Baryons under Strong Magnetic Fields or in Theories with Space-dependent $\theta$-term

TL;DR

This paper uses holographic methods to analyze how baryons behave in theories with strong magnetic fields or space-dependent $ heta$-terms, revealing anisotropic effects on their structure and dissociation patterns.

Contribution

It develops a generic analytic framework for anisotropic theories and uncovers how baryon shape, stability, and dissociation depend on anisotropy and quark proximity.

Findings

Baryon quark distribution becomes elliptic with increasing anisotropy.

Baryons dissociate in stages depending on quark proximity to anisotropic direction.

Anisotropy does not alter the universal stability condition of baryons.

Abstract

Baryonic states are sufficiently complex to reveal physics that is hidden in the mesonic bound states. Using gauge/gravity correspondence we study analytically and numerically baryons in theories with space-dependent $\theta$-term, or theories under strong magnetic fields. Such holographic studies on baryons are accommodated in a generic analytic framework we develop for anisotropic theories, where their qualitative features are common irrespective of the source that triggers the anisotropy. We find that the distribution of the quarks forming the state, depends on the angle between the baryon and the anisotropic direction. Its shape is increasingly elliptic with respect to the strength of the field sourcing the anisotropy, counterbalancing the broken rotational invariance on the gluonic degrees of freedom. Strikingly, the baryons dissociate in stages with a process that depends on the proximity of the quarks to the anisotropic direction, where certain quark pairs abandon the bound state first, followed by the closest pairs to them as the temperature increases. This observation may also serve as a way to identify the nature of certain exotic states. Finally, we investigate holographic baryons with decreased number of quarks and explain why in theories under consideration the presence of anisotropy does not modify the universal stability condition in contrast to the usual trend.