Showing 1–50 of 52 results for author: Chung, H S

$Υ(nS)$ Production within Jets at the LHC

Authors: Taewook Ha, Hee Sok Chung, Daekyoung Kang, Yunlu Wang, Haixiang Zhu

Abstract: Heavy quarkonium production inside jets offers a sensitive probe of QCD dynamics and bound-state formation mechanisms. While recent studies demonstrate that charmonium-in-jet observables effectively discriminate among competing nonrelativistic QCD (NRQCD) long-distance matrix element (LDME) sets, whether this discriminating power persists in the bottomonium sector remains an open question. Here, w… ▽ More Heavy quarkonium production inside jets offers a sensitive probe of QCD dynamics and bound-state formation mechanisms. While recent studies demonstrate that charmonium-in-jet observables effectively discriminate among competing nonrelativistic QCD (NRQCD) long-distance matrix element (LDME) sets, whether this discriminating power persists in the bottomonium sector remains an open question. Here, we present the first phenomenological study of $Υ(1S)$, $Υ(2S)$, and $Υ(3S)$ production inside jets using the fragmenting jet function (FJF) framework at next-to-leading order (NLO), incorporating DGLAP evolution, threshold resummation, and feeddown contributions from higher bottomonium states. In sharp contrast to charmonium, we find that bottomonium-in-jet momentum-fraction ($z_H$) distributions exhibit a universal shape that is remarkably insensitive to the choice of LDME sets. We show that this universality stems from the strong dominance of the S-wave spin-triplet color-octet ($^3S_1^{[8]}$) production mechanism reinforced by $χ_b$ feeddown transitions. Our predictions capture both the characteristic large-$z_H$ peak and the spectral broadening with increasing jet transverse momentum observed in recent CMS measurements. These results establish a clear physical distinction between charmonium and bottomonium fragmentation inside jets, providing a theoretical benchmark for future high-precision measurements at the LHC. △ Less

Submitted 19 August, 2026; originally announced August 2026.

Comments: 30 pages, 11 figures

Resummation of threshold double logarithms in quarkonium fragmentation functions

Authors: Hee Sok Chung, U-Rae Kim, Jungil Lee

Abstract: We develop a formalism for resumming threshold double logarithms that appear in fragmentation functions for production of heavy quarkonia. Threshold singularities appear in fixed-order calculations of quarkonium fragmentation functions in the nonrelativistic QCD factorization formalism due to radiation of soft gluons. Because of this, fixed-order quarkonium fragmentation functions are not positive… ▽ More We develop a formalism for resumming threshold double logarithms that appear in fragmentation functions for production of heavy quarkonia. Threshold singularities appear in fixed-order calculations of quarkonium fragmentation functions in the nonrelativistic QCD factorization formalism due to radiation of soft gluons. Because of this, fixed-order quarkonium fragmentation functions are not positive definite, and can lead to unphysically negative cross sections. This problem can be resolved by resumming threshold logarithms to all orders in perturbation theory, which renders the fragmentation functions finite and ensures the positivity of cross sections. We present a detailed derivation of the resummation formalism and derive the formula for resummed quarkonium fragmentation functions, which can be computed entirely within perturbation theory without the need for nonperturbative model functions. △ Less

Submitted 27 April, 2026; v1 submitted 12 February, 2026; originally announced February 2026.

Comments: 61 pages, 4 figures, minor revisions, version published in Phys. Rev. D

Journal ref: Phys. Rev. D 113, 074029 (2026)

$J/ψ$ Production Within Jets at the EIC

Authors: Yunlu Wang, Hee Sok Chung, Taewook Ha, Daekyoung Kang, U-Rae Kim

Abstract: We present theoretical predictions for the transverse-momentum distribution of $J/ψ$ produced within jets at the upcoming Electron-Ion Collider (EIC). Utilizing the semi-inclusive fragmenting jet function (FJF) framework, our calculation achieves next-to-leading order (NLO) accuracy in the strong coupling and leading-logarithmic (LL) accuracy by resumming both collinear and threshold logarithms. I… ▽ More We present theoretical predictions for the transverse-momentum distribution of $J/ψ$ produced within jets at the upcoming Electron-Ion Collider (EIC). Utilizing the semi-inclusive fragmenting jet function (FJF) framework, our calculation achieves next-to-leading order (NLO) accuracy in the strong coupling and leading-logarithmic (LL) accuracy by resumming both collinear and threshold logarithms. In contrast to the gluon-dominated regime of the LHC, EIC photoproduction is characterized by an enhanced quark-initiated component, offering a complementary probe into the charmonium production mechanism governed by nonperturbative long-distance matrix elements (LDMEs). We examine the impact of representative LDME sets, demonstrating the EIC's distinct discriminating power for the mechanisms. We find that quark contributions are particularly significant in the small momentum fraction region. This region is also shown to be sensitive to both the jet radius $R$ and the experimental muon identification criteria for the $J/ψ\to μ^+μ^-$ decay channel. These findings establish quarkonium-in-jet observables at the EIC as a vital, independent probe for constraining the production mechanisms and advancing our understanding of heavy quarkonium formation. △ Less

Submitted 9 January, 2026; originally announced January 2026.

Comments: 18 pages, 6 figures

NRQCD Re-Confronts LHCb Data on Quarkonium Production within Jets

Authors: Yunlu Wang, Daekyoung Kang, Hee Sok Chung

Abstract: We compare LHCb measurements of $J/ψ$ and $ψ(2S)$ transverse momentum distributions within jets with QCD calculations, which may be crucial in understanding the quarkonium production mechanism. Our theoretical calculations are based on the fragmenting jet function formalism, while the nonperturbative formation of quarkonia is described by the nonrelativistic QCD factorization formalism. We include… ▽ More We compare LHCb measurements of $J/ψ$ and $ψ(2S)$ transverse momentum distributions within jets with QCD calculations, which may be crucial in understanding the quarkonium production mechanism. Our theoretical calculations are based on the fragmenting jet function formalism, while the nonperturbative formation of quarkonia is described by the nonrelativistic QCD factorization formalism. We include the newest refinements in the perturbative calculation including resummation of threshold and DGLAP logarithms. We find that the $ψ(2S)$ data has the potential to discriminate between the different production mechanisms proposed in the literature. △ Less

Submitted 25 July, 2025; originally announced July 2025.

Comments: 7 pages, 1 table, 4 figures; Comments welcome

Hadroproduction data support tetraquark hypothesis for $χ_{c1} (3872)$

Authors: Wai Kin Lai, Hee Sok Chung

Abstract: We show that the recently proposed tetraquark hypothesis for the nature of the $χ_{c1}(3872)$ results in a formalism for inclusive production rates that has no unknown parameters. We employ this formalism to compute hadroproduction rates of $χ_{c1}(3872)$ at the Large Hadron Collider, which agree with measured prompt and nonprompt cross sections. Thus we find that the tetraquark hypothesis for… ▽ More We show that the recently proposed tetraquark hypothesis for the nature of the $χ_{c1}(3872)$ results in a formalism for inclusive production rates that has no unknown parameters. We employ this formalism to compute hadroproduction rates of $χ_{c1}(3872)$ at the Large Hadron Collider, which agree with measured prompt and nonprompt cross sections. Thus we find that the tetraquark hypothesis for $χ_{c1}(3872)$ is well supported by hadroproduction data. △ Less

Submitted 24 August, 2025; v1 submitted 11 May, 2025; originally announced May 2025.

Comments: 7 pages, 3 figures, minor revisions, references added, data for figures available as ancillary file, version to appear in Phys. Rev. D

Resummation of threshold double logarithms in inclusive production of heavy quarkonium

Authors: Hee Sok Chung, U-Rae Kim, Jungil Lee

Abstract: We resum threshold double logarithms in inclusive production of heavy quarkonium that arise from singularities near the boundary of phase space. This resolves the catastrophic failure in the conventional approach based on fixed-order perturbation theory calculations in nonrelativistic QCD, where quarkonium cross sections at large transverse momentum can turn negative. We identify the root cause of… ▽ More We resum threshold double logarithms in inclusive production of heavy quarkonium that arise from singularities near the boundary of phase space. This resolves the catastrophic failure in the conventional approach based on fixed-order perturbation theory calculations in nonrelativistic QCD, where quarkonium cross sections at large transverse momentum can turn negative. We identify the root cause of this negative cross section problem as the appearance of threshold logarithms in radiative corrections, and resum them to all orders in perturbation theory at the leading double logarithmic level. We find that resummation of threshold logarithms is imperative for describing measured $J/ψ$ production rates at large transverse momentum. △ Less

Submitted 10 November, 2025; v1 submitted 17 January, 2025; originally announced January 2025.

Comments: 11 pages, 3 figures, includes ancillary files for data in Phys.Rev.Lett. 134, 071902 (2025), talk given by Hee Sok Chung at the XVIth Quark Confinement and the Hadron Spectrum, Aug. 18-24 2024, Cairns, Australia, version published in PoS

Resummation of threshold double logarithms in hadroproduction of heavy quarkonium

Authors: Hee Sok Chung, U-Rae Kim, Jungil Lee

Abstract: We resum threshold double logarithms that appear in inclusive production of heavy quarkonium. This resolves the catastrophic failure of fixed-order perturbation theory where quarkonium cross sections at large transverse momentum can turn negative due to large radiative corrections. We find that resummation is imperative for describing measured prompt production rates of $J/ψ$ at large transverse m… ▽ More We resum threshold double logarithms that appear in inclusive production of heavy quarkonium. This resolves the catastrophic failure of fixed-order perturbation theory where quarkonium cross sections at large transverse momentum can turn negative due to large radiative corrections. We find that resummation is imperative for describing measured prompt production rates of $J/ψ$ at large transverse momentum. △ Less

Submitted 21 February, 2025; v1 submitted 8 August, 2024; originally announced August 2024.

