Precise determination of the B_(c)→τν_(τ) branching ratio provides an advantageous opportunity for under-standing the electroweak structure of the Standard Model,measuring the CKM matrix element |V_(cb)|,and probi...Precise determination of the B_(c)→τν_(τ) branching ratio provides an advantageous opportunity for under-standing the electroweak structure of the Standard Model,measuring the CKM matrix element |V_(cb)|,and probing new physics models.In this paper,we discuss the potential of measuring the process B_(c)→ τν_(τ)withτdecaying leptonically at the proposed Circular Electron Positron Collider(CEPC).We conclude that during the Z pole opera-tion,the channel signal can achieve five-σsignificance with~10^9 Z decays,and the signal strength accuracies for B_(c)→τν_(τ) can reach around 1%level at the nominal CEPC Z pole statistics of one tillion Z decays,assuming the total B_(c)→τν_(τ) yield is 3.6x 10^(6).Our theoretical analysis indicates the accuracy could provide a strong constraint on the general effective Hamiltonian for the b→cτν transition.If the total Be yield can be determined to 0(1%)level of accuracy in the future,these results also imply|V_(cb)| could be measured up to 0(1%)level of accuracy.展开更多
基金This study was supported by the National Key Programme for S&T Research and Development(2016YFA0400400)the Beijing Municipal Science Technology Commission(Z181100004218003,Z 191100007219010)+2 种基金the Natural Science Foundation of China(11735010,11911530088,11775110,11690034)the Natural Science Foundation of Shanghai(15DZ2272100)the DFG Emmy-Noether(BE 6075/1-1)。
文摘Precise determination of the B_(c)→τν_(τ) branching ratio provides an advantageous opportunity for under-standing the electroweak structure of the Standard Model,measuring the CKM matrix element |V_(cb)|,and probing new physics models.In this paper,we discuss the potential of measuring the process B_(c)→ τν_(τ)withτdecaying leptonically at the proposed Circular Electron Positron Collider(CEPC).We conclude that during the Z pole opera-tion,the channel signal can achieve five-σsignificance with~10^9 Z decays,and the signal strength accuracies for B_(c)→τν_(τ) can reach around 1%level at the nominal CEPC Z pole statistics of one tillion Z decays,assuming the total B_(c)→τν_(τ) yield is 3.6x 10^(6).Our theoretical analysis indicates the accuracy could provide a strong constraint on the general effective Hamiltonian for the b→cτν transition.If the total Be yield can be determined to 0(1%)level of accuracy in the future,these results also imply|V_(cb)| could be measured up to 0(1%)level of accuracy.
