Annihilation-Type Charmless Radiative Decays of B Meson in Non-universal Z^\prime Model

TL;DR

This paper investigates rare charmless radiative B meson decays, showing that non-universal Z' models can significantly enhance their branching ratios, making them detectable and useful for probing new physics beyond the standard model.

Contribution

It introduces the impact of non-universal Z' bosons on rare B meson decays, demonstrating potential enhancements in branching ratios and CP asymmetries beyond standard model predictions.

Findings

Standard model predicts very small branching ratios (~10^{-12} to 10^{-10})

Non-universal Z' model can increase branching ratios to detectable levels (~10^{-8} to 10^{-10})

Large CP asymmetries predicted in certain parameter spaces

Abstract

We study charmless pure annihilation type radiative B decays within the QCD factorization approach. After adding the vertex corrections to the naive factorization approach, we find that the branching ratios of $\bar{B}^0_d\to\phi\gamma$, $\bar{B}^0_s\to\rho^0\gamma$ and $\bar{B}^0_s\to\omega\gamma$ within the standard model are at the order of $\mathcal{O}(10^{-12})$, $\mathcal{O}(10^{-10})$ and $\mathcal{O}(10^{-11})$, respectively. The smallness of these decays in the standard model makes them sensitive probes of flavor physics beyond the standard model. To explore their physics potential, we have estimated the contribution of $Z^\prime$ boson in the decays. Within the allowed parameter space, the branching ratios of these decay modes can be enhanced remarkably in the non-universal $Z^\prime$ model: The branching ratios can reach to $\mathcal{O}(10^{-8})$ for $\bar B_s^0 \to \rho^0(\omega)\gamma$ and $\mathcal{O}(10^{-10})$ for the $\bar B_d^0 \to \phi \gamma$, which are large enough for LHC-b and/or Super B-factories to detect those channels in near future. Moreover, we also predict large CP asymmetries in suitable parameter space. The observation of these modes could in turn help us to constrain the $Z'$ mass within the model.