# 36th Annual International Symposium on Lattice Field Theory

Jul 22 – 28, 2018
Kellogg Hotel and Conference Center
EST timezone

## Control of SU(3) symmetry breaking effects in calculations of B meson decay constant

Jul 25, 2018, 3:20 PM
20m
103 (Kellogg Hotel and Conference Center)

### 103

#### Kellogg Hotel and Conference Center

219 S Harrison Rd, East Lansing, MI 48824
Weak Decays and Matrix Elements

### Description

Early B physics experiments have left us with a number of puzzles in heavy flavour physics. New lattice calculations and greater understanding of QCD effects in the Standard Model will be needed to support greater experimental precision in the coming years. In particular, the B meson decay constant is involved in calculations of CKM matrix elements and useful to measurements of the branching ratio B $\to \tau \nu$ expected at the Belle II Experiment. We extend the QCDSF studies of SU(3) breaking of light decay constants into the heavy-flavour regime to examine the effects of SU(3) breaking on $f_B$ and $f_{B_s}$. $b$-quarks are generated using an anisotropic clover-improved heavy-quark action. The decay constants $f_B$ and $f_{B_s}$ will be presented for a variety of light quark masses, from the SU(3) symmetric point toward the physical quark masses. In order to focus on the SU(3) symmetry breaking effects in our extrapolation to the physical point, we choose u,d,s quark masses in each simulation such that the average quark mass, $m = m_u + m_d + m_s$, is constant and equal to its physical value. Results will be presented at a number of different lattice spacings and volumes, toward calculations of $f_B$ and $f_{B_s}$ at the physical point.