Chiral phase structure of QCD with many flavors

By H. Gies, J. Jaeckel. 2005

156 citations recorded by the source corpus.

We investigate QCD with a large number of massless flavors with the aid of renormalization group flow equations. We determine the critical number of flavors separating the phases with and without chiral symmetry breaking in SU(Nc) gauge theory with many fermion flavors. Our analysis includes all possible fermionic interaction channels in the pointlike four-fermion limit. Constraints from gauge invariance are resolved explicitly and regulator-scheme dependencies are studied. Our findings confirm the existence of an Nf window where the system is asymptotically free in the ultraviolet, but remains massless and chirally invariant on all scales, approaching a conformal fixed point in the infrared. Our prediction for the critical number of flavors of the zero-temperature chiral phase transition in SU(3) is Nfcr=10.0±0.29 (fermion)+1.55-0.63 (gluon), with the errors arising from approximations in the fermionic and gluonic sectors, respectively.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7ddd47dc9e76032e9149edc1a13c3905e2c51591

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Citations in the corpus

Hyperscaling relations in mass-deformed conformal gauge theories (2010, background): “Recent results have appeared recently, that address this problem either from an RG point of view [18, 19, 20], or from a gauge/string duality perspective [21, 22, 23].”
Supersymmetry inspired QCD beta function (2007, background): “Further studies of the nonsupersymmetric conformal window and its properties can be found in [9, 10, 11, 12, 13, 14].”
Walking, weak first-order transitions, and complex CFTs (2018, background): “This is the scenario advocated in [5], where the new fixed point is called QCD∗ (see also [43]).”
The nonperturbative functional renormalization group and its applications (2020, unknown): “Indeed, the smallness of the βfunction in this regime supports the reliability of semi-perturbative approximations, while the nonperturbative FRGsetup is required and well-suited to unravel the fixed points and non-trivial scalings, for FRG-works see [1002–1007], for a QED3 analogue see [1008].”
Fundamental composite dynamics: A review (2020, methodology): “Several scenarios have been envisioned for this type of phase transition ranging from a Berezinskii–Kosterlitz–Thouless (BKT)-like phase transition [11], used in four dimensions in [12, 10, 13, 14, 15, 16, 17], to a jumping (non-continuous) phase transition [18].”