Fermions and baryons as open-string states from brane junctions

TL;DR

This paper explores the dynamics of fermionic and bosonic open-string states from brane junctions in supergravity, providing evidence that these states can model baryon operators and analyzing their mass scaling and level crossing behavior.

Contribution

It systematically studies BPS brane junctions, derives their equations of motion, and demonstrates their potential to describe baryon operators with expected mass scaling and supersymmetric degeneracy.

Findings

Fermionic and bosonic fluctuations are degenerate due to supersymmetry.

Mass of fermionic states scales as N_c^2 in the large-N_c limit.

Analytical explanation of avoided level crossing after including higher operators.

Abstract

There has been recent progress towards understanding the dynamics of world-volume fermions that arise as open-string modes from brane intersections in the probe limit $(N_f/N_c \rightarrow 0)$. In this work we consider all possible BPS brane junctions in Type IIA/B supergravity theories. We study in detail the dynamics of these states by deriving their equations of motion. We show the expected degeneracy of the bosonic and fermionic fluctuations as is expected due to the preserved supersymmetry. We also give some supporting evidence and refine the notion that these states can effectively describe baryon operators in a certain regime of the field theory's parameter space. Our piece of evidence is the demonstration of the expected scaling of the mass in the large-$N_c$ limit of the theory for these fermionic states; $M^2 \sim N^2_c$. Finally, we explain analytically the avoided level crossing that was observed in a previous work after the inclusion of higher dimension operators in the field theory.