Cosmological phase transitions are events during which the universe evolves from a metastable state to a stable state, through a process of bubble nucleation. The bubbles of the stable phase expand, collide, and interact with the cosmic fluid, leading to the production of gravitational waves. Such signals could be detectable by current and upcoming interferometer experiments.
This...
I will discuss gravitational waves produced during the confinement phase transition in SU(N) Yang-Mills, using a holographic description. I will highlight the role of the kinetic term of the effective action.
I will present a new framework for baryogenesis and leptogenesis based on a supercooled confining first order phase transition (PT).
With respect to the case of weakly coupled PTs, the rate asymmetry is enhanced by the decays of hadrons of the strong dynamics after the PT and washout effects from inverse decays are suppressed.
Therefore, our setup extends the parameter space of successful...
We present a novel realization of leptogenesis from the decays of sterile (right-handed) neutrinos (RHNs) produced from runaway bubble collisions at a first order phase transition. Such configurations can produce heavy RHNs with mass many orders of magnitude above the scale of symmetry breaking, thereby enabling (non-resonant) leptogenesis without the need for high reheat temperatures while...
We propose a simple model that can alleviate the $H_0$ tension while remaining consistent with big bang nucleosynthesis (BBN). It is based on a dark sector described by a standard Lagrangian featuring a $SU(N)$ gauge symmetry with $N\geq3$ and a massive scalar field with a quartic coupling. The scalar acts as a dark Higgs leading to spontaneous symmetry breaking $SU(N)\to SU(N\!-\!1)$ via a...
"We analyze the role of higher-order thermal corrections for supercooled phase transition, and to what extent they can be computed using dimensionally reduced effective field theory (3D EFT). This framework requires high-temperature (HT) expansion to be valid, which seems challenging due to the presence of supercooling. We show how to reliably use the HT expansion in dimensionally reduced...
We study the dynamics of axions at first-order phase transitions in non-Abelian gauge theories. When the duration of the phase transition is short compared to the timescale of the axion oscillations, the axion dynamics is similar to the trapped misalignment mechanism. On the other hand, if this is not the case, the axions are initially expelled from the inside of the bubbles, generating axion...
Recently, cosmological first-order phase transition (FOPT) that slowly takes place has attracted much attention. On one hand, it predicts larger amplitude of stochastic gravitational wave background (SGWB), which is actually in a nice agreement with the recent PTAs result. On the other hand, inhomogeneity during FOPT may lead to the formation of primordial black holes (PBHs). In our study, we...
The 15 year data release of the pulsar timing array (PTA) observatory NANOGrav has given decisive evidence for a stochastic gravitational wave (GW) signal at nano-Hertz frequencies. The standard astrophysical explanation of the data -- merging black hole binaries -- can be improved by introducing an additional cosmological source of a stochastic GW signal. An intriguing possibility for this is...
Different thermal resummation techniques impact the gravitational wave (GW) spectra from cosmological first-order phase transitions predicted in a given particle physics model. To investigate this effect, we perform large-scale parameter scans of the electroweak phase transition (EWPT) in the dynamical real-singlet extension of the Standard Model (SM) using three different perturbative...
The dynamics of a cosmological first order phase transition are governed by the interactions of a scalar field, which tunnels to a new vacuum state and results in the nucleation of bubbles. If the interactions of the scalar field with the plasma are sufficiently weak, instant reheating can not be assumed and the energy density of the universe is dominated by the field oscillations after the...
