Vector interaction bounds in NJL-like models from LQCD estimated curvature of the chiral crossover line

TL;DR

This paper refines bounds on vector interactions in a 2+1 flavor NJL model using latest lattice QCD data, predicts curvature coefficients' behavior, and locates the critical endpoint consistent with lattice bounds.

Contribution

It provides improved constraints on vector interactions in NJL models from lattice QCD results and analyzes their effects on curvature coefficients and the critical endpoint.

Findings

Vector interaction bounds allow both attraction and repulsion.

Flavor mixing significantly influences curvature coefficients.

Critical endpoint location is consistent with lattice QCD bounds.

Abstract

We obtain improved bounds on both the flavor-independent and -dependent vector interactions in a $2+1$-flavor Nambu\textendash Jona-Lasinio (NJL) model using the latest precise LQCD results of the curvature coefficients of the chiral crossover line. We find that these lattice estimated curvature coefficients allow for both attractive and repulsive types of interactions in both the cases. With this constrained ranges of vector interactions, we further predict the behavior of the second $(\kappa_2^B)$ and fourth $(\kappa_4^B)$ order curvature coefficients as a function of the strangeness chemical potential $(\mu_S)$. We observe that the flavor mixing effects, arising from the flavor-independent vector interaction as well as from the 't Hooft interaction, play an important role in $k_2^B$. We propose that the mixing effects due to the vector interaction can be separated from those arising from the 't Hooft interaction by analyzing the behavior of $k_2^B$ as a function of $\mu_S$. Finally, we locate the critical endpoint in the $T-\mu_B$ plane using the model-estimated ranges of vector interactions and find the model's predictions to be consistent with the latest LQCD bounds.