Conformal model for gravitational waves and dark matter: a status update

Abstract

We present an updated analysis of the first-order phase transition associated with symmetry breaking in the early Universe in a classically scale-invariant model extended with a new SU(2) gauge group. Including recent developments in understanding supercooled phase transitions, we compute all of its characteristics and significantly constrain the parameter space. We then predict gravitational wave spectra generated during this phase transition and by computing the signal-to-noise ratio we conclude that this model is well-testable (and falsifiable) with LISA. We also provide predictions for the relic dark matter abundance. It is consistent with observations in a rather narrow part of the parameter space. We strongly constrain the so-called supercool dark matter scenario based on an improved description of percolation and reheating after the phase transition as well as the inclusion of the running of couplings. Finally, we devote attention to the renormalisation-scale dependence of the results. Even though our main results are obtained with the use of renormalisation-group improved effective potential, we also perform a fixed-scale analysis which proves that the dependence on the scale is not only qualitative but also quantitative.

Supercool exit: Gravitational waves from QCD-triggered conformal symmetry breaking

“…Our results are relevant for a wide class of models which feature similar dynamics. Examples are the scaleinvariant U(1) B-L [63,66,67,70] or SU(2) X extended SM [69,72], as well as strongly coupled SM extensions [43,77]. Such strongly supercooled phase transi-tions remain an exciting open topic.…”

“…As a consequence, the breaking of the electroweak (EW) symmetry is realised dynamically, either by radiative corrections [26][27][28][29][30][31][32][33][34][35] or strong dynamics [36][37][38][39][40][41][42][43]. Classically conformal theories therefore not only alleviate the hierarchy problem [44], but can also account for dark matter [45][46][47][48][49][50][51][52][53][54][55][56], generate the baryon asymmetry of the universe [57][58][59][60][61][62], and produce a SGWB [63][64][65][66][67][68][69][70][71][72].…”

Implication of nano-Hertz stochastic gravitational wave on dynamical dark matter through a dark first-order phase transition

“…The (classical) scale-invariance or conformal symmetry is realized by preventing any massive parameters in the Lagrangian. See [44,45] for details. Generally, the classically flat direction of the scalar field is lifted by radiative corrections, the conformal symmetry is therefore radiatively broken.…”

Dark phase transition from WIMP: complementary tests from gravitational waves and colliders

“…A strong first-order phase transition in a dark Abelian gauge sector was widely considered via a scale-invariant scalar potential [8][9][10][11][12][13][14][15][16] or a scale-breaking one [17][18][19][20][21][22]. Moreover, the interesting connection among the phase transition, GW and DM has received increased attention [14,[23][24][25][26][27][28][29][30][31][32], where complementary tests from DM detection and GW interferometers can be a promising avenue to probe the dark sector. In this respect, the hidden world becomes not so dark as its name suggests, since we will be able to not only hear but also see the dark.…”