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

作　　者：Ying-Ying Fan Zhen-Jun Xiao Ru-Min Wang Bing-Zhong Li 

机构地区：[1]College of Physics and Electronic Engineering, Xinyang Normal University [2]Department of Physics and Institute of Theoretical Physics,Nanjing Normal University

出　　处：《Science Bulletin》2015年第23期2009-2015,共7页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China(11235005;11105115and 11505148);the key project of Henan’s Universities(15A140033)

摘　　要：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.In this paper, we studied the semileptonic decays B→D^((*)l-_l) by using the ‘‘pQCD+Lattice QCD'' method. We made the extrapolation for the six relevant form factors by using the input values obtained from the p QCD factorization approach in the low q^2 region of 0≤q2≤m_t^2 and the lattice QCD input at the endpoint q^2=q_(max)~2. We then calculated the ratios R(D) and R(D)* of the branching ratios B(B→D^((*)l-_l) )and found numerically that(1) the ‘‘pQCD+ Lattice QCD'' predictions for the branching ratios B(B→D^((*)l-_l))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)=0:337_(0.037)^(0.038)and R(D*)=0:269_(0.020)^(0.021 ); they agree with the data within 2δ deviation, in other words, one can explain the ‘‘R(D)-puzzle'' in the framework of the Standard Model.

关 键 词：＂R（D^（＊））-puzzle＂ · → D^（＊）lvl decays ·The pQCD approach · Lattice QCD 

分 类 号：O571.3[理学—粒子物理与原子核物理]