Lepton flavor violating $\Lambda_b\to\Lambda\ell_1\ell_2$ decay

Abstract

Inspired by the recent hints of lepton flavor universality violation in $b\to s\ell\ell$ and $b\to c\ell\nu$ transitions, we study lepton flavor violating exclusive $\Lambda_b\to\Lambda\ell_1^+\ell_2^-$ ($\ell_1\neq \ell_2$) decay, which is forbidden in the Standard Model. Starting from a general effective Hamiltonian for a $b\to s\ell_1^+\ell_2^-$ transition that includes vector and axial-vector operators, and scalar and pseudo-scalar operators, we derive a two-fold decay distribution of $\Lambda_b\to\Lambda\ell_1^+\ell_2^-$. The distribution helps us to construct the differential branching ratio and the lepton side forward-backward asymmetry, which are studied in a vector leptoquark model. The parameter space of the vector leptoquark model is constrained by low energy observables.