SuperIso: A program for calculating the isospin asymmetry of B -> K* gamma in the MSSM

TL;DR

The paper tackles constraining MSSM parameter space using the isospin asymmetry in $B \rightarrow K^* \gamma$ within minimal flavor violation. It presents SuperIso, a C99 program that computes the NLO SUSY contributions to $\Delta_{0-}$ via an effective Hamiltonian and QCD factorization, and also provides the inclusive branching ratio $\mathcal{B}(b \rightarrow s \gamma)$ for cross-check. It supports mSUGRA, AMSB, and GMSB through SLHA inputs and can interface with ISAJET or SOFTSUSY for spectra, with a modular design for adding more observables. Validation shows good agreement with SM expectations and other codes, and demonstrates that $\Delta_{0-}$ can impose strong constraints, particularly at high $\tan\beta$.

Abstract

We present a program for calculating the isospin symmetry breaking of the B -> K* gamma decay in the MSSM with minimal flavor violation. This program calculates the NLO supersymmetric contributions to the isospin asymmetry, using the effective Hamiltonian approach and within the QCD factorization method. We show that isospin symmetry breaking proves to be a very restrictive observable, in particular in the mSUGRA parameter space. The program also calculates the inclusive branching ratio associated to b -> s gamma transition, as a comparison reference.

Figures (1)

• Figure 1: Isospin asymmetry in function of $m_{1/2}$ in the mSUGRA parameter space (in the top) and of $m_{3/2}$ in the AMSB parameter space (in the bottom), for several values of $\tan\beta$. The dashed violet horizontal line corresponds to the experimental limit of bellebabar.