SPHALERONS AND THE ELECTROWEAK PHASE TRANSITION

1992 ◽  
Vol 03 (05) ◽  
pp. 783-797 ◽  
Author(s):  
JOCHEN KRIPFGANZ

In the first part of the talk, a short review of baryon number violation in the electroweak standard model is given. I concentrate on perturbative estimates for the electroweak phase transition. A strong first order phase transition could be relevant both for a possible generation of the baryon asymmetry of the universe, and the survival of this asymmetry afterwards. In the second part of the talk, some lattice results for the electroweak phase transition are presented. They tend to indicate a transition more strongly first order than predicted by perturbation theory. A definite condusion cannot be drawn, however, because of severe finite size effects.

2014 ◽  
Vol 29 (15) ◽  
pp. 1450078 ◽  
Author(s):  
Tran Huu Phat ◽  
Nguyen Van Thu

The finite-sized effect caused by compactified space–time is scrutinized by means of the linear sigma model with constituent quarks at finite temperature T and chemical potential μ, where the compactified spatial dimension with length L is taken along the Oz direction. We find several finite-size effects associated with compactified length L: (a) There are two types of Casimir energy corresponding to two types of quarks, untwisted and twisted quarks. (b) For untwisted quarks, a first-order phase transition emerges at intermediate values of L when the Casimir effect is not taken into account and is enhanced by Casimir energy at small L. (c) For twisted quarks, the phase transition is cross-over everywhere when μ≤200 MeV . When μ> 200 MeV there occurs a first-order phase transition at large L and becomes cross-over at smaller L.


2021 ◽  
Vol 36 (05) ◽  
pp. 2150024
Author(s):  
Shehu AbdusSalam ◽  
Mohammad Javad Kazemi ◽  
Layla Kalhor

For a cosmological first-order electroweak phase transition, requiring no sphaleron washout of baryon number violating processes leads to a lower bound on the strength of the transition. The velocity of the boundary between the phases, the so-called bubble wall, can become ultrarelativistic if the friction due to the plasma of particles is not sufficient to retard the wall’s acceleration. This bubble “runaway” should not occur if a successful baryon asymmetry generation due to the transition is required. Using Boedeker–Moore criterion for bubble wall runaway, within the context of an extension of the Standard Model of particle physics with a real gauge-single scalar field, we show that a nonrunaway transition requirement puts an upper bound on the strength of the first-order phase transition.


1994 ◽  
Vol 09 (28) ◽  
pp. 2599-2610 ◽  
Author(s):  
AZUSA YAMAGUCHI ◽  
AKIO SUGAMOTO

The baryogenesis is reanalyzed based on the model by Cohen et al., in which the lepton number, generated by the neutrinos scattering from the bubble walls appearing in the development of the electroweak phase transition, is converted to the baryon number excess through the sphaleron transition. A formula obtained in this paper on the lepton number production rate is correct for both the thin and thick walls within the linear approximation. Investigation on the time development of the first order phase transition is simulated, including the temporal change of the wall velocity as well as the fusion effect of the bubbles. The details of such phase transition dynamics are found to affect considerably the final value of the baryon number excess.


1992 ◽  
Vol 03 (05) ◽  
pp. 947-960 ◽  
Author(s):  
T. TRAPPENBERG

The transfer matrix method to describe finite size effects due to tunneling are worked out for Z(2)- and Z(3)-symmetric models. We used this method to extract the surface tension σ in the SU(3) gauge theory at the finite temperature phase transition on lattices with an extent T=2 in the euclidean time direction. We also discuss if the confined phase completely wets the deconfined phase at this first order phase transition.


2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Aleksandr Azatov ◽  
Miguel Vanvlasselaer ◽  
Wen Yin

Abstract In this paper we present a novel mechanism for producing the observed Dark Matter (DM) relic abundance during the First Order Phase Transition (FOPT) in the early universe. We show that the bubble expansion with ultra-relativistic velocities can lead to the abundance of DM particles with masses much larger than the scale of the transition. We study this non-thermal production mechanism in the context of a generic phase transition and the electroweak phase transition. The application of the mechanism to the Higgs portal DM as well as the signal in the Stochastic Gravitational Background are discussed.


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