Long-Range $N-J/\psi$ Interaction from an Operator Product Expansion Perspective

TL;DR

This paper investigates the long-range attraction between nucleons and J/ψ mesons using operator product expansion and QCD sum rules, providing insights into the interaction's origin and effects in dense matter.

Contribution

It introduces a method to analyze the long-range N-J/ψ interaction via four-quark operators within the OPE framework, connecting lattice results with QCD sum rule calculations.

Findings

The calculated mass decrease aligns qualitatively with lattice QCD results.

The approach links chiral symmetry restoration effects to heavy meson masses.

The long-range attraction can be partly explained by two-pion exchange mechanisms.

Abstract

A recent lattice QCD study has shown that the $N-J/\psi$ potential is attractive at all distances, and its long-range tail is well described by two-pion exchange. Here, we study to what extent the long-range part of the attraction can be reproduced from the perspective of the operator product expansion (OPE). This is accomplished by extracting the leading-order four-quark operator that couples to two pions and calculating its contribution to the $J/\psi$ mass in nuclear matter, to linear order in density, within the QCD sum rule framework. Using previous estimates of the four-quark operators for the chiral symmetric and breaking parts, we obtain a mass decrease that is smaller in magnitude but qualitatively consistent with the attraction obtained in the lattice QCD calculation. By expressing the interaction in terms of four-quark operators, we can analyze the effects of chiral symmetry restoration in dense matter on the masses of the $J/\psi$ and other mesons composed of heavy quarks.