New physics in $\Delta {\Gamma }_d$

Abstract

We analyze the possibility of having new physics effects in the decay rate difference, $\Delta {\Gamma }_d$, of neutral $B_d$ mesons. Three different sources of enhancement are considered, CKM unitarity violations, beyond standard model effects in the tree-level dimension six operators $(\bar{d}p)({\bar{p}}^{\prime }b)$ with $p,p^{\prime }=u,c$; and large enhancements of the almost unconstrained operators $(\bar{d}b)(\bar{\tau }\tau )$. We find that deviations of several hundred per cent from the standard model prediction of $\Delta {\Gamma }_d$ are not excluded by current experimental data.

Comments: Proceedings of the workshop "Flavorful Ways to New Physics", October 28-31 2014, Freudenstadt, Germany