Electric polarizability of the neutron in dynamical quark ensembles

TL;DR

This paper adapts the background field method to dynamical quark ensembles to measure the neutron's electric polarizability, carefully accounting for gauge field effects, and finds a small negative value at a high pion mass.

Contribution

It introduces a method to accurately compute neutron electric polarizability in dynamical quark simulations, addressing gauge field complications.

Findings

Neutron electric polarizability is small and slightly negative at m_pi=759 MeV.

The adapted method effectively disentangles polarizability effects from gauge field mass shifts.

Results demonstrate the feasibility of polarizability calculations in dynamical quark ensembles.

Abstract

The background field method for measuring the electric polarizability of the neutron is adapted to the dynamical quark case, resulting in the calculation of (certain space-time integrals over) three- and four-point functions. Particular care is taken to disentangle polarizability effects from the effects of subjecting the neutron to a constant background gauge field; such a field is not a pure gauge on a finite lattice and engenders a mass shift of its own. At a pion mass of m_pi = 759 MeV, a small, slightly negative electric polarizability is found for the neutron.