Phase transition and vacuum stability in the classically conformal B–L model

Abstract

Within classically conformal models, the spontaneous breaking of scale invariance is usually associated to a strong first order phase transition that results in a gravitational wave background within the reach of future space-based interferometers. In this paper we study the case of the classically conformal gauged B-L model, analysing the impact of this minimal extension of the Standard Model on the dynamics of the electroweak symmetry breaking and derive its gravitational wave signature. Particular attention is paid to the problem of vacuum stability and to the role of the QCD phase transition, which we prove responsible for concluding the symmetry breaking transition in part of the considered parameter space. Finally, we calculate the gravitational wave signal emitted in the process, finding that a large part of the parameter space of the model can be probed by LISA. * carlo.marzo@kbfi.ee † luca.marzola@cern.ch ‡ ville.vaskonen@kcl.ac.uk 1 We refer the reader to for analyses of non-conformal B-L models.

Gravitational waves from chiral phase transition in a conformally extended standard model

“…As we see from figure 8, the reduction factor for Ω sw is of order 10 −2 in our model. where τsw is defined in (53).…”

Testing the Seesaw Mechanism and Leptogenesis with Gravitational Waves

“…Firstly, super-cooling increases the duration of the phase transition leading to larger bubbles whose collisions emit lower frequency gravitational waves and secondly in such a scenario the temperature the phase transition takes places is significantly lower than the breaking scale, T * v. In principle, if T * v/10 high frequency gravitational wave experiments are sensitive to the lower range of parameter space v ∼ 10 9 GeV. Some work has done in this direction [45,46], however, for a more generic probe of phase transitions from the seesaw scale, high-frequency gravitational wave detectors are required. Such a detector provides a unique tool to uncover physics at very early Universe, and hence should be pursued.…”

Gravitational waves from scale-invariant vector dark matter model: probing below the neutrino-floor

“…where V high−T is derived from Eq. (18) using high temperature approximation (20) with only x 2 term, i.e.,…”

“…Particularly, conformal DM models with Higgs portal are attractive because they can solve DM problem and at the same time can generate a strongly first order phase transition [8][9][10][11]. GWs due to first order phase transition have been studied within models where the scale-invariant symmetry is broken due to Coleman-Weinberg mechanism [12][13][14][15][16][17][18][19][20] or models with DM candidate [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Conformal * a.mohamadnejad@ut.ac.ir symmetry also proposed as a possible solution for hierarchy problem [40].…”