相关论文: Cosmic abundances of SIMP dark matter
We give a review on the thermal average of the annihilation cross-sections for $3\rightarrow 2$ and general higher-order processes. Thermal average of higher order annihilations highly depend on the velocity of dark matter, especially, for…
If dark matter (DM) is a weakly interacting massive particle (WIMP) that is a thermal relic of the early Universe, then its total self-annihilation cross section is revealed by its present-day mass density. The canonical thermally averaged…
We present a new paradigm for achieving thermal relic dark matter. The mechanism arises when a nearly secluded dark sector is thermalized with the Standard Model after reheating. The freezeout process is a number-changing 3->2 annihilation…
The decoupling of a cold relic, during a decaying-particle-dominated cosmological evolution is analyzed, the relic density is calculated both numerically and semi-analytically and the results are compared with each other. Using plausible…
The relic abundance of thermal dark matter particles is generally assumed to be inversely proportional to their annihilation rate, which is therefore constrained by the present matter density, <sigma v> ~ 10^{-26} Omega_{dm}^{-1} cm^3…
We investigate the relic abundance of asymmetric Dark Matter particles that were in thermal equilibrium in the early universe. The standard analytic calculation of the symmetric Dark Matter is generalized to the asymmetric case. We…
We show that the relic abundance of thermal dark matter annihilating via a long-range interaction, is significantly affected by the formation and decay of dark matter bound states in the early universe, if the dark matter mass is above a…
We summarize here our studies \cite{Chu:2022xuh,Chu:2023jyb,Chu:2024rrv} on two distinct scenarios for MeV-mass thermal dark matter freeze-out. First, we determine the minimal viable mass for dark matter below tens of MeV, considering…
Using the upper bound on the inelastic reaction cross-section implied by S-matrix unitarity, we derive the thermally averaged maximum dark matter (DM) annihilation rate for general $k \rightarrow 2$ number-changing reactions, with $k \geq…
Motivated by the hypothesis that dark matter self-interactions provide a solution to the small-scale structure formation problems, we investigate the possibilities that the relic density of a self-interacting dark matter candidate can…
We study the general properties of the freezeout of a thermal relic. We give analytic estimates of the relic abundance for an arbitrary freezeout process, showing when instantaneous freezeout is appropriate and how it can be corrected when…
We propose and study a scalar extension of the Standard Model which respects a $\mathbb{Z}_3$ symmetry remnant of the spontaneous breaking of a global $U(1)_\text{DM}$ symmetry. Consequently, this model has a natural dark matter candidate…
In the standard thermal relic scenario, dark matter remains in chemical equilibrium with the Standard Model radiation bath until freeze-out occurs at $T \sim m_X/20$, where $m_X$ is the dark matter mass. In this familiar class of models,…
We propose a mechanism of elementary thermal dark matter with mass up to $10^{14}$ GeV, within a standard cosmological history, whose relic abundance is determined solely by its interactions with the Standard Model, without violating the…
The thermal relic density of dark matter is conventionally set by two-body annihilations. We point out that in many simple models, $3 \to 2$ annihilations can play an important role in determining the relic density over a broad range of…
We consider a light scalar dark matter candidate with mass in the GeV range whose $p$-wave annihilation is enhanced through a Breit-Wigner resonance. The annihilation actually proceeds in the $s$-channel via a dark photon mediator whose…
We show that the relic abundance of the minority component of asymmetric dark matter can be very sensitive to the expansion rate of the Universe and the temperature of transition between a non-standard pre-Big Bang Nucleosynthesis…
We re-examine unitarity bounds on the annihilation cross section of thermal-WIMP dark matter. For high-mass pointlike dark matter, it is generic to form WIMP bound states, which, together with Sommerfeld enhancement, affects the relic…
The relic abundance of particle and antiparticle dark matter (DM) need not be vastly different in thermal asymmetric dark matter (ADM) models. By considering the effect of a primordial asymmetry on the thermal Boltzmann evolution of coupled…
We investigate the relic density n_\chi of non-relativistic long-lived or stable particles \chi in non-standard cosmological scenarios. We calculate the relic abundance starting from arbitrary initial temperatures of the radiation-dominated…