Fermions and baryons as open-string states from brane junctions

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 (Nf/Nc → 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-Nc limit of the theory for these fermionic states; M2 ∼ $$ {N}_c^2 $$ N c 2 . 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.

Gauge/gravity dual dynamics for the strongly coupled sector of composite Higgs models

“…Here we will investigate this dynamics using holography. The D7-brane action, extended to its fermionic sector, naturally describes baryons (super-partners of the mesons) consisting of three fermions (a quark an anti-quark and an adjoint fermion in the root N = 2 theory) as fermionic fields in the DBI action [34,[54][55][56]. We phenomenologically extend this description to describe the top partners which are also usually constructed from three constituents.…”

“…In the D3/probe D7 system some fermionic superpartners of the mesons are made of a quark, an anti-quark and a gaugino and are described by fermionic excitations of the D7 world volume theory [34,54]. Indeed in a preparatory paper we carefully worked through the D3/probe D7 system example [55] (see also [56]) and that work will lead us here. That a three fermion bound state can have such a description in a top down model suggests phenomenologically a proton made of 3 quarks in QCD or the top partners in the models we will discuss below could reasonable be modelled by simply placing a fermion in the bulk.…”

“…Note that we impose these boundary conditions at ρ = L IR rather than at ρ = 0 as in the supersymmetric case in [55,56].…”

Gluodynamics and deconfinement phase transition under rotation from holography

“…It is quite interesting to see that both chiral phase transition and deconfinement phase transition could be well studied from holographic method, motivated by the discovery of the Anti-de Sitter/conformal field theory(AdS/CFT) correspondence [26][27][28]. Besides the topdown brane systems [29][30][31][32][33][34][35][36], in bottom up approach, the Einstein-Maxwell-dilaton(EMD) system [37][38][39][40][41][42][43][44][45][46][47]provides a good starting point to investigate deconfinement phase transition, while the chiral phase transition [48][49][50][51][52][53][54][55][56][57][58] and light meson spectra [59][60][61][62][63][64][65][66][67][68] could be well described in the soft-wall model [69]. The order parameters of both chiral transition and deconfining transition, chiral condensate qq and expectation value of Polyakov loop L respectively, could be easily extracted from holographic dictionary.…”

Electric conductivity with the magnetic field and the chiral anomaly in a holographic QCD model

“…[21] for a review on holographic QCD matter at finite B, and also Ref. [22] for a related work on the baryon operator). The SSM is one of the most established holographic QCD models and it has the same low-energy degrees of freedom as QCD.…”