We study the energy budget of a first-order cosmological phase transition, which is an important factor in the prediction of the resulting gravitational wave spectrum. Formerly, this analysis was based mostly on simplified models as for example the bag equation of state. Here, we present a model-independent approach that is exact up to the temperature dependence of the speed of sound in the broken phase. We find that the only relevant quantities that enter in the hydrodynamic analysis are the speed of sound in the broken phase and a linear combination of the energy and pressure differences between the two phases which we call pseudotrace (normalized to the enthalpy in the broken phase). The pseudotrace quantifies the strength of the phase transition and yields the conventional trace of the energy-momentum tensor for a relativistic plasma (with speed of sound squared of one third).We study this approach in several realistic models of the phase transition and also provide a code snippet that can be used to determine the efficiency coefficient for a given phase transition strength and speed of sound. It turns out that our approach is accurate to the percent level for moderately strong phase transitions, while former approaches give at best the right order of magnitude.

We perform an extensive analysis of linear fluctuations during preheating in Higgs inflation in the Einstein frame, where the fields are minimally coupled to gravity, but the field-space metric is nontrivial. The self-resonance of the Higgs and the Higgsed gauge bosons are governed by effective masses that scale differently with the nonminimal couplings and evolve differently in time. Coupled metric perturbations enhance Higgs self-resonance and make it possible for Higgs inflation to preheat solely through this channel. For ξ 100 the total energy of the Higgs-inflaton condensate can be transferred to Higgs particles within 3 efolds after the end of inflation. For smaller values of the nonminimal coupling preheating takes longer, completely shutting off at around ξ 30. The production of gauge bosons is dominated by the gauge boson mass and the field space curvature. For large values of the nonminimal coupling ξ 1000, it is possible for the Higgs condensate to transfer the entirety of its energy into gauge fields within one oscillation. For smaller values of the nonminimal coupling gauge bosons decay very quickly into fermions, thereby shutting off Bose enhancement. Estimates of non-Abelian interactions indicate that they will not suppress preheating into gauge bosons for ξ 1000.1 For inflation on the flat plateau one should consider ξ 440 (e.g. [20]). In models of hilltop or inflection point inflation, smaller values of ξ are possible, although UV corrections are expected to be larger. In order to provide a treatment of Higgs inflation as complete as possible without referring to specific unknown physics, we choose to consider a broad range of non-minimal couplings that go below ξ ≈ 400. 2 See [25] for a way to alter the predictions of α-attractor models through multi-field effects.

We investigate electroweak baryogenesis within the framework of the Standard Model Effective Field Theory. The Standard Model Lagrangian is supplemented by dimension-six operators that facilitate a strong first-order electroweak phase transition and provide sufficient CP violation. Two explicit scenarios are studied that are related via the classical equations of motion and are therefore identical at leading order in the effective field theory expansion. We demonstrate that formally higher-order dimension-eight corrections lead to large modifications of the matter-antimatter asymmetry. The effective field theory expansion breaks down in the modified Higgs sector due to the requirement of a first-order phase transition. We investigate the source of the breakdown in detail and show how it is transferred to the CP-violating sector. We briefly discuss possible modifications of the effective field theory framework.

We provide an easy method to obtain the kinetic energy fraction in gravitational waves, generated during a cosmological first-order phase transition, as a function of only the wall velocity and quantities that can be determined from the particle physics model at the nucleation temperature. This generalizes recent work that achieved this goal for detonations. Here we present the corresponding results for deflagrations and hybrids. Unlike for detonations, the sound speed in the symmetric phase also enters the analysis. We perform a detailed comparison between our model-independent approach and other approaches in the literature. We provide a Python code snippet to determine the kinetic energy fraction K as a function of the wall velocity, the two speeds of sound and the strength parameter of the phase transition. We also assess how realistic sizable deviations in speed of sound are close to the phase transition temperature in a specific model.

We investigate the role of leptons in electroweak baryogenesis by studying a relatively simple framework inspired by effective field theory that satisfies all Sakharov conditions. In particular, we study the effectiveness of CP-violating source terms induced by dimension-six Yukawa interactions for quarks and charged leptons. Despite the relatively small Yukawa coupling, CP-violating source terms involving taus are quite effective and can account for the observed matter-antimatter asymmetry. We obtain analytical and numerical expressions for the total baryon asymmetry, the former providing important insight into what makes lepton CP violation relatively effective compared to quark CP violation. Leptons also play an important role if the CP-violating source involves top quarks. While the tau Yukawa coupling in the Standard Model is small, it significantly enhances the baryon asymmetry by transferring the chiral asymmetry in quarks, which is washed out by strong sphalerons, to a chiral asymmetry in leptons. We conclude that leptons should not be ignored even if CP violation is limited to the quark sector. The role of leptons can be further increased in scenarios of new physics with additional chiral-symmetry-breaking interactions between quarks and leptons, as can happen in models with additional Higgs bosons or leptoquarks. Finally, we study CP-violating dimension-six Yukawa interactions for lighter quarks and leptons but conclude that these lead to too small baryon asymmetries.Understanding the prevalence of matter over antimatter in our universe is one of the great challenges in particle physics and cosmology. The baryon asymmetry can be extracted from the Planck data on the cosmic microwave background [1]with n b and s the baryon number and entropy density respectively. To dynamically explain this number requires satisfying the three Sakharov conditions [2]: 1) baryon number violation, 2) charge (C) and charge-parity (CP) violation, and 3) out-of-equilibrium dynamics. The standard model (SM) only fulfills the first one -electroweak sphaleron transitions active at high temperatures violate baryon number -and physics beyond the standard model is needed to explain the baryon asymmetry in the universe. Of the existing baryogenesis theories, electroweak baryogenesis (EWBG) is particularly interesting as it is linked to electroweak scale physics and can be tested in experiments. The (minimal) beyond-the-Standard Model (BSM) ingredients in this scenario are new sources of CP violation, and an extended scalar sector that can give rise to a first-order electroweak phase transition that provides the necessary out-of-equilibrium dynamics. Both ingredients can be probed by the large hadron collider (LHC), for instance via searches for new scalars [3][4][5][6], precision Higgs studies [7,8], and CP-odd collider observables [9][10][11][12][13]. Typically, the best constraints on new sources of CP violation, however, come from electric dipole moment measurements [14][15][16]. Gravitational waves produced during a first-order ...