Contribution of vector resonances to the {\bar B}_d^0 -> {\bar K}^{*0} mu^+ mu^- decay

TL;DR

This paper analyzes how vector resonances affect the decay ar;B_d^0ar;K^{*0} mu+ mu-, showing that resonance contributions can significantly alter decay observables even outside charmonia regions.

Contribution

It provides a detailed calculation of resonance effects on decay distributions, highlighting their importance in interpreting experimental data.

Findings

Resonance contributions can significantly modify decay branching ratios.

Inclusion of resonances affects polarization and asymmetry measurements.

Results depend on unknown phases of certain decay amplitudes.

Abstract

The fully differential angular distribution for the rare flavor-changing neutral current decay \bar{B}_d^0 -> \bar{K}^{*0} (-> K- pi+) mu+ mu- is studied. The emphasis is placed on accurate treatment of the contribution from the processes \bar{B}_d^0 -> \bar{K}^{*0} (-> K- pi+) V with intermediate vector resonances V = rho(770), omega(782), phi(1020), J/psi, psi(2S), ... decaying into the mu+ mu- pair. The dilepton invariant-mass dependence of the branching ratio, longitudinal polarization fraction f_L of the \bar{K}^{*0} meson, and forward-backward asymmetry A_{FB} is calculated and compared with data from Belle, CDF and LHCb. It is shown that inclusion of the resonance contribution may considerably modify the branching ratio, calculated in the SM without resonances, even in the invariant-mass region far from the so-called charmonia cuts applied in the experimental analyses. This conclusion crucially depends on values of the unknown phases of the B^0 -> K^{*0} J/psi and B^0 -> K^{*0} psi(2S) decay amplitudes with zero helicity.