized neutron stars of supercritical fields have attracted attention to vacuum birefringence, a unique feature of nonlinear electrodynamics. We propose a formulation of vacuum birefringence that incorporates the effects of the weaker electric field added to the extremely strong magnetic field. To do so, we first derive a closed analytical expression for the one-loop effective Lagrangian for the combined magnetic and electric fields by using an explicit formula of the one-loop effective Lagrangian for an arbitrarily strong magnetic field. We then employ the expression to derive the polarization and magnetization of the vacuum, from which the permittivity and permeability for weak probe fields are obtained. Finally, we find the refractive indices and the associated polarization vectors for the case of parallel magnetic and electric fields. The proposed formulation predicts that an electric field along the magnetic field reduces the birefringence and rotates the polarization vectors. Such effects should be taken into account for accurate polarimetry of the x-rays from magnetized neutron stars, which will prove the fundamental aspect of the strong field quantum electrodynamics (QED) and explore the extreme fields of astrophysical bodies. △ Less

Submitted 11 February, 2022; originally announced February 2022.

Journal ref: Eur. Phys. J. C 83, 104 (2023)

Magnetars as Laboratories for Strong Field QED

Authors: Chul Min Kim, Sang Pyo Kim

Abstract: A strong electromagnetic field polarizes the vacuum and in the presence of an electric field creates pairs of a charged particle and its anti-particle. Magnetars, highly magnetized neutron stars with magnetic field comparable to or greater than the Schwinger field, give a significant amount of the vacuum polarization and vacuum birefringence and the induced electric field can create the electron-p… ▽ More A strong electromagnetic field polarizes the vacuum and in the presence of an electric field creates pairs of a charged particle and its anti-particle. Magnetars, highly magnetized neutron stars with magnetic field comparable to or greater than the Schwinger field, give a significant amount of the vacuum polarization and vacuum birefringence and the induced electric field can create the electron-positron pairs, which are strong field quantum electrodynamics (QED) processes. In this paper, we use a closed formula for the one-loop effective action in the presence of a supercritical magnetic field and a subcritical electric field, find the vacuum birefringence analytically and numerically, and then discuss possible measurements in magnetars. △ Less

Submitted 4 December, 2021; originally announced December 2021.

Comments: Proceedings for the 17th Italian-Korean Symposium on Relativistic Astrophysics, Korea, August 2-6, 2021; 8 pages, three figures

Leveraging Quantum Annealer to identify an Event-topology at High Energy Colliders

Authors: Minho Kim, Pyungwon Ko, Jae-hyeon Park, Myeonghun Park

Abstract: With increasing energy and luminosity available at the Large Hadron collider (LHC), we get a chance to take a pure bottom-up approach solely based on data. This will extend the scope of our understanding about Nature without relying on theoretical prejudices. The required computing resource, however, will increase exponentially with data size and complexities of events if one uses algorithms based… ▽ More With increasing energy and luminosity available at the Large Hadron collider (LHC), we get a chance to take a pure bottom-up approach solely based on data. This will extend the scope of our understanding about Nature without relying on theoretical prejudices. The required computing resource, however, will increase exponentially with data size and complexities of events if one uses algorithms based on a classical computer. In this letter we propose a simple and well motivated method with a quantum annealer to identify an event-topology, a diagram to describe the history of particles produced at the LHC. We show that a computing complexity can be reduced significantly to the order of polynomials which enables us to decode the "Big" data in a very clear and efficient way. Our method achieves significant improvements in finding a true event-topology, more than by a factor of two compared to a conventional method. △ Less

Submitted 15 November, 2021; originally announced November 2021.

Comments: 7 pages, 8 figures, and 2 tables

Report number: KIAS--P21050

Phase-Integral Formulation of Dynamically Assisted Schwinger Pair Production

Authors: Chul Min Kim, Alexander Fedotov, Sang Pyo Kim

Abstract: We present a phase-integral formulation of dynamically assisted Schwinger pair production of scalar charges to find the pair production density under a strong low-frequency field and a weak high-frequency field. The leading WKB action was the Schwinger formula determined by the constant field, whose corrections are determined by the Keldysh parameter for the oscillating field, $mω_{q}/qE_{q}$. We… ▽ More We present a phase-integral formulation of dynamically assisted Schwinger pair production of scalar charges to find the pair production density under a strong low-frequency field and a weak high-frequency field. The leading WKB action was the Schwinger formula determined by the constant field, whose corrections are determined by the Keldysh parameter for the oscillating field, $mω_{q}/qE_{q}$. We found a systematic expression of the leading WKB action as a power series in the Keldysh parameter, of which coefficients are given as integrals of the product of fields in the complex time domain. For the case of a strong constant field superimposed with a weak oscillating field, we provided explicit formulas and proposed a procedure for numerical evaluation. The presented phase-integral formulation should provide a clear simple method for quantitatively analyzing the leading-order features of dynamically assisted Schwinger pair production. △ Less

Submitted 21 September, 2021; originally announced September 2021.

A Cosmological Constant That is Too Small

Authors: Mehmet Demirtas, Manki Kim, Liam McAllister, Jakob Moritz, Andres Rios-Tascon

Abstract: We construct a vacuum of string theory in which the magnitude of the vacuum energy is $< 10^{-123}$ in Planck units. Regrettably, the sign of the vacuum energy is negative, and some supersymmetry remains unbroken. We construct a vacuum of string theory in which the magnitude of the vacuum energy is $< 10^{-123}$ in Planck units. Regrettably, the sign of the vacuum energy is negative, and some supersymmetry remains unbroken. △ Less

Submitted 10 January, 2022; v1 submitted 19 July, 2021; originally announced July 2021.

Comments: 6 pages. A more detailed analysis appears in our companion paper 2107.09064. v2: typo fixed, results unchanged; approximately matches version published in PRL

Conifold Vacua with Small Flux Superpotential

Authors: Mehmet Demirtas, Manki Kim, Liam McAllister, Jakob Moritz

Abstract: We introduce a method for finding flux vacua of type IIB string theory in which the flux superpotential is exponentially small and at the same time one or more complex structure moduli are stabilized exponentially near to conifold points. We introduce a method for finding flux vacua of type IIB string theory in which the flux superpotential is exponentially small and at the same time one or more complex structure moduli are stabilized exponentially near to conifold points. △ Less

Submitted 3 February, 2022; v1 submitted 7 September, 2020; originally announced September 2020.

Comments: 44 pages, 5 figures. v2: extended discussion of near-conifold expansion of prepotential, references added

Journal ref: Fortschr. Phys. 2020, 68, 2000085

Portraying Double Higgs at the Large Hadron Collider

Authors: Jeong Han Kim, Minho Kim, Kyoungchul Kong, Konstantin T. Matchev, Myeonghun Park

Abstract: We examine the discovery potential for double Higgs production at the high luminosity LHC in the final state with two $b$-tagged jets, two leptons and missing transverse momentum. Although this dilepton final state has been considered a difficult channel due to the large backgrounds, we argue that it is possible to obtain sizable signal significance, by adopting a deep learning framework making fu… ▽ More We examine the discovery potential for double Higgs production at the high luminosity LHC in the final state with two $b$-tagged jets, two leptons and missing transverse momentum. Although this dilepton final state has been considered a difficult channel due to the large backgrounds, we argue that it is possible to obtain sizable signal significance, by adopting a deep learning framework making full use of the relevant kinematics along with the jet images from the Higgs decay. For the relevant number of signal events we obtain a substantial increase in signal sensitivity over existing analyses. We discuss relative improvements at each stage and the correlations among the different input variables for the neutral network. The proposed method can be easily generalized to the semi-leptonic channel of double Higgs production, as well as to other processes with similar final states. △ Less

Submitted 17 September, 2019; v1 submitted 17 April, 2019; originally announced April 2019.

