Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userContinuum-Mediated Self-Interacting Dark Matter
83
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Dark matter may self-interact through a continuum of low-mass states. This happens if dark matter couples to a strongly-coupled nearly-conformal hidden sector. This type of theory is holographically described by brane-localized dark matter interacting with bulk fields in a slice of 5D anti-de Sitter space. The long-range potential in this scenario depends on a non-integer power of the spatial separation, in contrast to the Yukawa potential generated by the exchange of a single 4D mediator. The resulting self-interaction cross section scales like a non-integer power of velocity. We identify the Born, classical and resonant regimes and investigate them using state-of-the-art numerical methods. We demonstrate the viability of our continuum-mediated framework to address the astrophysical small-scale structure anomalies. Investigating the continuum-mediated Sommerfeld enhancement, we demonstrate that a pattern of resonances can occur depending on the non-integer power. We conclude that continuum mediators introduce novel power-law scalings which open new possibilities for dark matter self-interaction phenomenology.
rate research
Read More
We present models of resonant self-interacting dark matter in a dark sector with QCD, based on analogies to the meson spectra in Standard Model QCD. For dark mesons made of two light quarks, we present a simple model that realizes resonant self-interaction (analogous to the $phi$-K-K system) and thermal freeze-out. We also consider asymmetric dark matter composed of heavy and light dark quarks to realize a resonant self-interaction (analogous to the $Upsilon(4S)$-B-B system) and discuss the experimental probes of both setups. Finally, we comment on the possible resonant self-interactions already built into SIMP and ELDER mechanisms while making use of lattice results to determine feasibility.
We propose a self-interacting boosted dark matter (DM) scenario as a possible origin of the recently reported excess of electron recoil events by the XENON1T experiment. The Standard Model has been extended with two vector-like fermion singlets charged under a dark $U(1)_D$ gauge symmetry to describe the dark sector. While the presence of light vector boson mediator leads to sufficient DM self-interactions to address the small scale issues of cold dark matter, the model with GeV scale DM can explain the XENON1T excess via scattering of boosted DM component with electrons at the detector. The requirement of large annihilation rate of heavier DM into the lighter one for sufficient boosted DM flux leads to suppressed thermal relic abundance. A hybrid setup of thermal and non-thermal contribution from late decay of a scalar can lead to correct relic abundance. All these requirements leave a very tiny parameter space for sub-GeV DM keeping the model very predictive for near future experiments.
Light vector mediators can naturally induce velocity-dependent dark matter self-interactions while at the same time allowing for the correct dark matter relic abundance via thermal freeze-out. If these mediators subsequently decay into Standard Model states such as electrons or photons however, this is robustly excluded by constraints from the Cosmic Microwave Background. We study to what extent this conclusion can be circumvented if the vector mediator is stable and hence contributes to the dark matter density while annihilating into lighter degrees of freedom. We find viable parts of parameter space which lead to the desired self-interaction cross section of dark matter to address the small-scale problems of the collisionless cold dark matter paradigm while being compatible with bounds from the Cosmic Microwave Background and Big Bang Nucleosynthesis observations.
The existence of dark matter particles that carry phenomenologically relevant self-interaction cross sections mediated by light dark sector states is considered to be severely constrained through a combination of experimental and observational data. The conclusion is based on the assumption of specific dark matter production mechanisms such as thermal freeze-out together with an extrapolation of a standard cosmological history beyond the epoch of primordial nucleosynthesis. In this work, we drop these assumptions and examine the scenario from the perspective of the current firm knowledge we have: results from direct and indirect dark matter searches and cosmological and astrophysical observations, without additional assumptions on dark matter genesis or the thermal state of the very early universe. We show that even in the minimal set-up, where dark matter particles self-interact via a kinetically mixed vector mediator, a significant amount of parameter space remains allowed. Interestingly, however, these parameter regions imply a meta-stable, light mediator, which in turn calls for modified search strategies.
We consider a simple class of models where dark radiation has self-interactions and therefore does not free stream. Such dark radiation has no anisotropic stress (or viscosity), leaving a distinct signature on the CMB angular power spectrum. Specifically we study a possibility that hidden gauge bosons and/or chiral fermions account for the excess of the effective number of neutrino species. They have gauge interactions and remain light due to the unbroken hidden gauge symmetry, leading to Delta N_{rm eff} simeq 0.29 in some case.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
