Finite volume effects on the electric polarizability of neutral hadrons in lattice QCD

TL;DR

This study investigates finite volume effects on the electric polarizability of neutral hadrons in lattice QCD, performing extrapolations to infinite volume and physical quark masses, revealing mild effects for kaons and significant volume dependence for neutrons.

Contribution

It provides a detailed analysis of finite volume effects on hadron polarizabilities and offers extrapolated results consistent with chiral perturbation theory, especially for neutrons.

Findings

Finite volume effects are mild for neutral kaons.

Neutron polarizability shows strong volume dependence.

Results agree with chiral perturbation theory after corrections.

Abstract

We study the finite volume effects on the electric polarizability for the neutron, neutral pion, and neutral kaon using eight dynamically generated two-flavor nHYP-clover ensembles at two different pion masses: 306(1) and 227(2) MeV. An infinite volume extrapolation is performed for each hadron at both pion masses. For the neutral kaon, finite volume effects are relatively mild. The dependence on the quark mass is also mild and a reliable chiral extrapolation can be performed along with the infinite volume extrapolation. Our result is $\alpha_{K^0}^\mbox{phys}=0.356(74) \times 10^{-4} \mbox{fm}^3$. In contrast, for neutron the electric polarizability depends strongly on the volume. After removing the finite volume corrections, our neutron polarizability results are in good agreement with $\chi$PT. For the connected part of the neutral pion polarizability, the negative trend persists, and it is not due to finite volume effects, but likely sea quark charging effects.