Related papers: Resonant Assisted Annihilation
We study a light thermal scalar dark matter (DM) model with a light scalar mediator mixed with the standard model Higgs boson, including both the theoretical bounds and the current experimental constraints. The thermal scalar DM with the…
We study the phenomenology and detection prospects of a sub-GeV Dirac dark matter candidate with resonantly enhanced annihilations via a dark photon mediator. The model evades cosmological constraints on light thermal particles in the early…
Dark matter may be a thermal relic whose abundance is set by mutual annihilations among multiple species. Traditionally, this coannihilation scenario has been applied to weak scale dark matter that is highly degenerate with other states. We…
Dark matter (DM) annihilation can be significantly enhanced through narrow resonances or the Sommerfeld enhancement effect, with both mechanisms potentially combining in a super-resonant annihilation process. In such scenarios, the…
We study the cosmological signatures of Invisibly Annihilating Dark Matter (IAnDM), where DM annihilates into dark radiation particles that are decoupled from the Standard Model (SM). In the simple benchmark model we consider here, such…
Chemical equilibrium is a commonly made assumption in the freeze-out calculation of coannihilating dark matter. We explore the possible failure of this assumption and find a new conversion-driven freeze-out mechanism. Considering a…
We present a framework in which three classes of dark matter number-changing processes can affect both the relic abundance via thermal freeze-out in the early universe and the generation of indirect cosmic-ray signals today. These processes…
We propose a Two-Loop induced radiative neutrino model with hidden gauged $U(1)$ symmetry, in which a dark matter of Dirac fermion arises. The relic density gets contribution from annihilation and semi-annihilation due to a residual…
Recent indirect searches of dark matter using gamma-ray, radio, and cosmic-ray data have provided some stringent constraints on annihilating dark matter. In this article, we propose a new indirect method to constrain annihilating dark…
We consider a model of dark matter where the mediator corresponds to a superposition of a scalar and pseudoscalar, and the scenario where, after reheating, the number densities of the dark sector particles, i.e. the dark matter and the…
In the simplest models of asymmetric dark matter (ADM) annihilation signals are not expected, since the DM is non-self-conjugate and the relic density of anti-DM is negligible. We investigate a new class of models in which a symmetric DM…
Dark matter semi-annihilation is a process through which two dark matter candidates annihilate to a single dark matter particle and a non-dark matter particle. Such processes are common when the symmetry stabilizing the dark matter differs…
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 explore the phenomenology of having a second epoch of dark matter annihilation into dark radiation long after the standard thermal freeze-out. Such a hidden reannihilation process could affect visible sectors only gravitationally. As a…
In the context of Self-Interacting Dark Matter as a solution for the small-scale structure problems, we consider the possibility that Dark Matter could have been produced without being in thermal equilibrium with the Standard Model bath. We…
At the tail of its velocity distribution, cold dark matter (DM) can annihilate at finite temperature to states heavier than itself. We explore the possibility that DM freezeout is dictated by these "forbidden annihilations" at the…
Dark matter with strong self-interactions provides a compelling solution to several small-scale structure puzzles. Under the assumption that the coupling between dark matter and the Standard Model particles is suppressed, such strongly…
In this letter, we consider a class of scenarios in which the dark matter is part of a heavy hidden sector that is thermally decoupled from the Standard Model in the early universe. The dark matter freezes-out by annihilating to a lighter,…
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…
High-energy photons from dark matter annihilation contribute to the cosmic gamma-ray background (CGB). Since dark matter particles are weakly interacting, annihilation can happen only in high density regions such as dark matter halos. The…