arXiv subjects

Xi-Jie Zhan

Publications and source records attributed to Xi-Jie Zhan.

14 recordsLinked to original sources

arXiv2026

Resolved photoproduction of the $B_c$ meson in electron-proton collisions

We present a systematic study of $B_c$ meson photoproduction at electron--proton colliders within the framework of nonrelativistic QCD (NRQCD) factorization. In addition to the dominant direct channel $γ+g\to B_c+X$, we include resolved contributions initiated by $g+g$ and $q+\bar q (q=u,d,s)$ subprocesses. Total cross sections and transverse-momentum distributions are calculated for several collider configurations, including HERA, LHeC, FCC-$ep$, and EIC. The numerical results show that the direct $γ+g$ channel provides the leading contribution over the entire kinematic range. However, the resolved $g+g$ channel yields a non-negligible correction, reaching the level of $\mathcal{O}(10\%)$ in the low-$p_T$ region where most events are produced, and it becomes increasingly important at higher collision energies. The $q+\bar q$ channel is found to be numerically insignificant.

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arXiv2023

Photoproduction of doubly heavy baryons at future $e^+e^-$ colliders

The photoprodution of doubly heavy baryon ($Ξ_{cc},Ξ_{bb},Ξ_{bc}$) is investigated in the context of future high-energy and high-luminosity $e^+e^-$ colliders. The study incorporates two sources of initial photons, namely the LBS photon and the WWA photon. Alongside the direct photoproduction via the sub-process $γ+γ\rightarrow Ξ_{QQ^{'}} +\bar{Q}+\bar{Q^{'}}$ ($Q^{(')}=c,b$), the resolved photoproduction channels are specifically considered, encompassing the sub-processes $γ+ g \rightarrow Ξ_{QQ^{'}} +\bar{Q}+\bar{Q^{'}}$, $g + g \rightarrow Ξ_{QQ^{'}} +\bar{Q}+\bar{Q^{'}}$, and $q + \bar{q} \rightarrow Ξ_{QQ^{'}} +\bar{Q}+\bar{Q^{'}}$ with $q=u,d,s$. Within the framework of non-relativistic QCD, two $(cc(bb))$-diquark configurations, ${}_{\bar{\textbf{3}}}[{}^3S_1]$ and ${}_{\textbf{6}}[{}^1S_0]$, and four $(bc)$-diquark configurations, $(bc)_{\bar{\textbf{3}}}[{}^3S_1]$, $(bc)_{\textbf{6}}[{}^1S_0]$, $(bc)_{\textbf{6}}[{}^3S_1]$ and $(bc)_{\bar{\textbf{3}}}[{}^1S_0]$, are considered in the calculations. Numerical results show that the single resolved photoproduction processes provide dominant contributions under certain collision configuration. At the future $e^+e^-$ colliders, the doubly heavy baryon generated via the photoproduction mechanism is promisingly observable and can be well studied.

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arXiv2023

Photoproduction of $P$-wave doubly charmed baryon at future $e^+e^-$ collider

The photoproduction of $P$-wave doubly charmed baryon ($Ξ_{cc}$) is investigated in the context of future high-energy and high-luminosity $e^+e^-$ colliders. The direct photoproduction via the sub-process $γ+γ\rightarrow Ξ_{cc} +\bar{c}+\bar{c}$ and the resolved channel $γ+g \rightarrow Ξ_{cc} +\bar{c}+\bar{c}$ are considered. Within the framework of non-relativistic QCD, the calculation encompasses four $P$-wave $(cc)$-diquark configurations: $(cc)_{\bar{\textbf{3}}}[{}^1P_1]$, $(cc)_{\textbf{6}}[{}^3P_0]$, $(cc)_{\textbf{6}}[{}^3P_1]$ and $(cc)_{\textbf{6}}[{}^3P_2]$. The two $S$-wave states, $(cc)_{\bar{\textbf{3}}}[{}^3S_1]$ and $(cc)_{\textbf{6}}[{}^1S_0]$, are also included for comparison. The cross sections, as well as the differential distributions involving transverse momentum, rapidity, and angular variables, have been computed. Numerical results reveal that the resolved photoproduction process plays a significant role and can provide dominant contributions. The photoproduction rate of the $P$-wave $Ξ_{cc}$ is approximately one order of magnitude lower than that of the $S$-wave.

