Keith A. Olive

Spectator Dark Matter and the Higgs Portal

Stephen E. Henrich, Yann Mambrini, Keith A. Olive

Light scalar spectators generically acquire large stochastic fluctuations during inflation, which can lead to a catastrophic overproduction of dark matter if the resulting primordi…

Radiative Corrections and Reheating in Supergravity Models of Inflation

John Ellis, Tony Gherghetta, Kunio Kaneta +2

We consider the effects of radiative corrections in Starobinsky-like models of inflation, concentrating on models of inflation formulated in N=1 no-scale supergravity. Inflaton cou…

Leptogenesis and Low Reheating Temperatures

Marcos A. G. Garcia, Stephen E. Henrich, Wenqi Ke +1

We study leptogenesis during non-instantaneous reheating in the canonical type-I seesaw framework, with the dominant source of right-handed neutrino (RHN) production being non-ther…

Reheating in No-Scale Models of Inflation

Ignatios Antoniadis, John Ellis, Dimitri V. Nanopoulos +2

Analogously to the suppression of inflaton decays into conformally-coupled scalar fields in the original Starobinsky $R + R^{2}$ model of inflation, inflaton decays to Standard Model…

Searching for UFOs from the early universe: direct detection prospects for relativistically decoupling dark matter

Stephen E. Henrich, Yann Mambrini, Keith A. Olive

Particles that decouple relativistically from the Standard Model bath during reheating represent a versatile class of well-motivated cold dark matter candidates. In fact, ultrarela…

Radiative Corrections in Supergravity Models of Inflation

John Ellis, Tony Gherghetta, Kunio Kaneta +2

Supergravity provides the natural supersymmetric framework for early universe cosmology. A broad class of inflationary models in no-scale supergravity yields tree-level predictions…

Planck-Scale Effects on Nucleon Decay in Minimal Supersymmetric SU(5)

John Ellis, Jason L. Evans, Shihwen Hor +2

We examine the impact on the phenomenology of the minimal supersymmetric SU(5) Grand Unified Theory (GUT) of dimension-5 operators with coefficients suppressed by the Planck mass s…

Z' portal dark matter from post-inflationary reheating: WIMPs, FIMPs, and UFOs

Stephen E. Henrich, Yann Mambrini, Keith A. Olive

We investigate the production of dark matter (DM) via a heavy $Z^{'}$ mediator during the post-inflationary reheating epoch. In particular, we study production from three mechanisms w…

Ultra-relativistic freeze-out: a bridge from WIMPs to FIMPs

Stephen E. Henrich, Yann Mambrini, Keith A. Olive

We re-examine the case for dark matter (DM) produced by ultra-relativistic freeze-out (UFO). UFO is the mechanism by which Standard Model (SM) neutrinos decouple from the radiation…

Constraints on Attractor Models of Inflation and Reheating from Planck, BICEP/Keck, ACT DR6, and SPT-3G Data

John Ellis, Marcos A. G. Garcia, Keith A. Olive +1

We analyze the latest cosmic microwave background (CMB) constraints on the scalar spectral index $n_{s}$ and tensor-to-scalar ratio $r$ from Planck 2018, BICEP/Keck 2018, the Atacama…

Effects of Radiative Corrections on Starobinsky Inflation

John Ellis, Tony Gherghetta, Kunio Kaneta +2

We analyze radiative corrections to the Starobinsky model of inflation arising from self-interactions of the inflaton, and from its Yukawa couplings, $y$ , to matter fermions, and d…

Deformations of Starobinsky Inflation in No-Scale SU(5) and SO(10) GUTs

John Ellis, Marcos A. G. Garcia, Natsumi Nagata +2

The original Starobinsky $R + R^{2}$ model of inflation is consistent with Planck and other measurements of the CMB, but recent results from the ACT and SPT Collaborations hint that…

Phenomenological Constraints on Higgs reheating

Yann Cado, Mathieu Gross, Yann Mambrini +1

In many models of inflation, reheating is realized through a coupling between the inflaton and the Higgs boson. Often, the mass of the inflaton is of order $1 0^{13}$ GeV determined…

Ultra-Relativistic Freeze-Out During Reheating

Stephen E. Henrich, Mathieu Gross, Yann Mambrini +1

We perform a thorough investigation of (ultra)relativistic freeze-out (UFO) during reheating. While the standard WIMP (non-relativistic freeze-out) and FIMP (freeze-in) paradigms h…

How Accidental was Inflation?

Ignatios Antoniadis, John Ellis, Wenqi Ke +2

Data on the cosmic microwave background (CMB) are discriminating between different models of inflation, disfavoring simple monomial potentials whilst being consistent with models w…

Scalar Field Fluctuations and the Production of Dark Matter

Marcos A. G. Garcia, Wenqi Ke, Yann Mambrini +2

One of the simplest possible candidates for dark matter is a stable scalar singlet beyond the Standard Model. If its mass is below the Hubble scale during inflation, long-wavelengt…

Aspects of Gravitational Portals and Freeze-in during Reheating

Stephen E. Henrich, Yann Mambrini, Keith A. Olive

We conduct a systematic investigation of freeze-in during reheating while taking care to include both direct and indirect production of dark matter (DM) via gravitational portals a…

The Role of the Curvaton Post-Planck

Gongjun Choi, Wenqi Ke, Keith A. Olive

The expected improvements in the precision of inflationary physics observables including the scalar spectral index $n_{s}$ and the tensor-to-scalar ratio $r$ will reveal more than…

Non-universal SUSY models, $g_{μ} - 2$ , $m_{H}$ and dark matter

John Ellis, Keith A. Olive, Vassilis C. Spanos

We study the anomalous magnetic moment of the muon, $g_{μ} - 2 \equiv 2 a_{μ}$ , in the context of supersymmetric models beyond the CMSSM, where the unification of either the gaugino mas…

Inflaton Production of Scalar Dark Matter through Fluctuations and Scattering

Gongjun Choi, Marcos A. G. Garcia, Wenqi Ke +3

We study the effects on particle production of a Planck-suppressed coupling between the inflaton and a scalar dark matter candidate, $χ$ . In the absence of this coupling, the domin…

Inflaton decay in No-Scale Supergravity and Starobinsky-like models

Yohei Ema, Marcos A. G. Garcia, Wenqi Ke +2

We consider the decay of the inflaton in Starobinsky-like models arising from either an $R + R^{2}$ theory of gravity or $N = 1$ no-scale supergravity models. If Standard Model matter is…

Bare mass effects on the reheating process after inflation

Simon Clery, Marcos A. G. Garcia, Yann Mambrini +1

We consider the effects of a bare mass term for the inflaton, when the inflationary potential takes the form $V (ϕ) = λ ϕ^{k}$ about its minimum with $k \geq 4$ . We concentrate on $k = 4$ ,…