The Role of Collinear Photons in the Rare Decay anti-B --> X(s) l+ l-

TL;DR

This paper reviews the phenomenology of the rare decay   X_s l+ l-, emphasizing the impact of collinear photons and electromagnetic logarithms on experimental and theoretical analyses, aiding future collider searches for new physics.

Contribution

It provides a detailed analysis of collinear photon effects in  decays and offers practical recommendations for experimental treatment aligned with theoretical prescriptions.

Findings

Analysis of electromagnetic logarithms ln(m_b^2/m_l^2) in decay

Comparison of BaBar and Belle analysis methods

Recommendations for treating collinear photons in experiments

Abstract

We review the phenomenology of the rare decay \bar B -> X_s l+ l-. We present the results of a detailed phenomenological analysis and discuss the role of the decay in the search for new physics at present and future colliders. Moreover, we extensively elaborate on the size of electromagnetic logarithms ln(m_b^2/m_l^2) in view of experimental cuts. We point out the differences in the analyses of BaBar and Belle and give suggestions on how to treat collinear photons in the experimental analyses. These recommendations correspond precisely to theoretical prescriptions and can be combined with measurements performed at a Super-B factory.