Exotic Multi-quark States in the Deconfined Phase from Gravity Dual Models

TL;DR

This paper investigates exotic multi-quark bound states in the deconfined quark-gluon plasma using gravity dual models, revealing their stability and phase behavior at high chemical potential and low temperature.

Contribution

It introduces and analyzes three types of exotic multi-quark states in the deconfined phase, extending the understanding of quark matter beyond normal baryons.

Findings

Exotic states have similar binding properties to mesons and baryons.

Exotic states are less stable than normal baryons but more stable than the vacuum at high chemical potential.

Phase diagram analysis shows exotic states dominate in certain thermodynamic conditions.

Abstract

In the deconfined phase of quark-gluon plasma, it seems that most of the quarks, antiquarks and gluons should be effectively free in the absence of the linear confining potential. However, the remaining Coulomb-type potential between quarks in the plasma could still be sufficiently strong that certain bound states, notably of heavy quarks such as $J/\psi$ are stable even in the deconfined plasma up to a certain temperature. Baryons can also exist in the deconfined phase provided that the density is sufficiently large. We study three kinds of exotic multi-quark bound states in the deconfined phase of quark-gluon plasma from gravity dual models in addition to the normal baryon. They are $k$-baryon, $(N+\bar{k})$-baryon and a bound state of $j$ mesons which we call "$j$-mesonance". Binding energies and screening lengths of these exotic states are studied and are found to have similar properties to those of mesons and baryons at the leading order. Phase diagram for the exotic nuclear phases is subsequently studied in the Sakai-Sugimoto model. Even though the exotics are less stable than normal baryons, in the region of high chemical potential and low temperature, they are more stable thermodynamically than the vacuum and chiral-symmetric quark-gluon plasma phases ($\chi$S-QGP).