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We consider dark matter (DM) with very weak couplings to the standard model (SM), such that its self-annihilation cross section is much smaller than the canonical one, $\langle\sigma v\rangle_{\chi\chi} \ll…

High Energy Physics - Phenomenology · Physics 2019-04-18 Mathias Garny , Jan Heisig , Marco Hufnagel , Benedikt Lülf , Stefan Vogl

The coannihilation mechanism is a well-motivated alternative to the simple thermal freeze-out mechanism, where the dark matter relic density can be obtained through the coannihilation with a partner particle of similar mass with dark…

High Energy Physics - Phenomenology · Physics 2022-04-08 Jinhui Guo , Yuxuan He , Jia Liu , Xiao-Ping Wang

We propose a new mechanism for thermal dark matter freezeout, termed Co-Decaying Dark Matter. Multi-component dark sectors with degenerate particles and out-of-equilibrium decays can co-decay to obtain the observed relic density. The dark…

High Energy Physics - Phenomenology · Physics 2016-12-08 Jeff Asaf Dror , Eric Kuflik , Wee Hao Ng

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…

High Energy Physics - Phenomenology · Physics 2016-03-23 Nicolas Bernal , Xiaoyong Chu , Camilo Garcia-Cely , Thomas Hambye , Bryan Zaldivar

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…

High Energy Physics - Phenomenology · Physics 2014-10-30 Yonit Hochberg , Eric Kuflik , Tomer Volansky , Jay G. Wacker

Semi-annihilation is a generic feature of dark matter theories stabilised by symmetries larger than a $Z_2$. It contributes to thermal freeze out, but is irrelevant for direct and collider searches. This allows semi-annihilating dark matter…

High Energy Physics - Phenomenology · Physics 2017-03-08 Yi Cai , Andrew Spray

We study a novel dark matter production mechanism based on the freeze-in through semi-production, i.e. the inverse semi-annihilation processes. A peculiar feature of this scenario is that the production rate is suppressed by a small initial…

High Energy Physics - Phenomenology · Physics 2021-06-08 Andrzej Hryczuk , Maxim Laletin

This work presents an asymmetric dark matter model with relic density determined by the freeze-out of asymmetric semi-annihilations into long-lived particles slowly decaying into the Standard Model states. We carefully consider the $CPT$…

High Energy Physics - Phenomenology · Physics 2025-04-17 Tomáš Blažek , Peter Maták , Viktor Zaujec

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,…

High Energy Physics - Phenomenology · Physics 2026-05-20 Dan Hooper , Gordan Krnjaic , Gabriele Montefalcone

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…

High Energy Physics - Phenomenology · Physics 2018-03-28 Raffaele Tito D'Agnolo , Cristina Mondino , Joshua T. Ruderman , Po-Jen Wang

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…

High Energy Physics - Phenomenology · Physics 2025-11-19 Geneviève Bélanger , Aoife Bharucha , Sreemanti Chakraborti , Rashidul Islam , Sophie Mutzel

Non-thermal dark matter generation is an appealing alternative to the standard paradigm of thermal WIMP dark matter. We reconsider non-thermal production mechanisms in a systematic way, and develop a numerical code for accurate computations…

High Energy Physics - Phenomenology · Physics 2011-09-08 Giorgio Arcadi , Piero Ullio

We propose a new mechanism where a multi-component dark sector generates the observed dark matter abundance and baryon asymmetry and thus addresses the coincidence between the two. The thermal freeze-out of dark matter annihilating into…

High Energy Physics - Phenomenology · Physics 2022-03-08 Xiaoyong Chu , Yanou Cui , Josef Pradler , Michael Shamma

Kinetic decoupling of dark matter typically happens much later than chemical freeze-out. In fact, local thermal equilibrium is an important assumption for the usual relic density calculations based on solving the Boltzmann equation (for its…

High Energy Physics - Phenomenology · Physics 2018-05-03 Tobias Binder , Torsten Bringmann , Michael Gustafsson , Andrzej Hryczuk

We consider the possibility that thermalized dark-matter particles acquire their mass thanks to the spontaneous breaking of a symmetry below some critical temperature. We describe the regime where a freeze out mechanism takes place shortly…

High Energy Physics - Phenomenology · Physics 2020-03-30 Hervé Partouche

We study the effects of modifying the expansions history of the Universe on Dark Matter freezeout. We derived a modified Boltzmann equation for freeze-out for an arbitrary energy density in the early Universe and provide an analytic…

High Energy Physics - Phenomenology · Physics 2019-08-26 Alexandre Poulin

Conversion-driven freeze-out is an appealing mechanism to explain the observed relic density while naturally accommodating the null-results from direct and indirect detection due to a very weak dark matter coupling. Interestingly, the…

High Energy Physics - Phenomenology · Physics 2024-09-04 Jan Heisig , Andre Lessa , Lucas Magno D. Ramos

We explore dark matter genesis beyond the WIMP paradigm, focusing on the mechanism of conversion-driven freeze-out. This mechanism enables the thermalization of dark matter despite its very weak couplings. While the scenario evades…

High Energy Physics - Phenomenology · Physics 2025-04-11 Jan Heisig

The phenomena of dark matter and the baryon asymmetry pose two of the most pressing questions in today's fundamental physics. Conversion-driven freeze-out has emerged as a successful mechanism to generate the observed dark matter relic…

High Energy Physics - Phenomenology · Physics 2024-11-12 Jan Heisig

We present a new paradigm of dark matter freeze-out, where the annihilation of dark matter particles is catalyzed. We discuss in detail the regime that the depletion of dark matter proceeds via $2\chi \to 2A'$ and $3A' \to 2\chi$ processes,…

High Energy Physics - Phenomenology · Physics 2021-08-11 Chuan-Yang Xing , Shou-Hua Zhu
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