Reannihilation of self-interacting dark matter

Binder, Tobias; Gustafsson, M.; Kamada, Ayuki; Sandner, Stefan; Wiesner, Max

doi:10.1103/physrevd.97.123004

Cited by 50 publications

(51 citation statements)

References 112 publications

(237 reference statements)

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“…(Bremsstrahlung of dark mediators has also been invoked to lift the p-wave suppression [63].) Moreover, s-wave annihilation processes may lead to a period of reannihilation in the early universe, after DM kinetic decoupling [64].…”

Section: Resultsmentioning

confidence: 99%

Dark matter bound states via emission of scalar mediators

Oncala

Petraki

2019

J. High Energ. Phys.

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If dark matter (DM) couples to a force carrier that is much lighter than itself, then it may form bound states in the early universe and inside haloes. While bound-state formation via vector emission is known to be efficient and have a variety of phenomenological implications, the capture via scalar emission typically requires larger couplings and is relevant to more limited parameter space, due to cancellations in the radiative amplitude. However, this result takes into account only the trilinear DM-DM-mediator coupling. Theories with scalar mediators include also a scalar potential, whose couplings may participate in the radiative transitions. We compute the contributions of these couplings to the radiative capture, and determine the parameter space in which they are important.ArXiv ePrint: 1808.04854

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Section: Resultsmentioning

confidence: 99%

Dark matter bound states via emission of scalar mediators

Oncala

Petraki

2019

J. High Energ. Phys.

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“…For certain ratios of φ ≡ m V /(α χ M) there exist a bound-state solution with zero binding energy (E = 0). For those special cases the Sommerfeld enhancement factor scales as S(v rel ) ∝ v −2 rel for v rel m V /M α χ , called on-resonance regime, leading to an interesting observational impact on cosmology at very late times [74,75]. Roughly, those poles where the spectral function would diverge are at the on-resonance condition φ = 6/(m 2 π 2 ) where m is integer8.…”

Section: B Spectral Function Sommerfeld Enhancement Factor and Decamentioning

confidence: 99%

Dark matter Sommerfeld-enhanced annihilation and bound-state decay at finite temperature

2018

Self Cite

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Traditional computations of the dark matter (DM) relic abundance, for models where attractive self-interactions are mediated by light force-carriers and bound states exist, rely on the solution of a coupled system of classical on-shell Boltzmann equations. This idealized description misses important thermal effects caused by the tight coupling among force-carriers and other charged relativistic species potentially present during the chemical decoupling process. We develop for the first time a comprehensive ab-initio derivation for the description of DM long-range interactions in the presence of a hot and dense plasma background directly from non-equilibrium quantum field theory. Our results clarify a few conceptional aspects of the derivation and show that under certain conditions the finite temperature effects can lead to sizable modifications of DM Sommerfeld-enhanced annihilation and bound-state decay rates. In particular, the scattering and bound states get strongly mixed in the thermal plasma environment, representing a characteristic difference from a pure vacuum theory computation. The main result of this work is a novel differential equation for the DM number density, written down in a form which is manifestly independent under the choice of what one would interpret as a bound or a scattering state at finite temperature. The collision term, unifying the description of annihilation and bound-state decay, turns out to have in general a non-quadratic dependence on the DM number density. This generalizes the form of the conventional Lee-Weinberg equation which is typically adopted to describe the freeze-out process. We prove that our number density equation is consistent with previous literature results under certain limits. In the limit of vanishing finite temperature corrections our central equation is fully compatible with the classical on-shell Boltzmann equation treatment. So far, finite temperature corrected annihilation rates for long-range force systems have been estimated from a method relying on linear response theory. We prove consistency between the latter and our method in the linear regime close to chemical equilibrium.

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“…Furthermore, the strong velocity dependence of σv anni suggests that the usual freeze-out can hardly work, as for SIDM with light mediators decaying into visible particles [110][111][112][113]. Nevertheless, the DM abundance might arise from other SIDM production mechanisms [104].…”

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confidence: 99%

Velocity Dependence from Resonant Self-Interacting Dark Matter

2019

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The dark matter density distribution in small-scale astrophysical objects may indicate that dark matter is self-interacting, while observations from clusters of galaxies suggest that the corresponding cross section depends on the velocity. Using a model-independent approach, we show that resonant self-interacting dark matter (RSIDM) can naturally explain such a behavior. In contrast to what is often assumed, this does not require a light mediator. We present explicit realizations of this mechanism and discuss the corresponding astrophysical constraints.Dark matter (DM) makes up more than 80% of the matter in the Universe today and played a crucial role in forming stars and galaxies, and hence us. Yet its nature is unknown. Currently the best pieces of information come from astrophysical observations. N-body simulations of collisionless DM predict astrophysical halos with DM density following a universal profile that scales as ρ ∝ r −3 in its outskirts but exhibits a central cusp, ρ ∝ r −β , with β 1, referred to as the Navarro-Frenk-White (NFW) profile [1][2][3]. Nevertheless, many studies show hints of a DM mass deficit in the inner regions of certain halos. Notably, observations indicate that numerous dwarf galaxies [4-6] and some low-surface-brightness spiral galaxies [7-9] have a shallower central DM density, better described by a core of constant density, i.e., by β 0. This is known as the core-vs-cusp problem. Although it is more pressing in small-scale objects, shallower DM density profiles -with a slope of β 0.5-have been reported for certain galaxy clusters [10,11]. Moreover, the DM mass deficit also manifests itself in halos that are less dense than what simulations suggest if they host the galaxies that we observe. This is the too-bigto-fail problem, observed for the subhalos of the Milky Way [12], Andromeda [13] and the Local Group [14].Several explanations for these discrepancies have been discussed in the literature. The systematic uncertainties introduced in deriving DM distributions from observations of luminous objects are one of them. Most importantly, the motions of HI gas and stars may not be faithful tracers of the DM circular velocity [16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Baryonic processes are another conceivable explanation for the discrepancies, since the aforementioned simulations only include collisionless DM. Solutions along this line include supernova-driven baryonic winds [30][31][32][33], DM heating due to star formation [34], infalling baryonic clumps [35][36][37][38] as well as active galactic nuclei or black holes [39]. Nonetheless, there is no consensus on why systematic uncertainties or baryonic processes lead to a seemingly universal mass deficit at various scales.A more exciting possibility consists of considering DM collisions in the inner regions of astrophysical objects [40]. This is known as self-interacting dark matter (SIDM). N-body simulations [41][42][43][44][45][46] confirm that DM scattering processes indeed reduce the central density of DM halos...

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Reannihilation of self-interacting dark matter

Cited by 50 publications

References 112 publications

Dark matter bound states via emission of scalar mediators

Dark matter bound states via emission of scalar mediators

Dark matter Sommerfeld-enhanced annihilation and bound-state decay at finite temperature

Velocity Dependence from Resonant Self-Interacting Dark Matter

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