Beyond Miransky scaling

Braun, Jens; Fischer, Christian; Gies, Holger

doi:10.1103/physrevd.84.034045

Cited by 78 publications

(117 citation statements)

References 119 publications

(231 reference statements)

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“…For SB normalised W 0 or W 0 = 24/11 ( figures 13 and 14), T h and T end decrease with increasing x f , in qualitative agreement with estimates based on field theory [74][75][76][77]. Decreasing W 0 to 12/11 (figure 15), however, the x f dependence becomes almost flat, and for W 0 = 0 ( figure 16) the temperatures increase with x f up to x f 3.5.…”

Section: Jhep01(2013)093supporting

confidence: 74%

On finite-temperature holographic QCD in the Veneziano limit

Alho

Järvinen

Kajantie

et al. 2013

J. High Energ. Phys.

197

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Holographic models in the T = 0 universality class of QCD in the limit of large number N c of colors and N f massless fermion flavors, but constant ratio x f = N f /N c , are analyzed at finite temperature. The models contain a 5-dimensional metric and two scalars, a dilaton sourcing TrF 2 and a tachyon dual toqq. The phase structure on the T, x f plane is computed and various 1st order, 2nd order transitions and crossovers with their chiral symmetry properties are identified. For each x f , the temperature dependence of p/T 4 and the condensate qq is computed. In the simplest case, we find that for x f up to the critical x c ∼ 4 there is a 1st order transition on which chiral symmetry is broken and the energy density jumps. In the conformal window x c < x f < 11/2, there is only a continuous crossover between two conformal phases. When approaching x c from below, x f → x c , temperature scales approach zero as specified by Miransky scaling.

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Section: Jhep01(2013)093supporting

confidence: 74%

On finite-temperature holographic QCD in the Veneziano limit

Alho

Järvinen

Kajantie

et al. 2013

J. High Energ. Phys.

197

View full text Add to dashboard Cite

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“…(14), the N f dependence of the critical temperature T c (N f ) emerges from the N f dependent renormalisation flow at the chiral phase transition scale µ ∼ Λ QCD m τ . The N f dependence of T c as well as its novel non-analytic behaviour in the pre-conformal region becomes free from the choice of the reference scale [47] by using an N f independent UV reference scale much larger than T c . …”

Section: The Critical Number Of Flavor and The Vanishing Critical mentioning

confidence: 99%

“…Before going to details, we first explain the basic idea which follows the FRG analysis by Braun and Gies [47]. They used the τ lepton mass m τ = 1.777 (GeV) as an N f independent UV reference scale for theories with any number of flavors.…”

Section: The Critical Number Of Flavor and The Vanishing Critical mentioning

confidence: 99%

“…One possibility is to observe the Miransky-Yamawaki essential singularity [61]. Alternatively, in an FRG approach [47], the pseudo-critical line is almost linear with N f for small N f , and displays a singular behaviour when approaching N * f , which could be the only observable effects, beyond Miransky scaling. A jumping scenario in which the change from a QCD dynamics to the conformal window is abrupt is also a distinct possibility [56].…”

mentioning

confidence: 99%

“…The high temperature path to conformality Chiral symmetry is restored at high temperatures -in the so-called quark-gluon plasma (QGP) phase. Both physics intuition and phenomenological analysis based on functional renormalization group [47] and finite temperature holographic QCD [49] indicate that the conformal phase of cold, many flavor QCD and the high temperature chirally symmetric phase are continuously connected. In particular, the onset of the conformal window coincides with the vanishing of the transition temperature, and the conformal window appears as a zero temperature limit of a possibly strongly interacting QGP.…”

mentioning

confidence: 99%

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One, two, zero: Scales of strong interactions

Lombardo

Miura

Silva

et al. 2014

Int. J. Mod. Phys. A

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We discuss our results on QCD with a number of fundamental fermions ranging from zero to sixteen. These theories exhibit a wide array of fascinating phenomena which have been under close scrutiny, especially in recent years, first and foremost is the approach to conformality. To keep this review focused, we have chosen scale generation, or lack thereof as a guiding theme, however the discussion will be set in the general framework of the analysis of the phases and phase transitions of strong interactions at zero and nonzero temperature. I. ADDING MATTER : QCD WITH AN ARBITRARY FLAVOR NUMBERUsual QCD dynamics is characterized by spontaneous symmetry breaking and dynamical mass generation, with the associated scale Λ QCD . However, when the number of flavors exceeds a critical number, an infra-red fixed point (IRFP) appears and prevents the coupling from growing large enough to break chiral symmetry. The theory is then scale invariant -even conformal invariant. In the intermediate region, the coupling 'walks' rather than runs between two typical scales -this is the phenomena of scale separation for which our results provide a preliminary evidence. From a general field theory viewpoint, the analysis of the phase diagram of strong interactions as a function of the number of flavor adds to our knowledge of the theoretical basis of strong interactions and their fundamental mechanisms. From a phenomenological viewpoint, this study deals with a class of models which might play a relevant role in model building beyond the standard model (BSM) [1][2][3][4][5][6], which explain the origin of mass using strong coupling mechanisms realized in QCD with a large number of flavors. All these topics are under active scrutiny both theoretically and experimentally A. ConformalityConformal invariance is anticipated to emerge in the non-Abelian gauge theory with many species (flavors) of fermions [59][60][61][62][63]. This is due to the IRFP for N f > N * f at a coupling which is not strong enough to break chiral symmetry: a second zero of the two-loop beta-function of a non-Abelian gauge theory implies, at least perturbatively, the appearance of IRFP conformal symmetry [59,60]. In color SU(3) gauge theory with N f massless fundamental fermions, the second zero appears at N f 8.05, before the loss of asymptotic freedom (LAF) B. Pre-conformalityThe direct inspection of theories at fixed N f is often inconclusive, especially close to the expected threshold N * f . An alternative approach to establish the existence of the conformal window is to (try to) observe directly the approach to conformality by monitoring the evolution of the results obtained in the broken phase as a function of N f .Moreover, the pre-conformal dynamics at flavor numbers just before the onset of conformal invariance might serve as a paradigm for the BSM model buildings that invokes non-perturbative mechanisms of electroweak symmetry breaking [3][4][5][6]. In such pre-conformal region, the coupling should vary little -should walk -with the scale, at

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Beyond Miransky scaling

Cited by 78 publications

References 119 publications

On finite-temperature holographic QCD in the Veneziano limit

On finite-temperature holographic QCD in the Veneziano limit

One, two, zero: Scales of strong interactions

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