Extraction of the resonance parameters at finite times

TL;DR

This paper introduces a model-independent technique to determine resonance parameters directly from Euclidean correlation functions at finite times, validated through lattice calculations and comparisons with existing methods.

Contribution

The paper presents a novel, model-independent approach for extracting resonance parameters from lattice Euclidean correlators, applicable at finite times.

Findings

Successful extraction of Delta-resonance parameters at one loop in Small Scale Expansion.

Application of the method to a 1+1-dimensional Ising model with consistent results.

Comparison with Luescher's approach demonstrates the method's validity.

Abstract

In this paper we propose a model-independent method to extract the resonance parameters on the lattice directly from the Euclidean 2-point correlation functions of the field operators at finite times. The method is tested in case of the two-point function of the Delta-resonance, calculated at one loop in Small Scale Expansion. Further, the method is applied to a 1+1-dimensional model with two coupled Ising spins and the results are compared with earlier ones obtained by using Luescher's approach.