Fate of homogeneous ${\mathbb{Z}}_2$-symmetric scalar condensates

Abstract

Dark matter, if represented by a ${\mathbb{Z}}_2$-symmetric scalar field, can manifest as both particles and condensates. In this paper, we study the evolution of an oscillating homogeneous condensate of a ${\mathbb{Z}}_2$-symmetric scalar field in a thermal plasma in an FLRW universe. We focus on the perturbative regime where the oscillation amplitude is sufficiently small so that parametric resonance is inefficient. This perturbative regime necessarily comprises the late stage of the condensate decay and determines its fate. The coupled coarse-grained equations of motion for the condensate, radiation, and spacetime are derived from first principles using nonequilibrium quantum field theory. We obtain analytical expressions for the relevant microscopic quantities that enter the equations of motion and solve the latter numerically. We find that there is always a nonvanishing relic abundance for a condensate with a ${\mathbb{Z}}_2$ symmetry that is not spontaneously broken. This is because its decay rate decreases faster than the Hubble parameter at late times due to either the amplitude dependence or the temperature dependence in the condensate decay rate. Consequently, accounting for the condensate contribution to the overall dark matter relic density is essential for ${\mathbb{Z}}_2$ scalar singlet dark matter.

56 pages, 17 figures; v2: refs updated, minor changes, matches the version published in JCAP

References in corpus (25)

• Dynamics of dark energy
• Cosmology and the Fate of Dilatation Symmetry
• Gauge Singlet Scalars as Cold Dark Matter
• Flux Compactification
• The Dawn of FIMP Dark Matter: A Review of Models and Constraints
• Reheating and Post-inflationary Production of Dark Matter
• Inflaton Oscillations and Post-Inflationary Reheating
• Physics of String Flux Compactifications
• Quantum Boltzmann Equations and Leptogenesis
• Dynamics of oscillating scalar field in thermal environment
• Kadanoff-Baym Approach to Flavour Mixing and Oscillations in Resonant Leptogenesis
• Green's function method for handling radiative effects on false vacuum decay
• Increasing Temperature toward the Completion of Reheating
• Implications of time-dependent inflaton decay on reheating and dark matter production
• Reheating and Dark Matter Freeze-in in the Higgs-$R^2$ Inflation Model
• On finite density effects on cosmic reheating and moduli decay and implications for Dark Matter production
• Criterion for ultra-fast bubble walls: the impact of hydrodynamic obstruction
• Logarithmically divergent friction on ultrarelativistic bubble walls
• Thermal Field Theory in real-time formalism: concepts and applications for particle decays
• Gradient effects on false vacuum decay in gauge theory
• From QFT to Boltzmann: Freeze-in in the presence of oscillating condensates
• Scalar field damping at high temperatures
• False vacuum decay rates, more precisely
• Dissipation of oscillating scalar backgrounds in an FLRW universe
• The limits of the strong $CP$ problem

Cited by in corpus (4)

• Bubble wall dynamics from nonequilibrium quantum field theory
• New insights into axion freeze-in
• Non-thermal production of heavy vector dark matter from relativistic bubble walls
• Decay of a scalar condensate in two different approaches