Probing the QCD vacuum with an abelian chromomagnetic field: A study within an effective model

TL;DR

This study investigates how the QCD vacuum responds to an external abelian chromomagnetic field using a non-local Nambu-Jona Lasinio model with the Polyakov loop, comparing results with lattice data on deconfinement and chiral symmetry restoration.

Contribution

It introduces a model-based analysis of the QCD vacuum's response to chromomagnetic fields, highlighting a linear relationship with deconfinement temperature and exploring the separation of deconfinement and chiral transitions.

Findings

Deconfinement temperature scales linearly with the square root of the field strength.

Qualitative agreement with lattice results on deconfinement temperature behavior.

Discrepancy in the correlation between deconfinement and chiral symmetry restoration at high field strengths.

Abstract

We study the response of the QCD vacuum to an external abelian chromomagnetic field in the framework of a non local Nambu-Jona Lasinio model with the Polyakov loop. We use the Lattice results on the deconfinement temperature of the pure gauge theory to compute the same quantity in the presence of dynamical quarks. We find a linear relationship between the deconfinement temperature with quarks and the squared root of the applied field strength, $gH$, in qualitative (and to some extent also quantitative) agreement with existing Lattice calculations. On the other hand, we find a discrepancy on the approximate chiral symmetry restoration: while Lattice results suggest the deconfinement and the chiral restoration remain linked even at non-zero value of $gH$, our results are consistent with a scenario in which the two transitions are separated as $gH$ is increased.