Saxion Cosmology for Thermalized Gravitino Dark Matter

Abstract

In all supersymmetric theories, gravitinos, with mass suppressed by the Planck scale, are an obvious candidate for dark matter; but if gravitinos ever reached thermal equilibrium, such dark matter is apparently either too abundant or too hot, and is excluded. However, in theories with an axion, a saxion condensate is generated during an early era of cosmological history and its late decay dilutes dark matter. We show that such dilution allows previously thermalized gravitinos to account for the observed dark matter over very wide ranges of gravitino mass, keV < $m_{3/2}$ < TeV, axion decay constant, $10^9$ GeV < $f_a$ < $10^{16}$ GeV, and saxion mass, 10 MeV < $m_s$ < 100 TeV. Constraints on this parameter space are studied from BBN, supersymmetry breaking, gravitino and axino production from freeze-in and saxion decay, and from axion production from both misalignment and parametric resonance mechanisms. Large allowed regions of $(m_{3/2},f_a,m_s)$ remain, but differ for DFSZ and KSVZ theories. Superpartner production at colliders may lead to events with displaced vertices and kinks, and may contain saxions decaying to $(WW,ZZ,hh),gg,\gamma \gamma$ or a pair of Standard Model fermions. Freeze-in may lead to a sub-dominant warm component of gravitino dark matter, and saxion decay to axions may lead to dark radiation.

30 pages, 4 figures

References in corpus (5)

• Big-Bang Nucleosynthesis and Gravitino
• Topological susceptibility in finite temperature (2+1)-flavor QCD using gradient flow
• Gravitino or Axino Dark Matter with Reheat Temperature as high as $10^{16}$ GeV
• Solving Cosmological Problems of Supersymmetric Axion Models in an Inflationary Universe
• Unified Models of the QCD Axion and Supersymmetry Breaking

Cited by in corpus (12)

• Long-Lived Particles at the Energy Frontier: The MATHUSLA Physics Case
• QCD Axion Dark Matter with a Small Decay Constant
• Dark Matter Freeze-in Production in Fast-Expanding Universes
• Imprint of a scalar era on the primordial spectrum of gravitational waves
• Displaced new physics at colliders and the early universe before its first second
• Explosive Axion Production from Saxion
• Axion Dark Radiation: Hubble Tension and Hyper-kamiokande Neutrino Experiment
• The Supersymmetric R-Parity Violating Dine-Fischler-Srednicki-Zhitnitsky Axion Model
• Searching for Metastable Particles with Sub-Millimeter Displaced Vertices at Hadron Colliders
• Common Origin of Warm Dark Matter and Dark Radiation
• A QCD R-Axion
• Fingerprints of freeze-in dark matter in an early matter-dominated era