用PQCDS推进网络环境下高校图书馆个性化信息服务

当今社会,人们对信息的需求飞速发展,网络环境为图书馆个性化信息服务提供了技术条件。借鉴"PQCDS生产"指导思想,可以有效推进在网络环境下高校图书馆个性化信息服务工作。

用PQCD方法研究J/ψ→PP的弱衰变过程

采用PQCD方法,对C宇称破缺的J/ψ→πη,πη′,ηη′过程,以及奇异量子数不守恒的J/ψ→πK,Kη,Kη′过程进行了唯象学研究,结合BESIII实验和STCF实验进展进行了讨论,结果显示这些弱作用过程的分支比很小,无法在BESIII实验上被探测到,J/ψ→ηη′过程的分支在10^(-11)量级,有可能被未来的STCF实验观测到.

B→ρ(ω,φ)η(′)Decays and NLO Contributions in pQCD Approach

By employing the perturbative QCD （pQCD） factorization approach, we calculate some important next- to-leading-order （NLO） contributions to the two-body charmless hadronic decays B^＋ →ρ^＋η（＇） and B^0 → ρ^0（ω, φ）η（＇）, induced by the vertex QCD corrections, the quark-loops as well as the chromo-magnetic penguins. From the numerical results and phenomenological analysis we find that （a） for B^± → ρ^±η（＇） （B^0 → ρ^0（ω, φ）η（＇）decays, the partial NLO contributions to branching ratios are small （large） in magnitude; and （b） the pQCD predictions for ACP^dir（B^± → ρ^±η（＇）） are consistent with the data, while the predicted .ACP（B^0 → ρ^0（ω）η（＇）） are generally large in magnitude and could be tested by the forthcoming LHCb experiments.

Study Pure Annihilation Decays Bs^0（B^-0 s）→D^±π^-＋ in PQCD Approach

The rare decays Bs^0（B^-0 s）→D^±π^-＋ can occur only via annihilation-type diagrams in the standard model. In this paper, we calculate branching ratios of these decays in perturbative QCD approach ignoring soft final state interaction. From our calculation, we find that their branching ratios are at O（10^-6） with large CP asymmetry, which may be measured in LHC-b experiment in the future.

PQCD因子化方法计算BS0→ψ(3770)Kπ

对B介子衰变的深入研究不仅可以为探索CP破坏起源提供大量素材,而且可以为研究衰变过程中的QCD动力学机制提供模型。如今,微扰QCD(PQCD)因子化方法已经成为研究B介子衰变的主要方法之一。本文在标准模型框架下利用PQCD因子化方法将衰变末态的两个轻介子视作轻介子对K*(1430)0,如此一来就将B介子三体衰变简化为类两体衰变,然后基于此计算BS0介子衰变为ψ(3770)K*(1430)0的衰变概率。这一衰变道未来在实验上被发现之后,可以帮助人们了解ψ(3770)介子的混合机制。

pQCD因子化方法计算B介子三体非轻衰变

微扰QCD(pQCD)因子化方法已经广泛应用于计算B介子的非轻衰变,随着对微扰QCD框架的不断完善,人们对B介子的研究也从最初的两体衰变问题逐渐转化为对其多体衰变的计算,既往研究表明,利用pQCD因子化方法计算所得的B介子多体衰变分支比与实验结果拟合较好,进一步验证了该方法的有效性。从B介子的研究背景出发,详细介绍pQCD因子化方法,并以 B_(s)^(0)→α_(0)(980)K^(+)K^(-)这一具体衰变道为例,简述用pQCD方法计算其分支比的过程。

B→f_0(980)(π,η^((')) decays in the PQCD approach

Based on the assumption of a two-quark structure of the scalar meson f0（980） ,we calculate the branching ratios and CP-violating asymmetries for the four B → f0（980） π and B → f0（980） η^（＇） decays by employing the perturbative QCD（pQCD） factorization approach. The leading order pQCD predictions for branching ratios are,Br（B^-→ f0（980） π^-） ～ 2.5×10^-6,Br（Bˉ^0 → f0（980） π^0） ～ 2.6×10^-7,Br（Bˉ^0 → f0（980） η） ～ 2.5×10^-7 and Br（Bˉ^0 → f0（980） η ） ～ 6.7×10^-7,which are consistent with both the QCD factorization predictions and the experimental upper limits.

B→πη('),η(')η(') decays and NLO contributions in the pQCD approach

By employing the perturbative QCD （pQCD） factorization approach, we calculate the full leading and the partial next-to-leading order （NLO） contributions to the seven B →πη（′） and η（′）η（′） decays. For B^＋→ π＋η（′） decays, the pQCD predictions for their decay rates agree very well with the data after the inclusion of the small NLO contributions. For neutral decays, the pQCD predictions are also consistent with the experimental upper limits and can be tested by the LHC experiments. The measured value of dir .Acp^dir（π＋η）= 19±7% can also be accommodated by the pQCD approach.

