Mr Edwin Lizarazo (University of Southampton)
We present an update on our calculation of short distance contributions to semi-leptonic form factors for rare $B$ decays. Results for $B_s \to \phi \ell^+\ell^-$ at three lattice spacings of $a^-1 = 1.78$, 2.38, and 2.76 GeV are shown. Our calculations are based on RBC-UKQCD's $N_f = 2+1$ domain-wall fermion and Iwasaki gauge field ensembles. The heavy $b$-quarks are simulated using the relativistic heavy quark action and domain-wall fermions are used for the light quarks.