Despite the shortcomings of the Standard Model, all experimental observations so far have not indicated the existence of new physics (NP) at or near the TeV scale. The gravitational channel is another promising avenue to test NP and can potentially probe particles with masses far beyond those accessible at current collider experiments. With this in mind, we perform a phenomenological study of...
We explore the implications of low reheating temperatures in the early Universe, focusing on scenarios where a minimal threshold of $4$ MeV is crucial to preserve the accuracy of Big Bang Nucleosynthesis (BBN) predictions. We specifically investigate the freeze-in mechanism, wherein Dark Matter (DM) candidates are Boltzmann suppressed due to their mass exceeding the reheating temperature....
We analyze two-dimensional scattering matrices for particles transforming in the fundamental representation of the U(N) global symmetry group, assuming no bound states. In particular, we use the S-matrix bootstrap formalism to construct the allowed space of S-matrices for such processes, which in turn need to be consistent with the usual conditions of unitarity, crossing and analyticity....
Conformal field theories (CFTs) are a subset of quantum field theories which are invariant under conformal transformations. CFTs are of great theoretical interest, partly due to the AdS/CFT conjecture, which asserts that a gravitational theory living in $d$-dimensional Anti-de Sitter (AdS) space is dual to a CFT on the $(d-1)$-dimensional boundary of this space. This is a powerful...
The presently open problem of the Hubble tension is shown to be removed in the context of a modified theory of gravity with a non-minimal coupling between curvature and matter. By evolving the cosmological parameters that match the cosmic microwave background data until their values from direct late-time measurements, we will show how to obtain an agreement between different experimental...
What does a black hole look like? In 1 + 3 spacetime dimensions, the optical appearance of a black hole is a bidimensional region in the observer’s sky often called the black hole shadow, as supported by the EHT observations. In higher dimensions this question is more subtle and observational setup dependent. Previous studies considered the shadows of higher dimensional black holes to remain...