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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 $15ab^{-1}$.

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arXiv2022

Photoproduction of the $B_c$ meson at the future $e^+e^-$ colliders

In the present paper, we study the photoproduction of various $S$-wave $B_c$ states, i.e. $B_c(1{}^1S_0)$, $B_c^*(1{}^1S_0)$, $B_c(2{}^1S_0)$ and $B^*_c(2{}^3S_1)$, at future $e^+e^-$ colliders within the framework of non-relativistic QCD. Two sources of the initial photons can be realized in the production, i.e., the LBS photon and the WWA photon. In addition to the direct photoproduction via the sub-process, $γ+ γ\rightarrow B_c + b + \bar{c}$, we also calculate the resolved photoproduction via the sub-processes, $γ+ g \rightarrow B_c + b + \bar{c}$ and $q + \bar{q} \rightarrow B_c + b + \bar{c}$ with $q=u,d,s,g$, respectively. Numerical results indicate that the contributions from the single resolved photoproduction are significant and even dominant at certain collision configuration. At the future high-energy and high-luminosity $e^+e^-$ colliders, the $B_c$ meson generated via the photoproduction mechanism is promisingly observable and can be well studied.

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arXiv2022

Next-to-leading order QCD corrections to $Z\to η_Q+Q+\bar{Q}$

It has been found that at a high luminosity $e^+ e^-$ collider, sizable $η_c+c\bar{c}X$ and $η_b+b\bar{b}X$ events can be produced when it works around the $Z$ peak. In this paper, we calculate the decay widths of $Z \to η_c+c+\bar{c}+X$ and $Z \to η_b+b+\bar{b}+X$ up to next-to-leading order (NLO) accuracy. We find that the NLO corrections are significant in these two processes. After including the NLO corrections, the decay widths of $Z \to η_c+c+\bar{c}+X$ and $Z \to η_b+b+\bar{b}+X$ are enhanced by about $37\%$ and $28\%$ for the case of $μ_R=2m_c$ and $μ_R=2m_b$, respectively. The differential decay widths $dΓ/ds_1$ and $dΓ/dz$ for these two decay processes are also analyzed.

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arXiv2022

Inclusive $J/ψ$ photoproduction at the ILC within the framework of non-relativistic QCD

Based on the non-relativistic quantum chromodynamics factorization framework, we study the inclusive $J/ψ$ photoproduction at the future high energy $e^+e^-$ collider, International Linear Collider(ILC), where the initial photons come from the back-scattering of laser and electron (positron). The intermediate states, $c\bar{c}$$({}^3\!S_1^{[\textbf{1}]}$,${}^1\!S_0^{[\textbf{8}]}$,${}^3\!S_1^{[\textbf{8}]}$,${}^3\!P_{0,1,2}^{[\textbf{8}]})$, and resolved photoproduction processes are considered. Numerical results show that the cross section of $J/ψ$ photoproduction at the ILC could be very large, and the single resolved process via $c\bar{c}({}^1\!S_0^{[\textbf{8}]})$ intermediate state dominates primarily the production. We also present various kinematic distributions for $J/ψ$ photoproduction. Combining the high luminosity of the collision, $J/ψ$ photoproduction at the ILC shall provide a good platform to test the NRQCD factorization.

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arXiv2020

Inclusive $Υ(1S,2S,3S)$ photoproduction at the CEPC

The inclusive $Υ(1S,2S,3S)$ photoproduction at the future Circular-Electron-Positron-Collider (CEPC) is studied based on the non-relativistic QCD (NRQCD). Including the contributions from both direct and resolved photons, we present different distributions for $Υ(1S,2S,3S)$ production and the results show there will be considerable events, which means that a well measurements on the $Υ$ photoprodution could be performed to further study on the heavy quarkonium physics at electron-positron collider in addition to hadron colliders. This supplement study is very important to clarify the current situation of the heavy quarkonium production mechanism.