The B→D^(*)lv_l decays in the pQCD approach with the Lattice QCD input

In this decays B → D^（＊）l^-vl paper, we studied by using the the semileptonic ＂pQCD ＋ Lattice QCD＂ method. We made the extrapolation for the six relevant form factors by using the input values obtained from the pQCD factorization approach in the low q2 region of 0 ≤ q^2≤≤mt^2 and the lattice QCD input at the endpoint q^2 = q^2max· We then calculated the ratios R（D） and R（D^＊） of the branching ratios B（B→ D^（＊）l^-vl） and found numeri- cally that （1） the ＂pQCD ＋ Lattice QCD＂ predictions for the branching ratios B（B → D^（＊）l^-vl） agree well with the measured values within one standard deviation; and （2） the ＂pQCD ＋ Lattice QCD＂ predictions for the ratios R（D^（＊）） are R（D） =0.037-0.037^＋0.038 and R（D^＊） = 20269-03020^＋03021;they agree with the data within 2σ deviation, in other words, one can explain the ＂R（D（^＊）-puzzle＂ in the framework of the Standard Model.

Semileptonic decays B_c■(η_c, J/ψ)l■_l in the “PQCD+Lattice” approach

We study the semileptonic decaysBc-→(ηc,J/ψ)l-■lusing the PQCD factorization approach with the newly defined distribution amplitudes of the B c meson and a new kind of parametrization for extrapolating the form factors which takes into account the recent lattice QCD results.We find the following main results:(a)the PQCD predictions of the branching ratios of theBc→(ηc,J/ψ)l■decays are smaller by about 5%-16%when the lattice results are taken into account in the extrapolation of the relevant form factors;(b)the PQCD predictions of the ratio Rηc,RJ/ψand of the longitudinal polarization PτareRηc=0.34±0.01,RJ/ψ=0.28±0.01,Pτ(ηc)=0.37±0.01and Pτ(J/ψ)=-0.55±0.01;and(c)after including the lattice results,the theoretical predictions slightly change:Rηc=0.31±0.01,RJ/ψ=0.27±0.01,Pτ(ηc)=0.36±0.01andPτ(J/ψ)=-0.53±0.01.The theoretical predictions of RJ/ψagree with the measurements within the errors.The other predictions could be tested by the LHCb experiment in the near future.

Branching ratio and CP asymmetry of Bs→K0＊ （1430）η（＇） decays in the PQCD approach

In the two-quark model supposition for K0＊（1430）, which can be viewed as either the first excited state （ScenarioⅠ） or the lowest lying state （Scenario Ⅱ）, the branching ratios and the direct CP-violating asymmetries for decays s0 → K0＊0（1430）η （’） are studied by employing the perturbative QCD factorization approach. We find the following results： （a） The CP averaged branching ratios ofs0 → K0＊0 （1430）η ands0→ K0＊0（1430）η’ are small and both in the order of 10-7 . If one views K0＊ （1430） as the lowest lying state, B（s0→K0＊0（1430）η） ≈ 3.9×10-7 and B（s0→K0＊0（1430）η’） ≈ 7.8×10-7.（b） While the direct CP-violating asymmetries of these two decays are not small： if we still take the parameters of K0＊ （1430） in scenario , ACPdir（s0→K0＊0（1430）η） ≈ 56.2% and ACPdir（s0→ K0＊0（1430）η’） ≈ 42.4%. （c） The annihilation contributions will play an important role in accounting for future data, because both the branching ratios and the direct CP asymmetries of these two decays are sensitive to the annihilation type contributions.

Semileptonic decays B/Bs→(D^(?),D^(?)s)lνl in the PQCD approach with the lattice QCD input

We study the semileptonic B/Bs→(D^(?),D^(?)s)lνl decays in the framework of the Standard Model(SM),by employing the perturbative QCD(PQCD)factorization formalism combined with the lattice QCD input for the relevant transition form factors.We calculate the branching ratios B(B(s)→D^(?)(s)lνl)with l=(e,μ,τ),the ratios of the branching fractions R(D^(?))and R(D^(?)s),and the physical observables Pτ(D^(?)(s)),FL(D?(s))and AFB(τ).The“PQCD+Lattice”predictions for B(B→D^(?)lνl)and R(D^(?))agree with the available experimental measurements within errors.For the ratios R(Ds)and R(D^?s),the"PQCD+Lattice"predictions agree with the other predictions.For Pτ(D^?)and FL(D^?),our theoretical predictions agree with the measured values within errors.Our theoretical predictions of the semileptonic B/Bs decays considered could be tested in the near future by the LHCb and Belle II experiments.

