Ultralight Fermionic Dark Matter

Abstract

Conventional lore from Tremaine and Gunn excludes fermionic dark matter lighter than a few hundred eV, based on the Pauli exclusion principle. We highlight a simple way of evading this bound with a large number of species that leads to numerous non-trivial consequences. In this scenario there are many distinct species of fermions with quasi-degenerate masses and no couplings to the standard model. Nonetheless, gravitational interactions lead to constraints from measurements at the LHC, of cosmic rays, of supernovae, and of black hole spins and lifetimes. We find that the LHC constrains the number of distinct species, bosons or fermions lighter than $\sim 500$ GeV, to be $N\lesssim 10^{62}$. This, in particular, implies that roughly degenerate fermionic dark matter must be heavier than $\sim 10^{-14}$ eV, which thus relaxes the Tremaine-Gunn bound by $\sim 16$ orders of magnitude. Slightly weaker constraints applying to masses up to $\sim 100$ TeV exist from cosmic ray measurements while various constraints on masses $\lesssim 10^{-10}$ eV apply from black hole observations. We consider a variety of phenomenological bounds on the number of species of particles. Finally, we note that there exist theoretical considerations regarding quantum gravity which could impose more severe constraints that may limit the number of physical states to $N\lesssim 10^{32}$.

arXiv comment9 pages, 2 figures, comments welcome; v2: clarifying remarks, matches published version

References in corpus (43)

• The Hierarchy Problem and New Dimensions at a Millimeter
• New Dimensions at a Millimeter to a Fermi and Superstrings at a TeV
• GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs
• Phenomenology, Astrophysics and Cosmology of Theories with Sub-Millimeter Dimensions and TeV Scale Quantum Gravity
• String Axiverse
• Ultralight scalars as cosmological dark matter
• Axions In String Theory
• Effective Field Theory, Black Holes, and the Cosmological Constant
• Test of the Equivalence Principle Using a Rotating Torsion Balance
• What is the lowest possible reheating temperature?
• GRAVITY AND GLOBAL SYMMETRIES
• Black Holes and Large N Species Solution to the Hierarchy Problem
• Black Hole Bound on the Number of Species and Quantum Gravity at LHC
• Black Hole Superradiance Signatures of Ultralight Vectors
• Search for dark matter and other new phenomena in events with an energetic jet and large missing transverse momentum using the ATLAS detector
• New Test of the Gravitational $1/r^2$ Law at Separations down to 52 $\mu$m
• Ultra Light Boson Dark Matter and Event Horizon Telescope Observations of M87*
• Dynamical Dark Matter: I. Theoretical Overview
• Open Questions in Cosmic-Ray Research at Ultrahigh Energies
• Viscoelastic hydrodynamics and holography
• Nnaturalness
• Unitarity and the three flavour neutrino mixing matrix
• Dynamical Dark Matter: II. An Explicit Model
• Quantum gravity at a TeV and the renormalization of Newton's constant
• Higher-spin massless S-matrices in four-dimensions
• Quantum Information and Gravity Cutoff in Theories with Species
• Constructing the Tree-Level Yang-Mills S-Matrix Using Complex Factorization
• MICROSCOPE limits for new long-range forces and implications for unified theories
• Phenomenology of 10^32 Dark Sectors
• Phase space mass bound for fermionic dark matter from dwarf spheroidal galaxies
• Manyfold Universe
• Nature of Microscopic Black Holes and Gravity in Theories with Particle Species
• Cores in Dwarf Galaxies from Fermi Repulsion
• New mass bound on fermionic dark matter from a combined analysis of classical dSphs
• Tensor Bounds on the Hidden Universe
• Gravity Induced Non-Local Effects in the Standard Model
• Gravitons, Bose-symmetry, and Bonus-scaling
• Stringent constraints on the light boson model with supermassive black hole spin measurements
• Black hole evaporation and semiclassicality at large D
• Ultra light Thomas-Fermi Dark Matter
• Freezing-in the Hierarchy Problem
• Effective field theory, large number of particle species, and holography
• Gravitational Interactions and Neutrino Masses

Cited by in corpus (22)

• The NANOGrav 15-year Data Set: Search for Signals from New Physics
• Probing the Particle Spectrum of Nature with Evaporating Black Holes
• Multifield Ultralight Dark Matter
• Bounds on boosted dark matter from direct detection: The role of energy-dependent cross sections
• Black Hole Evaporation Beyond the Standard Model of Particle Physics
• Constraints on cosmic-ray boosted dark matter with realistic cross section
• The domain of thermal dark matter candidates
• Theoretical bounds on dark matter masses
• Near-horizon microstructure and superradiant instability of black holes
• Supermassive black hole seeds from sub-keV dark matter
• Phenomenological implications on a hidden sector from the Festina Lente bound
• The Muon Magnetic Moment and Physics Beyond the Standard Model
• Evaporating black holes: constraints on anomalous emission mechanisms
• Exploring millicharged dark matter components from the shadows
• On the Interaction between Ultralight Bosons and Quantum-Corrected Black Holes
• Constraints on the maximal number of dark degrees of freedom from black hole evaporation, cosmic rays, colliders, and supernovae
• On the Tremaine-Gunn Limit with Mass-Varying Particles
• Investigating sub-MeV dark matter annihilation to neutrinos using direct detection experiments
• Self-gravitating quantum stars with a globally relevant Bohm potential
• Ultraviolet-Infrared Bounds and Minimum Coupling in Effective Field Theories
• Black Hole Cold Brew: Fermi Degeneracy Pressure
• Imprints of fermionic and bosonic mixed dark matter on the 21-cm signal at cosmic dawn