Comments: 37 pages. Matched to published version. Revisions in section 1, 2. Replaced figures. Added references. Conclusions unchanged

Journal ref: JHEP 09 (2019) 047

Higgs Physics at the HL-LHC and HE-LHC

Authors: M. Cepeda, S. Gori, P. Ilten, M. Kado, F. Riva, R. Abdul Khalek, A. Aboubrahim, J. Alimena, S. Alioli, A. Alves, C. Asawatangtrakuldee, A. Azatov, P. Azzi, S. Bailey, S. Banerjee, E. L. Barberio, D. Barducci, G. Barone, M. Bauer, C. Bautista, P. Bechtle, K. Becker, A. Benaglia, M. Bengala, N. Berger , et al. (352 additional authors not shown)

Abstract: The discovery of the Higgs boson in 2012, by the ATLAS and CMS experiments, was a success achieved with only a percent of the entire dataset foreseen for the LHC. It opened a landscape of possibilities in the study of Higgs boson properties, Electroweak Symmetry breaking and the Standard Model in general, as well as new avenues in probing new physics beyond the Standard Model. Six years after the… ▽ More The discovery of the Higgs boson in 2012, by the ATLAS and CMS experiments, was a success achieved with only a percent of the entire dataset foreseen for the LHC. It opened a landscape of possibilities in the study of Higgs boson properties, Electroweak Symmetry breaking and the Standard Model in general, as well as new avenues in probing new physics beyond the Standard Model. Six years after the discovery, with a conspicuously larger dataset collected during LHC Run 2 at a 13 TeV centre-of-mass energy, the theory and experimental particle physics communities have started a meticulous exploration of the potential for precision measurements of its properties. This includes studies of Higgs boson production and decays processes, the search for rare decays and production modes, high energy observables, and searches for an extended electroweak symmetry breaking sector. This report summarises the potential reach and opportunities in Higgs physics during the High Luminosity phase of the LHC, with an expected dataset of pp collisions at 14 TeV, corresponding to an integrated luminosity of 3 ab$^{-1}$. These studies are performed in light of the most recent analyses from LHC collaborations and the latest theoretical developments. The potential of an LHC upgrade, colliding protons at a centre-of-mass energy of 27 TeV and producing a dataset corresponding to an integrated luminosity of 15 ab$^{-1}$, is also discussed. △ Less

Submitted 19 March, 2019; v1 submitted 31 January, 2019; originally announced February 2019.

Comments: Report from Working Group 2 on the Physics of the HL-LHC, and Perspectives at the HE-LHC, 364 pages

Report number: CERN-LPCC-2018-04

Beyond the Standard Model Physics at the HL-LHC and HE-LHC

Authors: X. Cid Vidal, M. D'Onofrio, P. J. Fox, R. Torre, K. A. Ulmer, A. Aboubrahim, A. Albert, J. Alimena, B. C. Allanach, C. Alpigiani, M. Altakach, S. Amoroso, J. K. Anders, J. Y. Araz, A. Arbey, P. Azzi, I. Babounikau, H. Baer, M. J. Baker, D. Barducci, V. Barger, O. Baron, L. Barranco Navarro, M. Battaglia, A. Bay , et al. (272 additional authors not shown)

Abstract: This is the third out of five chapters of the final report [1] of the Workshop on Physics at HL-LHC, and perspectives on HE-LHC [2]. It is devoted to the study of the potential, in the search for Beyond the Standard Model (BSM) physics, of the High Luminosity (HL) phase of the LHC, defined as $3~\mathrm{ab}^{-1}$ of data taken at a centre-of-mass energy of $14~\mathrm{TeV}$, and of a possible futu… ▽ More This is the third out of five chapters of the final report [1] of the Workshop on Physics at HL-LHC, and perspectives on HE-LHC [2]. It is devoted to the study of the potential, in the search for Beyond the Standard Model (BSM) physics, of the High Luminosity (HL) phase of the LHC, defined as $3~\mathrm{ab}^{-1}$ of data taken at a centre-of-mass energy of $14~\mathrm{TeV}$, and of a possible future upgrade, the High Energy (HE) LHC, defined as $15~\mathrm{ab}^{-1}$ of data at a centre-of-mass energy of $27~\mathrm{TeV}$. We consider a large variety of new physics models, both in a simplified model fashion and in a more model-dependent one. A long list of contributions from the theory and experimental (ATLAS, CMS, LHCb) communities have been collected and merged together to give a complete, wide, and consistent view of future prospects for BSM physics at the considered colliders. On top of the usual standard candles, such as supersymmetric simplified models and resonances, considered for the evaluation of future collider potentials, this report contains results on dark matter and dark sectors, long lived particles, leptoquarks, sterile neutrinos, axion-like particles, heavy scalars, vector-like quarks, and more. Particular attention is placed, especially in the study of the HL-LHC prospects, to the detector upgrades, the assessment of the future systematic uncertainties, and new experimental techniques. The general conclusion is that the HL-LHC, on top of allowing to extend the present LHC mass and coupling reach by $20-50\%$ on most new physics scenarios, will also be able to constrain, and potentially discover, new physics that is presently unconstrained. Moreover, compared to the HL-LHC, the reach in most observables will generally more than double at the HE-LHC, which may represent a good candidate future facility for a final test of TeV-scale new physics. △ Less

Submitted 13 August, 2019; v1 submitted 19 December, 2018; originally announced December 2018.

Comments: Report from Working Group 3 on the Physics of the HL-LHC, and Perspectives at the HE-LHC; v2: final version updated with the latest contributions and summaries; 239 pages + refs; v3: typos and character misprint in Fig. 7.2 fixed; v4: added one missing author

Report number: CERN-LPCC-2018-05

Unruh effect and Schwinger pair creation under extreme acceleration by ultraintense lasers

Authors: Chul Min Kim, Sang Pyo Kim

Abstract: A detector undergoing a huge acceleration measures a thermal distribution with the Unruh temperature out of the Minkowski vacuum. Though such huge accelerations occur naturally in astrophysics and gravity, one may design untraintense laser facility to detect the Unruh effect and simulate laboratory astrophysics. We derive the QED vacuum polarization and the vacuum persistence amplitude as well as… ▽ More A detector undergoing a huge acceleration measures a thermal distribution with the Unruh temperature out of the Minkowski vacuum. Though such huge accelerations occur naturally in astrophysics and gravity, one may design untraintense laser facility to detect the Unruh effect and simulate laboratory astrophysics. We derive the QED vacuum polarization and the vacuum persistence amplitude as well as the Schwinger pair creation in an accelerating frame when a constant electric field exists in the Minkowski spacetime. We advance a thermal interpretation of Schwinger pair creation in the Rindler space. △ Less

Submitted 6 December, 2017; originally announced December 2017.

Comments: LaTex 8 pages, 1 figure; contribution to Laser Plasma Accelerators 2017

Search for Nonstandard Neutrino Interactions with IceCube DeepCore

Authors: IceCube Collaboration, M. G. Aartsen, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, M. Ahrens, I. Al Samarai, D. Altmann, K. Andeen, T. Anderson, I. Ansseau, G. Anton, C. Argüelles, J. Auffenberg, S. Axani, H. Bagherpour, X. Bai, J. P. Barron, S. W. Barwick, V. Baum, R. Bay, J. J. Beatty, J. Becker Tjus, K. -H. Becker , et al. (296 additional authors not shown)

Abstract: As atmospheric neutrinos propagate through the Earth, vacuum-like oscillations are modified by Standard-Model neutral- and charged-current interactions with electrons. Theories beyond the Standard Model introduce heavy, TeV-scale bosons that can produce nonstandard neutrino interactions. These additional interactions may modify the Standard Model matter effect producing a measurable deviation from… ▽ More As atmospheric neutrinos propagate through the Earth, vacuum-like oscillations are modified by Standard-Model neutral- and charged-current interactions with electrons. Theories beyond the Standard Model introduce heavy, TeV-scale bosons that can produce nonstandard neutrino interactions. These additional interactions may modify the Standard Model matter effect producing a measurable deviation from the prediction for atmospheric neutrino oscillations. The result described in this paper constrains nonstandard interaction parameters, building upon a previous analysis of atmospheric muon-neutrino disappearance with three years of IceCube-DeepCore data. The best fit for the muon to tau flavor changing term is $ε_{μτ}=-0.0005$, with a 90\% C.L. allowed range of $-0.0067 <ε_{μτ}< 0.0081$. This result is more restrictive than recent limits from other experiments for $ε_{μτ}$. Furthermore, our result is complementary to a recent constraint on $ε_{μτ}$ using another publicly available IceCube high-energy event selection. Together, they constitute the world's best limits on nonstandard interactions in the $μ-τ$ sector. △ Less

Submitted 20 September, 2017; originally announced September 2017.

