Semileptonic decays Bc■(ηc, J/ψ)l■l in the “PQCD+Lattice” approach

作者：胡学卿; 金苏平; 肖振军^*

来源：Chinese Physics C, 2020, 44(02): 55-65.

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.

• 单位
  南京师范大学