Comments: 7 pages, 3 figures, minor revisions, version published in Physical Review Letters

Journal ref: Phys. Rev. Lett. 134, 071902 (2025)

Color-octet nonrelativistic QCD matrix elements for heavy quarkonium decays in the refined Gribov-Zwanziger theory

Authors: Hee Sok Chung

Abstract: We determine color-octet nonrelativistic QCD matrix elements for quarkonium decays from moments of the two-point correlation function of the QCD field-strength tensor computed in the refined Gribov-Zwanziger theory. We find that a tree-level calculation in the refined Gribov-Zwanziger theory can give a suitable description of the QCD field-strength correlation function at both short and long dista… ▽ More We determine color-octet nonrelativistic QCD matrix elements for quarkonium decays from moments of the two-point correlation function of the QCD field-strength tensor computed in the refined Gribov-Zwanziger theory. We find that a tree-level calculation in the refined Gribov-Zwanziger theory can give a suitable description of the QCD field-strength correlation function at both short and long distances, which leads to moments that are infrared finite and can be properly renormalized. By using the color-octet matrix elements we obtain, we quantitatively improve the nonrelativistic effective field theory description of quarkonium decay rates, especially for the $χ_{QJ}$ and $η_Q$ states, where $Q =c$ or $b$. △ Less

Submitted 5 March, 2024; v1 submitted 16 December, 2023; originally announced December 2023.

Comments: 21 pages, 3 figures, minor revisions, version published in Phys. Rev. D

Journal ref: Phys. Rev. D 109, 054001 (2024)

Mesonic decay constant and mass ratios and the conformal window

Authors: Hee Sok Chung, Daniel Nogradi

Abstract: Two particular ratios related to mesons are proposed for the study of the conformal window in $SU(3)$ gauge theory and fundamental fermions. Lattice and other studies indicate that the lower end, $N_f^*$, is at around 7 - 13 flavors which is a wide range without a clear consensus. Here we propose the decay constant to mass ratios of mesons, $f_{PS,V} / m_V$, as a proxy since below the conformal wi… ▽ More Two particular ratios related to mesons are proposed for the study of the conformal window in $SU(3)$ gauge theory and fundamental fermions. Lattice and other studies indicate that the lower end, $N_f^*$, is at around 7 - 13 flavors which is a wide range without a clear consensus. Here we propose the decay constant to mass ratios of mesons, $f_{PS,V} / m_V$, as a proxy since below the conformal window lattice studies have shown that they are largely $N_f$-independent while at the upper end of the conformal window they are vanishing. The drop from the non-zero constant value to zero at $N_f = 16.5$ might be indicative of $N_f^*$. We compute $f_V / m_V$ to N$^3$LO and $f_{PS} / m_V$ to NNLO order in (p)NRQCD. The results are unambiguously reliable just below $N_f = 16.5$, hence the results are expanded á la Banks-Zaks in $\varepsilon = 16.5 - N_f$. The convergence properties of the series and matching with the non-perturbative infinite volume, continuum and chiral extrapolated lattice results at $N_f = 10$ suggest that the perturbative results might be reliable down to $N_f = 12$. A sudden drop is observed at $N_f = 12$ and $N_f = 13$ in $f_V / m_V$ and $f_{PS} / m_V$, respectively. △ Less

Submitted 14 November, 2023; originally announced November 2023.

Comments: The 40th International Symposium on Lattice Field Theory (Lattice 2023), July 31st - August 4th, 2023, Fermi National Accelerator Laboratory

Resummation and renormalization of kinematical effects in inclusive $P$-wave quarkonium production

Authors: Hee Sok Chung

Abstract: We investigate the renormalization properties of the shape function formalism for inclusive production of $P$-wave heavy quarkonia, which arises from resumming a class of corrections coming from kinematical effects associated with the motion of the heavy quark and antiquark pair relative to the quarkonium. Such kinematical effects are encoded in the nonperturbative shape functions, which are norma… ▽ More We investigate the renormalization properties of the shape function formalism for inclusive production of $P$-wave heavy quarkonia, which arises from resumming a class of corrections coming from kinematical effects associated with the motion of the heavy quark and antiquark pair relative to the quarkonium. Such kinematical effects are encoded in the nonperturbative shape functions, which are normalized to the corresponding nonrelativistic QCD long-distance matrix elements. By using the known ultraviolet divergences in the matrix elements, we derive the large-momentum asymptotic behavior of the shape functions. This strongly constrains the form of the shape functions and significantly reduces the dependence on the nonperturbative model. Based on these results we show that the shape function formalism at loop level can be useful in taming the threshold logarithms at large transverse momentum, and at small transverse momentum the kinematical corrections reduce the sizes of $χ_c$ and $χ_b$ cross sections which may improve agreement with measurements. △ Less

Submitted 3 July, 2023; v1 submitted 30 March, 2023; originally announced March 2023.

Comments: 51 pages, 11 figures, minor revisions, version published in JHEP

Journal ref: JHEP07(2023)007

The $f_\varrho / m_\varrho$ and $f_π/ m_\varrho$ ratios and the conformal window

Authors: Hee Sok Chung, Daniel Nogradi

Abstract: The $f_\varrho / m_\varrho$ ratio is calculated at N$^3$LO order within perturbative (p)NRQCD with $N_f$ flavors of mass degenerate fermions. The massless limit of the ratio is expanded á la Banks-Zaks in $ε= 16.5 - N_f$ leading to reliable predictions close to the upper end of the conformal window. The comparison of the NNLO and N$^3$LO results indicate that the Banks-Zaks expansion may be reliab… ▽ More The $f_\varrho / m_\varrho$ ratio is calculated at N$^3$LO order within perturbative (p)NRQCD with $N_f$ flavors of mass degenerate fermions. The massless limit of the ratio is expanded á la Banks-Zaks in $ε= 16.5 - N_f$ leading to reliable predictions close to the upper end of the conformal window. The comparison of the NNLO and N$^3$LO results indicate that the Banks-Zaks expansion may be reliable down to twelve flavors. Previous lattice calculations combined with the KSRF relations provide us with the same ratio for the range $2 \leq N_f \leq 10$. Assuming a monotonous dependence on $N_f$ leads to an estimate for the lower end of the conformal window, $N_f^* \simeq 12$, by matching the non-perturbative and our perturbative results. In any case an abrupt change is observed in $f_\varrho / m_\varrho$ at twelve flavors. As a cross-check we also consider the $f_π/ m_\varrho$ ratio for which lattice results are also available. The perturbative calculation at present is only at the NNLO level which is insufficient for a reliable and robust matching between the low $N_f$ and high $N_f$ regions. Nonetheless, using the relative size of the N$^3$LO correction of $f_\varrho / m_\varrho$ for estimating the same for $f_π/ m_\varrho$ leads to the estimate $N_f^* \simeq 13$. △ Less

Submitted 15 May, 2023; v1 submitted 13 February, 2023; originally announced February 2023.

Comments: 8 pages, 2 figures, published version, references added

Quarkonium production and polarization: where do we stand?

Authors: Hee Sok Chung

Abstract: We review the current status of heavy quarkonium production phenomenology based on nonrelativistic effective field theories, focusing on spin-triplet $S$-wave states such as $J/ψ$, $ψ(2S)$, and $Υ$. We present some representative examples for heavy quarkonium production mechanisms proposed in the literature, which vary significantly depending on the choice of data employed in analyses. We then dis… ▽ More We review the current status of heavy quarkonium production phenomenology based on nonrelativistic effective field theories, focusing on spin-triplet $S$-wave states such as $J/ψ$, $ψ(2S)$, and $Υ$. We present some representative examples for heavy quarkonium production mechanisms proposed in the literature, which vary significantly depending on the choice of data employed in analyses. We then discuss the rôle of polarization in discriminating between the different possible scenarios for quarkonium production. Other observables that may be useful in pinpointing the production mechanism are also introduced, such as the $η_c$ production, associated production of $J/ψ$ plus a gauge boson, and $J/ψ$ production at the Electron-Ion Collider. △ Less

Submitted 18 November, 2022; originally announced November 2022.

Comments: 12 pages, 3 tables, talk given by Hee Sok Chung at The XVth Quark confinement and the Hadron spectrum, 1-6 August 2022, Stavanger, Norway

Inclusive production of $J/ψ$, $ψ(2S)$, and $Υ$ states in pNRQCD

Authors: Nora Brambilla, Hee Sok Chung, Antonio Vairo, Xiang-Peng Wang

Abstract: Under some assumptions on the hierarchy of relevant energy scales, we compute the nonrelativistic QCD (NRQCD) long-distance matrix elements (LDMEs) for inclusive production of $J/ψ$, $ψ(2S)$, and $Υ$ states based on the potential NRQCD (pNRQCD) effective field theory. Based on the pNRQCD formalism, we obtain expressions for the LDMEs in terms of the quarkonium wavefunctions at the origin and unive… ▽ More Under some assumptions on the hierarchy of relevant energy scales, we compute the nonrelativistic QCD (NRQCD) long-distance matrix elements (LDMEs) for inclusive production of $J/ψ$, $ψ(2S)$, and $Υ$ states based on the potential NRQCD (pNRQCD) effective field theory. Based on the pNRQCD formalism, we obtain expressions for the LDMEs in terms of the quarkonium wavefunctions at the origin and universal gluonic correlators, which do not depend on the heavy quark flavor or the radial excitation. This greatly reduces the number of nonperturbative unknowns and substantially enhances the predictive power of the nonrelativistic effective field theory formalism. We obtain improved determinations of the LDMEs for $J/ψ$, $ψ(2S)$, and $Υ$ states thanks to the universality of the gluonic correlators, and obtain phenomenological results for cross sections and polarizations at large transverse momentum that agree well with measurements at the LHC. △ Less

Submitted 1 April, 2023; v1 submitted 31 October, 2022; originally announced October 2022.

