Concealing Dirac neutrinos from cosmic microwave background

Abstract

The existence of prolonged radiation domination prior to the Big Bang Nucleosynthesis (BBN), starting just after the inflationary epoch, is not yet established unanimously. If instead, the universe undergoes a non-standard cosmological phase, it will alter the Hubble expansion rate significantly and may also generate substantial entropy through non-adiabatic evolution. This leads to a thumping impact on the properties of relic species decoupled from the thermal bath before the revival of the standard radiation domination in the vicinity of the BBN. In this work, considering the Dirac nature of neutrinos, we have studied decoupling of ultra-relativistic right-handed neutrinos (${\nu }_R$s) in presence of two possible non-standard cosmological phases. While in both cases we have modified Hubble parameters causing faster expansions in the early universe, one of the situations predicts a non-adiabatic evolution and thereby a slower redshift of the photon temperature due to the expansion. Considering the most general form of the collision term with Fermi-Dirac distribution and Pauli blocking factors, we have solved the Boltzmann equation numerically to obtain $\Delta {\mathrm{N}}_{\mathrm{eff}}$ for the three right-handed neutrinos. We have found that for a large portion of parameter space, the combined effect of early decoupling of ${\nu }_R$ as well as the slower redshift of photon bath can easily hide the signature of right-handed neutrinos, in spite of precise measurement of $\Delta {\mathrm{N}}_{\mathrm{eff}}$, at the next generation CMB experiments like CMB-S4, SPT-3G etc. This however will not be applicable for the scenarios with only fast expansion.

arXiv comment31 pages, 9 figures, Version accepted for publication in JCAP

References in corpus (59)

• Observation of electron-antineutrino disappearance at Daya Bay
• Observation of Reactor Electron Antineutrino Disappearance in the RENO Experiment
• Indication of Electron Neutrino Appearance from an Accelerator-produced Off-axis Muon Neutrino Beam
• Indication for the disappearance of reactor electron antineutrinos in the Double Chooz experiment
• Cuba - a library for multidimensional numerical integration
• Equilibrium State of a Massless Self-Interacting Scalar Field in the De Sitter Background
• Relic neutrino decoupling including flavour oscillations
• Largest temperature of the radiation era and its cosmological implications
• Wino Cold Dark Matter from Anomaly-Mediated SUSY Breaking
• MeV-scale Reheating Temperature and Thermalization of Neutrino Background
• Reheating in Inflationary Cosmology: Theory and Applications
• Supersymmetry Breaking in the Early Universe
• Cosmological-Parameter Determination with Microwave Background Maps
• CMB-S4 Science Case, Reference Design, and Project Plan
• Production of massive particles during reheating
• The Neutrino Puzzle: Anomalies, Interactions, and Cosmological Tensions
• Relic neutrino decoupling with flavour oscillations revisited
• Flavor structures of charged fermions and massive neutrinos
• The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe
• keV sterile neutrino dark matter in gauge extensions of the standard model
• Neutrino decoupling in the early Universe
• Electron neutrino and antineutrino appearance in the full MINOS data sample
• The oscillation effects on thermalization of the neutrinos in the universe with low reheating temperature
• Precision Early Universe Thermodynamics made simple: $N_{\mathrm{eff}}$ and Neutrino Decoupling in the Standard Model and beyond
• Coherent Propagation of PeV Neutrinos and the Dip in the Neutrino Spectrum at IceCube
• A Non-thermal WIMP Miracle
• Neutrino decoupling beyond the Standard Model: CMB constraints on the Dark Matter mass with a fast and precise $N_{\mathrm{eff}}$ evaluation
• Thermal Dark Matter From A Highly Decoupled Sector
• PeV-Scale Dark Matter as a Thermal Relic of a Decoupled Sector
• Neutrino energy transport in weak decoupling and big bang nucleosynthesis
• Observational Constraints on Secret Neutrino Interactions from Big Bang Nucleosynthesis
• On the reheating stage after inflation
• When the Universe Expands Too Fast: Relentless Dark Matter
• Thermalization after inflation and production of massive stable particles
• Dark Matter Freeze-in Production in Fast-Expanding Universes
• Production of massive stable particles in inflaton decay
• BBN constraints on the annihilation of MeV-scale dark matter
• Increasing Neff with particles in thermal equilibrium with neutrinos
• Observing Dirac neutrinos in the cosmic microwave background
• Dirac neutrinos and $N_{\mathrm{eff}}$
• Inflatable Dark Matter
• Reheating the Standard Model from a hidden sector
• Neutrino-Dark Matter Connections in Gauge Theories
• Minimal Dirac Neutrino Mass Models from $U(1{)}_R$ Gauge Symmetry and Left-Right Asymmetry at Colliders
• Dirac neutrinos and $N_{\mathrm{eff}}$ II: the freeze-in case
• Cosmological beam dump: constraints on dark scalars mixed with the Higgs boson
• Neutrino Portal to FIMP Dark Matter with an Early Matter Era
• Neutrino non-standard interactions meet precision measurements of $N_{\mathrm{eff}}$
• Connecting Light Dirac Neutrinos to a Multi-component Dark Matter Scenario in Gauged $B-L$ Model
• Light Dirac neutrino portal dark matter with observable $\Delta N_{\mathrm{eff}}$
• Non-thermal cosmic neutrino background
• Relic Right-handed Dirac Neutrinos and Implications for Detection of Cosmic Neutrino Background
• Light Dark Matter from Entropy Dilution
• Thermal Goldstino Production with Low Reheating Temperatures
• Unraveling the Dirac Neutrino with Cosmological and Terrestrial Detectors
• Observing Left-Right Symmetry in the Cosmic Microwave Background
• Simple estimate of BBN sensitivity to light freeze-in dark matter
• Dirac dark matter, dark radiation, and the type-II seesaw mechanism in alternative $U(1{)}_X$ standard model
• Imprints of MeV Scale Hidden Dark Sector at Planck Data

Cited by in corpus (5)

• CMB signature of non-thermal Dark Matter produced from self-interacting dark sector
• Collider and CMB complementarity of leptophilic dark matter with light Dirac neutrinos
• Reviewing the prospect of fermion triplets as dark matter and source of baryon asymmetry in non-standard cosmology
• Light Thermal Self-Interacting Dark Matter in the Shadow of Non-Standard Cosmology
• Phenomenology of Dirac neutrino EFTs up to dimension six