The supercooled universe

Abstract

Strongly-coupled theories at the TeV can naturally drive a long period of supercooling in the early universe. Trapped into the deconfined phase, the universe could inflate and cool down till the temperature reaches the QCD strong scale. We show how at these low temperatures QCD effects are important and could trigger the exit from the long supercooling era. We also study the implications on relic abundances. In particular, the latent heat released at the end of supercooling could be the reason for the similarities between dark matter and baryon energy densities. The axion abundance could also be significantly affected, allowing for larger values of the axion decay constant. Finally, we discuss how a long supercooling epoch could lead to an enhanced gravitational wave signal.

Peccei-Quinn phase transition at LIGO

“…7 (taking N = 3 and choosing different values of F a ). The value of T * is the reheating temperature after the phase transition is completed which is found to be T * 1.8 √ N /g 1/4 * T c [36]. Using this and (3.37), we obtain the relation…”

“…To address this phase transition quantitatively, we will follow the strongly coupled models studied in Ref. [35][36][37] which have a weakly-coupled five-dimensional version via holography. This helps to reduce the number of parameters, although the conclusions can be extended to models without holographic versions [36].…”

“…[35][36][37] which have a weakly-coupled five-dimensional version via holography. This helps to reduce the number of parameters, although the conclusions can be extended to models without holographic versions [36]. : Predicted values of T * and β/H * (black lines) for strongly-coupled PQ models (see Section 3.4 for details) for F a = 10 8 , 10 9 and 10 10 GeV.…”

“…We assume that the strong sector has a global U (1) P Q ⊗SU (3) c symmetry with an U (1) P Q −SU (3) c −SU (3) c anomaly (this means that its constituents must be colored under SU (3) c ). We also assume that the confinement scale Λ c is determined by a potential for the dilaton µ given by 36) where the dependence of the quartic coupling λ(µ) on µ is dictated by the explicit breaking of scale invariance (several examples are given in [36]). We identify the mass gap Λ c with the dilaton VEV, µ = Λ c .…”

“…The free-energy of the unconfined phase is given by F dec −π 2 N 2 T 4 /8, while in the confined phase F conf = V eff ( µ ). Thus, the critical temperature at which the confined phase is energetically favorable follows as [36] T c 0.3 × 10 10 GeV (Λ c m dil ) 1/2 10 10 GeV , (3.38) where m dil is the dilaton mass. The rate of the phase transition from the unconfined to the confined phase is in most of the cases dominated by vacuum tunneling whose bounce action is roughly given by [36]…”