NEHOP'25 - New Horizons in Primordial Black Hole Physics

Session

PBHs from inflation

19 May 2025, 09:20

Brussels

21. Stochastic inflation beyond slow roll

David Wands

19/05/2025, 09:20

Stochastic inflation offers a non-perturbative framework with which to calculate the distribution of density perturbations and in particular large, but rare fluctuations in the non-Gaussian tail of the distribution that could give rise to primordial black holes. Strongly enhanced density perturbations from single-field inflation require deviations from slow roll, and there are a number of...

10. Calculation of primordial non-Gaussianity from ultra slow-roll inflation

Alejandro Perez Rodriguez (Universidad Autonoma de Madrid)

19/05/2025, 09:50

The probability of large primordial scalar perturbations (leading to primordial black hole formation and the concurrent GW backgrounds) is sensitive to the tail of the PDF of primordial curvature perturbations. We analyse such tails in inflationary models featuring an ultra slow-roll phase, known to enhance both the amplitude and non-Gaussianity of curvature perturbations at small scales. We...

5. From the inflaton potential to PBH abundance

Syksy Räsänen

19/05/2025, 10:10

I will discuss how to calculate the PBH abundance and mass distribution starting from the inflationary potential, taking into account stochastic effects and using the compaction function. We determine the radial profiles directly from stochastic calculation, and do not assume Gaussianity. I will outline progress and how to address the remaining open issues.

26. Mapping inflationary loop corrections to boundary terms

Dr Laura Iacconi (Queen Mary University of London)

19/05/2025, 11:00

Both single- and multi-field models of inflation might lead to enhanced scalar fluctuations on scales much smaller than those seeding the large-scale structure formation. In these scenarios, it is possible that the spike of power at high wavenumber might induce large corrections to the scalar power spectrum, e.g. in the form of loop corrections, potentially endangering the perturbativity of...

32. Ultraslow-roll inflation on the lattice: backreaction and nonlinear effects

Angelo Caravano

19/05/2025, 11:20

Violating the slow-roll regime in the final stages of inflation can significantly enhance curvature perturbations, a scenario often invoked in models producing primordial black holes and small-scale scalar-induced gravitational waves. In this regime, tree-level computations may become insufficient, and nonlinear corrections can play a crucial role. In this talk, I will discuss how lattice...

33. Eternal inflation in primordial black hole models

Eemeli Tomberg (UCLouvain)

19/05/2025, 11:40

Inflationary models with an inflection point potential may produce a significant abundance of primordial black holes. I show that in typical models, inflation is eternal near the inflection point, that is, the volume of the inflating region diverges at late times. The inflating space then has a fractal structure, with eternal inflation taking place inside type II black holes. I discuss the...

58. Stochastic Dynamics during Inflation

Parth Bhargava (ICG, Portsmouth)

19/05/2025, 12:00

Quantum fluctuations during inflation in the very early universe inevitably generate inhomogeneities and anisotropies across all observable scales and beyond. In the stochastic approach to modeling inflationary dynamics, these quantum fluctuations are incorporated as stochastic noise. We employ the formalism of stochastic inflation to examine the role of quantum diffusion during inflation....