Constraining New Physics in B-->pi+pi- with Reparametrization Invariance and QCD Factorization

TL;DR

This paper demonstrates how reparametrization invariance and QCD factorization can be used to constrain new physics contributions in B meson decays, particularly affecting CP-violating phases and decay amplitudes.

Contribution

It introduces a novel approach to express B->pi+pi- decay amplitudes with a dependence on beta, enabling new constraints on new physics in B meson mixing and decay.

Findings

Constraints on new physics contributions to CP-violating phase phi_d

Bounds on additional new-physics amplitudes in B->pi+pi-

Reparametrization invariance aids in analyzing decay amplitudes

Abstract

Usually, B->pi+pi- decays are expressed in terms of weak amplitudes explicitly dependent on the CKM weak phase alpha or gamma. In this letter, we show that the weak amplitudes can be rewritten such that a manifest dependence on beta emerges instead. Based on this, we constrain new-physics contributions to the CP-violating phase phi_d in B_0 anti-B_0 mixing. Further, we apply reparametrization invariance and use QCD factorization predictions to investigate the bounds on an additional new-physics amplitude in B->pi+pi-.