Refined Bounds on MeV-scale Thermal Dark Sectors from BBN and the CMB

Abstract

New light states thermally coupled to the Standard Model plasma alter the expansion history of the Universe and impact the synthesis of the primordial light elements. In this work, we carry out an exhaustive and precise analysis of the implications of MeV-scale BSM particles in Big Bang Nucleosynthesis (BBN) and for Cosmic Microwave Background (CMB) observations. We find that, BBN observations set a lower bound on the thermal dark matter mass of $m_{\chi }>0.4\text{MeV}$ at $2\sigma$. This bound is independent of the spin and number of internal degrees of freedom of the particle, of the annihilation being s-wave or p-wave, and of the annihilation final state. Furthermore, we show that current BBN plus CMB observations constrain purely electrophilic and neutrinophilic BSM species to have a mass, $m_{\chi }>3.7\text{MeV}$ at $2\sigma$. We explore the reach of future BBN measurements and show that upcoming CMB missions should improve the bounds on light BSM thermal states to $m_{\chi }>(10-15)\text{MeV}$. Finally, we demonstrate that very light BSM species thermally coupled to the SM plasma are highly disfavoured by current cosmological observations.

28 pages, 10 figures, 7 tables. v2. References and minor clarifications added. Matches published version in JCAP

References in corpus (32)

• Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics Beyond LambdaCDM
• The Clustering of the SDSS DR7 Main Galaxy Sample I: A 4 per cent Distance Measure at z=0.15
• Results from a search for dark matter in the complete LUX exposure
• Dark Matter Results From 54-Ton-Day Exposure of PandaX-II Experiment
• Precise Relic WIMP Abundance and its Impact on Searches for Dark Matter Annihilation
• The trouble with $H_0$
• New Fixed-Target Experiments to Search for Dark Gauge Forces
• Search for a dark photon in e+e- collisions at BABAR
• Searching for Dark Matter Annihilation in Recently Discovered Milky Way Satellites with Fermi-LAT
• Primordial Nucleosynthesis: from precision cosmology to fundamental physics
• The WIMPless Miracle: Dark Matter Particles without Weak-scale Masses or Weak Interactions
• The effects of He I 10830 on helium abundance determinations
• Light Dark Matter: Models and Constraints
• Relic neutrino decoupling with flavour oscillations revisited
• LEP Shines Light on Dark Matter
• New Limits on Hidden Photons from Past Electron Beam Dumps
• Probing a Secluded U(1) at B-factories
• Cosmology With a Very Light $L_{\mu }-L_{\tau }$ Gauge Boson
• Probing cosmological parameters with the CMB: Forecasts from full Monte Carlo simulations
• SENSEI: Direct-Detection Constraints on Sub-GeV Dark Matter from a Shallow Underground Run Using a Prototype Skipper-CCD
• Big Bang Nucleosynthesis as a Probe of New Physics
• Making dark matter out of light: freeze-in from plasma effects
• BBN And The CMB Constrain Neutrino Coupled Light WIMPs
• Toward (Finally!) Ruling Out Z and Higgs Mediated Dark Matter Models
• The primordial deuterium abundance of the most metal-poor damped Lyman-alpha system
• Leptophobic Dark Matter at Neutrino Factories
• Signatures of sub-GeV dark matter beams at neutrino experiments
• BBN constraints on the annihilation of MeV-scale dark matter
• Testing MeV dark matter with neutrino detectors
• Supernova Constraints on Massive (Pseudo)Scalar Coupling to Neutrinos
• Mono-Neutrino at DUNE: New Signals From Neutrinophilic Thermal Dark Matter
• Neutrino Masses from a Dark Neutrino Sector below the Electroweak Scale

Cited by in corpus (9)

• Precise WIMP Dark Matter Abundance and Standard Model Thermodynamics
• Neutrino experiments probe hadrophilic light dark matter
• Testing dark matter interactions with CMB spectral distortions
• Searching for Sub-GeV Dark Matter in the Galactic Centre using Hyper-Kamiokande
• Search for U(1)${}_{L_{\mu }-L_{\tau }}$ charged Dark Matter with neutrino telescope
• Cosmological Bounds on sub-GeV Dark Vector Bosons from Electromagnetic Energy Injection
• Displaced Searches for Light Vector Bosons at Belle II
• Probing the muon $g-2$ with future beam dump experiments
• Explaining lepton-flavor non-universality and self-interacting dark matter with $L_{\mu }-L_{\tau }$