Münster 2017 – scientific programme

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T: Fachverband Teilchenphysik

T 19: Flavourphysik (Theorie)

T 19.3: Talk

Monday, March 27, 2017, 17:15–17:30, VSH 06

Precision calculation of B → X_c τ ν and the R(D^(*)) puzzle — •Farnoush Shahriaran, Thomas Mannel, and Aleksey V. Rusov — University of Siegen

We calculate the decay width of inclusive B → X_cτν_τ process including power corrections up to Λ_QCD/m_b³ order and radiative corrections to the partonic level. We show that our result is in a tension with the sum of the rates of the exclusive B→ Dτν, B→ D^*τν and B→ D^**τν decays.
For solving this puzzle, we include contributions from two possible new physics four-Fermi operators, (NP vector right-handed and left-handed scalar operators), with arbitrary couplings that can accommodate the measured central value of the ratio R(D) and R(D^*). We performed the calculation of the decay with of the process B→ X_cτν_τ in the presence of thees operators at tree level at leading order in 1/m_b expansion. The updated prediction is consistent with the sum of the branching fractions of exclusive modes.