The Width Difference of $B_d$ Mesons

Abstract

We estimate $\text{dg}/{\Gamma }_d$, including $1/m_b$ contributions and part of the next-to-leading order QCD corrections. We find that adding the latter corrections decreases the value of $\text{dg}/{\Gamma }_d$ computed at the leading order by a factor of almost 2. We also show that under certain conditions an upper bound on the value of $\text{dg}/{\Gamma }_d$ in the presence of new physics can be derived. With the high statistics and accurate time resolution of the upcoming LHC experiment, the measurement of $\text{dg}$ seems to be possible. This measurement would be important for an accurate measurement of $\sin (2\beta )$ at the LHC. In addition, we point out the possibility that the measurement of the width difference leads to a clear signal for new physics.

Comments: 5 pages, latex. Talk given at International Europhysics Conference on High-Energy Physics (HEP 2001), Budapest, Hungary, 12-18 Jul 2001