Comments: 10 pages, 6 figures

Journal ref: Phys. Rev. D 97, 072009 (2018)

Neutrino Interferometry for High-Precision Tests of Lorentz Symmetry with IceCube

Authors: IceCube Collaboration, M. G. Aartsen, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, M. Ahrens, I. Al Samarai, D. Altmann, K. Andeen, T. Anderson, I. Ansseau, G. Anton, C. Argüelles, J. Auffenberg, S. Axani, H. Bagherpour, X. Bai, J. P. Barron, S. W. Barwick, V. Baum, R. Bay, J. J. Beatty, J. Becker Tjus, K. -H. Becker , et al. (298 additional authors not shown)

Abstract: Lorentz symmetry is a fundamental space-time symmetry underlying the Standard Model of particle physics and gravity. However, unified theories, such as string theory, allow for violation of this symmetry. Thus, the discovery of Lorentz symmetry violation could be the first hint of these theories. Here, we use high-energy atmospheric neutrinos observed at the IceCube Neutrino Observatory to search… ▽ More Lorentz symmetry is a fundamental space-time symmetry underlying the Standard Model of particle physics and gravity. However, unified theories, such as string theory, allow for violation of this symmetry. Thus, the discovery of Lorentz symmetry violation could be the first hint of these theories. Here, we use high-energy atmospheric neutrinos observed at the IceCube Neutrino Observatory to search for anomalous neutrino oscillations as signals of Lorentz violation. The large range of neutrino energies and propagation baselines, together with high statistics, let us perform the most precise test of space-time symmetry in the neutrino sector to date. We find no evidence for Lorentz violation. This allows us to constrain the size of the dimension-four operator in the Standard-Model Extension for Lorentz violation to the $10^{-28}$ level and to set limits on higher dimensional operators of that theory. These are among the most stringent limits on Lorentz violation across all fields of physics. △ Less

Submitted 4 September, 2018; v1 submitted 11 September, 2017; originally announced September 2017.

Comments: Accepted version by Nature Physics, will be removed from here on Jan. 15, 2018. Journal Reference: Nature Physics (2018) s41567-018-0172-2

Search for sterile neutrino mixing using three years of IceCube DeepCore data

Authors: IceCube Collaboration, M. G. Aartsen, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, M. Ahrens, I. Al Samarai, D. Altmann, K. Andeen, T. Anderson, I. Ansseau, G. Anton, M. Archinger, C. Argüelles, J. Auffenberg, S. Axani, X. Bai, S. W. Barwick, V. Baum, R. Bay, J. J. Beatty, J. Becker Tjus, K. -H. Becker, S. BenZvi , et al. (283 additional authors not shown)

Abstract: We present a search for a light sterile neutrino using three years of atmospheric neutrino data from the DeepCore detector in the energy range of approximately $10-60~$GeV. DeepCore is the low-energy sub-array of the IceCube Neutrino Observatory. The standard three-neutrino paradigm can be probed by adding an additional light ($Δm_{41}^2 \sim 1 \mathrm{\ eV^2}$) sterile neutrino. Sterile neutrinos… ▽ More We present a search for a light sterile neutrino using three years of atmospheric neutrino data from the DeepCore detector in the energy range of approximately $10-60~$GeV. DeepCore is the low-energy sub-array of the IceCube Neutrino Observatory. The standard three-neutrino paradigm can be probed by adding an additional light ($Δm_{41}^2 \sim 1 \mathrm{\ eV^2}$) sterile neutrino. Sterile neutrinos do not interact through the standard weak interaction, and therefore cannot be directly detected. However, their mixing with the three active neutrino states leaves an imprint on the standard atmospheric neutrino oscillations for energies below 100 GeV. A search for such mixing via muon neutrino disappearance is presented here. The data are found to be consistent with the standard three neutrino hypothesis. Therefore we derive limits on the mixing matrix elements at the level of $|U_{\mu4}|^2 < 0.11 $ and $|U_{\tau4}|^2 < 0.15 $ (90% C.L.) for the sterile neutrino mass splitting $Δm_{41}^2 = 1.0$ eV$^2$. △ Less

Submitted 26 June, 2017; v1 submitted 16 February, 2017; originally announced February 2017.

Comments: 13 pages, 9 figures; changes made to match the published version

Journal ref: Phys. Rev. D 95, 112002 (2017)

Examining the origin of dark matter mass at colliders

Authors: Minho Kim, Hye-Sung Lee, Myeonghun Park, Mengchao Zhang

Abstract: As conventional dark matter scenarios have been probed extensively so far, the physics of a light dark matter charged under a new gauge group (dark gauge group) becomes one of new research avenues in many theoretical and experimental studies. We examine properties of a dark photon showering, the radiation process of light gauge bosons from energetic dark matter particles produced at the Large Hadr… ▽ More As conventional dark matter scenarios have been probed extensively so far, the physics of a light dark matter charged under a new gauge group (dark gauge group) becomes one of new research avenues in many theoretical and experimental studies. We examine properties of a dark photon showering, the radiation process of light gauge bosons from energetic dark matter particles produced at the Large Hadron Collider (LHC). This showering process provides different signatures at the LHC depending on the property of dark matter under the dark gauge group. We show that the LHC experiment can identify the chirality of a dark matter, which leads to understanding the mass origin of particles in the dark sector. △ Less

Submitted 30 August, 2018; v1 submitted 8 December, 2016; originally announced December 2016.

Comments: Added new figures, conclusions unchanged, published version

Report number: CTPU-16-45

Journal ref: Phys. Rev. D 98, 055027 (2018)

Search for the $0^{--}$ Glueball in $Υ(1S)$ and $Υ(2S)$ decays

Authors: Belle Collaboration, S. Jia, C. P. Shen, C. Z. Yuan, I. Adachi, H. Aihara, S. Al Said, D. M. Asner, T. Aushev, R. Ayad, V. Babu, I. Badhrees, A. M. Bakich, V. Bansal, E. Barberio, P. Behera, B. Bhuyan, J. Biswal, G. Bonvicini, A. Bozek, M. Bračko, T. E. Browder, D. Červenkov, P. Chang, V. Chekelian , et al. (146 additional authors not shown)

Abstract: We report the first search for the $J^{PC}=0^{--}$ glueball in $Υ(1S)$ and $Υ(2S)$ decays with data samples of $(102\pm2)$ million and $(158\pm4)$ million events, respectively, collected with the Belle detector. No significant signals are observed in any of the proposed production modes, and the 90\% credibility level upper limits on their branching fractions in $Υ(1S)$ and $Υ(2S)$ decays are obta… ▽ More We report the first search for the $J^{PC}=0^{--}$ glueball in $Υ(1S)$ and $Υ(2S)$ decays with data samples of $(102\pm2)$ million and $(158\pm4)$ million events, respectively, collected with the Belle detector. No significant signals are observed in any of the proposed production modes, and the 90\% credibility level upper limits on their branching fractions in $Υ(1S)$ and $Υ(2S)$ decays are obtained. The inclusive branching fractions of the $Υ(1S)$ and $Υ(2S)$ decays into final states with a $χ_{c1}$ are measured to be $\BR(Υ(1S)\to χ_{c1}+ anything) = (1.90\pm 0.43(stat.)\pm 0.14(syst.))\times 10^{-4}$ with an improved precision over prior measurements and $\BR(Υ(2S)\to χ_{c1}+ anything) = (2.24\pm 0.44(stat.)\pm 0.20(syst.))\times 10^{-4}$ for the first time. △ Less

Submitted 4 January, 2017; v1 submitted 21 November, 2016; originally announced November 2016.

Comments: 19 pages, 17 figures, Fig.10b was polished, but all the results unchanged. Paper was published in PRD

Report number: Belle Preprint 2016-12; KEK Preprint 2016-50

Journal ref: Phys. Rev. D 95, 012001 (2017)

Identifying a new particle with jet substructures

Authors: Chengcheng Han, Doojin Kim, Minho Kim, Kyoungchul Kong, Sung Hak Lim, Myeonghun Park

Abstract: We investigate a potential of measuring properties of a heavy resonance X, exploiting jet substructure techniques. Motivated by heavy higgs boson searches, we focus on the decays of X into a pair of (massive) electroweak gauge bosons. More specifically, we consider a hadronic Z boson, which makes it possible to determine properties of X at an earlier stage. For $m_X$ of O(1) TeV, two quarks from a… ▽ More We investigate a potential of measuring properties of a heavy resonance X, exploiting jet substructure techniques. Motivated by heavy higgs boson searches, we focus on the decays of X into a pair of (massive) electroweak gauge bosons. More specifically, we consider a hadronic Z boson, which makes it possible to determine properties of X at an earlier stage. For $m_X$ of O(1) TeV, two quarks from a Z boson would be captured as a "merged jet" in a significant fraction of events. The use of the merged jet enables us to consider a Z-induced jet as a reconstructed object without any combinatorial ambiguity. We apply a conventional jet substructure method to extract four-momenta of subjets from a merged jet. We find that jet substructure procedures may enhance features in some kinematic observables formed with subjets. Subjet momenta are fed into the matrix element associated with a given hypothesis on the nature of X, which is further processed to construct a matrix element method (MEM)-based observable. For both moderately and highly boosted Z bosons, we demonstrate that the MEM with current jet substructure techniques can be a very powerful discriminator in identifying the physics nature of X. We also discuss effects from choosing different jet sizes for merged jets and jet-grooming parameters upon the MEM analyses. △ Less

Submitted 15 March, 2017; v1 submitted 20 September, 2016; originally announced September 2016.

