Analysis of Bc → τντ at CEPC

Precise determination of the B-c -> tau nu(tau) branching ratio provides an advantageous opportunity for understanding 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 -> tau nu(tau) with tau decaying leptonically at the proposed Circular Electron Positron Collider (CEPC). We conclude that during the Z pole operation, the channel signal can achieve five-sigma significance with similar to 10(9) Z decays, and the signal strength accuracies for B-c -> tau nu(tau) can reach around 1% level at the nominal CEPC Z pole statistics of one trillion Z decays, assuming the total B-c -> tau nu(tau) yield is 3.6 x 10(6). Our theoretical analysis indicates the accuracy could provide a strong constraint on the general effective Hamiltonian for the b -> c tau nu transition. If the total B-c yield can be determined to O(1%) level of accuracy in the future, these results also imply |V-cb| could be measured up to O(1%) level of accuracy.

Automated summary

This paper discusses the potential of measuring the B-c -> tau nu(tau) process at the proposed CEPC, with results showing high signal strength accuracy during Z pole operation. Future determination of the total B-c yield at the O(1%) level may also lead to more precise measurements of |V-cb|.