24-30 July 2016
Highfield Campus, University of Southampton
Europe/London timezone

Calculation of hadronic matrix elements contributing to the $B_s-\bar{B}_s$ width difference

27 Jul 2016, 10:40
20m
Building B2a Room 2065 (Highfield Campus, University of Southampton)

Building B2a Room 2065

Highfield Campus, University of Southampton

Talk Weak Decays and Matrix Elements Weak Decays and Matrix Elements

Speaker

Dr Matthew Wingate (University of Cambridge)

Description

The width difference $\Delta \Gamma_s$ is one of three observables, along with the mass splitting $\Delta M_s$ and the semileptonic CP asymmetry $a^s_{\mathrm{SL}}$, whose measurements completely constrain the physics of $B_s-\bar{B}_s$ oscillations. One of the dominant uncertainties in theoretical calculations of the width difference is due to not knowing matrix elements of dimension-7 operators beyond the vacuum saturation approximation. In particular, progress requires a first-principles calculation of the matrix element of $R_2$, a $\Delta B = 2$ operator with a derivative acting on the strange quark field. We discuss our methodology and present preliminary results of a calculation of $\langle B_s | R_2 | \bar{B}_s\rangle$ using nonrelativistic $b$ quarks and highly-improved staggered $s$ quarks on the MILC Collaboration's $n_f = 2+1+1$ configurations.

Primary author

Dr Matthew Wingate (University of Cambridge)

Co-authors

Prof. Christine Davies (University of Glasgow) Dr Christopher Monahan (Rutgers University) Prof. G. Peter Lepage (Cornell University) Prof. Junko Shigemitsu (Ohio State University)

Presentation Materials