Damping of inhomogeneities in neutralino dark matter (original) (raw)
Related papers
Particle candidates for dark matter: A Case for (dominant or subdominant) relic neutralinos
2001
After a short introduction on particle candidates for dark matter within possible extensions of the standard model, we concentrate on Weakly Interacting Massive Particles, and on one of their most interesting physical realizations: the neutralino. We analyze how detectability of relic neutralinos by direct and indirect means is related to their local and cosmological densities; we use simple general arguments to discusss different scenarios where relic neutralinos make up the dominant bulk of dark matter or only a small fraction of it. Our general arguments are further corroborated by specific numerical results. We show to which extent the present experiments of direct searches for WIMPs, when interpreted in terms of relic neutralinos, probe interesting regions of the supersymmetric parameter space. Our analysis is performed in a number of different supersymmetric schemes.
Neutralinos as dark matter candidates
1994
We review some properties of the neutralino as a candidate for dark matter in the Universe. After presentation of evaluations for the neutralino relic abundance, possibilities for its direct and indirect detections are discussed, with emphasis for measurements at neutrino telescopes.
Constraints on dark matter particles from theory, galaxy observations, andN-body simulations
Physical Review D, 2008
Mass bounds on dark matter (DM) candidates are obtained for particles that decouple in or out of equilibrium while ultrarelativistic with arbitrary isotropic and homogeneous distribution functions. A coarse grained Liouville invariant primordial phase space density D is introduced which depends solely on the distribution function at decoupling. The density D is explicitly computed and combined with recent photometric and kinematic data on dwarf spheroidal satellite galaxies in the Milky Way (dShps) and the observed DM density today yielding upper and lower bounds on the mass, primordial phase space densities and velocity dispersion of the DM candidates. Combining these constraints with recent results from N-body simulations yield estimates for the mass of the DM particles in the range of a few keV. We establish in this way a direct connection between the microphysics of decoupling in or out of equilibrium and the constraints that the particles must fulfill to be suitable DM candidates. If chemical freeze out occurs before thermal decoupling, light bosonic particles can Bose-condense. We study such Bose-Einstein condensate (BEC) as a dark matter candidate. It is shown that depending on the relation between the critical (Tc) and decoupling (T d) temperatures, a BEC light relic could act as CDM but the decoupling scale must be higher than the electroweak scale. The condensate hastens the onset of the non-relativistic regime and tightens the upper bound on the particle's mass. A non-equilibrium scenario which describes particle production and partial thermalization, sterile neutrinos produced out of equilibrium and other DM models is analyzed in detail and the respective bounds on mass, primordial phase space density and velocity dispersion are obtained. Thermal relics with m ∼ few keV that decouple when ultrarelativistic and sterile neutrinos produced resonantly or non-resonantly lead to a primordial phase space density compatible with cored dShps and disfavor cusped satellites. Light Bose-condensed DM candidates yield phase space densities consistent with cores and if Tc ≫ T d also with cusps. Phase space density bounds on particles that decoupled non-relativistically combined with recent results from N-body simulations suggest a potential tension for WIMPs with m ∼ 100 GeV, T d ∼ 10 MeV.
Constraining dark matter candidates from structure formation
2001
We show that collisional damping of adiabatic primordial fluctuations yields constraints on the possible range of mass and interaction rates of Dark Matter particles. Our analysis relies on a general classification of Dark Matter candidates, that we establish independently of any specific particle theory or model. From a relation between the collisional damping scale and the Dark Matter interaction rate, we find that Dark Matter candidates must have cross-sections at decoupling < ∼ 10 −33 m dm 1MeV cm 2 with photons and < ∼ 10 −37 m dm 1MeV cm 2 with neutrinos, to explain the observed primordial structures of 10 9 M ⊙ . These damping constraints are particularly relevant for Warm Dark Matter candidates. They also leave open less known regions of parameter space corresponding to particles having rather high interaction rates with other species than neutrinos and photons.
