Effects of right-handed charged currents on the determinations of |V_ub| and |V_cb|

Abstract

We study the effect of a right-handed coupling of quarks to the W-boson on the measurements of |V_ub| and |V_cb|. It is shown that such a coupling can remove the discrepancies between the determinations of |V_ub| from B\to\pi\ell\nu, B^+\to\tau^+ \nu and B\to X_u\ell\nu. Further the measurements of |V_cb| from B\to D^*\ell\nu, B\to D\ell\nu and inclusive B\to X_c\ell\nu decays can be brought into better agreement. We demonstrate that a right-handed coupling can be generated within the MSSM by a finite gluino-squark loop. The effect involves the parameters \delta^{u RL}_{23} and \delta^{u RL}_{13} of the squark mass matrices, which are poorly constrained from other processes. On the other hand, all gluino-squark corrections to the regular left-handed coupling of the W-boson are found to be too small to be relevant.