CP Violation and Strong Phases from Penguins in $\bf B^{\pm}\rightarrow PP$ and $\bf B^{\pm}\rightarrow VP$ Decays

TL;DR

This paper calculates direct CP-violating asymmetries in charged B meson decays to two pseudoscalar or vector-pseudoscalar final states, highlighting potential asymmetries up to 20% due to interference effects.

Contribution

It introduces a model for calculating strong phases from penguin diagrams at order alpha_s, incorporating absorptive parts and CPT constraints, to predict CP asymmetries in B decays.

Findings

Partial rate asymmetries can reach up to 20%.

Asymmetries are sensitive to internal momentum transfer assumptions.

Charge asymmetries serve as clear evidence for direct CP violation.

Abstract

We calculate direct CP-violating rate asymmetries in charged $B\to PP$ and $B\to VP$ decays arising from the interference of amplitudes with different strong and CKM phases. The perturbative strong phases develop at order $\alpha_s$ from absorptive parts of one-loop matrix elements of the next-to-leading logarithm corrected effective Hamiltonian. CPT constraints are maintained. Based on this model, we find that partial rate asymmetries between charge conjugate $B^{\pm}$ decays can be as high as 20\% for certain channels with branching ratios in the $10^{-6}$ range. Because the $c\bar{c}$ threshold lies so close to the physical momentum scale, the asymmetries depend sensitively on the model assumptions used to evaluate the imaginary parts of the matrix elements, in particular, on the internal momentum transfer. The charge asymmetries of partial rates would provide unambiguous evidence for direct CP violation.