Comments: 36 pages, 11 figures, published in JHEP

Report number: CTPU-16-19, IPMU16-0133, PITT-PACC-1608, CERN-TH-2016-218

Journal ref: JHEP 01 (2017) 027

WIMP Dark Matter in Composite Higgs Models and the Dilaton Portal

Authors: Manki Kim, Seung J. Lee, Alberto Parolini

Abstract: We study under which conditions a scalar particle is a viable WIMP Dark Matter candidate with Higgs and dilaton interactions. The theory is a composite Higgs model with top partial compositeness where both the Higgs and the Dark Matter candidate arise as pseudo Goldstone boson of the coset SO(6)/SO(5) from a new physics sector. We highlight the role of the dilaton in direct and indirect searches.… ▽ More We study under which conditions a scalar particle is a viable WIMP Dark Matter candidate with Higgs and dilaton interactions. The theory is a composite Higgs model with top partial compositeness where both the Higgs and the Dark Matter candidate arise as pseudo Goldstone boson of the coset SO(6)/SO(5) from a new physics sector. We highlight the role of the dilaton in direct and indirect searches. We find that a Dark Matter particle with a mass around 200-400 GeV and a relatively light dilaton are a fair prediction of the model. △ Less

Submitted 17 February, 2016; originally announced February 2016.

Comments: 16 pages

Spin Resonance Effect on Pair Production in Rotating Electric Fields

Authors: Chul Min Kim, Sang Pyo Kim

Abstract: We advance a new analytical method for the Dirac equation in two-dimensional, homogeneous, time-dependent electric fields, which expresses the Cauchy problem of the two-component spinor and its derivative as the time-ordered integral of the transition rate of the time-dependent eigenspinors and the time-dependent energy eigenvalues. The in-vacuum at later times evolves from that at the past infini… ▽ More We advance a new analytical method for the Dirac equation in two-dimensional, homogeneous, time-dependent electric fields, which expresses the Cauchy problem of the two-component spinor and its derivative as the time-ordered integral of the transition rate of the time-dependent eigenspinors and the time-dependent energy eigenvalues. The in-vacuum at later times evolves from that at the past infinity and continuously make transitions between eigenspinors and between positive and negative frequencies of the time-dependent energy eigenvalues. The production of electron and positron pairs is given by the coefficient of the negative frequency at the future infinity which evolves from the positive frequency at the past infinity. In the adiabatic case when the time scale for the rotation of eigenspinors and energy eigenvalues is much longer than the electron Compton time, we find the spin-resonance effect on the pair production, which is simply determined by the spin rotation, the pair production and the continuous transmission coefficients between the energy eigenvalues without the change of spin states. △ Less

Submitted 17 January, 2016; v1 submitted 11 January, 2016; originally announced January 2016.

Comments: RevTex 10 pages; Eq. (56) corrected

Three-photon-annihilation contributions to positronium energies at order $m α^7$

Authors: Gregory S. Adkins, Minji Kim, Christian Parsons, Richard N. Fell

Abstract: Positronium spectroscopy (n=1 hyperfine splitting, n=2 fine structure, and the 1S-2S interval) has reached a precision of order 1 MHz. Vigorous ongoing efforts to improve the experimental results motivate the calculation of the positronium energy levels at order $m α^7$. In this work we present the result for a complete class of such contributions--those involving virtual annihilation of positroni… ▽ More Positronium spectroscopy (n=1 hyperfine splitting, n=2 fine structure, and the 1S-2S interval) has reached a precision of order 1 MHz. Vigorous ongoing efforts to improve the experimental results motivate the calculation of the positronium energy levels at order $m α^7$. In this work we present the result for a complete class of such contributions--those involving virtual annihilation of positronium to three photons in an intermediate state. We find an energy shift of $2.6216(11) m α^7/(n π)^3$ for the spin-triplet S state with principal quantum number n. △ Less

Submitted 28 July, 2015; originally announced July 2015.

Comments: 5 pages, 2 figures

Search for Resonances Decaying to Top and Bottom Quarks with the CDF Experiment

Authors: CDF Collaboration, T. Aaltonen, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, F. Anza', G. Apollinari, J. A. Appel, T. Arisawa, A. Artikov, J. Asaadi, W. Ashmanskas, B. Auerbach, A. Aurisano, F. Azfar, W. Badgett, T. Bae, A. Barbaro-Galtieri, V. E. Barnes, B. A. Barnett, P. Barria, P. Bartos, M. Bauce , et al. (380 additional authors not shown)

Abstract: We report on a search for charged massive resonances decaying to top ($t$) and bottom ($b$) quarks in the full data set of proton-antiproton collisions at center-of-mass energy of $\sqrt{s} = 1.96$ TeV collected by the CDF~II detector at the Tevatron, corresponding to an integrated luminosity of 9.5 $fb^{-1}$. No significant excess above the standard model (SM) background prediction is observed. W… ▽ More We report on a search for charged massive resonances decaying to top ($t$) and bottom ($b$) quarks in the full data set of proton-antiproton collisions at center-of-mass energy of $\sqrt{s} = 1.96$ TeV collected by the CDF~II detector at the Tevatron, corresponding to an integrated luminosity of 9.5 $fb^{-1}$. No significant excess above the standard model (SM) background prediction is observed. We set 95% Bayesian credibility mass-dependent upper limits on the heavy charged particle production cross section times branching ratio to $t b$. Using a SM extension with a $W^{\prime}$ and left-right-symmetric couplings as a benchmark model, we constrain the $W^{\prime}$ mass and couplings in the 300 to 900 GeV/$c^2$ range. The limits presented here are the most stringent for a charged resonance with mass in the range 300 -- 600 GeV/$c^2$ decaying to top and bottom quarks. △ Less

Submitted 7 April, 2015; originally announced April 2015.

Comments: submitted to Phys. Rev. Lett

Report number: FERMILAB-PUB-15-123-PPD

Journal ref: Phys. Rev. Lett. 115, 061801 (2015)

Measurement of the $\bar{B} \rightarrow X_s γ$ Branching Fraction with a Sum of Exclusive Decays

Authors: Belle Collaboration, T. Saito, A. Ishikawa, H. Yamamoto, A. Abdesselam, I. Adachi, H. Aihara, S. Al Said, K. Arinstein, D. M. Asner, T. Aushev, R. Ayad, A. M. Bakich, V. Bansal, B. Bhuyan, A. Bobrov, A. Bondar, G. Bonvicini, A. Bozek, M. Bračko, T. E. Browder, D. Červenkov, A. Chen, B. G. Cheon, K. Chilikin , et al. (157 additional authors not shown)

Abstract: We use 772$\times 10^6$ $B \bar{B}$ meson pairs collected at the $Υ(4S)$ resonance with the Belle detector to measure the branching fraction for $\bar{B} \rightarrow X_s γ$. Our measurement uses a sum-of-exclusives approach in which 38 of the hadronic final states with strangeness equal to $+1$, denoted by $X_s$, are reconstructed. The inclusive branching fraction for $M_{X_s}<$ 2.8 GeV/$c^2$, whi… ▽ More We use 772$\times 10^6$ $B \bar{B}$ meson pairs collected at the $Υ(4S)$ resonance with the Belle detector to measure the branching fraction for $\bar{B} \rightarrow X_s γ$. Our measurement uses a sum-of-exclusives approach in which 38 of the hadronic final states with strangeness equal to $+1$, denoted by $X_s$, are reconstructed. The inclusive branching fraction for $M_{X_s}<$ 2.8 GeV/$c^2$, which corresponds to a minimum photon energy of 1.9 GeV, is measured to be ${\cal B}(\bar{B} \rightarrow X_s γ)=(3.51\pm0.17\pm0.33)\times10^{-4}$, where the first uncertainty is statistical and the second is systematic. △ Less

Submitted 26 November, 2014; originally announced November 2014.

