Bound on V+A admixture in the b -> c current from inclusive vs. exclusive semileptonic decays of B mesons

Abstract

An admixture of a right-handed $b \to c$ current in the semileptonic weak decays of the $B$ mesons would give a significantly different contribution to the inclusive rate of the decays $B \to l \nu X_c$ as compared to the exclusive decay $B \to D^* l \nu$ at zero recoil. Thus a difference in the values of $|V_{cb}|$ extracted from the data on these two types of decay would measure such admixture. The present marginal mismatch in determination of $|V_{cb}|$ by the two methods can be interpreted as corresponding to $g_R/g_L \approx 0.14 \pm 0.18$.