Heavy Dark Matter
Dark Matter could be considerably heavier than other known particles
Dark Matter (DM) composes 25% of the energy budget of the observable universe. Weakly Interacting Massive Particles (WIMPs) around the TeV scale have since long been among the best-motivated and most studied DM candidates. However, the absence of experimental evidence for such particles either in colliders, at telescopes or in underground laboratories, leaves the community more and more skeptical of their existence. This encourages model-building and studies of new methods of detection beyond the WIMP paradigm. I am interested in studying the possibility that DM is much heavier than the WIMP (TeV) scale. Due to unitarity constraints in Quantum Field Theory, DM can not be heavier than about 100 TeV if it was once at thermal equilibrium with the Standard Model - the so-called thermal DM scenario - otherwise it is overproduced in the early universe. I worked on two mechanisms which dilute the DM abundance in the Early universe, hence allowing to evade the unitarity bound on the DM mass at 100 TeV. I also studied novel methods of detection of such heavy hidden sectors, based on their imprint on a spectrum of gravitational-waves from primordial origins (see gravitational archaeology below)
Published in: JCAP 07 (2020) 032 e-Print: 1912.02569 [hep-ph]
We revisit in details the gravitational wave spectrum from local and global cosmic string in arbitrary cosmology. We study in particular the impact of an early non-standard matter era, kination era and inflation era.
We account for particle production.
Published in: JCAP 07 (2020) 016 e-Print: 1912.03245 [hep-ph]
We focus on the presence of an early matter era and deduce the constraints on particle physics model (heavy dark photon, heavy moduli and gravitationally-produced relic)
PBHs, with masses smaller than 1000 tons (10^9 g), evaporate before the onset of Big-Bang nucleosynthesis, making their detection a challenging task. We propose a strategy to probe the existence of these PBHs through GWs emitted by local and global cosmic strings. Our study provides new insights on the suppression of the GW spectrum and how the spectral shape of local-string GWs can give us information on the duration of the matter era. We have also discovered a novel feature, the double-step suppression, which is universal to any early matter-dominated era, not just specific to PBHs. This research could help set constraints on PBHs with masses between 10^6 and 10^9 g for local strings and between 10^4 and 10^9 g for global strings.
e-Print: 2111.01150 [hep-ph]
In a long and detailed paper, we study how the potential detection of gravitational waves of primordial origin (cosmic strings, inflation, 1stOPTs) would tell us about the existence of a kination-dominated era. We study in details how such a kination era can arise from a rotating complex scalar field of Affleck-Dine type.
e-Print: 2108.10328 [hep-ph]
We study the enhancement of gravitational wave amplitude from primordial inflation in presence of a kination era induced by a rotation complex scalar field.
