Lattice QCD Calculation of the Pion Mass Splitting.

Xu Feng,Michael Joseph Riberdy,Luchang Jin

doi:10.1103/physrevlett.128.052003

Abstract

We use the infinite volume reconstruction method to calculate the charged and neutral pion mass difference. The hadronic tensor is calculated using lattice QCD and then combined with an analytic photon propagator, and the mass splitting is calculated with exponentially suppressed finite-volume errors. The calculation is performed using six gauge ensembles generated with 2+1-flavor domain wall fermions, and five ensembles are at the physical pion mass. Both Feynman and Coulomb gauges are adopted in the calculation and agree well when the lattice spacing approaches zero. After performing the continuum extrapolation and examining the residual finite-volume effects, we obtain the pion mass splitting Δm_{π}=4.534(42)_{stat}(43)_{sys} MeV, which agrees well with experimental measurements.

Highlights

Introduction.—One of the central goals in high energy physics is understanding the nature of the matter that we observe in the Universe
The anomalous decay rate of the neutral pion led to the discovery of Adler-Bell-Jackiw anomaly of quantum electrodynamics (QED) [26,27], which revealed for the first time the violation of classical symmetry by quantum corrections
In this Letter, we focus on the study of the mass splitting between the charged and neutral pions, which represents the interplay between two fundamental interactions, the strong and the electromagnetic

Summary

Introduction

Introduction.—One of the central goals in high energy physics is understanding the nature of the matter that we observe in the Universe. Precision calculation based on the lattice formulation of quantum chromodynamics (QCD), the theory of the strong interaction, can manifest its success by computing the various hadron spectra, which agree well with experimental measurements [1]. When the precision reaches percent or subpercent level, another fundamental force, electromagnetic interaction, is urged to be considered in theoretical calculations, its effects are suppressed by a factor of the fine-structure constant αEM ≈ 1=137.

Results

Conclusion