Cosmological phase transition of spontaneous confinement

Abstract

The dynamics of a cosmological (de)confinement phase transition is studied in nearly conformally invariant field theories, where confinement is predominantly spontaneously generated and associated with a light "dilaton" field. We show how the leading contribution to the transition rate can be computed within the dilaton effective theory. In the context of Composite Higgs theories, we demonstrate that a simple scenario involving two renormalization-group fixed points can make the transition proceed much more rapidly than in the minimal scenario, thereby avoiding excessive dilution of matter abundances generated before the transition. The implications for gravitational wave phenomenology are discussed. In general, we find that more (less) rapid phase transitions are associated with weaker (stronger) gravitational wave signals. The various possible features of the strongly coupled composite Higgs phase transition discussed here can be concretely modeled at weak coupling within the AdS/CFT dual Randall-Sundrum extra-dimensional description, which offers important insights into the nature of the transition and its theoretical control. These aspects will be presented in a companion paper.

Phase transitions in perturbative walking dynamics

“…(2.5). Now, we would like to compare our results for the scalon potential with the results obtained for the dilaton in the models with spontaneous confinement transitions [17,20,21]. This class of scenarios are usually considered as partial UV completions of the composite Higgs models inspired by the extra-dimensional Randall-Sundrum [34] (RS) models with Goldberger-Wise [35] (GW) radius stabilization.…”

“…AdS/CFT duality relates them to strongly coupled, large N, approximate CFT models. If the dilaton is the lightest degree of freedom, it will dominate the low energy potential, which after integrating out the heavy species will become (we use the notations of [21]):…”

“…The specific case of QCD with eight flavors, N f = 8, N c = 3, which is believed to be close to the exit of the conformal window [11] has been studied on lattice [12][13][14][15][16] finding the remnants of the walking behavior, however the analysis of the phase transitions are still inconclusive. AdS/CFT duality presents another avenue to address the problem [17] (for the recent studies, see [18][19][20][21][22]), however the analysis of the PT was done only for the context of light dilaton. In this study, we instead analyze the phase transition in the toy model proposed in [23] where the walking and complex CFT occur at weak coupling.…”

“…If such PT had occurred in the early history of the universe while it was cooling down it might lead to very interesting phenomena. Particularly the holographic analysis of models with near conformal dynamics has shown that the transition is of the first order and generically leads to the strong signal in stochastic gravitational wave spectrum [20,21,[24][25][26][27]. However the holographic results are valid only if the dilaton field is much lighter than the rest of the composite resonances.…”

Gravitational imprints from heavy Kaluza-Klein resonances

“…In this paper we cover this issue for the minimal five-dimensional (5D) warp model [1] with a stabilizing field with a bulk polynomial potential. Studies of the holographic phase transition have been performed with great detail in the literature [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Here we make a step forward in several aspects: (i) We take into account the full backreaction of the scalar field on the gravitational metric, using the superpotential mechanism and methods proposed in Ref.…”