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1. Thermocoupled early dark energy

   https://doi.org/10.1103/PhysRevD.111.063551  

   Kamionkowski, Marc; Mathur, Anubhav (March 2025, Physical Review D)

   Early dark energy solutions to the Hubble tension introduce an additional scalar field which is frozen at early times but becomes dynamical around matter-radiation equality. In order to alleviate the tension, the scalar’s share of the total energy density must rapidly shrink from $\sim 10\%$at the onset of matter domination to $\ll 1\%$by recombination. This typically requires a steep potential that is imposed rather than emerging from a concrete particle physics model. Here, we point out an alternative possibility: a homogeneous scalar field coupled quadratically to a cosmological background of light thermal relics (such as the Standard Model neutrino) will acquire an effective potential which can reproduce the dynamics necessary to alleviate the tension. We identify the relevant parameter space for this “thermocoupled” scenario and study its unique phenomenology at the background level, including the back-reaction on the neutrino mass. Follow-up numerical work is necessary to determine the constraints placed on the model by early time measurements. Published by the American Physical Society2025 

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2. Dark matter catalyzed baryon destruction

   https://doi.org/10.1103/PhysRevD.111.023005  

   Ema, Yohei; McGehee, Robert; Pospelov, Maxim; Ray, Anupam (January 2025, Physical Review D)

   WIMP-type dark matter may have additional interactions that break baryon number, leading to induced nucleon decays which are subject to direct experimental constraints from proton decay experiments. In this work, we analyze the possibility of continuous baryon destruction, deriving strong limits from the dark matter accumulating inside old neutron stars, as such a process leads to excess heat generation. We construct the simplest particle dark matter model that breaks the baryon and lepton numbers separately but conserves $B-L$. Virtual exchange by DM particles in this model results in dinucleon decay via $nn\to n\overline{\nu }$and $np\to n{e}^{+}$processes. Published by the American Physical Society2025 

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3. Probing light dark matter through cosmic-ray cooling in active galactic nuclei

   https://doi.org/10.1103/PhysRevD.110.L011701  

   Herrera, Gonzalo; Murase, Kohta (July 2024, Physical Review D)

   Recent observations of high-energy neutrinos from active galactic nuclei (AGN), NGC 1068 and TXS $0506+056$, suggest that cosmic rays (CRs) are accelerated in the vicinity of the central supermassive black hole and high-energy protons and electrons can cool efficiently via interactions with ambient photons and gas. The dark matter density may be significantly enhanced near the black hole, and CRs could lose energies predominantly due to scatterings with the ambient dark matter particles. We propose CR cooling in AGN as a new probe of dark matter-proton and dark matter-electron scatterings. Under plausible astrophysical assumptions, our constraints on sub-GeV dark matter can be the strongest derived to date. Some of the parameter space favored by thermal light dark matter models might already be probed with current multimessenger observations of AGN. Published by the American Physical Society2024 

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4. Dark-Matter-Induced Nucleon Decay Signals in Mesogenesis

   https://doi.org/10.1103/PhysRevLett.132.081002  

   Berger, Joshua; Elor, Gilly (February 2024, Physical Review Letters)

   We introduce and study the first class of signals that can probe the dark matter in mesogenesis, which will be observable at current and upcoming large volume neutrino experiments. The well-motivated mesogenesis scenario for generating the observed matter-antimatter asymmetry necessarily has dark matter charged under the baryon number. Interactions of these particles with nuclei can induce nucleon decay with kinematics differing from spontaneous nucleon decay. We calculate the rate for this process and develop a simulation of the signal that includes important distortions due to nuclear effects. We estimate the sensitivity of DUNE, Super-Kamiokande, Hyper-Kamiokande, and JUNO to this striking signal. Published by the American Physical Society2024 

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5. Standard model $CP$ violation is enough

   https://doi.org/10.1103/glgl-v4v6  

   Elor, Gilly; Houtz, Rachel; Ipek, Seyda; Ulloa, Martha (July 2025, Physical Review D)

   Is the standard model charge-parity ( $CP$) violation ever enough to generate the observed baryon asymmetry? Yes! We introduce a mechanism of baryogenesis (and dark matter production) that can generate the entire observed baryon asymmetry of the Universe using the $CP$violation within standard model systems—a feat which no other mechanism currently proposed can achieve. Baryogenesis proceeds through a mesogenesis scenario but with well motivated additional dark sector dynamics: a field generates present day mass contributions for the particle mediating the decay responsible for baryogenesis. The effect is an enhancement of baryon production while evading present day collider constraints. The $CP$violation comes entirely from standard model contributions to neutral meson systems. Meanwhile, the dark dynamics generate gravitational waves that may be searched for with current and upcoming pulsar timing arrays, as we demonstrate with an example potential that is tuned to generate domain walls that annihilate later. This mechanism, , motivates probing a new parameter space as well as improving the sensitivity of existing mesogenesis searches at hadron and electron colliders. Published by the American Physical Society2025 

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