Formation of galaxies and large-scale structure with cold dark matter
Nature, 1984
The dark matter that appears to be gravitationally dominant on all scales larger than galactic cores may consist of axions, stable photinos, or other collisionless particles whose velocity dispersion in the early universe is so small that -fluctuations of galactic size or larger are not damp~ed by free streaming. An attractive feature of this cold dark matter hypothesis is its considerable predictive power: the post-recombination fluctuation spectrum is calculable, and it in turn governs the formation of galaxies and clusters. Good agreement with the data is obtained for a Zeldovich (j&l2 a: k;) spectrum of primordial fluctuations.
Journal of Cosmology and Astroparticle Physics, 2007
The viability of the lightest neutralino as a dark matter candidate in the next-to-minimal supersymmetric standard model is analysed. We carry out a thorough analysis of the parameter space, taking into account accelerator constraints as well as bounds on low-energy observables, such as the muon anomalous magnetic moment and rare K and B meson decays. The neutralino relic density is also evaluated and consistency with present bounds imposed. Finally, the neutralino direct detection cross section is calculated in the allowed regions of the parameter space and compared to the sensitivities of present and projected dark matter experiments. Regions of the parameter space are found where experimental constraints are fulfilled, the lightest neutralino has the correct relic abundance and its detection cross section is within the reach of dark matter detectors. This is possible in the presence of very light singlet-like Higgses and when the neutralino is either light enough so that some annihilation channels are kinematically forbidden, or has a large singlino component.
Neutralino Dark Matter in a Class of Unified Theories
1992
The cosmological significance of the neutralino sector is studied for a class of supersymmetric grand unified theories in which electroweak symmetry breaking is seeded by a gauge singlet. Extensive use is made of the renormalization group equations to significantly reduce the parameter space, by deriving analytic expressions for all the supersymmetry-breaking couplings in terms of the universal gaugino mass m 1/2 , the universal scalar mass m 0 and the coupling A. The composition of the lightest supersymmetric partner is determined exactly below the W mass, no approximations are made for sfermion masses, and all particle exchanges are considered in calculating the annihilation cross-section; the relic abundance is then obtained by an analytic approximation. We find that in these models, stable neutralinos may make a significant contribution to the dark matter in the universe.
Low-mass neutralino dark matter in supergravity scenarios: phenomenology and naturalness
Journal of Cosmology and Astroparticle Physics, 2017
The latest experimental results from the LHC and dark matter (DM) searches suggest that the parameter space allowed in supersymmetric theories is subject to strong reductions. These bounds are especially constraining for scenarios entailing light DM particles. Previous studies have shown that light neutralino DM in the Minimal Supersymmetric Standard Model (MSSM), with parameters defined at the electroweak scale, is still viable when the low energy spectrum of the model features light sleptons, in which case, the relic density constraint can be fulfilled. In view of this, we have investigated the viability of light neutralinos as DM candidates in the MSSM, with parameters defined at the grand unification scale. We have analysed the optimal choices of non-universalities in the soft supersymmetry-breaking parameters for both, gauginos and scalars, in order to avoid the stringent experimental constraints. We show that light neutralinos, with a mass as low as 25 GeV, are viable in supergravity scenarios if the gaugino mass parameters at high energy are very non universal, while the scalar masses can remain of the same order. These scenarios typically predict a very small cross section of neutralinos off protons and neutrons, thereby being very challenging for direct detection experiments. However, a potential detection of smuons and selectrons at the LHC, together with a hypothetical discovery of a gamma-ray signal from neutralino annihilations in dwarf spheroidal galaxies could shed light on this kind of solutions. Finally, we have investigated the naturalness of these scenarios, taking into account all the potential sources of tuning. Besides the electroweak fine-tuning, we have found that the tuning to reproduce the correct DM relic abundance and that to match the measured Higgs mass can also be important when estimating the total degree of naturalness.
Neutralino dark matter beyond CMSSM universality
Journal of High Energy Physics, 2003
We study the effect of departures from SUSY GUT universality on the neutralino relic density, and both its direct and indirect detection, especially by neutrino telescopes. We find that the most interesting models are those with a value of M 3 | GU T lower than the universal case.