Twisted valence quarks and hadron interactions on the lattice

TL;DR

This paper shows that twisted boundary conditions in lattice QCD allow for improved extraction of nucleon-nucleon phase shifts without needing new gauge configurations, even with unquenched calculations.

Contribution

It demonstrates that low-lying two-hadron energies are unaffected by sea quark boundary conditions, enabling practical benefits of twisted boundary conditions in unquenched lattice QCD.

Findings

Low-lying two-hadron energies are independent of sea quark boundary conditions.

Twisted boundary conditions can be used without generating new gauge configurations.

Advantages in phase shift extraction are preserved in unquenched calculations.

Abstract

We consider QCD with valence and sea quarks obeying different boundary conditions. We point out that the energy of low lying two hadron states do not depend on the boundary condition of the sea quarks (up to exponentially small corrections). Thus, the advantages in using twisted boundary conditions on the lattice QCD extraction of nucleon-nucleon phase shifts can be gained without the need of new gauge configurations, even in fully unquenched calculations.