Within the framework of the perturbative QCD approach,we calculate the time-like B（c ）Bc（Bc＊）form factors F（Q^2）and A2（Q^2）.We include relativistic corrections and QCD corrections,either of which can give abo...Within the framework of the perturbative QCD approach,we calculate the time-like B（c ）Bc（Bc＊）form factors F（Q^2）and A2（Q^2）.We include relativistic corrections and QCD corrections,either of which can give about20%correction to the leading-order contribution,but there are cancellation effects between them.We calculate the cross sections of the e^＋e^-→Bc-Bc＋（Bc＊＋）processes.The cross sections are enhanced at the Z pole to beσ^（P P）（Q=m Z）～1.3×10^-5pb andσ^（P V）（Q=m Z）～2.5×10^-5pb,which are still too small to be detected by proposed e~＋e^-colliders such as the Circular Electron Positron Collider.展开更多
In this paper,we summarize the existing methods of solving the evolution equation of the leading-twist B-meson LCDA.Then,in the Mellin space,we derive a factorization formula with next-to-leading-logarithmic(NLL)resum...In this paper,we summarize the existing methods of solving the evolution equation of the leading-twist B-meson LCDA.Then,in the Mellin space,we derive a factorization formula with next-to-leading-logarithmic(NLL)resummation for the form factors FA,V in the B→γℓνdecay at leading power inΛ/mb.Furthermore,we investigate the power suppressed local contributions,factorizable non-local contributions(which are suppressed by 1/Eγand 1/mb),and soft contributions to the form factors.In the numerical analysis,which employs the two-loop-level hard function and the jet function,we find that both the resummation effect and the power corrections can sizably decrease the form factors.Finally,the integrated branching ratios are also calculated for comparison with future experimental data.展开更多
基金Supported by Natural Science Foundation of Shandong Province,China(ZR2015AQ006)National Natural Science Foundation of China(11521505,11621131001,11447009,11505098,11765012)R.H.Li is partly supported by the plan of Young Creative Talents under the Talent of the Prairie project of the Inner Mongolia
文摘Within the framework of the perturbative QCD approach,we calculate the time-like B（c ）Bc（Bc＊）form factors F（Q^2）and A2（Q^2）.We include relativistic corrections and QCD corrections,either of which can give about20%correction to the leading-order contribution,but there are cancellation effects between them.We calculate the cross sections of the e^＋e^-→Bc-Bc＋（Bc＊＋）processes.The cross sections are enhanced at the Z pole to beσ^（P P）（Q=m Z）～1.3×10^-5pb andσ^（P V）（Q=m Z）～2.5×10^-5pb,which are still too small to be detected by proposed e~＋e^-colliders such as the Circular Electron Positron Collider.
基金Y.B.W is Supported in part by the National Natural Science Foundation of China(NSFC)(11675082,11735010)。
文摘In this paper,we summarize the existing methods of solving the evolution equation of the leading-twist B-meson LCDA.Then,in the Mellin space,we derive a factorization formula with next-to-leading-logarithmic(NLL)resummation for the form factors FA,V in the B→γℓνdecay at leading power inΛ/mb.Furthermore,we investigate the power suppressed local contributions,factorizable non-local contributions(which are suppressed by 1/Eγand 1/mb),and soft contributions to the form factors.In the numerical analysis,which employs the two-loop-level hard function and the jet function,we find that both the resummation effect and the power corrections can sizably decrease the form factors.Finally,the integrated branching ratios are also calculated for comparison with future experimental data.
