Reanalysis of pion pion phase shifts from K -> pi pi decays

TL;DR

This paper refines the extraction of pion pion phase shift differences from K to pi pi decays by using updated experimental data and improved theoretical methods, achieving more precise results.

Contribution

It provides a more accurate and robust reanalysis of phase shifts by incorporating recent data and advanced analysis techniques.

Findings

Phase shift difference delta_0 - delta_2 = (52.5 ± 0.8_exp ± 2.8_theor) degrees

Enhanced precision over previous analyses

Improved understanding of isospin violation effects

Abstract

We re-investigate the impact of isospin violation for extracting the s-wave pion pion scattering phase shift difference delta_0(M_K) - delta_2(M_K) from K -> pi pi decays. Compared to our previous analysis in 2003, more precise experimental data and improved knowledge of low-energy constants are used. In addition, we employ a more robust data-driven method to obtain the phase shift difference delta_0(M_K) - delta_2(M_K) = (52.5 \pm 0.8_{exp} \pm 2.8_{theor}) degrees.