Mixing-InducedCPAsymmetries in RadiativeBDecays in and beyond the Standard Model

Abstract

In the Standard Model (SM) the photon in radiativeB 0 andB s decays is predominantly left-handed. Thus, mixing induced CP asymmetries in b → sγ and b → dγ are suppressed by m s /m b and m d /m b , respectively, and are very small. In many extensions of the SM, such as the left-right symmetric model (LRSM), SU(2) × U(1) models with exotic fermions and SUSY, the amplitude of right-handed photons grows proportional to the virtual heavy fermion mass, which can lead to large asymmetries. As an example, in the LRSM, asymmetries larger than 50% are possible even when radiative decay rate measurements agree with SM predictions.

Future prospects for the determination of the Wilson coefficient $ C_{{^{{7\gamma }}}}^{\prime } $

“…For the generic radiative decay of the neutral B-meson into any hadronic self-conjugate state f CP , B(t) → f CP γ, neglecting direct CP -violation and the small width difference between two B-mesons, the CP -asymmetry is given by [14] …”

“…• An indirect determination of the photon polarization, proposed by Atwood et al [14,15], is the measurement of the time-dependent mixing-induced CP -asymmetry in the radiative neutral B-mesons decays B → f CP γ (where f CP is the CPeigenstate). Prominent examples are B → K * (→ K S π 0 )γ, and B s → φγ.…”

Search for new physics at a super-B factory

“…While the use of the rate and the direct CP asymmetry measurements in radiative decays of the B have received much attention for a very long time [30], discussions on mixing-induced (time dependent) CP in these modes are more recent [31]. This class of CP provides a very clean test of the SM and is very sensitive to presence of right handed currents of BSM origin [31].…”

“…This class of CP provides a very clean test of the SM and is very sensitive to presence of right handed currents of BSM origin [31].…”

Flavor Physics Techniques and Sensitivities at LHCb

“…The large lifetime difference for B s ensures some sensitivity to the polarization amplitude ratio, A ∆ q . The reliable SM prediction [6] at the next-to-next leading order for this polarization term can be confronted with the experimental data to check for New Physics in loop. Approximately 11 × 10 3 B s → Φγ signal events are expected to be recosntructed and selected with LHCb per nominal year of data taking with a background over signal ratio of less than 90% [5].…”