Sommerfeld enhancements for thermal relic dark matter

By Jonathan L. Feng, M. Kaplinghat, Hai-Bo Yu. 2010

256 citations recorded by the source corpus.

The annihilation cross section of thermal relic dark matter determines both its relic density and indirect detection signals. We determine how large indirect signals may be in scenarios with Sommerfeld-enhanced annihilation, subject to the constraint that the dark matter has the correct relic density. This work refines our previous analysis through detailed treatments of resonant Sommerfeld enhancement and the effect of Sommerfeld enhancement on freeze out. Sommerfeld enhancements raise many interesting issues in the freeze out calculation, and we find that the cutoff of resonant enhancement, the equilibration of force carriers, the temperature of kinetic decoupling, and the efficiency of self-interactions for preserving thermal velocity distributions all play a role. These effects may have striking consequences; for example, for resonantly-enhanced Sommerfeld annihilation, dark matter freezes out but may then chemically recouple, implying highly suppressed indirect signals, in contrast to naive expectations. In the minimal scenario with standard astrophysical assumptions, and tuning all parameters to maximize the signal, we find that, for force-carrier mass m{sub {phi}=}250 MeV and dark matter masses m{sub X}=0.1, 0.3, and 1 TeV, the maximal Sommerfeld enhancement factors are S{sub eff}=7, 30, and 90, respectively. Such boosts are too small to explain both the PAMELA and Fermimore » excesses. Nonminimal models may require smaller boosts, but the bounds on S{sub eff} could also be more stringent, and dedicated freeze out analyses are required. For concreteness, we focus on 4{mu} final states, but we also discuss 4e and other modes, deviations from standard astrophysical assumptions and nonminimal particle physics models, and we outline the steps required to determine if such considerations may lead to a self-consistent explanation of the PAMELA or Fermi excesses.« less

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/f8391125b6b8b2bd185df3728a8f2942d088be76

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Citations in the corpus

Bound-state formation for thermal relic dark matter and unitarity (2014, background): “where [26]”
Benchmarks for dark matter searches at the LHC (2014, background): “The annihilation of two coloured particles, in the non-relativistic limit, is strongly affected by non-perturbative Sommerfeld QCD corrections [90] (see also [91–96]), which describe initial state attraction or repulsion due the strong force.”
Higgs portal, fermionic dark matter, and a Standard Model like Higgs at 125 GeV (2012, background): “Let us emphasize that in our toy model dark matter does couple to two mediators, in which case the computation of the exact Sommerfeld factor is more involved [46] than the results in [45].”
An Introduction to Particle Dark Matter (2019, background): “…of homogeneity and isotropy: Note that this bound is not valid in presence of Sommerfeld enhancements annihilation, see, for example, Reference [19]. and the covariant Liouville operator can be written in the following form: The number density of a given species is given by the integral over…”
Asymmetric dark matter from leptogenesis (2011, background): “JHEP05(2011)106 in our Galaxy [ 53 , 54]. But in our framework, this tension is resolved because the DM abundance follows from the asymmetry produced by leptogenesis, not from the annihilation rate at decoupling.”
Subhaloes in self-interacting galactic dark matter haloes (2012, background): “We refer the reader to Feng et al. (2010b); Finkbeiner et al. (2011); Loeb & Weiner (2011) for details on the particle physics model and its available parameter space.”