18-24 June 2017
Palacio de Congresos
Europe/Madrid timezone
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Andalucía I
Weak Decays and Matrix Elements

$\Lambda_b \to \Lambda(1520) \ell^+\ell^-$ form factors with moving NRQCD


  • Mr. Gumaro RENDON

Primary authors


The decay $\Lambda_b \to \Lambda(1520)(\to p^+ K^-) \mu^+\mu^-$ is a baryonic analogue of the mesonic process $\bar{B}^0 \to \bar{K}^{*0}(892)(\to \pi^+ K^-) \mu^+\mu^-$, in which tensions between theory and experiment have been observed. Here we give an update on our lattice calculations of $\Lambda_b \to \Lambda(1520)$ form factors. To allow an exact projection to the $J^P=\frac32^-$ quantum numbers of the $\Lambda(1520)$, we work in the $\Lambda(1520)$ rest frame, which means that very high $\Lambda_b$ momenta are required to cover a useful range of $q^2$. In our initial study presented in 2016, we had used an anisotropic clover action for the $b$ quark, which leads to large discretization errors at high momenta. Here we report on a new calculation in which the $b$ quark is implemented with moving NRQCD, a boosted version of lattice NRQCD that allows us to study a kinematic region not accessible before.