Mass spectrum of N* and source optimization

TL;DR

This paper computes nucleon mass spectra using correlation functions, employing group theory to optimize sources for better overlap with higher spin states, and analyzes mass splittings between states.

Contribution

It introduces a source optimization method using group theory to improve the extraction of nucleon masses and spin states in lattice QCD simulations.

Findings

Clear mass splittings between low-lying and excited states.

Effective use of group theory for source design.

Successful identification of positive and negative parity states.

Abstract

We have computed correlation functions for nucleons and extracted the masses for positive- and negative-parities. Use of group theory plays an important role in obtaining sources that have good overlap to higher spin states and minimum contamination from unwanted states. In the simulation three distinct sources and corresponding sinks that transform according to the $G_1$ irreducible representations are tested and used to form matrices of correlation functions. Diagonalizations give us clear mass splittings between low-lying states and excited states for both parities.