The rotator spectrum in the delta-regime of the O(n) effective field theory in 3 and 4 dimensions

TL;DR

This paper calculates the low-lying spectrum of the O(n) effective field theory in the delta-regime for 3 and 4 dimensions using lattice regularization, enabling determination of physical constants like F and rho.

Contribution

It provides a detailed NNL order calculation of the spectrum in the delta-regime, connecting lattice results to physical constants in QCD and condensed matter systems.

Findings

Determined pion decay constant F in QCD with 2 flavors.

Calculated spin stiffness rho in 2+1 dimensional antiferromagnets.

Validated the spectrum calculations through numerical simulations.

Abstract

The low lying spectrum of the O(n) effective field theory is calculated in the delta-regime in 3 and 4 space-time dimensions using lattice regularization to NNL order. It allows, in particular, to determine, using numerical simulations in different spatial volumes, the pion decay constant F in QCD with 2 flavours or the spin stiffness rho for an antiferromagnet in d=2+1 dimensions.