arXiv subjects

Xavier Pritchard

Publications and source records attributed to Xavier Pritchard.

4 recordsLinked to original sources

arXiv2026

Bumpy inflation from explosive particle production

We present a first-principles derivation of an effective inflaton potential with a bumpy feature. We consider the coupling of a spectator field \chi to the inflaton \phi such that \chi is massive enough for almost all values of \phi, but becomes massless when the inflaton crossed the value \phi_\star. This gives rise to a burst of \chi-particle production at \phi=\phi_\star. By taking the backreaction of the particle production, we obtain a bumpy feature in the effective potential.

astro-ph.CO↗

arXiv2025

Beyond Standard Model equation of state and primordial black holes

The Standard Model of particle physics successfully describes all known fundamental particles and their interactions; however, it leaves several unanswered questions. Theories beyond the Standard Model typically introduce new particles and symmetries to address these issues. In the early universe, when such particles become non-relativistic, or the symmetries are broken, there are associated reductions in the equation of state of the primordial plasma. These reductions lead to an exponential enhancement in the formation rate of primordial black holes. In this paper, we calculate the equation of state for several supersymmetric and composite Higgs models, which naturally predict a large number of additional degrees of freedom. Using these equations of state, we compute some example primordial black hole abundances, which we find can be enhanced by up to 20 orders of magnitude.

astro-ph.CO↗

arXiv2025

Robust {\mu}-distortion constraints on primordial supermassive black holes from cubic (gNL) non-Gaussian perturbations

We make the first calculation of the spectral distortion constraints on the primordial curvature power spectrum in the limit of large cubic non-Gaussianity. This calculation involves computing a 2-loop integral, which we perform analytically. Despite being non-perturbatively non-Gaussian, we show that the constraints only change significantly from the case of Gaussian perturbations in the high-k tail, where spectral distortions become weak. We conclude that generating primordial supermassive black holes requires even more extreme forms of non-Gaussianity. We also argue why the mu-distortion constraint is unlikely to significantly change even in the presence of more extreme local non-Gaussianity.

astro-ph.CO↗

arXiv2024

Constraining the impact of standard model phase transitions on primordial black holes

Phase transitions in the early universe lead to a reduction in the equation of state of the primordial plasma. This exponentially enhances the formation rate of primordial black holes. However, this sensitivity to the equation of state is the same that primordial black hole abundances show to the primordial curvature power spectrum amplitude. In this paper, we investigate peaked power spectra and show the challenges associated with motivating populations of primordial black holes with standard model enhancements. The parametrisation of different power spectra plays an important role in this discussion. The allowed parameter space consistent with a large QCD phase transition impact on the primordial black hole abundance differs greatly. This is particularly evident for broader spectra. We also show that, in our framework, the electroweak phase transition cannot significantly affect the overall abundance.

astro-ph.CO↗