arXiv subjects

Jia-Wei Zhang

Publications and source records attributed to Jia-Wei Zhang.

23 records · Page 2Linked to original sources

arXiv2012

$B_c$ Meson Production around the $Z^0$ Peak at a High Luminosity $e^+ e^-$ Collider

Considering the possibility to build an $e^+ e^-$ collider at the energies around the $Z^0$-boson resonance with a planned luminosity so high as ${\cal L}\propto 10^{34}\sim 10^{36}cm^{-2}s^{-1}$ (super $Z$-factory), we make a detailed discussion on the $(c\bar{b})$-quarkonium production through $e^{+}+e^{-}\rightarrow (c\bar{b})[n]+b+\bar{c}$ within the framework of non-relativistic QCD. To simplify the hard-scattering amplitude as much as possible and to derive analytic expressions for the purpose of future events simulation, we adopt the "improved trace technology" to do our calculation, which deals with the hard scattering amplitude directly at the amplitude level other than the conventional way at the squared-amplitude level. Total cross-section uncertainties caused by the quark masses are predicted by taking $m_c=1.50\pm0.30$ GeV and $m_b=4.90\pm0.40$ GeV. If all higher $(c\bar{b})$-quarkonium states decay to the ground state $B_c$ ($|(c\bar{b})_{\bf 1}[^1S_0]>$) with 100% efficiency, we obtain $σ_{e^{+}+e^{-}\rightarrow B_{c}+b+\bar{c}} =5.190^{+6.222}_{-2.419}$ pb, which shows that about $10^5 \sim 10^7$ $B_c$ events per operation year can be accumulated in the super $Z$-factory. If taking the collider energy runs slightly off the $Z^0$-peak, i.e. $\sqrt{S}=(1.00\pm0.05) m_Z$, the total cross-section shall be lowered by about one-order from its peak value. Such a super $Z$-factory shall provide another useful platform to study the properties of $B_c$ meson, or even the properties of its excited $P$-wave states, in addition to its production at the hadronic colliders Tevatron and LHC.

hep-ph↗

arXiv2011

Production of the $P$-Wave Excited $B_c$-States through the $Z^0$ Boson Decays

In Ref.[7],we have dealt with the production of the two color-singlet $S$-wave $(c\bar{b})$-quarkonium states $B_c(|(c\bar{b})_{\bf 1}[^1S_0]>)$ and $B^*_c(|(c\bar{b})_{\bf 1}[^3S_1]>)$ through the $Z^0$ boson decays. As an important sequential work, we make a further discussion on the production of the more complicated $P$-wave excited $(c\bar{b})$-quarkonium states, i.e. $|(c\bar{b})_{\bf 1}[^1P_1]>$ and $|(c\bar{b})_{\bf 1}[^3P_J]>$ (with $J=(1,2,3)$). More over, we also calculate the channel with the two color-octet quarkonium states $|(c\bar{b})_{\bf 8}[^1S_0]g>$ and $|(c\bar{b})_{\bf 8}[^3S_1]g>$, whose contributions to the decay width maybe at the same order of magnitude as that of the color-singlet $P$-wave states according to the naive nonrelativistic quantum chromodynamics scaling rules. The $P$-wave states shall provide sizable contributions to the $B_c$ production, whose decay width is about 20% of the total decay width $Γ_{Z^0\to B_c}$. After summing up all the mentioned $(c\bar{b})$-quarkonium states' contributions, we obtain $Γ_{Z^0\to B_c} =235.9^{+352.8}_{-122.0}$ KeV, where the errors are caused by the main uncertainty sources.

hep-ph↗

arXiv2011

Hadronic Production of the Doubly Heavy Baryon $Ξ_{bc}$ at LHC

We investigate the hadronic production of the doubly heavy baryon $Ξ_{bc}$ at the large hadron collider (LHC), where contributions from the four $(bc)$-diquark states $(bc)_{\bf\bar{3},6}[^1S_0]$ and $(bc)_{\bf\bar{3},6}[^3S_1]$ have been taken into consideration. Numerical results show that under the condition of $p_T>4$ GeV and $|y|<1.5$, sizable $Ξ_{bc}$ events about $ 1.7\times 10^7$ and $3.5\times10^9$ per year can be produced for the center-of-mass energy $\sqrt{S}=7$ TeV and $\sqrt{S}=14$ TeV respectively. For experimental usage, the total and the interested differential cross-sections are estimated under some typical $p_T$- and $y$- cuts for the LHC detectors CMS, ATLAS and LHCb. Main uncertainties are discussed and a comparative study on the hadronic production of $Ξ_{cc}$, $Ξ_{bc}$ and $Ξ_{bb}$ at LHC are also presented.

hep-ph↗

arXiv2011

New results on Pionic Twist-3 Distribution Amplitudes within the QCD Sum Rules

We present an improved calculation on the pionic twist-3 distribution amplitudes $ϕ^π_{p}$ and $ϕ^π_σ$, which are studied within the QCD sum rules. By adding all the uncertainties in quadrature, it is found that $<ξ^2_p>=0.248^{+0.076}_{-0.052}$, $<ξ^4_p>=0.262^{+0.080}_{-0.055}$, $<ξ^2_σ>=0.102^{+0.035}_{-0.025}$ and $<ξ^4_σ>=0.094^{+0.028}_{-0.020}$. Furthermore, with the help of these moments, we construct a model for the twist-3 wave functions $ψ^π_{p,σ}(x,\mathbf{k}_\bot)$, which have better end-point behavior and are helpful for perturbative QCD approach. The obtained twist-3 distribution amplitudes are adopted to calculate the $B\toπ$ transition form factor $f^+_{Bπ}$ within the QCD light-cone sum rules up to next-to-leading order. By suitable choice of the parameters, we obtain a consistent $f^+_{Bπ}$ with those obtained in the literature.

hep-ph↗

arXiv2009

Hadronic production of $B^{(*)}_s$ at TEVATRON and LHC

We study the hadronic production of $B_s$ and $B_s^*$ mesons within the fixed-flavor-number scheme, in which the dominant gluon-gluon fusion mechanism is dealt with by using the complete $α_s^4$ approach. Main theoretical uncertainties for $B_s$ and $B_s^*$ production at TEVATRON and LHC are presented. It is found that when $m_s$ increases by steps of 0.1 GeV, the integrated cross section of $B^{(*)}_s$ decreases by $80%-100%$, when $m_b$ increases by steps of 0.1 GeV, it changes to be $\sim 10%$. While the uncertainties caused by the parton distribution function and the factorization scale varies within the region of 1/5 to 1/3. Considering possible kinematic cut on the transverse momentum and the rapidity cut for the detectors at TEVATRON and LHC, we also make estimations on the $B_s$ and $B_s^*$ production with various kinematic cuts.

hep-ph↗