Revisiting the Kπ puzzle in the pQCD factorization approach

In this paper,we calculated the branching ratios and direct CP violation of the four B→Kπ decays with the inclusion of all currently known next-to-leading order（NLO） contributions by employing the perturbative QCD（pQCD） factorization approach.We found that（a） Besides the 10%enhancement from the NLO vertex corrections,the quark-loops and magnetic penguins,the NLO contributions to the form factors can provide an additional^15%enhancement to the branching ratios,and lead to a very good agreement with the data;（b） The NLO pQCD predictions are A_（CP）^（dir）（B^0→K~＋π~0）=（-6.5±3.1）%and A_（CP）^（dir）（B~＋→K~＋π~0）=（2.2±2.0）%,become well consistent with the data due to the inclusion of the NLO contributions.

HERA光生过程中的强子与光子产生

本文讨论了HERA 硬光生过程中的强子和光子产生问题。在QCD 领头级近似之下计算了单、双光子的产生截面。结果表明:在低xt 情况下,分解过程的贡献很重要,不应当把分解过程看作直接过程的高阶修正,而应当把它视为独立的过程进行研究。因此,利用光生过程来研究夸克、胶子的强子和光子碎裂函数,以及研究质子和光子的部分子分布函数是可行的。

B→D_s^((*))η^(('))Decays in Perturbative QCD

In this paper,we calculate the branching ratios for B^+→D_s^+η,B^+→D_s^+η′,B^+→D_s^(*+)η and B^+→D_s^(*+)η′decays by employing the perturbative QCD (pQCD) factorization approach.Under the two kinds of η-η′ mixingschemes,the quark-flavor mixing scheme and the singlet-octet mixing scheme,we find that the calculated branchingratios agree well with the currently available experimental upper limits.We also consider the so called 'f_D_s puzzle',byusing two groups of parameters about the D_s^((*)) meson decay constants,that are f_D_s = 241 MeV,f_D_s~* = 272 MeV andf_D_s = 274 MeV,f_D_s~* = 312 MeV,to calculate the branching ratios for the considered decays.We find that the resultschange 30% by using these two different kinds of paramters.

微扰QCD方法下的B→D_s^(*)ρ(ω)衰变(英文)

在微扰QCD因子化方法的框架下计算了B+→Ds(*)ρ0,B+→Ds(*)ω0和B+→Ds(*)+ρ-衰变道的分支比.通过计算发现衰变道B+→Ds(*)+ρ0,B+→D(s*)+ω0和B0→Ds(*)+ρ-的分支比在10-5量级,而B0D(s*)+ρ-衰变道的分支比最大,约为1.2×10-4.在这些衰变道中,对于末态包含两个矢量介子的衰变,径向激化的贡献是主要的,并且大于80%;而两个横向激化的贡献是被rDs(*)、rρ(ω)的幂次压低的.

ρ介子类时形状因子领头扭度的次领头阶研究

介子形状因子的研究对了解介子内部结构和相关动力学区域具有非常重要的意义。采用基于因子化理论的微扰QCD(PQCD)因子化方法,考虑湮灭过程e^(+)e^(-)→ρ^(+)ρ^(-)中ρ介子类时形状因子领头扭度的次领头阶贡献。利用解析延拓的方法直接将类空形状因子计算得到类时形状因子的解析修正函数,并做数值计算。结合大动量区域下ρ介子类时形状因子领头扭度的领头阶和次领头阶的贡献随Q^(2)的变化曲线,发现考虑次领头阶的修正后,形状因子会有20%的涨幅。通过计算得出了湮灭过程e^(+)e^(-)→ρ^(+)ρ^(-)在s=112GeV^(2)时的散射截面值,并与实验数据做比较。

Investigation of proton structure function F_(2)^(p)at HERA in light of an analytical solution to the Balitsky–Kovchegov equation

In this paper,the proton structure function F_(2)^(p)(x,Q^(2))at small-x is investigated using an analytical solution to the Balitsky–Kovchegov(BK)equation.In the context of the color dipole description of deep inelastic scattering(DIS),the structure function F_(2)^(p)(x,Q^(2))is computed by applying the analytical expression for the scattering amplitude N(k,Y)derived from the BK solution.At transverse momentum k and total rapidity Y,the scattering amplitude N(k,Y)represents the propagation of the quark-antiquark dipole in the color dipole description of DIS.Using the BK solution we extracted the integrated gluon density xg(x,Q^(2))and then compared our theoretical estimation with the LHAPDF global data fits,NNPDF3.1sx and CT18.Finally,we have investigated the behavior of F_(2)^(p)(x,Q^(2))in the kinematic region of 10^(-5)≤x≤10^(-2)and 2.5 GeV^(2)≤Q^(2)≤60 GeV^(2).Our predicted results for F_(2)^(p)(x,Q^(2))within the specified kinematic region are in good agreement with the recent high-precision data for F_(2)^(p)(x,Q^(2))from HERA(H1 Collaboration)and the LHAPDF global parametrization group NNPDF3.1sx.

HERA分解光生J/ψ(英文)

研究了ＨＥＲＡ分解光生过程中的Ｊ／ψ产生．结果表明该过程可以用来测量光子及质子中的部分子分布，也可以用于测量胶子和重夸克的Ｊ／ψ碎裂机制以检验微扰ＱＣＤ．