arXiv subjects

Kamil Mudrunka

Publications and source records attributed to Kamil Mudrunka.

4 recordsLinked to original sources

arXiv2026

Inflation and Reheating by Dynamical Torsion

In gravity theories with torsion, inflation can be driven by the dynamical torsion. Since it naturally has a derivative coupling to the axial current consisting of Standard Model particles, the reheating dynamics should be much different from conventional inflation models like Starobinsky inflation. We calculate the inflaton decay rate in detail and find that, although the 2 body decay into the fermion pair is vanishing in the massless fermion limit, the anomaly-induced 2 body decay into the gauge bosons and 3 body decay involving the Higgs boson are non-vanishing and they give sizable contributions to the total decay width of the inflaton. This gives a natural lower bound on the reheating temperature in the inflation model with dynamical torsion.

hep-ph↗

arXiv2026

High Frequency Spectrum of Primordial Gravitational Waves

During inflation long wavelength gravitational waves are produced, which form stochastic background in the present universe with very wide range of frequencies. Higher frequency gravitational waves never experience super-Hubble-radius regime, but they are also amplified after inflation due to the inflaton oscillation. Taking account of the inflaton dynamics after inflation, the spectrum of such quantum-mechanically produced gravitational waves may extend to much higher frequencies than previously thought. In this paper we calculate the spectrum of high frequency gravitational waves produced during and after inflation in detail, in particular focusing on the connection between the low and high frequency regime, and show that the detailed spectrum can distinguish inflation models.

hep-ph↗

arXiv2025

Inflation with Gauss-Bonnet correction: beyond slow-roll

If a coupling between the inflaton and the Gauss-Bonnet term is introduced, many models of inflation that were ruled out by the most recent Planck data can be made viable again. The predictions for the scalar spectral index and tensor-to-scalar ratio are typically computed using the slow-roll approximation. In this paper we instead study the full equations of motion and determine the necessary initial conditions for reasonable inflation epoch. We derive the conditions under which the Friedmann equation admits positive solutions for the Hubble parameter. Then we study the possibility of the inflaton becoming trapped in a local potential minimum induced by the Gauss-Bonnet term. Finally we demonstrate the results on monomial potential models with a quadratic and a quartic potential and show that the slow-roll approximation becomes imprecise in the quartic case.

gr-qc↗

arXiv2024

Probing Gauss-Bonnet-Corrected Inflation with Gravitational Waves

The low energy effective action of quantum gravity may include the higher curvature terms such as the Gauss-Bonnet term. The inflaton dynamics may be affected by the Gauss-Bonnet term if there is an inflaton-Gauss-Bonnet coupling. We show that an inflation model with a simple power law potential is made viable if it is coupled to the Gauss-Bonnet term since the prediction on the scalar spectral index and the tensor-to-scalar ratio are modified. We further point out that such a model predicts huge amount of gravitational waves at the high frequency range around 100GHz--100THz through the perturbative inflaton decay into gravitons induced by the Gauss-Bonnet term. Thus the spectrum of high frequency gravitational background is a unique feature of the inflation models with a Gauss-Bonnet correction.

astro-ph.CO↗