Delta I = 3/2, K to Pi Pi Decays with a Nearly Physical Pion Mass

TL;DR

This study computes the Delta I = 3/2 K to Pi Pi decay amplitude using near-physical pion and kaon masses on lattice QCD, providing preliminary results with reduced systematic errors.

Contribution

It presents the first calculation of the decay amplitude with nearly physical pion mass and energy-conserving kinematics on large dynamical lattices.

Findings

Preliminary value for Re(A_2) is 1.396(81)_stat(160)_sys x 10^(-8) GeV.

Preliminary value for Im(A_2) is -8.46(45)_stat(1.95)_sys x 10^(-13) GeV.

Uses antiperiodic boundary conditions to achieve non-zero pion momentum.

Abstract

The Delta I = 3/2 K to Pi Pi decay amplitude is calculated on RBC/UKQCD 32^3 x 64, L_s=32 dynamical lattices with 2+1 flavors of domain wall fermions using the DSDR and Iwasaki gauge action. The calculation is performed with a single pion mass (m_pi=141.9(2.3) MeV, partially quenched) and kaon mass (m_K=507.4(8.5) MeV) which are nearly physical, and with nearly energy conserving kinematics. Antiperiodic boundary conditions in two spatial directions are used to give the two pions non-zero ground state momentum. Results for time separations of 20, 24, 28 and 32 between the kaon and two-pion sources are computed and an error weighted average is performed to reduce the error. We find prelimenary results for Re(A_2)=1.396(081)_stat(160)_sys x 10^(-8) GeV and Im(A_2) = -8.46(45)_stat(1.95)_sys x 10^(-13) GeV.