Cosmological particle production and pairwise hotspots on the CMB

Abstract

Heavy particles with masses much bigger than the inflationary Hubble scale H*, can get non-adiabatically pair produced during inflation through their couplings to the inflaton. If such couplings give rise to time-dependent masses for the heavy particles, then following their production, the heavy particles modify the curvature perturbation around their locations in a time-dependent and scale non-invariant manner. This results into a non-trivial spatial profile of the curvature perturbation that is preserved on superhorizon scales and eventually generates localized hot or cold spots on the CMB. We explore this phenomenon by studying the inflationary production of heavy scalars and derive the final temperature profile of the spots on the CMB by taking into account the subhorizon evolution, focusing in particular on the parameter space where pairwise hot spots (PHS) arise. When the heavy scalar has an $$ \mathcal{O} $$ O (1) coupling to the inflaton, we show that for an idealized situation where the dominant background to the PHS signal comes from the standard CMB fluctuations themselves, a simple position space search based on applying a temperature cut, can be sensitive to heavy particle masses M0/H* ∼ $$ \mathcal{O} $$ O (100). The corresponding PHS signal also modifies the CMB power spectra and bispectra, although the corrections are below (outside) the sensitivity of current measurements (searches).

Cosmological gravitational particle production of massive spin-2 particles

“…For instance, a benchmark parameter point predicts f local nl ∼ 30, which is now excluded by Planck's constraint f local nl = −0.9 ± 5.1 (Akrami et al, 2020a). CGPP can also lead to rare 'hot spots' in the CMB (Kim et al, 2021(Kim et al, , 2023. These examples illustrate the capability of current and future probes of CMB non-Gaussianity to test CGPP.…”

“…In the WIM-Pzilla regime, the dark matter's mass is assumed to reside close to the inflationary Hubble scale and the inflaton mass scale, m χ ≈ H e ≈ m φ . This is because CGPP is strongly suppressed for m χ ≫ H e ≈ m φ , making production of heavier particles ineffective -however see Kannike et al (2017); Kim et al (2021Kim et al ( , 2023 -and because several considerations disfavored m χ ≪ H e ≈ m φ . For spin-1 /2 particles and conformally-coupled spin-0 particles, CGPP is suppressed for small m χ , making it difficult to accommodate all the dark matter for masses below the WIMPzilla regime; see Sec.…”

The Tachyonic Higgs and the Inflationary Universe

“…Imprints in the CMB: Particle production during inflation is known to modify the primordial power spectrum [59], and produce CMB "hotspots" [60].…”

Classical cosmological collider physics and primordial features

“…In this work, we explicitly break the scale invariance through the introduction of primordial features, which also introduce more arbitrary energy scales and couplings. In scenarios studied in [100][101][102][103][104][105], there are non-shift-symmetric couplings of the inflaton to a heavy field. This coupling can lead to a time-dependent mass for the heavy field, facilitating its cosmological production when the effective mass of the heavy field passes through a minimum.…”