Comments: 50 pages, 17 figures, 3 tables, minor revisions, version published in JHEP

Report number: TUM-EFT 170/22

Journal ref: JHEP03(2023)242

Production and polarization of $S$-wave quarkonia in potential nonrelativistic QCD

Authors: Nora Brambilla, Hee Sok Chung, Antonio Vairo, Xiang-Peng Wang

Abstract: Based on the potential nonrelativistic QCD formalism, we compute the nonrelativistic QCD long-distance matrix elements (LDMEs) for inclusive production of $S$-wave heavy quarkonia. This greatly reduces the number of nonperturbative unknowns and brings in a substantial enhancement in the predictive power of the nonrelativistic QCD factorization formalism. We obtain improved determinations of the LD… ▽ More Based on the potential nonrelativistic QCD formalism, we compute the nonrelativistic QCD long-distance matrix elements (LDMEs) for inclusive production of $S$-wave heavy quarkonia. This greatly reduces the number of nonperturbative unknowns and brings in a substantial enhancement in the predictive power of the nonrelativistic QCD factorization formalism. We obtain improved determinations of the LDMEs and find cross sections and polarizations of $J/ψ$, $ψ(2S)$, and excited $Υ$ states that agree well with LHC data. Our results may have important implications in pinning down the heavy quarkonium production mechanism. △ Less

Submitted 27 June, 2022; v1 submitted 15 March, 2022; originally announced March 2022.

Comments: 6 pages, 2 figures, 2 tables, minor corrections, version published as a Letter in Phys. Rev. D

Report number: TUM-EFT 168/22

Journal ref: Phys. Rev. D 105, L111503 (2022)

QCD Static Force in Gradient Flow

Authors: Nora Brambilla, Hee Sok Chung, Antonio Vairo, Xiang-Peng Wang

Abstract: We compute the QCD static force and potential using gradient flow at next-to-leading order in the strong coupling. The static force is the spatial derivative of the static potential: it encodes the QCD interaction at both short and long distances. While on the one side the static force has the advantage of being free of the $O(Λ_{\rm QCD})$ renormalon affecting the static potential when computed i… ▽ More We compute the QCD static force and potential using gradient flow at next-to-leading order in the strong coupling. The static force is the spatial derivative of the static potential: it encodes the QCD interaction at both short and long distances. While on the one side the static force has the advantage of being free of the $O(Λ_{\rm QCD})$ renormalon affecting the static potential when computed in perturbation theory, on the other side its direct lattice QCD computation suffers from poor convergence. The convergence can be improved by using gradient flow, where the gauge fields in the operator definition of a given quantity are replaced by flowed fields at flow time $t$, which effectively smear the gauge fields over a distance of order $\sqrt{t}$, while they reduce to the QCD fields in the limit $t \to 0$. Based on our next-to-leading order calculation, we explore the properties of the static force for arbitrary values of $t$, as well as in the $t \to 0$ limit, which may be useful for lattice QCD studies. △ Less

Submitted 1 February, 2022; v1 submitted 15 November, 2021; originally announced November 2021.

Comments: 24 pages, 8 figures, 1 table

Report number: TUM-EFT 152/21

Journal ref: JHEP01(2022)184

Inclusive Hadroproduction of $P$-wave Heavy Quarkonia in pNRQCD

Authors: Hee Sok Chung

Abstract: We compute NRQCD long-distance matrix elements that appear in the inclusive production cross sections of $P$-wave heavy quarkonia in the framework of potential NRQCD. The formalism developed in this work applies to strongly coupled charmonia and bottomonia. This makes possible the determination of color-octet NRQCD long-distance matrix elements without relying on measured cross section data, which… ▽ More We compute NRQCD long-distance matrix elements that appear in the inclusive production cross sections of $P$-wave heavy quarkonia in the framework of potential NRQCD. The formalism developed in this work applies to strongly coupled charmonia and bottomonia. This makes possible the determination of color-octet NRQCD long-distance matrix elements without relying on measured cross section data, which has not been possible so far. We obtain results for inclusive production cross sections of $χ_{cJ}$ and $χ_{bJ}$ at the LHC, which are in good agreement with measurements. △ Less

Submitted 11 November, 2021; originally announced November 2021.

Comments: 8 pages, 5 figures, contribution to the proceedings of A Virtual Tribute to Quark Confinement and the Hadron Spectrum (vConf21), August 2nd-6th 2021

Report number: TUM-EFT 158/21

$P$-wave quarkonium wavefunctions at the origin in the $\overline{\rm MS}$ scheme

Authors: Hee Sok Chung

Abstract: We compute $P$-wave quarkonium wavefunctions at the origin in the $\overline{\rm MS}$ scheme based on nonrelativistic effective field theories. We include nonperturbative effects from the long-distance behaviors of the potential, while the short-distance behaviors are determined from perturbative QCD. We obtain $\overline{\rm MS}$-renormalized $P$-wave quarkonium wavefunctions at the origin that h… ▽ More We compute $P$-wave quarkonium wavefunctions at the origin in the $\overline{\rm MS}$ scheme based on nonrelativistic effective field theories. We include nonperturbative effects from the long-distance behaviors of the potential, while the short-distance behaviors are determined from perturbative QCD. We obtain $\overline{\rm MS}$-renormalized $P$-wave quarkonium wavefunctions at the origin that have the correct scale dependences that are expected from factorization formalisms, so that the dependences on the scheme and scale cancel in physical quantities. This greatly reduces the theoretical uncertainties associated with scheme and scale dependences in predictions of decay and production rates. Based on the calculation of the $P$-wave wavefunctions at the origin in this work, we make first-principles predictions of electromagnetic decay rates and exclusive electromagnetic production rates of $P$-wave charmonia and bottomonia, and compare them with measurements. △ Less

Submitted 5 October, 2021; v1 submitted 29 June, 2021; originally announced June 2021.

Comments: 80 pages, 5 figures, 3 tables, minor revisions, version published in JHEP

Report number: TUM-EFT 145/21

Journal ref: JHEP09(2021)195

Inclusive Production of Heavy Quarkonia in pNRQCD

Authors: Nora Brambilla, Hee Sok Chung, Antonio Vairo

Abstract: We develop a formalism for computing inclusive production cross sections of heavy quarkonia based on the nonrelativistic QCD and the potential nonrelativistic QCD effective field theories. Our formalism applies to strongly coupled quarkonia, which include excited charmonium and bottomonium states. Analogously to heavy quarkonium decay processes, we express nonrelativistic QCD long-distance matrix… ▽ More We develop a formalism for computing inclusive production cross sections of heavy quarkonia based on the nonrelativistic QCD and the potential nonrelativistic QCD effective field theories. Our formalism applies to strongly coupled quarkonia, which include excited charmonium and bottomonium states. Analogously to heavy quarkonium decay processes, we express nonrelativistic QCD long-distance matrix elements in terms of quarkonium wavefunctions at the origin and universal gluonic correlators. Our expressions for the long-distance matrix elements are valid up to corrections of order $1/N_c^2$. These expressions enhance the predictive power of the nonrelativistic effective field theory approach to inclusive production processes by reducing the number of nonperturbative unknowns, and make possible first-principle determinations of long-distance matrix elements once the gluonic correlators are known. Based on this formalism, we compute the production cross sections of $P$-wave charmonia and bottomonia at the LHC, and find good agreement with measurements. △ Less

Submitted 8 September, 2021; v1 submitted 17 June, 2021; originally announced June 2021.

Comments: 39 pages, 8 figures, minor revisions, numerical results corrected, version published in JHEP

Report number: TUM-EFT 139/20

Journal ref: JHEP09(2021)032

Inclusive Hadroproduction of $P$-Wave Heavy Quarkonia in Potential Nonrelativistic QCD

Authors: Nora Brambilla, Hee Sok Chung, Antonio Vairo

Abstract: We compute the color-singlet and color-octet nonrelativistic QCD (NRQCD) long-distance matrix elements for inclusive production of $P$-wave quarkonia in the framework of potential NRQCD. In this way, the color-octet NRQCD long-distance matrix element can be determined without relying on measured cross section data, which has not been possible so far. We obtain inclusive cross sections of $χ_{cJ}$… ▽ More We compute the color-singlet and color-octet nonrelativistic QCD (NRQCD) long-distance matrix elements for inclusive production of $P$-wave quarkonia in the framework of potential NRQCD. In this way, the color-octet NRQCD long-distance matrix element can be determined without relying on measured cross section data, which has not been possible so far. We obtain inclusive cross sections of $χ_{cJ}$ and $χ_{bJ}$ at the LHC, which are in good agreement with data. In principle, the formalism developed in this Letter can be applied to all inclusive production processes of heavy quarkonia. △ Less

Submitted 25 February, 2021; v1 submitted 15 July, 2020; originally announced July 2020.

Comments: 6 pages, 2 figures, minor revisions, version published in Physical Review Letters

Report number: TUM-EFT 138/20

Journal ref: Phys. Rev. Lett. 126, 082003 (2021)

${\overline{\rm MS}}$ renormalization of $S$-wave quarkonium wavefunctions at the origin

Authors: Hee Sok Chung

Abstract: We compute $S$-wave quarkonium wavefunctions at the origin in the $\overline{\rm MS}$ scheme based on nonrelativistic effective field theories. We include the effects of nonperturbative long-distance behaviors of the potentials, while we determine the short-distance behaviors of the potentials in perturbative QCD. We obtain $\overline{\rm MS}$-renormalized quarkonium wavefunctions at the origin th… ▽ More We compute $S$-wave quarkonium wavefunctions at the origin in the $\overline{\rm MS}$ scheme based on nonrelativistic effective field theories. We include the effects of nonperturbative long-distance behaviors of the potentials, while we determine the short-distance behaviors of the potentials in perturbative QCD. We obtain $\overline{\rm MS}$-renormalized quarkonium wavefunctions at the origin that have the correct scale dependences that are expected from perturbative QCD, so that the scale dependences cancel in physical quantities. Based on the calculation of the wavefunctions at the origin, we make model-independent predictions of decay constants and electromagnetic decay rates of $S$-wave charmonia and bottomonia, and compare them with measurements. We find that the poor convergence of perturbative QCD corrections are substantially improved when we include corrections to the wavefunctions at the origin in the calculation of decay constants and decay rates. △ Less

Submitted 10 December, 2020; v1 submitted 3 July, 2020; originally announced July 2020.

