Reducing the Error on alpha in B-> pi pi, rho rho, rho pi
Abstract
Theoretical errors in the extraction of alpha from B -> pi^+ pi^-, rho^+ rho^-, rho pi decays are usually given in terms of upper bounds on alpha_eff-alpha obtained from isospin or from SU(3) relations, where alpha_eff is measured through CP asymmetries. We show that mild assumptions about magnitudes and strong phases of penguin and tree amplitudes (|P/T| < 1 and |delta| < pi/2) in B -> pi pi and B -> rho rho, imply alpha_eff > alpha, thus reducing by a factor two the error in alpha. Similarly, the assumptions |p_+-/t_+-| < 1, |\delta_-| < pi/2 <|\delta_+| in B -> rho pi lead to a cancellation between two terms in alpha_eff-alpha. Current data support these conditions.
Cite
@article{arxiv.hep-ph/0410170,
title = {Reducing the Error on alpha in B-> pi pi, rho rho, rho pi},
author = {M. Gronau and E. Lunghi and D. Wyler},
journal= {arXiv preprint arXiv:hep-ph/0410170},
year = {2010}
}
Comments
10 pages, 2 figures, small corrections, few references added, final version to appear in Phys. Lett. B