Strong and Electro-Weak Matter 2026

Session

Early Universe Contributions 2

19 Aug 2026, 14:00

F4050 (4th floor) (University of Helsinki Main Building)

16. Precise hydrodynamics in cosmological phase transitions

Flynn Linton (Monash University)

19/08/2026, 14:00

Early universe physics, inflation, electroweak phase transitions, and sources for gravitational waves

talk (15min)

Gravitational waves from an electroweak phase transition, expected to be visible to the next generation of detectors, offer a novel probe of particle physics by encoding information about the fields that drove the transition. Calculations of the gravitational wave power spectrum often adopt simplified equations of state to describe the relativistic hydrodynamics of the phase transition. These...

47. Scalar-Induced Gravitational Waves from Thermal Inflation in Supercooled Cosmic Phase Transitions

Tamara Caldas (Goethe University Frankfurt)

19/08/2026, 14:15

Early universe physics, inflation, electroweak phase transitions, and sources for gravitational waves

talk (15min)

We investigate the gravitational wave signatures of a supercooled cosmic phase transition within a classically conformal Standard Model extension, where quark condensation can trigger symmetry breaking via spinodal decomposition instead of conventional bubble nucleation. By studying the amplification of scalar fluctuations in the linear regime, we estimate the associated scalar-induced...

99. Gravitational waves from phase transitions in dark sectors

Daniil Krichevskiy (University of Stavanger)

19/08/2026, 14:30

Early universe physics, inflation, electroweak phase transitions, and sources for gravitational waves

talk (15min)

First-order phase transitions in a dark sector can produce an observable stochastic gravitational-wave background, and many models predicting such signals have been studied in the context of current and future gravitational-wave experiments. For moderately strong transitions, hydrodynamical simulations suggest that sound waves generated by the expansion and collisions of true-vacuum bubbles...

104. Gravitational wave predictions for Standard Model extensions using the Sound Shell Model

Mika Mäki (University of Helsinki)

19/08/2026, 14:45

Early universe physics, inflation, electroweak phase transitions, and sources for gravitational waves

talk (15min)

Gravitational waves from cosmological first-order phase transitions provide a probe of physics beyond the Standard Model that complements laboratory experiments. The gravitational wave spectrum can be computed in an effective theory of a relativistic fluid coupled to a scalar field, the order parameter of the phase transition. The coupling is effected through the effective potential and the...

14. Effective Field Theory for Thermal Phase Transitions

Andrii Dashko (University of Granada)

19/08/2026, 15:00

Early universe physics, inflation, electroweak phase transitions, and sources for gravitational waves

talk (15min)

We present a study of dimensional reduction as a tool for a precise and systematic description of thermally driven electroweak phase transitions (EWPT) in the early universe. Focusing on strong first-order transitions, which are relevant for gravitational wave cosmology, we examine higher-order dimensional reduction, the running of effective parameters within the effective field theory (EFT),...

56. Automated thermal field theory with AUTOTHERM: the gravitino example

Killian Bouzoud (SUBATECH)

19/08/2026, 15:15

Early universe physics, inflation, electroweak phase transitions, and sources for gravitational waves

talk (15min)

Our current understanding of the Universe's history, based on the standard models of particle physics and cosmology, can successfully reproduce a wide variety of experimental results. Key issues like the nature of dark matter (DM) or the baryon asymmetry of the Universe (BAU) need new physics beyond the Standard Model (BSM), with most solutions invoking the existence of new particle degrees of...

18. Thermal axion production at strong coupling

Eamonn Weitz (Universität Bielefeld)

19/08/2026, 15:30

Early universe physics, inflation, electroweak phase transitions, and sources for gravitational waves

talk (15min)

Thermal production of hot axions in the early universe has attracted much attention recently, owing to the fact that
it will be sensitive to upcoming precision constraints on $N_{\mathrm{eff}}$. The theoretical uncertainty associated with
such calculations is known to come primarily from the axion production rate, which has been
studied across a broad range temperatures and axion momenta...

105. Dark Energy from the Weak Axion

Pedro Bittar (Perimeter Insitute)

19/08/2026, 15:45

Early universe physics, inflation, electroweak phase transitions, and sources for gravitational waves

talk (15min)

Dynamical dark energy offers an alternative to a cosmological constant with distinct observational signatures. However, the small energy density scale, Hubble-sized mass, and Planckian excursions make simple models fine-tuned and unnatural. In this talk, we discuss a weak version of the axion that can naturally reproduce the scale hierarchies expected for dark energy. After identifying the...