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arXiv2020

Prompt $J/ψ$ photoproduction within the non-relativistic QCD framework at the CEPC

The prompt $J/ψ$ photoproduction within the non-relativistic QCD (NRQCD) framework at the future Circular Electron Positron Collider (CEPC) is studied, including the contributions from both direct and resolved photons. Employing different sets of long distance matrix elements, the total cross section is dominated by the color-octet channel. We present different kinematic distributions of $J/ψ$ production and the results show there will be about 50 $J/ψ$ events when the transverse momentum of $J/ψ$ is up to 20 GeV. It renders that the $J/ψ$ photoprodution at the CEPC is a well laboratory to test the NRQCD and further clarify the universality problem in NRQCD between electron positron collider and hadron collider.

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arXiv2018

Corrections to $R_{D}$ and $R_{D^{*}}$ in the BLMSSM

The deviation of the measurement of $R_{D}$ ($R_{D^{*}}$) from the Standard Model (SM) expectation is $2.3σ$ ($3.1σ$). $R_{D}$ ($R_{D^{*}}$) is the ratio of the branching fraction of $\overline{B} \rightarrow Dτ\overlineν_τ$ ($\overline{B} \rightarrow D^{*}τ\overlineν_τ$) to that of $\overline{B} \rightarrow Dl\overlineν_{l}$ ($\overline{B} \rightarrow D^{*}l\overlineν_{l}$), where $l = e$ or $μ$. This anomaly may imply the existence of new physics (NP). In this paper, we restudy this problem in the supersymmetric extension of the Standard Model with local gauged baryon and lepton numbers (BLMSSM), and give one-loop corrections to $R_{D}$ ($R_{D^{*}}$).

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arXiv2017

$Z\rightarrow l_i^{\pm}l_j^{\mp}$ processes in the BLMSSM

In a supersymmetric extension of the Standard Model(SM) where baryon and lepton numbers are local gauge symmetries (BLMSSM), we investigate the charged lepton flavor violating (CLFV) processes $Z\rightarrow l_i^{\pm}l_j^{\mp}$ after introducing the new gauginos and the right-handed neutrinos. In this model, the branching ratios of $Z\rightarrow l_i^{\pm}l_j^{\mp}$ are around ($10^{-8}\sim10^{-10}$), which approach the present experimental upper bounds. We hope that the branching ratios for these CLFV processes can be detected in the near future.

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arXiv2015

Lepton flavor violation in the BLMSSM

In a supersymmetric extension of the standard model with local gauged baryon and lepton numbers (BLMSSM), there are new sources for lepton flavor violation, because the right-handed neutrinos and new gauginos are introduced. In BLMSSM, we study the charged lepton flavor violating processes $l_j\rightarrow l_i+γ$ and $l_j\rightarrow 3l_i$ in detail. The numerical results show that in some parameter space the branching ratios for charged lepton flavor violating processes can be large enough to be detected in the near future.

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arXiv2015

The study of lepton EDM in CP violating BLMSSM

In the supersymmetric model with local gauged baryon and lepton numbers(BLMSSM), the CP violating effects are considered to study the lepton electric dipole moment(EDM). The CP violating phases in BLMSSM are more than those in the standard model(SM) and can give large contributions. The analysis of the EDMs for the leptons $e,μ, τ$ is shown in this work. It is in favour of exploring the source of CP violation and probing the physics beyond SM.

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arXiv2014

The corrections from one loop and two-loop Barr-Zee type diagrams to muon MDM in BLMSSM

In a supersymmetric extension of the standard model where baryon and lepton numbers are local gauge symmetries(BLMSSM) and the Yukawa couplings between Higgs doublets and exotic quarks are considered, we study the one loop diagrams and the two-loop Barr-Zee type diagrams with a closed Fermi(scalar) loop between the vector Boson and Higgs. Using the effective Lagrangian method, we deduce the Wilson coefficients of dimension 6 operators contributing to the anomalous magnetic moment of muon, which satisfies the electromagnetic gauge invariance. In the numerical analysis, we consider the experiment constraints from Higgs and neutrino data. In some parameter space, the new physics contribution is large and even reaches $24\times10^{-10}$, which can remedy the deviation well.

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