Comments: 13 pages, 21 figures, submitted to PRD

Report number: Belle Preprint 2014-15, KEK Preprint 2014-26

Journal ref: Phys. Rev. D 91, 052004 (2015)

Observation of the rare $B^0_s\toμ^+μ^-$ decay from the combined analysis of CMS and LHCb data

Authors: The CMS, LHCb Collaborations, :, V. Khachatryan, A. M. Sirunyan, A. Tumasyan, W. Adam, T. Bergauer, M. Dragicevic, J. Erö, M. Friedl, R. Frühwirth, V. M. Ghete, C. Hartl, N. Hörmann, J. Hrubec, M. Jeitler, W. Kiesenhofer, V. Knünz, M. Krammer, I. Krätschmer, D. Liko, I. Mikulec, D. Rabady, B. Rahbaran , et al. (2807 additional authors not shown)

Abstract: A joint measurement is presented of the branching fractions $B^0_s\toμ^+μ^-$ and $B^0\toμ^+μ^-$ in proton-proton collisions at the LHC by the CMS and LHCb experiments. The data samples were collected in 2011 at a centre-of-mass energy of 7 TeV, and in 2012 at 8 TeV. The combined analysis produces the first observation of the $B^0_s\toμ^+μ^-$ decay, with a statistical significance exceeding six sta… ▽ More A joint measurement is presented of the branching fractions $B^0_s\toμ^+μ^-$ and $B^0\toμ^+μ^-$ in proton-proton collisions at the LHC by the CMS and LHCb experiments. The data samples were collected in 2011 at a centre-of-mass energy of 7 TeV, and in 2012 at 8 TeV. The combined analysis produces the first observation of the $B^0_s\toμ^+μ^-$ decay, with a statistical significance exceeding six standard deviations, and the best measurement of its branching fraction so far. Furthermore, evidence for the $B^0\toμ^+μ^-$ decay is obtained with a statistical significance of three standard deviations. The branching fraction measurements are statistically compatible with SM predictions and impose stringent constraints on several theories beyond the SM. △ Less

Submitted 17 August, 2015; v1 submitted 17 November, 2014; originally announced November 2014.

Comments: Correspondence should be addressed to cms-and-lhcb-publication-committees@cern.ch

Report number: CERN-PH-EP-2014-220, CMS-BPH-13-007, LHCb-PAPER-2014-049

Journal ref: Nature 522, 68-72 (04 June 2015)

Measurement of indirect CP-violating asymmetries in $D^0\to K^+K^-$ and $D^0\to π^+π^-$ decays at CDF

Authors: CDF Collaboration, T. Aaltonen, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, J. A. Appel, T. Arisawa, A. Artikov, J. Asaadi, W. Ashmanskas, B. Auerbach, A. Aurisano, F. Azfar, W. Badgett, T. Bae, A. Barbaro-Galtieri, V. E. Barnes, B. A. Barnett, P. Barria, P. Bartos, M. Bauce, F. Bedeschi , et al. (377 additional authors not shown)

Abstract: We report a measurement of the indirect CP-violating asymmetries ($A_Γ$) between effective lifetimes of anticharm and charm mesons reconstructed in $D^0\to K^+ K^-$ and $D^0\to π^+π^-$ decays. We use the full data set of proton-antiproton collisions collected by the Collider Detector at Fermilab experiment and corresponding to $9.7$~fb$^{-1}$ of integrated luminosity. The strong-interaction decay… ▽ More We report a measurement of the indirect CP-violating asymmetries ($A_Γ$) between effective lifetimes of anticharm and charm mesons reconstructed in $D^0\to K^+ K^-$ and $D^0\to π^+π^-$ decays. We use the full data set of proton-antiproton collisions collected by the Collider Detector at Fermilab experiment and corresponding to $9.7$~fb$^{-1}$ of integrated luminosity. The strong-interaction decay $D^{*+}\to D^0π^+$ is used to identify the meson at production as $D^0$ or $\overline{D}^0$. We statistically subtract $D^0$ and $\overline{D}^0$ mesons originating from $b$-hadron decays and measure the yield asymmetry between anticharm and charm decays as a function of decay time. We measure $A_Γ(K^+K^-) = (-0.19 \pm 0.15 (stat) \pm 0.04 (syst))\%$ and $A_Γ(π^+π^-)= (-0.01 \pm 0.18 (stat) \pm 0.03 (syst))\%$. The results are consistent with the hypothesis of CP symmetry and their combination yields $A_Γ= (-0.12 \pm 0.12)\%$. △ Less

Submitted 6 January, 2015; v1 submitted 20 October, 2014; originally announced October 2014.

Comments: 8 pages, 3 figures, version published by Phys. Rev. D

Report number: FERMILAB-PUB-14-429-PPD

Journal ref: Phys. Rev. D 90, 111103 (2014)

Observation of $e^+e^- \to π^+ π^- π^0 χ_{bJ}$ and search for $X_b \to ωΥ(1S)$ at $\sqrt{s}\sim 10.867$ GeV

Authors: Belle Collaboration, X. H. He, C. P. Shen, C. Z. Yuan, Y. Ban, A. Abdesselam, I. Adachi, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, R. Ayad, S. Bahinipati, A. M. Bakich, V. Bansal, B. Bhuyan, A. Bondar, G. Bonvicini, A. Bozek, T. E. Browder, D. Červenkov, P. Chang, V. Chekelian, A. Chen, B. G. Cheon , et al. (136 additional authors not shown)

Abstract: The $e^+e^- \to π^+ π^- π^0 χ_{bJ}$ ($J=0,~1,~2$) processes are studied using a 118~fb$^{-1}$ data sample collected at a center-of-mass energy of 10.867 GeV, in the $Υ(10860)$ energy range, with the Belle detector. The $π^+ π^- π^0 χ_{b1}$, $π^+π^-π^0χ_{b2}$, $ωχ_{b1}$ signals and the evidence of $ωχ_{b2}$ are observed for the first time and the cross sections are measured. No significant… ▽ More The $e^+e^- \to π^+ π^- π^0 χ_{bJ}$ ($J=0,~1,~2$) processes are studied using a 118~fb$^{-1}$ data sample collected at a center-of-mass energy of 10.867 GeV, in the $Υ(10860)$ energy range, with the Belle detector. The $π^+ π^- π^0 χ_{b1}$, $π^+π^-π^0χ_{b2}$, $ωχ_{b1}$ signals and the evidence of $ωχ_{b2}$ are observed for the first time and the cross sections are measured. No significant $π^+π^-π^0χ_{b0}$ or $ωχ_{b0}$ signal is observed and 90\% confidence level upper limits on the cross sections for these two processes are obtained. In the $π^+π^-π^0$ invariant mass spectrum, significant non-$ω$ signals are also observed. We search for the $X(3872)$-like state with a hidden $b\bar{b}$ component (named $X_b$) decaying into $ωΥ(1S)$; no significant signal is observed with a mass between $10.55$ and $10.65$ GeV/$c^2$. △ Less

Submitted 11 September, 2014; v1 submitted 3 August, 2014; originally announced August 2014.

Comments: 7 pages, 3 figures, accepted for publication as a Letter in Physical Review Letters

Report number: Belle Preprint # 2014-11; KEK Preprint # 2014-18

Journal ref: Phys. Rev. Lett. 113, 142001 (2014)

The Physics of the B Factories

Authors: A. J. Bevan, B. Golob, Th. Mannel, S. Prell, B. D. Yabsley, K. Abe, H. Aihara, F. Anulli, N. Arnaud, T. Aushev, M. Beneke, J. Beringer, F. Bianchi, I. I. Bigi, M. Bona, N. Brambilla, J. B rodzicka, P. Chang, M. J. Charles, C. H. Cheng, H. -Y. Cheng, R. Chistov, P. Colangelo, J. P. Coleman, A. Drutskoy , et al. (2009 additional authors not shown)

Abstract: This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C. Please note that version 3 on the archive is the auxiliary… ▽ More This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C. Please note that version 3 on the archive is the auxiliary version of the Physics of the B Factories book. This uses the notation alpha, beta, gamma for the angles of the Unitarity Triangle. The nominal version uses the notation phi_1, phi_2 and phi_3. Please cite this work as Eur. Phys. J. C74 (2014) 3026. △ Less

Submitted 31 October, 2015; v1 submitted 24 June, 2014; originally announced June 2014.

