Gold-plated moments of nucleon structure functions in baryon chiral perturbation theory

TL;DR

This paper uses baryon chiral perturbation theory to predict moments of nucleon structure functions, achieving good agreement with experimental data at low momentum transfer and resolving the longstanding delta_LT puzzle.

Contribution

It provides leading and next-to-leading order parameter-free predictions for nucleon structure moments, successfully addressing the delta_LT puzzle.

Findings

Predictions agree with empirical data for most moments at low Q^2.

The delta_LT puzzle is resolved in this chiral perturbation theory calculation.

Results are free of adjustable parameters.

Abstract

We obtain leading- and next-to-leading order predictions of chiral perturbation theory for several prominent moments of nucleon structure functions. These free-parameter free results turn out to be in overall agreement with the available empirical information on nearly all of the considered moments, in the region of low-momentum transfer ($Q^2 < 0.3$ GeV$^2$). Especially surprising is the situation for the spin polarizability $\delta_{LT}$, which thus far was not reproducible in chiral perturbation theory for proton and neutron simultaneously. This problem, known as the "$\delta_{LT}$ puzzle," is not seen in the present calculation.