Comments: 62 pages, 9 figures, 2 tables, typos corrected, version published in JHEP

Report number: TUM-EFT 135/20

Journal ref: JHEP12(2020)065

FeynOnium: Using FeynCalc for automatic calculations in Nonrelativistic Effective Field Theories

Authors: Nora Brambilla, Hee Sok Chung, Vladyslav Shtabovenko, Antonio Vairo

Abstract: We present new results on FeynOnium, an ongoing project to develop a general purpose software toolkit for semi-automatic symbolic calculations in nonrelativistic Effective Field Theories (EFTs). Building upon FeynCalc, an existing Mathematica package for symbolic evaluation of Feynman diagrams, we have created a powerful framework for automatizing calculations in nonrelativistic EFTs (NREFTs) at t… ▽ More We present new results on FeynOnium, an ongoing project to develop a general purpose software toolkit for semi-automatic symbolic calculations in nonrelativistic Effective Field Theories (EFTs). Building upon FeynCalc, an existing Mathematica package for symbolic evaluation of Feynman diagrams, we have created a powerful framework for automatizing calculations in nonrelativistic EFTs (NREFTs) at tree- and 1-loop level. This is achieved by exploiting the novel features of FeynCalc that support manipulations of Cartesian tensors, Pauli matrices and nonstandard loop integrals. Additional operations that are common in nonrelativistic EFT calculations are implemented in a dedicated add-on called FeynOnium. While our current focus is on EFTs for strong interactions of heavy quarks, extensions to other systems that admit a nonrelativistic EFT description are planned for the future. All our codes are open-source and publicly available. Furthermore, we provide several example calculations that demonstrate how FeynOnium can be employed to reproduce known results from the literature. △ Less

Submitted 30 November, 2020; v1 submitted 27 June, 2020; originally announced June 2020.

Comments: 61 pages, no figures, matches the version accepted in JHEP. To obtain the programs, see https://github.com/FeynCalc

Report number: TUM-EFT 75/15, TTP19-021

Journal ref: JHEP 11 (2020) 130

Decay and electromagnetic production of strongly coupled quarkonia in pNRQCD

Authors: Nora Brambilla, Hee Sok Chung, Daniel Müller, Antonio Vairo

Abstract: We improve the pNRQCD approach to annihilation processes of heavy quarkonium and make first pNRQCD predictions for exclusive electromagnetic production of heavy quarkonium. We consider strongly coupled quarkonia, i.e., quarkonia that are not Coulombic bound states. Possible strongly coupled quarkonia include excited charmonium and bottomonium states. For these, pNRQCD provides expressions for the… ▽ More We improve the pNRQCD approach to annihilation processes of heavy quarkonium and make first pNRQCD predictions for exclusive electromagnetic production of heavy quarkonium. We consider strongly coupled quarkonia, i.e., quarkonia that are not Coulombic bound states. Possible strongly coupled quarkonia include excited charmonium and bottomonium states. For these, pNRQCD provides expressions for the decay and exclusive electromagnetic production NRQCD matrix elements that depend on the wavefunctions at the origin and few universal gluon field correlators. We compute electromagnetic decay widths and exclusive production cross sections, and inclusive decay widths into light hadrons for $P$-wave quarkonia at relative order $v^2$ and leading order, respectively. We also compute the decay widths of $2S$ and $3S$ bottomonium states into lepton pairs and their ratios with the inclusive widths into light hadrons at relative order $v^2$. △ Less

Submitted 17 April, 2020; v1 submitted 18 February, 2020; originally announced February 2020.

Comments: 50 pages, 4 figures, 12 tables, minor revisions, version published in JHEP

Report number: TUM-EFT 126/19

Journal ref: JHEP04(2020)095

Analytic Fourier-Feynman transforms via the series approximation

Authors: Hyun Soo Chung

Abstract: In this paper, we first establish an evaluation formula to calculate Wiener integrals of functionals on Wiener space. We then apply our evaluation formula to carry out very easily calculating for the analytic Fourier-Feynman transform of the functionals. Some examples are furnished to illustrate the usefulness of the evaluation formula. Finally, using the evaluation formula, we establish the serie… ▽ More In this paper, we first establish an evaluation formula to calculate Wiener integrals of functionals on Wiener space. We then apply our evaluation formula to carry out very easily calculating for the analytic Fourier-Feynman transform of the functionals. Some examples are furnished to illustrate the usefulness of the evaluation formula. Finally, using the evaluation formula, we establish the series approximation for the analytic Fourier-Feynman transform. △ Less

Submitted 29 December, 2019; originally announced December 2019.

MSC Class: 28C20; 60J65; 46G05

New method for fitting coefficients in standard model effective theory

Authors: Geoffrey T. Bodwin, Hee Sok Chung

Abstract: We present an alternative method for carrying out a principal-component analysis of Wilson coefficients in standard model effective field theory (SMEFT). The method is based on singular-value decomposition (SVD). The SVD method provides information about the sensitivity of experimental observables to physics beyond the standard model that is not accessible in the Fisher-information method. In prin… ▽ More We present an alternative method for carrying out a principal-component analysis of Wilson coefficients in standard model effective field theory (SMEFT). The method is based on singular-value decomposition (SVD). The SVD method provides information about the sensitivity of experimental observables to physics beyond the standard model that is not accessible in the Fisher-information method. In principle, the SVD method can also have computational advantages over diagonalization of the Fisher information matrix. We demonstrate the SVD method by applying it to the dimension-6 coefficients for the process of top-quark decay to a $b$ quark and a $W$ boson and use this example to illustrate some pitfalls in widely used fitting procedures. We also outline an iterative procedure for applying the SVD method to dimension-8 SMEFT coefficients. △ Less

Submitted 2 July, 2020; v1 submitted 20 December, 2019; originally announced December 2019.

Comments: 27 pages, 3 tables, minor clarifications, corrections, improvements in notation. Corresponds to published version

Report number: TUM-EFT 134/19

Journal ref: Phys. Rev. D 101, 115039 (2020)

Covariant calculation of a two-loop test of nonrelativistic QCD factorization

Authors: Geoffrey T. Bodwin, Hee Sok Chung, June-Haak Ee, U-Rae Kim, Jungil Lee

Abstract: We test the nonrelativistic QCD factorization conjecture for inclusive quarkonium production at two loops by carrying out a covariant calculation of the nonrelativistic quantum chromodynamics (NRQCD) long-distance matrix element (LDME) for a heavy-quark pair in an $S$-wave, color-octet state to fragment into a heavy-quark pair in a color-singlet state of arbitrary orbital angular momentum. The NRQ… ▽ More We test the nonrelativistic QCD factorization conjecture for inclusive quarkonium production at two loops by carrying out a covariant calculation of the nonrelativistic quantum chromodynamics (NRQCD) long-distance matrix element (LDME) for a heavy-quark pair in an $S$-wave, color-octet state to fragment into a heavy-quark pair in a color-singlet state of arbitrary orbital angular momentum. The NRQCD factorization conjecture for the universality of the LDME requires that infrared divergences that it contains be independent of the direction of the Wilson line that appears in its definition. We find this to be the case in our calculation. The results of our calculation differ in some respects from those of a previous calculation that was carried out by Nayak, Qiu, and Sterman using light-cone methods. We have identified the sources of some of these differences. The results of both calculations are consistent with the NRQCD factorization conjecture. However, the general principle that underlies this confirmation of NRQCD factorization at two-loop order has yet to be revealed. △ Less

Submitted 21 May, 2020; v1 submitted 12 October, 2019; originally announced October 2019.

Comments: 74 pages, 9 figures, minor reorganization and clarifications, typos corrected, published version

Journal ref: Phys. Rev. D 101, 096011 (2020)

Order $v^4$ corrections to Higgs boson decay into $J/ψ+ γ$

Authors: Nora Brambilla, Hee Sok Chung, Wai Kin Lai, Vladyslav Shtabovenko, Antonio Vairo

Abstract: The process $H \to J/ψ+ γ$, where $H$ is the Higgs particle, provides a way to probe the size and the sign of the Higgs-charm coupling. In order to improve the theoretical control of the decay rate, we compute order $v^4$ corrections to the decay rate based on the nonrelativistic QCD factorization formalism. The perturbative calculation is carried out by using automated computer codes. We also res… ▽ More The process $H \to J/ψ+ γ$, where $H$ is the Higgs particle, provides a way to probe the size and the sign of the Higgs-charm coupling. In order to improve the theoretical control of the decay rate, we compute order $v^4$ corrections to the decay rate based on the nonrelativistic QCD factorization formalism. The perturbative calculation is carried out by using automated computer codes. We also resum logarithms of the ratio of the masses of the Higgs boson and the $J/ψ$ to all orders in the strong coupling constant $α_s$ to next-to-leading logarithmic accuracy. In our numerical result for the decay rate, we improve the theoretical uncertainty, while our central value is in agreement with previous studies within errors. We also present numerical results for $H \to Υ(nS) + γ$ for $n=1,2$, and 3, which turn out to be extremely sensitive to the Higgs bottom coupling. △ Less

Submitted 26 September, 2019; v1 submitted 15 July, 2019; originally announced July 2019.

Comments: 40 pages, 2 figures, minor corrections, version published in Phys. Rev. D

Report number: TUM-EFT 123/19, P3H-19-016, TTP19-019

Journal ref: Phys. Rev. D 100, 054038 (2019)

Pseudoscalar Quarkonium+gamma Production at NLL+NLO accuracy

Authors: Hee Sok Chung, June-Haak Ee, Daekyoung Kang, U-Rae Kim, Jungil Lee, Xiang-Peng Wang

Abstract: We consider the exclusive pseudoscalar heavy-quarkonium (eta_{b,c}) production in association with a photon at future lepton colliders where the collider energies of O(10^2) GeV are far greater than the quarkonium mass. At these energies, the logarithm of mass to collision energy becomes increasingly large hence its resummation becomes particularly important. By making use of the light-cone-distri… ▽ More We consider the exclusive pseudoscalar heavy-quarkonium (eta_{b,c}) production in association with a photon at future lepton colliders where the collider energies of O(10^2) GeV are far greater than the quarkonium mass. At these energies, the logarithm of mass to collision energy becomes increasingly large hence its resummation becomes particularly important. By making use of the light-cone-distribution factorization formula, we resum the logarithms up to next-to-leading-logarithmic accuracy (NLL) that corresponds to order-alpha_s accuracy. We combine the resummed result with a known fixed-order result at next-to-leading order (NLO) such that both resummed-logarithmic terms and non-logarithmic terms are included at the same order in alpha_s. This allowed us to provide reliable predictions at accuracies of order alpha_s ranging from relatively low energies near quarkonium mass to the collider energies of O(10^2) GeV. We also include the leading relativistic corrections resummed at leading-logarithmic accuracy. Our prediction at the Belle energy is comparable with fixed-order predictions in literatures while it shows a large deviation from a recent Belle's upper limit by about 4 sigma. Finally, we make predictions for the energies of future Z and Higgs factories. △ Less

Submitted 21 October, 2019; v1 submitted 7 June, 2019; originally announced June 2019.