Comments: 928 pages, version 3 (arXiv:1406.6311v3) corresponds to the alpha, beta, gamma version of the book, the other versions use the phi1, phi2, phi3 notation

Report number: SLAC-PUB-15968, KEK Preprint 2014-3

Journal ref: Eur. Phys. J. C74 (2014) 3026

Evidence for the decay B0 --> K+K-pi0

Authors: The Belle Collaboration, V. Gaur, G. B. Mohanty, T. Aziz, I. Adachi, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, A. M. Bakich, A. Bala, K. Belous, V. Bhardwaj, B. Bhuyan, G. Bonvicini, A. Bozek, M. Bracko, T. E. Browder, P. Chang, V. Chekelian, A. Chen, P. Chen, B. G. Cheon, R. Chistov, K. Cho , et al. (146 additional authors not shown)

Abstract: We report a search for charmless hadronic decays of neutral B mesons to the final state K+K-pi0. The results are based on a 711 fb^-1 data sample that contains 772x10^6 BB-bar pairs, and was collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We find the first evidence for this decay with a significance of 3.5 standard deviations and measure its br… ▽ More We report a search for charmless hadronic decays of neutral B mesons to the final state K+K-pi0. The results are based on a 711 fb^-1 data sample that contains 772x10^6 BB-bar pairs, and was collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We find the first evidence for this decay with a significance of 3.5 standard deviations and measure its branching fraction as BF(B0 --> K+K-pi0) = [2.17 +/- 0.60(stat) +/- 0.24 (syst)]x10^-6. △ Less

Submitted 1 June, 2013; v1 submitted 19 April, 2013; originally announced April 2013.

Comments: 7 pages, 6 figures, published in Phys. Rev. D

Report number: Belle Preprint 2013-5, KEK Preprint 2013-1

Journal ref: Phys. Rev. D 87, 091101(R) (2013)

Study of $e^+ e^- \to π^+ π^- J/ψ$ and Observation of a Charged Charmonium-like State at Belle

Authors: Belle Collaboration, Z. Q. Liu, C. P. Shen, C. Z. Yuan, I. Adachi, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, T. Aziz, A. M. Bakich, A. Bala, K. Belous, B. Bhuyan, M. Bischofberger, A. Bondar, G. Bonvicini, A. Bozek, M. Bračko, J. Brodzicka, T. E. Browder, P. Chang, V. Chekelian, A. Chen, P. Chen , et al. (163 additional authors not shown)

Abstract: The cross section for $e^+ e^- \to π^+ π^- J/ψ$ between 3.8 GeV and 5.5 GeV is measured with a 967 fb$^{-1}$ data sample collected by the Belle detector at or near the $Υ(nS)$ ($n = 1,\ 2,\ ...,\ 5$) resonances. The Y(4260) state is observed, and its resonance parameters are determined. In addition, an excess of $π^+ π^- J/ψ$ production around 4 GeV is observed. This feature can be described by a… ▽ More The cross section for $e^+ e^- \to π^+ π^- J/ψ$ between 3.8 GeV and 5.5 GeV is measured with a 967 fb$^{-1}$ data sample collected by the Belle detector at or near the $Υ(nS)$ ($n = 1,\ 2,\ ...,\ 5$) resonances. The Y(4260) state is observed, and its resonance parameters are determined. In addition, an excess of $π^+ π^- J/ψ$ production around 4 GeV is observed. This feature can be described by a Breit-Wigner parameterization with properties that are consistent with the Y(4008) state that was previously reported by Belle. In a study of $Y(4260) \to π^+ π^- J/ψ$ decays, a structure is observed in the $M(π^\pm\jpsi)$ mass spectrum with $5.2σ$ significance, with mass $M=(3894.5\pm 6.6\pm 4.5) {\rm MeV}/c^2$ and width $Γ=(63\pm 24\pm 26)$ MeV/$c^{2}$, where the errors are statistical and systematic, respectively. This structure can be interpreted as a new charged charmonium-like state. △ Less

Submitted 1 May, 2013; v1 submitted 30 March, 2013; originally announced April 2013.

Comments: 10 pages, 5 figures, 2 tables, accepted by Phys. Rev. Lett

Report number: Belle Preprint 2013-6, KEK Preprint 2013-2

Journal ref: Phys. Rev. Lett. 110, 252002 (2013)

Updated search for the standard model Higgs boson in events with jets and missing transverse energy using the full CDF data set

Authors: CDF Collaboration, T. Aaltonen, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, J. A. Appel, T. Arisawa, A. Artikov, J. Asaadi, W. Ashmanskas, B. Auerbach, A. Aurisano, F. Azfar, W. Badgett, T. Bae, A. Barbaro-Galtieri, V. E. Barnes, B. A. Barnett, P. Barria, P. Bartos, M. Bauce, F. Bedeschi , et al. (386 additional authors not shown)

Abstract: We present an updated search for the Higgs boson produced in association with a vector boson in the final state with missing transverse energy and two jets. We use the full CDF data set corresponding to an integrated luminosity of 9.45 fb${}^{-1}$ at a proton-antiproton center-of-mass energy of $\sqrt{s}=1.96$ TeV. New to this analysis is the inclusion of a $b$-jet identification algorithm specifi… ▽ More We present an updated search for the Higgs boson produced in association with a vector boson in the final state with missing transverse energy and two jets. We use the full CDF data set corresponding to an integrated luminosity of 9.45 fb${}^{-1}$ at a proton-antiproton center-of-mass energy of $\sqrt{s}=1.96$ TeV. New to this analysis is the inclusion of a $b$-jet identification algorithm specifically optimized for $H\to b\bar{b}$ searches. Across the Higgs boson mass range $90 \le m_H \le 150$ GeV$/c^2$, the expected 95% credibility level upper limits on the $V H$ production cross section times the $H\to b\bar{b}$ branching fraction are improved by an average of 14% relative to the previous analysis. At a Higgs boson mass of 125 GeV$/c^2$, the observed (expected) limit is 3.06 (3.33) times the standard model prediction, corresponding to one of the most sensitive searches to date in this final state. △ Less

Submitted 18 January, 2013; originally announced January 2013.

Comments: Submitted to Phys. Rev. D

Report number: FERMILAB-PUB-13-018-E

First observation of exclusive $Υ(1S)$ and $Υ(2S)$ decays into light hadrons

Authors: Belle Collaboration, C. P. Shen, C. Z. Yuan, T. Iijima, I. Adachi, H. Aihara, D. M. Asner, T. Aushev, A. M. Bakich, A. Bay, K. Belous, B. Bhuyan, M. Bischofberger, G. Bonvicini, A. Bozek, M. Bračko, T. E. Browder, M. -C. Chang, P. Chang, A. Chen, P. Chen, B. G. Cheon, K. Chilikin, R. Chistov, I. -S. Cho , et al. (131 additional authors not shown)

Abstract: Using samples of 102 million $Υ(1S)$ and 158 million $Υ(2S)$ events collected with the Belle detector, we study exclusive hadronic decays of these two bottomonium resonances to the three-body final states $φK^+ K^-$, $ωπ^+ π^-$ and $K^{\ast 0}(892) K^- π^+ $, and to the two-body Vector-Tensor ($φf_2'(1525)$, $ωf_2(1270)$, $ρa_2(1320)$ and $K^{\ast 0}(892) \bar{K}_2^{\ast 0}(1430) $) and Axial-vect… ▽ More Using samples of 102 million $Υ(1S)$ and 158 million $Υ(2S)$ events collected with the Belle detector, we study exclusive hadronic decays of these two bottomonium resonances to the three-body final states $φK^+ K^-$, $ωπ^+ π^-$ and $K^{\ast 0}(892) K^- π^+ $, and to the two-body Vector-Tensor ($φf_2'(1525)$, $ωf_2(1270)$, $ρa_2(1320)$ and $K^{\ast 0}(892) \bar{K}_2^{\ast 0}(1430) $) and Axial-vector-Pseudoscalar ($K_1(1270)^+ K^-$, $K_1(1400)^+ K^- $ and $b_1(1235)^+ π^- $) pairs. Signals are observed for the first time in the $Υ(1S) \to φK^+ K^-$, $ωπ^+ π^-$, $K^{\ast 0} K^- π^+$, $K^{\ast0} K_2^{\ast 0}$ and $Υ(2S) \to φK^+ K^-$, $K^{\ast 0} K^- π^+$ decay modes. Branching fractions are determined for all the processes, while 90% confidence level upper limits are established on the branching fractions for the modes with a statistical significance less than $3σ$. The ratios of the branching fractions of $Υ(2S)$ and $Υ(1S)$ decays into the same final state are used to test a perturbative QCD prediction for OZI suppressed bottomonium decays. △ Less

Submitted 24 July, 2012; v1 submitted 6 May, 2012; originally announced May 2012.

