Research
Research
- How does inflation end?
- How is the Universe reheated?
- What survives from nonlinear post-inflationary dynamics?
Inflation & Reheating
I study how the very early Universe emerged from an inflationary stage and evolved towards the hot Big Bang. Inflation provides a remarkably successful framework for explaining the large-scale homogeneity of the Universe and the origin of primordial fluctuations, but its connection to particle physics and gravity remains far from unique.
A major part of my work focuses on the transition out of inflation. During reheating, the coherent energy stored in the inflationary background is transferred to other degrees of freedom through highly non-equilibrium processes. This stage may involve explosive particle production, parametric and tachyonic instabilities, fragmentation of scalar fields and the formation of localized structures such as oscillons.
I am particularly interested in situations where these nonlinear processes retain information about the underlying gravitational theory or the particle-physics sector. This makes the post-inflationary Universe a useful arena for connecting high-energy theory with potentially observable cosmological signatures.
- Is the electroweak vacuum stable?
- How does gravity affect vacuum decay?
- Can vacuum instability leave cosmological signatures?
Vacuum Stability
The measured Higgs and top-quark parameters suggest that the electroweak vacuum may be metastable rather than absolutely stable. Although its lifetime in the present Universe can be enormously long, the conditions encountered in the early Universe can be radically different and may significantly affect the fate of the Higgs field.
I investigate how curvature, inflationary dynamics, reheating and additional gravitational interactions modify vacuum stability and vacuum decay. In this context, gravity is not merely a spectator: it can change the effective Higgs dynamics, modify tunnelling rates and alter the conditions under which transitions between different vacuum configurations become possible.
This line of research provides a direct bridge between Standard Model physics and cosmology. It also raises the possibility that phenomena associated with vacuum instability may leave observable traces, for example through phase transitions or gravitational-wave production.
- How do cosmological phase transitions proceed?
- What gravitational-wave backgrounds do they generate?
- What can those signals reveal about high-energy physics?
Phase Transitions & Gravitational Waves
Cosmological phase transitions can transform the microscopic properties of a theory into macroscopic dynamics on very large scales. When such transitions are sufficiently violent, they may proceed through bubble nucleation, collisions, scalar-field gradients and turbulent or strongly nonlinear evolution.
I study phase transitions occurring during and after inflation, with particular emphasis on their real-time dynamics and on the gravitational radiation they can produce. These processes are especially interesting because gravitational waves propagate essentially unimpeded once generated, preserving information about epochs of the Universe that are otherwise extremely difficult to access.
The aim is to understand which features of an observed stochastic gravitational-wave background could be traced back to the underlying particle-physics model, the properties of the transition and the surrounding cosmological evolution.
- Can gravity produce the dark matter abundance?
- Can symmetries connect different cosmological epochs?
- What role can scale invariance play?
Dark Sector & Symmetries
I explore scenarios in which dark matter is produced through the gravitational and field dynamics of the early Universe rather than through conventional thermal interactions. Such mechanisms can generate a dark sector that is extremely weakly coupled to ordinary matter while still acquiring the abundance required by cosmological observations.
I am also interested in the role of symmetries as organizing principles for cosmological model building. In particular, scale invariance and its possible breaking provide a framework in which inflation, particle physics and the late-time accelerated expansion of the Universe may be linked to a common underlying structure.
These ideas motivate models in which apparently unrelated cosmological phenomena are different manifestations of the same fundamental degrees of freedom or symmetry-breaking pattern, offering a unified perspective across widely separated energy scales.