Speaker
Description
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 freedom in the early Universe. Studying the dynamics of those BSM particles throughout cosmological history involves intricate Thermal Field Theory (TFT) computations; those computations should also be as precise as possible, so as to be able to test the viability of BSM models. For example, determining the current-day abundance of a DM candidate for comparison with the expected quantity of DM in the Universe often requires computing the thermal production rate of this particle. The multiplication of BSM models makes it desirable to be able to perform such tasks automatically, to both save time and reduce the risk of errors.
In this talk, I present the first release of the AUTOTHERM code: a framework to automatically compute (i.e. with minimal user intervention) the thermal production rate of a particle, using only the Lagrangian as an input. AUTOTHERM differs from other already available codes by its automated implementation of Hard Thermal Loop (HTL) resummation; this is necessary to properly account for finite-temperature collective effects in the medium and avoid infrared (IR) divergences in the naive computation due to massless mediators. AUTOTHERM uses three different leading-order-equivalent schemes to describe the collective effects, allowing users to quantify the uncertainty inherent to the theoretical computation. In the HTL theory, the model dependence of the collective effects is contained entirely within the thermal masses of the mediators, which are computed automatically by AUTOTHERM.
During this talk I will use the example of the gravitino, the massive superpartner of the graviton and a popular DM candidate, as a common thread. I will present new results for the thermal gravitino production rate and also compare those results to the previous state of the art from the literature, highlighting how its gauge-dependent resummation yields a pathologically divergent result.
This talk is based on the upcoming 26XX.XXXX and 26XX.XXXX by Jacopo Ghiglieri, Greg Jackson, and myself.