Comments: 7 pages, 5 figures, 1 table, accepted for publication as a Rapid Communication in Physical Review D

Report number: Belle Preprint 2012-14; KEK Preprint 2012-6

Journal ref: Phys. Rev. D 86, 031102(R) (2012)

Strong constraints on the rare decays Bs -> mu+ mu- and B0 -> mu+ mu-

Authors: LHCb collaboration, R. Aaij, C. Abellan Beteta, A. Adametz, B. Adeva, M. Adinolfi, C. Adrover, A. Affolder, Z. Ajaltouni, J. Albrecht, F. Alessio, M. Alexander, S. Ali, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves Jr, S. Amato, Y. Amhis, J. Anderson, R. B. Appleby, O. Aquines Gutierrez, F. Archilli, A. Artamonov, M. Artuso, E. Aslanides , et al. (585 additional authors not shown)

Abstract: A search for Bs -> mu+ mu- and B0 -> mu+ mu- decays is performed using 1.0 fb^-1 of pp collision data collected at \sqrt{s}=7 TeV with the LHCb experiment at the Large Hadron Collider. For both decays the number of observed events is consistent with expectation from background and Standard Model signal predictions. Upper limits on the branching fractions are determined to be BR(Bs -> mu+ mu-) < 4.… ▽ More A search for Bs -> mu+ mu- and B0 -> mu+ mu- decays is performed using 1.0 fb^-1 of pp collision data collected at \sqrt{s}=7 TeV with the LHCb experiment at the Large Hadron Collider. For both decays the number of observed events is consistent with expectation from background and Standard Model signal predictions. Upper limits on the branching fractions are determined to be BR(Bs -> mu+ mu-) < 4.5 (3.8) x 10^-9 and BR(B0 -> mu+ mu-) < 1.0 (0.81) x 10^-9 at 95% (90%) confidence level. △ Less

Submitted 26 April, 2012; v1 submitted 20 March, 2012; originally announced March 2012.

Comments: 2+6 pages; 4 figures; Accepted for publication in Physical Review Letters

Report number: CERN-PH-EP-2012-072, LHCb-PAPER-2012-007

Journal ref: Phys. Rev. Lett. 108, 231801 (2012)

Determination of the sign of the decay width difference in the B_s system

Authors: LHCb Collaboration, R. Aaij, C. Abellan Beteta, B. Adeva, M. Adinolfi, C. Adrover, A. Affolder, Z. Ajaltouni, J. Albrecht, F. Alessio, M. Alexander, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves Jr, S. Amato, Y. Amhis, J. Anderson, R. B. Appleby, O. Aquines Gutierrez, F. Archilli, L. Arrabito, A. Artamonov, M. Artuso, E. Aslanides, G. Auriemma , et al. (572 additional authors not shown)

Abstract: The interference between the K+K- S-wave and P-wave amplitudes in B_s -> J/psi K+K- decays with the K+K- pairs in the region around the phi(1020) resonance is used to determine the variation of the difference of the strong phase between these amplitudes as a function of K+K- invariant mass. Combined with the results from our CP asymmetry measurements in B_s -> J/psi phi decays, we conclude that th… ▽ More The interference between the K+K- S-wave and P-wave amplitudes in B_s -> J/psi K+K- decays with the K+K- pairs in the region around the phi(1020) resonance is used to determine the variation of the difference of the strong phase between these amplitudes as a function of K+K- invariant mass. Combined with the results from our CP asymmetry measurements in B_s -> J/psi phi decays, we conclude that the B_s mass eigenstate that is almost CP =+1 is lighter and decays faster than the mass eigenstate that is almost CP =-1. This determines the sign of the decay width difference DeltaGamma_s == Gamma_L -Gamma_H to be positive. Our result also resolves the ambiguity in the past measurements of the CP violating phase phi_s to be close to zero rather than pi. These conclusions are in agreement with the Standard Model expectations. △ Less

Submitted 19 July, 2012; v1 submitted 21 February, 2012; originally announced February 2012.

Comments: 7 pages, 4 figures, published on Physical Review Letters

Report number: CERN-PH-EP-2012-050; LHCb-PAPER-2011-028

Journal ref: Phys. Rev. Lett. 108, 241801 (2012)

Search for the rare decays Bs -> mu+ mu- and B0 -> mu+ mu-

Authors: LHCb Collaboration, R. Aaij, C. Abellan Beteta, B. Adeva, M. Adinolfi, C. Adrover, A. Affolder, Z. Ajaltouni, J. Albrecht, F. Alessio, M. Alexander, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves Jr, S. Amato, Y. Amhis, J. Anderson, R. B. Appleby, O. Aquines Gutierrez, F. Archilli, L. Arrabito, A. Artamonov, M. Artuso, E. Aslanides, G. Auriemma , et al. (568 additional authors not shown)

Abstract: A search for the decays Bs -> mu+ mu- and B0 -> mu+ mu- is performed with 0.37 fb^-1 of pp collisions at sqrt{s} = 7 TeV collected by the LHCb experiment in 2011. The upper limits on the branching fractions are BR (Bs -> mu+ mu-) < 1.6 x 10^-8 and BR(B0 -> mu+ mu-) < 3.6 x 10^-9 at 95% confidence level. A combination of these results with the LHCb limits obtained with the 2010 dataset leads to BR… ▽ More A search for the decays Bs -> mu+ mu- and B0 -> mu+ mu- is performed with 0.37 fb^-1 of pp collisions at sqrt{s} = 7 TeV collected by the LHCb experiment in 2011. The upper limits on the branching fractions are BR (Bs -> mu+ mu-) < 1.6 x 10^-8 and BR(B0 -> mu+ mu-) < 3.6 x 10^-9 at 95% confidence level. A combination of these results with the LHCb limits obtained with the 2010 dataset leads to BR (Bs -> mu+ mu-) < 1.4 x 10^-8 and BR (B0 -> mu+ mu-) < 3.2 x 10^-9 at 95% confidence level. △ Less

Submitted 15 January, 2012; v1 submitted 7 December, 2011; originally announced December 2011.

Comments: 6+19 pages, 9 figures; minor changes; matches version accepted in Phys. Lett. B

Report number: CERN-PH-EP-2011-186; LHCb-PAPER-2011-025

Journal ref: Physics Letters B 708 (2012) 55-67

Measurements of the Branching fractions for $B_(s) -> D_(s)πππ$ and $Λ_b^0 -> Λ_c^+πππ$

Authors: LHCb Collaboration, R. Aaij, B. Adeva, M. Adinolfi, C. Adrover, A. Affolder, Z. Ajaltouni, J. Albrecht, F. Alessio, M. Alexander, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves Jr, S. Amato, Y. Amhis, J. Anderson, R. B. Appleby, O. Aquines Gutierrez, F. Archilli, L. Arrabito, A. Artamonov, M. Artuso, E. Aslanides, G. Auriemma, S. Bachmann , et al. (544 additional authors not shown)

Abstract: Branching fractions of the decays $H_b\to H_cπ^-π^+π^-$ relative to $H_b\to H_cπ^-$ are presented, where $H_b$ ($H_c$) represents B^0-bar($D^+$), $B^-$ ($D^0$), B_s^0-bar ($D_s^+$) and $Λ_b^0$ ($Λ_c^+$). The measurements are performed with the LHCb detector using 35${\rm pb^{-1}}$ of data collected at $\sqrt{s}=7$ TeV. The ratios of branching fractions are measured to be B(B^0-bar -> D^+π^-π^+π^… ▽ More Branching fractions of the decays $H_b\to H_cπ^-π^+π^-$ relative to $H_b\to H_cπ^-$ are presented, where $H_b$ ($H_c$) represents B^0-bar($D^+$), $B^-$ ($D^0$), B_s^0-bar ($D_s^+$) and $Λ_b^0$ ($Λ_c^+$). The measurements are performed with the LHCb detector using 35${\rm pb^{-1}}$ of data collected at $\sqrt{s}=7$ TeV. The ratios of branching fractions are measured to be B(B^0-bar -> D^+π^-π^+π^-)/ B(B^0-bar -> D^+π^-) = 2.38\pm0.11\pm0.21 B(B^- -> D^0π^-π^+π^-) / B(B^- -> D^0π^-) = 1.27\pm0.06\pm0.11 B(B_s^0-bar -> D_s^+π^-π^+π^-) / B(B_s^0-bar -> D_s^+π^-) = 2.01\pm0.37\pm0.20 B(Λ_b^0->Λ_c^+π^-π^+π^-) / B(Λ_b^0 -> Λ_c^+π^-) = 1.43\pm0.16\pm0.13. We also report measurements of partial decay rates of these decays to excited charm hadrons. These results are of comparable or higher precision than existing measurements. △ Less

Submitted 30 September, 2011; originally announced September 2011.