Comments: 26 pages, 4 figures, JHEP version

Journal ref: J. High Energ. Phys. (2019) 2019: 162

Review of quarkonium production: status and prospects

Authors: Hee Sok Chung

Abstract: Production cross sections of heavy quarkonia are considered as useful tools to study various aspects of QCD. We have entered a new era of quarkonium production phenomenology, with the help of new measurements from the LHC giving access to more varieties of observables, and recent theoretical developments that provided us a better understanding of the short-distance process in which quarkonia are p… ▽ More Production cross sections of heavy quarkonia are considered as useful tools to study various aspects of QCD. We have entered a new era of quarkonium production phenomenology, with the help of new measurements from the LHC giving access to more varieties of observables, and recent theoretical developments that provided us a better understanding of the short-distance process in which quarkonia are produced. With a more concrete understanding of perturbative corrections and a prolific collection of data, a satisfactory description of the quarkonium production mechanism might now be within reach. Unfortunately, the exact mechanism of quarkonium production still remains elusive. Even analyses based on the same formalism can lead to different descriptions of the production process and give contradicting predictions of processes involving heavy quarkonia. This implies that there are much more physics yet to be understood and much work yet to be done in quarkonium production phenomenology. In this paper, we review the current status of theoretical approaches and discuss possible strategies that may improve our understanding of heavy quarkonium production. △ Less

Submitted 29 November, 2018; originally announced November 2018.

Comments: 13 pages, 1 table, talk given by Hee Sok Chung at XIII Quark Confinement and the Hadron Spectrum, 31 July - 6 August 2018, Maynooth University, Ireland

Report number: TUM-EFT 115/18

Inclusive decays of $η_c$ and $η_b$ at NNLO with large $n_f$ resummation

Authors: Nora Brambilla, Hee Sok Chung, Javad Komijani

Abstract: Based on the nonrelativistic QCD factorization theorem, we resum QCD corrections to the inclusive decay rate of $η_c$ and $η_b$ in the large-$n_f$ limit using bubble chain resummation. By employing dimensional regularization, we show explicitly the cancellation of the infrared renormalon ambiguity in the factorization formula at leading order in $v$ in the large-$n_f$ limit, where $v$ is the typic… ▽ More Based on the nonrelativistic QCD factorization theorem, we resum QCD corrections to the inclusive decay rate of $η_c$ and $η_b$ in the large-$n_f$ limit using bubble chain resummation. By employing dimensional regularization, we show explicitly the cancellation of the infrared renormalon ambiguity in the factorization formula at leading order in $v$ in the large-$n_f$ limit, where $v$ is the typical heavy quark velocity inside the meson. We also make predictions of the ratio of the inclusive decay rate to the decay rate into two photons. By comparing our results with a fixed-order calculation we conclude that resummation of QCD corrections is crucial in making an unambiguous prediction. We also find significant corrections beyond the large-$n_f$ limit for the decay of $η_c$, which may imply that QCD corrections need to be resummed beyond the large-$n_f$ limit to make an accurate prediction of the decay rate. △ Less

Submitted 21 December, 2018; v1 submitted 5 October, 2018; originally announced October 2018.

Comments: 41 pages, 6 figures, minor corrections, reference added, version published in Phys. Rev. D

Report number: TUM-EFT 109/18

Journal ref: Phys. Rev. D 98, 114020 (2018)

QoE Enhancement Schemes for Video in Converged OFDMA Wireless Networks and EPONs

Authors: Divya Chitimalla, Biswanath Mukherjee, Massimo Tornatore, Sang-Soo Lee, Han-Hyub Lee, Soomyung Park, Hwan Seok Chung

Abstract: Bandwidth requirements of both wireless and wired clients in access networks continue to increase rapidly, primarily due to the growth of video traffic. Application awareness can be utilized in access networks to optimize quality of experience (QoE) of end clients. In this study, we utilize information at the client-side application (e.g., video resolution) to achieve superior resource allocation… ▽ More Bandwidth requirements of both wireless and wired clients in access networks continue to increase rapidly, primarily due to the growth of video traffic. Application awareness can be utilized in access networks to optimize quality of experience (QoE) of end clients. In this study, we utilize information at the client-side application (e.g., video resolution) to achieve superior resource allocation that improves user QoE. We emphasize optimizing QoE of the system rather than quality of service (QoS), as user satisfaction directly relies on QoE and optimizing QoS does not necessarily optimize QoE, as shown in this study. We propose application-aware resource-allocation schemes on an Ethernet passive optical network (EPON), which supports wireless (utilizing orthogonal frequency division multiple access) and wired clients running video-conference applications. Numerical results show that the application-aware resource-allocation schemes improve QoE for video-conference applications for wired and wireless clients. △ Less

Submitted 16 June, 2018; originally announced June 2018.

Comments: Journal of Optical Communications and Networking, 2018

Implementation of Maxwell's equations in the reconstruction of the magnetic field in the $g-2$ storage ring

Authors: Geoffrey T. Bodwin, Hee Sok Chung, Jose Repond

Abstract: We present a method for implementing the constraints that are implied by Maxwell's equations in fits to measurements of the magnetic field in the muon storage ring of the $g-2$ experiment. The method that we use makes use of toroidal-harmonic solutions of Laplace's equation. We point out that the fitting problem can be approximated well as a linear-algebra problem. We have devised an efficient alg… ▽ More We present a method for implementing the constraints that are implied by Maxwell's equations in fits to measurements of the magnetic field in the muon storage ring of the $g-2$ experiment. The method that we use makes use of toroidal-harmonic solutions of Laplace's equation. We point out that the fitting problem can be approximated well as a linear-algebra problem. We have devised an efficient algorithm for the linear-algebra problem that makes it possible to find a solution for $10^5$ data points and $10^4$ harmonics in less than an hour on a present-day desktop computer. We illustrate our method by applying it to some preliminary measurements of the magnetic field in the $g-2$ storage ring. △ Less

Submitted 3 July, 2019; v1 submitted 30 May, 2018; originally announced May 2018.

Comments: 23 pages, 10 figures, minor changes, version published in JINST

Report number: TUM-EFT 110/18

Journal ref: JINST 14 (2019) P07002

Addendum: New approach to the resummation of logarithms in Higgs-boson decays to a vector quarkonium plus a photon [Phys. Rev. D 95, 054018 (2017)]

Authors: Geoffrey T. Bodwin, Hee Sok Chung, June-Haak Ee, Jungil Lee

Abstract: In this addendum to Phys.\ Rev.\ D {\bf 95}, 054018 (2017) we recompute the rates for the decays of the Higgs boson to a vector quarkonium plus a photon, where the vector quarkonium is $J/ψ$, $Υ(1S)$, $Υ(2S)$, or $Υ(3S)$. We correct an error in the Abel-Padé summation formula that was used to carry out the evolution of the quarkonium light-cone distribution amplitude in Phys.\ Rev.\ D {\bf 95}, 05… ▽ More In this addendum to Phys.\ Rev.\ D {\bf 95}, 054018 (2017) we recompute the rates for the decays of the Higgs boson to a vector quarkonium plus a photon, where the vector quarkonium is $J/ψ$, $Υ(1S)$, $Υ(2S)$, or $Υ(3S)$. We correct an error in the Abel-Padé summation formula that was used to carry out the evolution of the quarkonium light-cone distribution amplitude in Phys.\ Rev.\ D {\bf 95}, 054018 (2017). We also correct an error in the scale of quarkonium wave function at the origin in Phys.\ Rev.\ D {\bf 95}, 054018 (2017) and introduce several additional refinements in the calculation. △ Less

Submitted 6 January, 2018; v1 submitted 28 September, 2017; originally announced October 2017.

Comments: 7 pages, [v2] Abel-Pade summation formula corrected, [v3] PRD version

Journal ref: Phys. Rev. D 96, 116014 (2017)

$Z$-boson decays to a vector quarkonium plus a photon

Authors: Geoffrey T. Bodwin, Hee Sok Chung, June-Haak Ee, Jungil Lee

Abstract: We compute the decay rates for the processes $Z\to V+γ$, where $Z$ is the $Z$ boson, $γ$ is the photon, and $V$ is one of the vector quarkonia $J/ψ$ or $Υ(nS)$, with $n=1$, $2$, or $3$. Our computations include corrections through relative orders $α_s$ and $v^2$ and resummations of logarithms of $m_Z^2/m_Q^2$, to all orders in $α_s$, at NLL accuracy. ($v$ is the velocity of the heavy quark $Q$ or… ▽ More We compute the decay rates for the processes $Z\to V+γ$, where $Z$ is the $Z$ boson, $γ$ is the photon, and $V$ is one of the vector quarkonia $J/ψ$ or $Υ(nS)$, with $n=1$, $2$, or $3$. Our computations include corrections through relative orders $α_s$ and $v^2$ and resummations of logarithms of $m_Z^2/m_Q^2$, to all orders in $α_s$, at NLL accuracy. ($v$ is the velocity of the heavy quark $Q$ or the heavy antiquark $\bar{Q}$ in the quarkonium rest frame, and $m_Z$ and $m_Q$ are the masses of $Z$ and $Q$, respectively.) Our calculations are the first to include both the order-$α_s$ correction to the light-cone distributions amplitude and the resummation of logarithms of $m_Z^2/m_Q^2$ and are the first calculations for the $Υ(2S)$ and $Υ(3S)$ final states. The resummations of logarithms of $m_Z^2/m_Q^2$ that are associated with the order-$α_s$ and order-$v^2$ corrections are carried out by making use of the Abel-Padé method. We confirm the analytic result for the order-$v^2$ correction that was presented in a previous publication, and we correct the relative sign of the direct and indirect amplitudes and some choices of scales in that publication. Our branching fractions for $Z\to J/ψ+γ$ and $Z\to Υ(1S)+γ$ differ by $2.0\,σ$ and $-4.0\,σ$, respectively, from the branching fractions that are given in the most recent publication on this topic (in units of the uncertainties that are given in that publication). However, we argue that the uncertainties in the rates are underestimated in that publication. △ Less

Submitted 22 January, 2018; v1 submitted 26 September, 2017; originally announced September 2017.

