摘要
The heavy quark effective field theory(HQEFT)provides an effective way to deal with heavy meson decays.In this paper,we adopt two different correlators to derive the light-cone sum rules(LCSR)for the B→πtransition form factors(TFFs)in the framework of HQEFT.We label the two LCSR results as LCSR-u and LCSR-R,which stand for the conventional correlator and the right-handed correlator.We observe that the correlation parameter|ρRU|for the branching ratio B(B→πlv_l)is^0.85,implying a consistency of LCSRs with the other correlators.Furthermore,we obtain|V_(ub)|_(LCSR-u)=(3.45_(-0.20)^(+0.28)±0.13_(exp))×10^(-3)and|V_(ub)|_(LCSR-R)=(3.38_(-0.16)^(+0.22)±0.12_(exp))×10^(-3).We also obtain R_π|_(LCSR-u)=0.68_(-0.09)^(+0.10)and R_π|_(LCSR-R)=0.65_(-0.11)^(+0.13),both of which agree with the lattice QCD predictions.Thus,HQEFT provides a useful framework for studying B meson decays.Moreover,by using the right-handed correlator,the twist-2 terms are dominant in TFF f^+(q^2),as their contribution is over^97%in the whole q^2 region,while the large twist-3 uncertainty of the conventional correlator is greatly suppressed.Hence,the LCSR-R predictions can be used to test the properties of the various models for the pion twist-2 distribution amplitudes.
The heavy quark effective field theory（HQEFT） provides an effective way to deal with heavy meson decays.In this paper,we adopt two different correlators to derive the light-cone sum rules（LCSR） for the B→π transition form factors（TFFs） in the framework of HQEFT.We label the two LCSR results as LCSR-u and LCSR-R,which stand for the conventional correlator and the right-handed correlator.We observe that the correlation parameter |ρRU| for the branching ratio B（B→πlvl） is～0.85,implying a consistency of LCSRs with the other correlators.Furthermore,we obtain |Vub|LCSR-u=(3.45-0.20+0.28±0.13exp)×10-3 and |Vub|LCSR-R=(3.38-0.16+0.22±0.12exp)×10-3.We also obtain Rπ|LCSR-u=0.68-0.09+0.10 and Rπ|LCSR-R=0.65-0.11+0.13,both of which agree with the lattice QCD predictions.Thus,HQEFT provides a useful framework for studying B meson decays.Moreover,by using the right-handed correlator,the twist-2 terms are dominant in TFF f+（q2）,as their contribution is over～97% in the whole q2 region,while the large twist-3 uncertainty of the conventional correlator is greatly suppressed.Hence,the LCSR-R predictions can be used to test the properties of the various models for the pion twist-2 distribution amplitudes.
基金
Supported in part by the Natural Science Foundation of China(11625520,11765007,11375008,11647307,11847301)
the Project of Guizhou Provincial Department of Science and Technology([2017]1089)
the Key Project for Innovation Research Groups of Guizhou Provincial Department of Education(KY[2016]028)