Comments: 26 pages, 9 figures

Report number: LHCb-PAPER-2011-016; CERN-PH-EP-2011-151

Journal ref: Phys.Rev.D84:092001,2011; Erratum: PhysRevD.85.039904 (2012)

Search for the rare decays Bs -->mumu and Bd -->mumu

Authors: LHCb Collaboration, R. Aaij, B. Adeva, M. Adinolfi, C. Adrover, A. Affolder, Z. Ajaltouni, J. Albrecht, F. Alessio, M. Alexander, P. Alvarez Cartelle, A. A. Alves Jr, S. Amato, Y. Amhis, J. Amoraal, J. Anderson, R. B. Appleby, O. Aquines Gutierrez, L. Arrabito, M. Artuso, E. Aslanides, G. Auriemma, S. Bachmann, D. S. Bailey, V. Balagura , et al. (520 additional authors not shown)

Abstract: A search for the decays Bs-->mumu and Bd-->mumu is performed with about 37 pb^{-1} of pp collisions at sqrt{s} = 7 TeV collected by the LHCb experiment at the Large Hadron Collider at CERN. The observed numbers of events are consistent with the background expectations. The resulting upper limits on the branching ratios are BR(Bs-->mumu) < 5.6 x 10^{-8} and BR(Bd-->mumu) <1.5 x 10^{-8} at 95% confi… ▽ More A search for the decays Bs-->mumu and Bd-->mumu is performed with about 37 pb^{-1} of pp collisions at sqrt{s} = 7 TeV collected by the LHCb experiment at the Large Hadron Collider at CERN. The observed numbers of events are consistent with the background expectations. The resulting upper limits on the branching ratios are BR(Bs-->mumu) < 5.6 x 10^{-8} and BR(Bd-->mumu) <1.5 x 10^{-8} at 95% confidence level. △ Less

Submitted 23 July, 2012; v1 submitted 12 March, 2011; originally announced March 2011.

Comments: 18 pages, 5 figures

Report number: LHCb-PAPER-2011-004; CERN-PH-EP-2011-029

Journal ref: Physics Letters B699 (2011) 330-340

First observation of Bs -> J/psi f0(980) decays

Authors: The LHCb Collaboration, R. Aaij, B. Adeva, M. Adinolfi, C. Adrover, A. Affolder, Z. Ajaltouni, J. Albrecht, F. Alessio, M. Alexander, P. Alvarez Cartelle, A. A. Alves Jr, S. Amato, Y. Amhis, J. Amoraal, J. Anderson, R. B. Appleby, O. Aquines Gutierrez, L. Arrabito, M. Artuso, E. Aslanides, G. Auriemma, S. Bachmann, D. S. Bailey, V. Balagura , et al. (523 additional authors not shown)

Abstract: Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the hadronic decay Bs -> J/psi f0(980) is observed. This CP eigenstate mode could be used to measure mixing-induced CP violation in the B_s system. Using a fit to the pi+ pi- mass spectrum with interfering resonances gives R_{f0/phi} = [Gamma(Bs -> J/psi f0, f0 -> pi+ pi-)]/[Gamma(Bs -> J/p… ▽ More Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the hadronic decay Bs -> J/psi f0(980) is observed. This CP eigenstate mode could be used to measure mixing-induced CP violation in the B_s system. Using a fit to the pi+ pi- mass spectrum with interfering resonances gives R_{f0/phi} = [Gamma(Bs -> J/psi f0, f0 -> pi+ pi-)]/[Gamma(Bs -> J/psi phi, phi -> K+K-)] = 0.252^{+0.046+0.027}_{-0.032-0.033}, where the uncertainties are statistical and systematic, respectively. △ Less

Submitted 2 March, 2011; v1 submitted 1 February, 2011; originally announced February 2011.

Comments: 11 pages, 6 figures. To be published in Physics Letters B

Report number: LHCb-PAPER-2011-002; CERN-PH-EP-2011-011

Journal ref: Phys.Lett.B698:115-122,2011

Measurement of sigma(pp -> b anti-b X) at \sqrt(s)=7 TeV in the forward region

Authors: LHCb Collaboration, R. Aaij, C. Abellan Beteta, B. Adeva, M. Adinolfi, C. Adrover, A. Affolder, M. Agari, Z. Ajaltouni, J. Albrecht, F. Alessio, M. Alexander, M. Alfonsi, P. Alvarez Cartelle, A. A. Alves Jr, S. Amato, Y. Amhis, J. Amoraal, J. Anderson, R. Antunes Nobrega, R. Appleby, O. Aquines Gutierrez, A. Arefyev, L. Arrabito, M. Artuso , et al. (606 additional authors not shown)

Abstract: Decays of b hadrons into final states containing a D0 meson and a muon are used to measure the b anti-b production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. In the pseudorapidity interval 2 < eta < 6 and integrated over all transverse momenta we find that the average cross-section to produce b-flavoured or anti-b-flavoured hadrons is (75.3 +/- 5.4 +/… ▽ More Decays of b hadrons into final states containing a D0 meson and a muon are used to measure the b anti-b production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. In the pseudorapidity interval 2 < eta < 6 and integrated over all transverse momenta we find that the average cross-section to produce b-flavoured or anti-b-flavoured hadrons is (75.3 +/- 5.4 +/- 13.0) microbarns. △ Less

Submitted 7 October, 2010; v1 submitted 14 September, 2010; originally announced September 2010.

Comments: 11 pages, 5 figures, to be published in Physics Lett. B; v2 minor changes

Report number: LHCb-PAPER-2010-002; CERN-PH-EP-2010-029

Journal ref: Phys.Lett.B694:209-216,2010

Direct and Indirect Detection of Neutralino Dark Matter and Collider Signatures in an $SO(10)$ Model with Two Intermediate Scales

Authors: Manuel Drees, Ju Min Kim, Eun-Kyung Park

Abstract: We investigate the detectability of neutralino Dark Matter via direct and indirect searches as well as collider signatures of an $SO(10)$ model with two intermediate scales. We compare the direct Dark Matter detection cross section and the muon flux due to neutralino annihilation in the Sun that we obtain in this model with mSUGRA predictions and with the sensitivity of current and future experime… ▽ More We investigate the detectability of neutralino Dark Matter via direct and indirect searches as well as collider signatures of an $SO(10)$ model with two intermediate scales. We compare the direct Dark Matter detection cross section and the muon flux due to neutralino annihilation in the Sun that we obtain in this model with mSUGRA predictions and with the sensitivity of current and future experiments. In both cases, we find that the detectability improves as the model deviates more from mSUGRA. In order to study collider signatures, we choose two benchmark points that represent the main phenomenological features of the model: a lower value of $|μ|$ and reduced third generation sfermion masses due to extra Yukawa coupling contributions in the Renormalization Group Equations, and increased first and second generation slepton masses due to new gaugino loop contributions. We show that measurements at the LHC can distinguish this model from mSUGRA in both cases, by counting events containing leptonically decaying $Z^0$ bosons, heavy neutral Higgs bosons, or like--sign lepton pairs. △ Less

Submitted 10 June, 2010; originally announced June 2010.

Comments: 21 pages, 16 figures

Journal ref: Phys.Rev.D82:095005,2010