Comments: 26 pages, [v2] references added / [v3] Equation (27) modified, 3 sentences added after Eq. (27), Reference [17] added / [v4] PRD version

Journal ref: Phys. Rev. D 97, 016009 (2018)

Higgs-Stoponium Mixing Near the Stop-Antistop Threshold

Authors: Geoffrey T. Bodwin, Hee Sok Chung, Carlos E. M. Wagner

Abstract: Supersymmetric extensions of the standard model contain additional heavy neutral Higgs bosons that are coupled to heavy scalar top quarks (stops). This system exhibits interesting field theoretic phenomena when the Higgs mass is close to the stop-antistop production threshold. Existing work in the literature has examined the digluon-to-diphoton cross section near threshold and has focused on enhan… ▽ More Supersymmetric extensions of the standard model contain additional heavy neutral Higgs bosons that are coupled to heavy scalar top quarks (stops). This system exhibits interesting field theoretic phenomena when the Higgs mass is close to the stop-antistop production threshold. Existing work in the literature has examined the digluon-to-diphoton cross section near threshold and has focused on enhancements in the cross section that might arise either from the perturbative contributions to the Higgs-to-digluon and Higgs-to-diphoton form factors or from mixing of the Higgs boson with stoponium states. Near threshold, enhancements in the relevant amplitudes that go as inverse powers of the stop-antistop relative velocity require resummations of perturbation theory and/or nonperturbative treatments. We present a complete formulation of threshold effects at leading order in the stop-antistop relative velocity in terms of nonrelativistic effective field theory. We give detailed numerical calculations for the case in which the stop-antistop Green's function is modeled with a Coulomb-Schrödinger Green's function. We find several general effects that do not appear in a purely perturbative treatment. Higgs-stop-antistop mixing effects displace physical masses from the threshold region, thereby rendering the perturbative threshold enhancements inoperative. In the case of large Higgs-stop-antistop couplings, the displacement of a physical state above threshold substantially increases its width, owing to its decay width to a stop-antistop pair, and greatly reduces its contribution to the cross section. △ Less

Submitted 24 January, 2017; v1 submitted 15 September, 2016; originally announced September 2016.

Comments: 45 pages, 13 figures, minor corrections, references added, figures 2--5 updated, version published in Phys. Rev. D

Report number: CERN-TH-2016-200, EFI-16-18

Journal ref: Phys. Rev. D 95, 015013 (2017)

New approach to the resummation of logarithms in Higgs-boson decays to a vector quarkonium plus a photon

Authors: Geoffrey T. Bodwin, Hee Sok Chung, June-Haak Ee, Jungil Lee

Abstract: We present a calculation of the rates for Higgs-boson decays to a vector heavy-quarkonium state plus a photon, where the heavy quarkonium states are the J/psi and the Upsilon(nS) states, with n=1, 2, or 3. The calculation is carried out in the light-cone formalism, combined with nonrelativistic QCD factorization, and is accurate at leading order in m_Q^2/m_H^2, where m_Q is the heavy-quark mass an… ▽ More We present a calculation of the rates for Higgs-boson decays to a vector heavy-quarkonium state plus a photon, where the heavy quarkonium states are the J/psi and the Upsilon(nS) states, with n=1, 2, or 3. The calculation is carried out in the light-cone formalism, combined with nonrelativistic QCD factorization, and is accurate at leading order in m_Q^2/m_H^2, where m_Q is the heavy-quark mass and m_H is the Higgs-boson mass. The calculation contains corrections through next-to-leading order in the strong-coupling constant alpha_s and the square of the heavy-quark velocity v, and includes a resummation of logarithms of m_H^2/m_Q^2 at next-to-leading logarithmic accuracy. We have developed a new method, which makes use of Abel summation, accelerated through the use of Pade approximants, to deal with divergences in the resummed expressions for the quarkonium light-cone distribution amplitudes. This approach allows us to make definitive calculations of the resummation effects. Contributions from the order-alpha_s and order-v^2 corrections to the light-cone distribution amplitudes that we obtain with this new method differ substantially from the corresponding contributions that one obtains from a model light-cone distribution amplitude [M. Koenig and M. Neubert, J. High Energy Phys. 08 (2015) 012]. Our results for the real parts of the direct-process amplitudes are considerably smaller than those from one earlier calculation [G. T. Bodwin, H. S. Chung, J.-H. Ee, J. Lee, and F. Petriello, Phys. Rev. D 90, 113010 (2014)], reducing the sensitivity to the Higgs-boson--heavy-quark couplings, and are somewhat smaller than those from another earlier calculation [M. Koenig and M. Neubert, J. High Energy Phys. 08 (2015) 012]. However, our results for the standard-model Higgs-boson branching fractions are in good agreement with those in M. Koenig and M. Neubert, J. High Energy Phys. 08 (2015) 012. △ Less

Submitted 31 March, 2017; v1 submitted 22 March, 2016; originally announced March 2016.

Comments: 40 pages, improved discussion of the convergence of the nonrelativistic expansion, minor corrections and changes in nomenclature, version published in Phys. Rev. D

Journal ref: Phys. Rev. D 95, 054018 (2017)

Fragmentation contributions to hadroproduction of prompt $J/ψ$, $χ_{cJ}$, and $ψ(2S)$ states

Authors: Geoffrey T. Bodwin, Kuang-Ta Chao, Hee Sok Chung, U-Rae Kim, Jungil Lee, Yan-Qing Ma

Abstract: We compute fragmentation corrections to hadroproduction of the quarkonium states $J/ψ$, $χ_{cJ}$, and $ψ(2S)$ at leading power in $m_c^2/p_T^2$, where $m_c$ is the charm-quark mass and $p_T$ is the quarkonium transverse momentum. The computation is carried out in the framework of nonrelativistic QCD. We include corrections to the parton-production cross sections through next-to-leading order in th… ▽ More We compute fragmentation corrections to hadroproduction of the quarkonium states $J/ψ$, $χ_{cJ}$, and $ψ(2S)$ at leading power in $m_c^2/p_T^2$, where $m_c$ is the charm-quark mass and $p_T$ is the quarkonium transverse momentum. The computation is carried out in the framework of nonrelativistic QCD. We include corrections to the parton-production cross sections through next-to-leading order in the strong coupling $α_s$ and corrections to the fragmentation functions through second order in $α_s$. We also sum leading logarithms of $p_T^2/m_c^2$ to all orders in perturbation theory. We find that, when we combine these leading-power fragmentation corrections with fixed-order calculations through next-to-leading order in $α_s$, we are able to obtain good fits for $p_T\geq 10$ GeV to hadroproduction cross sections that were measured at the Tevatron and the LHC. Using values for the nonperturbative long-distance matrix elements that we extract from the cross-section fits, we make predictions for the polarizations of the quarkonium states. We obtain good agreement with measurements of the polarizations, with the exception of the CDF Run II measurement of the prompt $J/ψ$ polarization, for which the agreement is only fair. In the predictions for the prompt-$J/ψ$ cross sections and polarizations, we take into account feeddown from the $χ_{cJ}$ and $ψ(2S)$ states. △ Less

Submitted 1 March, 2016; v1 submitted 25 September, 2015; originally announced September 2015.

Comments: 41 pages, 21 figures, minor revisions, Figure 20 corrected, version published in Phys. Rev. D

Journal ref: Phys. Rev. D 93, 034041 (2016)

Fragmentation contributions to $J/ψ$ photoproduction at HERA

Authors: Geoffrey T. Bodwin, Hee Sok Chung, U-Rae Kim, Jungil Lee

Abstract: We compute leading-power fragmentation corrections to $J/ψ$ photoproduction at DESY HERA, making use of the nonrelativistic QCD factorization approach. Our calculations include parton production cross sections through order $α_s^3$, fragmentation functions though order $α_s^2$, and leading logarithms of the transverse momentum divided by the charm-quark mass to all orders in $α_s$. We find that th… ▽ More We compute leading-power fragmentation corrections to $J/ψ$ photoproduction at DESY HERA, making use of the nonrelativistic QCD factorization approach. Our calculations include parton production cross sections through order $α_s^3$, fragmentation functions though order $α_s^2$, and leading logarithms of the transverse momentum divided by the charm-quark mass to all orders in $α_s$. We find that the leading-power fragmentation corrections, beyond those that are included through next-to-leading order in $α_s$, are small relative to the fixed-order contributions through next-to-leading order in $α_s$. Consequently, an important discrepancy remains between the experimental measurements of the $J/ψ$ photoproduction cross section and predictions that make use of nonrelativistic-QCD long-distance matrix elements that are extracted from the $J/ψ$ hadroproduction cross-section and polarization data. △ Less

Submitted 18 November, 2015; v1 submitted 22 April, 2015; originally announced April 2015.

