arXiv subjects

Guang-Yu Wang

Publications and source records attributed to Guang-Yu Wang.

7 recordsLinked to original sources

arXiv2026

Next-to-leading order QCD and relativistic corrections to $Z \to J/ψ+Υ(nS)$

In this paper, we calculate the decay widths and branching fractions for the decays $Z \to J/ψ+Υ(nS)$ ($n=1,2,3$) at future super $Z$ factory and at the CEPC/FCC-ee, including both the relativistic and QCD corrections within the framework of nonrelativistic QCD. Both the relativistic and QCD corrections are found to be large and negative. Compared to the leading-order results, the decay widths are significantly reduced by the higher-order corrections due to significant numerical cancellations. Despite the resulting large theoretical uncertainties, sizable event rates from these rare decay channels could still be anticipated at future high-luminosity electron-positron colliders running around the Z-pole. Ultimately, our results provide an essential theoretical baseline, highlighting the necessity of incorporating even higher-order corrections and resummation techniques for future precision phenomenological studies.

hep-ph↗

arXiv2025

Lattice QCD calculation of charmed baryon decay constants at continuum limit and physical mass

We present the first principle calculation of charmed baryon decay constants employing 2+1 flavor gauge ensembles with lattice spacings ranging from 0.05 to 0.1 fm and pion masses between 136 and 310 MeV. Under $SU(3)$ flavor symmetry, we construct the charmed baryon interpolating operators and compute the corresponding hadronic matrix elements to extract the bare decay constants for each ensemble. The non-perturbative renormalization is performed via the symmetric momentum-subtraction scheme. After performing systematic chiral and continuum extrapolations, we obtain the decay constants with a precision of $8\sim 16\%$ from first principles.

hep-lat↗

arXiv2025

Investigate the glueball-like particle $X(2370)$ in $B$ meson decays

Based on the collected data on $J/ψ\to γK_S^0K_S^0η'$, the BESIII experiment has conducted an analysis of the mass and spin parity of the $X(2370)$ particle. The findings are consistent with the characteristics expected of the lightest pseudoscalar glueball. We point out that further exploration of this particle's nature can be pursued through investigations of heavy bottom meson decays. Assuming the identity of $X(2370)$ as a pseudoscalar glueball, we compute the form factors for $B\to X(2370)$ transitions in the factorization approach. With these results, the estimated branching fractions for semileptonic $B$ decays into $X(2370)$ can reach the order of $10^{-6}$ and those for nonleptonic decays can reach the order $10^{-8}$. These results suggest that decays of $B$ meson into $X(2370)$ are detectable at experimental facilities like Belle-II. Future experimental endeavors hold promise in expanding our understanding of glueball physics, contributing to the ongoing exploration surrounding this intriguing particle.

hep-ph↗

arXiv2024

Improved analysis of double $J/ψ$ production in $Z$-boson decay

In this paper, we present an improved calculation for the decay rate of the rare $Z$-boson decay into $J/ψ+ J/ψ$. This decay is dominated by the photon fragmentation mechanism, i.e., the transition $Z\to J/ψ+ γ^{*}$ followed by the fragmentation $γ^{*}\to J/ψ$. In our calculation, the amplitude of $γ^{*}\to J/ψ$ is extracted from the measured value of $Γ(J/ψ\to e^+ e^-)$, and the amplitude of $Z\to J/ψ+ γ^{*}$ is calculate through the light-cone approach. The higher-order QCD and relativistic corrections in the amplitude of $γ^{*}\to J/ψ$ and the large logarithms of $m_{_Z}^2/m_c^2$ that appear in the amplitude of $Z\to J/ψ+ γ^{*}$ are resummed in our calculation. Besides, the non-fragmentation amplitude is calculated based on the NRQCD factorization, and the next-to-leading order QCD and relativistic corrections are included. The obtained branching fraction for this $Z$ decay channel is $8.66 ^{+1.48} _{-0.69}\times 10^{-11}$.

hep-ph↗

arXiv2023

$Z$-boson decays into $S$-wave quarkonium plus a photon up to ${\cal O}(α_{s} v^2)$ corrections

In this paper, we calculate the decay widths and branching fractions for the decays $Z \to H+ γ$ up to ${\cal O}(α_{s} v^2)$ accuracy within the framework of nonrelativistic QCD, where $H$ stands for the $S$-wave quarkonium $η_c$, $J/ψ$, $η_b$ or $Υ$, respectively. To compare with the leading-order terms, those corrections show good perturbative behavior as expected. It is found that contributions from the next-to-leading order QCD correction ${\cal O}(α_{s}v^0)$, the relativistic correction ${\cal O}(α^{0}_{s}v^2)$ and their joint correction ${\cal O}(α_{s} v^2)$ are sizable and comparable to each other, especially for the charmonium case. Thus we need to take all of them into consideration for a sound estimation. For a high luminosity electron-positron collider running around the $Z$-pole, due to $Z$-boson resonance effect, sizable events could be produced from those rare decay channels.

hep-ph↗

arXiv2023

Higgs boson decays to $B_c$ meson in the fragmentation-function approach

In the paper, we present a calculation of the decay widths for the Higgs boson decays to the $B_c$, $B_c^*$, $B_c(2^1S_0)$ and $B_c^*(2^3S_1)$ mesons using the fragmentation-function approach. In the calculation, the fragmentation functions up to order $α_s^3$ based on the nonrelativistic QCD factorization theory are used, and the decay widths for $H\to Q+X$ and $H \to g+X$ at the partonic level are calculated up to order $α_s$. The large logarithms of $m_H^2/m_{Bc}^2$ are resummed up to next-to-leading logarithmic accuracy by solving the evolution equations for the running quark masses and the fragmentation functions. Compared to the leading-order decay widths based on the nonrelativistic QCD approach, the decay widths based on the fragmentation-function approach that include the higher-order QCD corrections are reduced significantly. Our numerical results show that there are about $1.2\times 10^5$ $B_c$ events via the Higgs decays to be produced at the HL-LHC with $3ab^{-1}$, and about $1.6\times 10^6$ $B_c$ events via the Higgs decays to be produced at the HE-LHC with $15ab^{-1}$.

hep-ph↗

arXiv2021

Inclusive production of heavy quarkonium $η_Q$ via $Z$ boson decays within the framework of nonrelativistic QCD

In the paper, the inclusive production of heavy quarkonium $η_Q$ ($Q=b$ or $c$) via $Z$ boson decays within the framework of nonrelativistic QCD effective theory are studied. The contributions from the leading color-singlet and color-octet Fock states are considered. Total and differential decay widths for the inclusive decays $Z \to η_Q+X$ are presented. It is found that the decays $Z\to η_Q +X$ are dominated by the $^3S_1^{[8]}$ component, so the decays can be inversely adopted to determine the values of the long-distance matrix elements $\langle {\cal O}^{η_{c}}(^{3}S_{1}^{[8]})\rangle$ and $\langle {\cal O}^{η_{b}}(^{3}S_{1}^{[8]})\rangle$, respectively. Our numerical results show that at an $e^+e^-$ collider running at the $Z$ pole with a high luminosity around $10^{35}{\rm cm}^{-2}{\rm s}^{-1}$ (a super $Z$ factory), there are about $4.5\times 10^7$ $η_c$ meson events and $6.1\times 10^5$ $η_b$ meson events to be produced per operation year, and the inclusive decays may be used for clarifying some problems on the heavy quarkonium $η_Q$ and nonrelativistic QCD.

hep-ph↗