BSM PANDEMIC Delta Series: Daniel Egana-Ugrinovic (Perimeter) and Cari Cesarotti (Harvard)


Daniel Egana-Ugrinovic (Perimeter Institute)

Title:  Probing ultra-light bosons with stellar tidal disruption events

Abstract:  Stars that pass close to supermassive black holes located in the center of galaxies can be violently disrupted by tidal forces, leading to fantastic flares that can be observed in the optical, UV and X-ray spectra. The rate for these tidal disruption events (TDE's) to occur in a given galaxy sensitively depends on the spin and mass of its central black hole. Black hole spin, on the other hand, can be uniquely affected by ultra-light bosons due to the superradiant instability. In this talk we demonstrate that this intimate connection between ultra-light bosons, the expected spins of super-massive black holes, and tidal disruption event rates, can be used to probe the existence of such particles. As an example, we show that a dedicated analysis of upcoming data from the Legacy Survey for Space and Time, which is expected to detect tens to hundreds of thousands of TDE's, could be performed to either discover or rule out ultra-light bosons with masses ranging from 10^(-18) to 10^(-20) eV.


Cari Cesarotti (Harvard University)

Title: Searching for New Physics at Muon Colliders

A high energy muon collider complex can provide new and complementary discovery potential to the LHC or future hadron colliders. New spin-1 bosons are a motivated class of exotic new physics models. In particular leptoquarks, dark photons, and L_\mu - L_\tau models have distinct production channels at hadron and lepton machines. We study a vector leptoquark model at a muon collider with √ s = 3, 14 TeV within a set of both UV and phenomenologically motivated flavor scenarios. We compute which production mechanism has the greatest reach for various values of the leptoquark mass and the coupling between leptoquark and Standard Model fermions. We find that we can probe leptoquark masses up to an order of magnitude beyond √ s with perturbative couplings. Additionally, we can also probe regions of parameter space unavailable to flavor experiments. In particular, all of the parameter space of interest to explain recent low-energy anomalies in B meson decays would be covered even by a √ s = 3 TeV collider. We also consider other applications of a muon collider complex, such as a beam dump, in the hunt for new vector physics.