Comments: 16 pages, 6 figures, minor revisions, version published in Phys. Rev. D

Journal ref: Phys. Rev. D 92, 074042 (2015)

Quark fragmentation into spin-triplet $S$-wave quarkonium

Authors: Geoffrey T. Bodwin, Hee Sok Chung, U-Rae Kim, Jungil Lee

Abstract: We compute fragmentation functions for a quark to fragment to a quarkonium through an $S$-wave spin-triplet heavy quark-antiquark pair. We consider both color-singlet and color-octet heavy quark-antiquark ($Q\bar Q$) pairs. We give results for the case in which the fragmenting quark and the quark that is a constituent of the quarkonium have different flavors and for the case in which these quarks… ▽ More We compute fragmentation functions for a quark to fragment to a quarkonium through an $S$-wave spin-triplet heavy quark-antiquark pair. We consider both color-singlet and color-octet heavy quark-antiquark ($Q\bar Q$) pairs. We give results for the case in which the fragmenting quark and the quark that is a constituent of the quarkonium have different flavors and for the case in which these quarks have the same flavors. Our results for the sum over all spin polarizations of the $Q\bar Q$ pairs confirm previous results. Our results for longitudinally polarized $Q\bar Q$ pairs agree with previous calculations for the same flavor cases and correct an error in a previous calculation for the different-flavor case. △ Less

Submitted 13 April, 2015; v1 submitted 22 December, 2014; originally announced December 2014.

Comments: 22 pages, 3 figures, minor revisions, version published in Phys. Rev. D

Journal ref: Phys. Rev. D 91, 074013 (2015)

Relativistic corrections to Higgs boson decays to quarkonia

Authors: Geoffrey T. Bodwin, Hee Sok Chung, June-Haak Ee, Jungil Lee, Frank Petriello

Abstract: We improve the theoretical predictions for the decays of the Higgs boson to an $S$-wave vector quarkonium plus a photon by calculating the relativistic correction of order $v^2$, where $v$ is the heavy-quark velocity in the quarkonium rest frame. Our numerical results are given for the $J/ψ$ and $Υ(nS)$ channels, with $n=1,2,3$. The numerical results include a previously calculated correction of o… ▽ More We improve the theoretical predictions for the decays of the Higgs boson to an $S$-wave vector quarkonium plus a photon by calculating the relativistic correction of order $v^2$, where $v$ is the heavy-quark velocity in the quarkonium rest frame. Our numerical results are given for the $J/ψ$ and $Υ(nS)$ channels, with $n=1,2,3$. The numerical results include a previously calculated correction of order $α_s$ and summations, to all orders in $α_s$, of leading logarithms of $m_H^2/m_Q^2$, where $m_H$ is the Higgs-boson mass and $m_Q$ is the heavy-quark mass. These QCD corrections apply to the contribution of leading order in $v$ and to part of the order-$v^2$ correction. For the remainder of the order-$v^2$ correction, we sum leading logarithms of $m_H/m_Q$ through order $α_s^2$. These refinements reduce the theoretical uncertainties in the direct-production amplitudes for $H \to J/ψ+γ$ and $H \to Υ(1S)+γ$ by approximately a factor of 3 and open the door to improved determinations at the LHC of the Higgs-boson Yukawa couplings to the charm and bottom quarks. △ Less

Submitted 19 December, 2014; v1 submitted 24 July, 2014; originally announced July 2014.

Comments: 24 pages, 2 figures, minor revisions, version published in PRD

Journal ref: Phys. Rev. D 90, 113010 (2014)

Double Logarithms in $e^+ e^- \to J/ψ+ η_c$

Authors: Geoffrey T. Bodwin, Hee Sok Chung, Jungil Lee

Abstract: Double logarithms of $Q^2/m_c^2$ that appear in the cross section for $e^+e^-\to J/ψ+ η_c$ at next-to-leading order (NLO) in the strong coupling $α_s$ account for the bulk of the NLO correction at $B$-factory energies. (Here, $Q^2$ is the square of the center-of-momentum energy, and $m_c$ is the charm-quark mass.) We analyze the double logarithms that appear in the contribution of each NLO Feynman… ▽ More Double logarithms of $Q^2/m_c^2$ that appear in the cross section for $e^+e^-\to J/ψ+ η_c$ at next-to-leading order (NLO) in the strong coupling $α_s$ account for the bulk of the NLO correction at $B$-factory energies. (Here, $Q^2$ is the square of the center-of-momentum energy, and $m_c$ is the charm-quark mass.) We analyze the double logarithms that appear in the contribution of each NLO Feynman diagram, and we find that the double logarithms arise from both the Sudakov and the end-point regions of the loop integration. The Sudakov double logarithms cancel in the sum over all diagrams. We show that the end-point region of integration can be interpreted as a pinch-singular region in which a spectator fermion line becomes soft or soft and collinear to a produced meson. This interpretation may be important in establishing factorization theorems for helicity-flip processes, such as $e^+e^-\to J/ψ+ η_c$, and in resumming logarithms of $Q^2/m_c^2$ to all orders in $α_s$. △ Less

Submitted 6 November, 2014; v1 submitted 7 June, 2014; originally announced June 2014.

Comments: 31 pages, 4 figures, 1 table, minor revisions, version published in PRD

Journal ref: Phys. Rev. D 90, 074028 (2014)

Fragmentation contributions to J/psi production at the Tevatron and the LHC

Authors: Geoffrey T. Bodwin, Hee Sok Chung, U-Rae Kim, Jungil Lee

Abstract: We compute leading-power fragmentation corrections to $J/ψ$ production at the Tevatron and the LHC. We find that, when these corrections are combined with perturbative corrections through next-to-leading order in the strong coupling constant $α_s$, we obtain a good fit to high-$p_T$ cross section data from the CDF and CMS Collaborations. The fitted long-distance matrix elements lead to predictions… ▽ More We compute leading-power fragmentation corrections to $J/ψ$ production at the Tevatron and the LHC. We find that, when these corrections are combined with perturbative corrections through next-to-leading order in the strong coupling constant $α_s$, we obtain a good fit to high-$p_T$ cross section data from the CDF and CMS Collaborations. The fitted long-distance matrix elements lead to predictions of near-zero $J/ψ$ polarization in the helicity frame at large $p_T$. △ Less

Submitted 9 July, 2014; v1 submitted 14 March, 2014; originally announced March 2014.

Comments: 5 pages, 4 figures, minor revisions, changes in notation, figures updated, version published in Physical Review Letters

Journal ref: Phys. Rev. Lett. 113, 022001 (2014)

Glyph Sorting: Interactive Visualization for Multi-dimensional Data

Authors: David H. S. Chung, Philip A. Legg, Matthew L. Parry, Rhodri Bown, Iwan W. Griffiths, Robert S. Laramee, Min Chen

Abstract: Glyph-based visualization is an effective tool for depicting multivariate information. Since sorting is one of the most common analytical tasks performed on individual attributes of a multi-dimensional data set, this motivates the hypothesis that introducing glyph sorting would significantly enhance the usability of glyph-based visualization. In this paper, we present a glyph-based conceptual fram… ▽ More Glyph-based visualization is an effective tool for depicting multivariate information. Since sorting is one of the most common analytical tasks performed on individual attributes of a multi-dimensional data set, this motivates the hypothesis that introducing glyph sorting would significantly enhance the usability of glyph-based visualization. In this paper, we present a glyph-based conceptual framework as part of a visualization process for interactive sorting of multivariate data. We examine several technical aspects of glyph sorting and provide design principles for developing effective, visually sortable glyphs. Glyphs that are visually sortable provide two key benefits: 1) performing comparative analysis of multiple attributes between glyphs and 2) to support multi-dimensional visual search. We describe a system that incorporates focus and context glyphs to control sorting in a visually intuitive manner and for viewing sorted results in an Interactive, Multi-dimensional Glyph (IMG) plot that enables users to perform high-dimensional sorting, analyse and examine data trends in detail. To demonstrate the usability of glyph sorting, we present a case study in rugby event analysis for comparing and analysing trends within matches. This work is undertaken in conjunction with a national rugby team. From using glyph sorting, analysts have reported the discovery of new insight beyond traditional match analysis. △ Less

Submitted 10 April, 2013; originally announced April 2013.

Comments: 10 pages, 6 figures

ACM Class: I.3.6; I.3.8

Endpoint Logarithms in e+e- -> J/psi + eta_c

Authors: Geoffrey T. Bodwin, Hee Sok Chung, Jungil Lee

Abstract: We investigate the origin of the double logarithms of Q^2/m_c^2 that appear in the calculation of the cross section for e+e- -> J/psi + eta_c at next-to-leading order in alpha_s. We find that, diagram-by-diagram, the double logarithms are accounted for by Sudakov double logarithms and endpoint double logarithms. The Sudakov double logarithms cancel in the sum over all diagrams, but the endpoint do… ▽ More We investigate the origin of the double logarithms of Q^2/m_c^2 that appear in the calculation of the cross section for e+e- -> J/psi + eta_c at next-to-leading order in alpha_s. We find that, diagram-by-diagram, the double logarithms are accounted for by Sudakov double logarithms and endpoint double logarithms. The Sudakov double logarithms cancel in the sum over all diagrams, but the endpoint double logarithms do not. We reinterpret the endpoint double logarithms in terms of a leading region of loop integration in which a spectator fermion line becomes soft. This reinterpretation may simplify the process of establishing an all-orders factorization theorem for this helicity-flip process, which, in turn, might allow one to resum logarithms of Q^2/m_c^2 to all orders in alpha_s. △ Less

Submitted 16 January, 2013; originally announced January 2013.

Comments: 9 pages, 1 figure, talk given by Hee Sok Chung at Xth Quark Confinement and the Hadron Spectrum, 8-12 October 2012, TUM Campus Garching, Munich, Germany

Report number: ANL-HEP-CP-13-4

Polarization of prompt J/psi in pp -> J/psi+X at sqrt{s}=200 GeV

Authors: Hee Sok Chung, Seyong Kim, Jungil Lee, Chaehyun Yu

Abstract: Within the framework of the nonrelativistic QCD factorization approach, we compute the cross section and polarization of prompt J/psi produced from proton-proton collisions at the center-of-momentum energy sqrt{s}=200 GeV. We present the transverse-momentum distribution in the forward-rapidity region 1.2 < |y| < 2.2 and the rapidity distribution over the transverse-momentum range 2 GeV < p_T < 20… ▽ More Within the framework of the nonrelativistic QCD factorization approach, we compute the cross section and polarization of prompt J/psi produced from proton-proton collisions at the center-of-momentum energy sqrt{s}=200 GeV. We present the transverse-momentum distribution in the forward-rapidity region 1.2 < |y| < 2.2 and the rapidity distribution over the transverse-momentum range 2 GeV < p_T < 20 GeV. The perturbative contributions are computed at leading order in the strong coupling constant. We predict slight transverse polarization of J/psi in the forward-rapidity region, while that for the mid-rapidity region is slightly longitudinal. The transverse-momentum distribution agrees well with the PHENIX preliminary data and the color-singlet-model prediction at next-to-leading order in alpha_s, but disagrees with the result from the leading-order color-singlet model or the s-channel-cut method. △ Less

Submitted 12 February, 2011; v1 submitted 9 December, 2010; originally announced December 2010.

