Constraints on a New Light Spin-One Particle from Rare b -> s Transitions
Abstract
The anomalously large like-sign dimuon charge asymmetry in semileptonic b-hadron decays recently measured by the D0 Collaboration may be hinting at the presence of CP-violating new physics in the mixing of Bs mesons. It has been suggested that the effect of a nonstandard spin-1 particle lighter than the b quark with flavor-changing couplings to b and s quarks can reproduce the D0 result within its one-sigma range. Here we explore the possibility that the new particle also couples to charged leptons l=e,mu and thus contributes to rare b -> s processes involving the leptons. We consider in particular constraints on its couplings from existing experimental data on the inclusive B -> Xs l+ l- and exclusive B -> K(*) l+ l- decays, as well as the anomalous magnetic moments of the leptons. We find that there is parameter space of the particle that is allowed by the current data. Future measurements of these B transitions and rare decays of the Bs meson, such as Bs -> (phi,eta,eta') l+ l- and Bs -> l+ l-, at LHCb and next-generation B factories can probe its presence or couplings more stringently.