Volume independence in the large N limit and an emergent fermionic symmetry

Gökçe Başar, Aleksey Cherman, Daniele Dorigoni, Mithat Ünsal

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Large-N volume independence in circle-compactified QCD with adjoint Weyl fermions implies the absence of any phase transitions as the radius is dialed to arbitrarily small values. This class of theories is believed to possess a Hagedorn density of hadronic states. It turns out that these properties are in apparent tension with each other, because a Hagedorn density of states typically implies a phase transition at some finite radius. This tension is resolved if there are degeneracies between the spectra of bosonic and fermionic states, as happens in the Nf=1 supersymmetric case. Resolution of the tension for Nf>1 then suggests the emergence of a fermionic symmetry at large N, where there is no supersymmetry. We can escape the Coleman-Mandula theorem since the N=∞ theory is free, with a trivial S matrix. We show an example of such a spectral degeneracy in a nonsupersymmetric toy example which has a Hagedorn spectrum.

Original languageEnglish (US)
Article number121601
JournalPhysical review letters
Issue number12
StatePublished - Sep 17 2013


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