Comments: 4 pages, 4 figures, minor corrections, version published in Phys. Rev. D

Journal ref: Phys.Rev.D83:037501,2011

NRQCD matrix elements for S-wave bottomonia and Gamma[eta_b(nS) -> gamma gamma] with relativistic corrections

Authors: Hee Sok Chung, Jungil Lee, Chaehyun Yu

Abstract: We determine the leading-order nonrelativistic quantum chromodynamics (NRQCD) matrix element < O_1 >_Upsilon and the ratio < q^2>_Upsilon, for Upsilon=Upsilon(nS) with n=1, 2, and 3 by comparing the measured values for Gamma[Upsilon -> e^+ e^-] with the NRQCD factorization formula in which relativistic corrections are resummed to all orders in the heavy-quark velocity v. The values for < q^2 >_Ups… ▽ More We determine the leading-order nonrelativistic quantum chromodynamics (NRQCD) matrix element < O_1 >_Upsilon and the ratio < q^2>_Upsilon, for Upsilon=Upsilon(nS) with n=1, 2, and 3 by comparing the measured values for Gamma[Upsilon -> e^+ e^-] with the NRQCD factorization formula in which relativistic corrections are resummed to all orders in the heavy-quark velocity v. The values for < q^2 >_Upsilon, which is the ratio of order-v^2 matrix element to < O_1 >_Upsilon, are new. They can be used for NRQCD predictions involving Upsilon(nS) and eta_b(nS) with relativistic corrections. As an application, we predict the two-photon decay rates for the spin-singlet states: Gamma[eta_b(1S) -> gamma gamma] = 0.512^{+0.096}_{-0.094} keV, Gamma[eta_b(2S) -> gamma gamma] = 0.235^{+0.043}_{-0.043} keV, and Gamma[eta_b(3S) -> gamma gamma] = 0.170^{+0.031}_{-0.031} keV. △ Less

Submitted 3 February, 2011; v1 submitted 6 November, 2010; originally announced November 2010.

Comments: 11 pages, minor corrections, version published in Phys. Lett. B

Journal ref: Phys.Lett.B697:48-51,2011

Polarization of prompt J/psi in proton-proton collisions at RHIC

Authors: Hee Sok Chung, Seyong Kim, Jungil Lee, Chaehyun Yu

Abstract: Within the framework of the nonrelativistic QCD (NRQCD) factorization approach, we compute the polarization of prompt J/psi produced at the Brookhaven's Relativistic Heavy-Ion Collider from proton-proton collisions at the center-of-momentum energy sqrt{s}=200 GeV. The perturbative contributions are computed at leading order in the strong coupling constant. The prediction reveals that the color-s… ▽ More Within the framework of the nonrelativistic QCD (NRQCD) factorization approach, we compute the polarization of prompt J/psi produced at the Brookhaven's Relativistic Heavy-Ion Collider from proton-proton collisions at the center-of-momentum energy sqrt{s}=200 GeV. The perturbative contributions are computed at leading order in the strong coupling constant. The prediction reveals that the color-singlet contribution severely underestimates the PHENIX preliminary data for the differential cross section integrated over the rapidity range |y|<0.35 and its contribution is strongly transversely polarized, which disagrees with the PHENIX preliminary data. After including the color-octet contributions, we find that the NRQCD predictions for both the cross section and polarization over the transverse-momentum range 1.5 GeV < p_T < 5 GeV (1.5 GeV < p_T < 2 GeV) integrated over the rapidity range |y|<0.35 (1.2 < |y| < 2.2) agree with the data within errors. △ Less

Submitted 15 January, 2010; v1 submitted 11 November, 2009; originally announced November 2009.

Comments: 5 pages, 2 figures, minor corrections, version published in Phys. Rev. D

Journal ref: Phys.Rev.D81:014020,2010

Recent Developments in Heavy-Quarkonium Phenomenology

Authors: Hee Sok Chung, Jungil Lee, Chaehyun Yu

Abstract: We review recent developments in heavy-quarkonium phenomenology within the nonrelativistic QCD factorization approach. Main issues we consider in this work include the polarization of prompt J/psi at the Fermilab Tevatron and the large relativistic and QCD corrections to double-charmonium production at the B factories. We also consider inclusive charm production in bottomonia decays. We review recent developments in heavy-quarkonium phenomenology within the nonrelativistic QCD factorization approach. Main issues we consider in this work include the polarization of prompt J/psi at the Fermilab Tevatron and the large relativistic and QCD corrections to double-charmonium production at the B factories. We also consider inclusive charm production in bottomonia decays. △ Less

Submitted 31 August, 2008; originally announced September 2008.

Comments: 8 pages, talk given by Jungil Lee at The Eighth International Conference on Hyperons, Charm and Beauty Hadrons (BEACH 2008), Columbia, South Carolina, USA, June 22-28, 2008

Exclusive heavy quarkonium + gamma production from e+ e- annihilation into a virtual photon

Authors: Hee Sok Chung, Jungil Lee, Chaehyun Yu

Abstract: We compute the cross section for exclusive production of a photon associated with a heavy quarkonium H of charge-conjugation parity C=+1 from e+ e- annihilation into a virtual photon at the center-of-momentum energy root-s=10.58 GeV. The NRQCD factorization formulas for the differential and total cross sections are obtained at leading order in the strong coupling and in the relative velocity of… ▽ More We compute the cross section for exclusive production of a photon associated with a heavy quarkonium H of charge-conjugation parity C=+1 from e+ e- annihilation into a virtual photon at the center-of-momentum energy root-s=10.58 GeV. The NRQCD factorization formulas for the differential and total cross sections are obtained at leading order in the strong coupling and in the relative velocity of the heavy quark in the quarkonium rest frame. The predicted cross sections for the S-wave spin-singlet cases are about 80 fb and 50 fb for H = eta_c and eta_c(2S), respectively. Among P-wave spin-triplet charmonia, chi_{c1} has a particularly large cross section of about 14 fb. The cross sections for bottomonium states eta_b and chi_{bJ} are about 3 fb. A rough estimate of the background reveals that the signal significances for charmonium processes are sufficiently large enough to be detected with ease with the integrated luminosities available at the present B factories. △ Less

Submitted 27 October, 2008; v1 submitted 12 August, 2008; originally announced August 2008.

Comments: 22 pages, 1 figure, version published in Phys. Rev. D

Journal ref: Phys.Rev.D78:074022,2008

Order-alpha_s corrections to the quarkonium electromagnetic current at all orders in the heavy-quark velocity

Authors: Geoffrey T. Bodwin, Hee Sok Chung, Jungil Lee, Chaehyun Yu

Abstract: We compute in order alpha_s the nonrelativistic QCD (NRQCD) short-distance coefficients that match quark-antiquark operators of all orders in the heavy-quark velocity v to the electromagnetic current. We employ a new method to compute the one-loop NRQCD contribution to the matching condition. The new method uses full-QCD expressions as a starting point to obtain the NRQCD contribution, thus grea… ▽ More We compute in order alpha_s the nonrelativistic QCD (NRQCD) short-distance coefficients that match quark-antiquark operators of all orders in the heavy-quark velocity v to the electromagnetic current. We employ a new method to compute the one-loop NRQCD contribution to the matching condition. The new method uses full-QCD expressions as a starting point to obtain the NRQCD contribution, thus greatly streamlining the calculation. Our results show that, under a mild constraint on the NRQCD operator matrix elements, the NRQCD velocity expansion for the quark-antiquark-operator contributions to the electromagnetic current converges. The velocity expansion converges rapidly for approximate J/psi operator matrix elements. △ Less

Submitted 14 January, 2009; v1 submitted 16 July, 2008; originally announced July 2008.

Comments: 35 pages, minor corrections, version published in Phys. Rev. D

Report number: ANL-HEP-PR-08-43

Journal ref: Phys.Rev.D79:014007,2009

Invariant-mass distribution of cc-bar in Upsilon(1S) -> cc-bar + X

Authors: Hee Sok Chung, Taewon Kim, Jungil Lee

Abstract: We calculate the invariant-mass distribution for the cc-bar pair produced in the inclusive Upsilon(1S) decay based on the color-singlet mechanism of the nonrelativistic quantum chromodynamics factorization approach at leading order in the bottom-quark velocity v_b in the meson rest frame. As the short-distance processes, we consider bb-bar -> g^*gg followed by g^* -> cc-bar and bb-bar -> gamma^*… ▽ More We calculate the invariant-mass distribution for the cc-bar pair produced in the inclusive Upsilon(1S) decay based on the color-singlet mechanism of the nonrelativistic quantum chromodynamics factorization approach at leading order in the bottom-quark velocity v_b in the meson rest frame. As the short-distance processes, we consider bb-bar -> g^*gg followed by g^* -> cc-bar and bb-bar -> gamma^* -> cc-bar at leading order in the strong coupling. The invariant-mass distribution of the bb-bar -> cc-bar gg contribution has a sharp peak just above the threshold and that of the bb-bar -> gamma^* -> cc-bar channel is concentrated at the maximally allowed kinematic end point. We predict that Gamma[Upsilon(1S) -> cc-bar+X]/Gamma[Upsilon(1S)->light hadrons] = 0.065 alpha_s, which is smaller than a previous result by about 20%. △ Less

Submitted 14 May, 2008; originally announced May 2008.

Comments: 15 pages, 1 figure

Journal ref: Phys.Rev.D78:114027,2008