An alternative scheme for effective range corrections in pionless EFT

TL;DR

This paper proposes a new method for incorporating effective range corrections in pionless EFT, which resums the range effects while controlling spurious poles, leading to improved convergence in finite volume calculations.

Contribution

It introduces an alternative resummation scheme for effective range corrections that mitigates singularities near unperturbed energies in pionless EFT.

Findings

Good convergence observed with the new scheme across various model potentials.

The alternative scheme reduces singular behavior in finite volume calculations.

Resummation of effective range improves the accuracy of EFT predictions.

Abstract

We discuss an alternative scheme for including effective range corrections in pionless effective field theory. The standard approach treats range terms as perturbative insertions in the T -matrix. In a finite volume this scheme can lead to singular behavior close to the unperturbed energies. We consider an alternative scheme that resums the effective range but expands the spurious pole of the T -matrix created by this resummation. We test this alternative expansion for several model potentials and observe good convergence.