When hadrons become unstable: a novel type of non-analyticity in chiral extrapolations

TL;DR

This paper investigates a novel non-analytic behavior in hadron mass extrapolations caused by resonance transitions, which can impact lattice QCD calculations of hadronic properties.

Contribution

It introduces a new type of non-analyticity in chiral extrapolations related to resonance-to-bound state transitions in hadronic scattering amplitudes.

Findings

Resonance transitions induce non-analyticities in hadron mass dependence.

Crossed channel amplitudes exhibit similar non-analytic behavior.

Implications for lattice QCD extrapolations of hadronic observables.

Abstract

Hadron masses show a specific dependence on the quark masses. Therefore, the variation of these masses can cause a resonance in a hadronic scattering amplitude to become a bound state. Consequently, the amplitude exhibits a non-analytic behavior at this transition. Crossed amplitudes, where the resonance can be exchanged in the t-channel, can be shown to exhibit the same phenomenon by s-->t analytic continuation. This entails possible kinks in lattice quark mass extrapolations needed to compute hadronic observables.