Supernova-Neutrino-Boosted Dark Matter from All Galaxies

It has been recently proposed that the boosted dark matter (BDM) by supernova neutrinos (SNν) from SN1987a or from the next Galactic supernova (SN) can serve as a novel component to probe nonvanishing interaction between dark matter (DM) and the standard model leptons [Y.-H. Lin et al., Phys. Rev. Lett. 130, 111002 (2023)PRLTAO0031-900710.1103/PhysRevLett.130.111002 and Y.-H. Lin et al., Phys. Rev. D 108, 083013 (2023)PRVDAQ2470-001010.1103/PhysRevD.108.083013]. In this Letter, we extend this concept and evaluate the present-day diffuse flux of SNν BDM originated from all galaxies at higher redshifts. We show that by considering this diffuse BDM (DBDM) component, the best sensitivity on the product of the energy-independent DM-ν and DM-electron cross sections, sqrt[σ_{χν}σ_{χe}]≃O(10^{-37})  cm^{2} for sub-MeV DM, can be obtained with large-size neutrino experiments such as Super-Kamiokande or Hyper-Kamiokande, surpassing the estimated SNν BDM bound from SN1987a. We also examine the impact due to the presence of DM spikes around the supermassive black holes in galaxies on SNν BDM and DBDM. Our results suggest that both the DBDM and the SNν BDM probes are robust to the uncertain properties of DM spikes, unless the next Galactic SN happens to occur at a location extremely close to or right behind the Galactic Center along the SN line of sight.

Searching for Afterglow: Light Dark Matter Boosted by Supernova Neutrinos

A novel analysis is performed, incorporating time-of-flight (TOF) information to study the interactions of dark matter (DM) with standard model particles. After supernova (SN) explosions, DM with mass m_{χ}≲O(MeV) in the halo can be boosted by SN neutrinos (SNν) to relativistic speed. The SNν boosted DM (BDM) arrives on Earth with TOF which depends only on m_{χ} and is independent of the cross section. These BDMs can interact with detector targets in low-background experiments and manifest as afterglow events after the arrival of SNν. The characteristic TOF spectra of the BDM events can lead to large background suppression and unique determination of m_{χ}. New cross section constraints on sqrt[σ_{χe}σ_{χν}] are derived from SN1987a in the Large Magellanic Cloud with data from the Kamiokande and Super-Kamiokande experiments. Potential sensitivities for the next galactic SN with Hyper-Kamiokande are projected. This analysis extends the existing bounds on sqrt[σ_{χe}σ_{χν}] over a broad range of r_{χ}=σ_{χν}/σ_{χe}. In particular, the improvement is by 1-3 orders of magnitude for m_{χ}<O(100  keV) for σ_{χe}∼σ_{χν}. Prospects of exploiting TOF information in other astrophysical systems to probe exotic physics with other DM candidates are discussed.

Consistent Theory of Kinetic Mixing and the Higgs Low-Energy Theorem

Extensions of the standard model of particle physics with new Abelian gauge groups allow for kinetic mixing between the new gauge bosons and the hypercharge gauge boson, resulting in mixing with the photon. In many models, the mixing with the hypercharge gauge boson captures only part of the kinetic mixing term with the photon, since the new gauge bosons can also mix with the neutral component of the SU(2)_{L} gauge bosons. We take these contributions into account and present a consistent description of kinetic mixing for general Abelian gauge groups both in the electroweak symmetric and the broken phase. We identify an effective operator that captures the kinetic mixing with SU(2)_{L} and demonstrate how renormalizable contributions arise if the charged fields only obtain their masses from electroweak symmetry breaking. For the first time, a low-energy theorem for the couplings of novel Abelian gauge bosons with the standard model Higgs boson is derived from the one-loop kinetic mixing amplitudes.

Simplest and Most Predictive Model of Muon g-2 and Thermal Dark Matter

The long-standing 4.2σ muon g-2 anomaly may be the result of a new particle species which could also couple to dark matter and mediate its annihilations in the early Universe. In models where both muons and dark matter carry equal charges under a U(1)_{L_{μ}-L_{τ}} gauge symmetry, the corresponding Z^{'} can both resolve the observed g-2 anomaly and yield an acceptable dark matter relic abundance, relying on annihilations which take place through the Z^{'} resonance. Once the value of (g-2)_{μ} and the dark matter abundance are each fixed, there is very little remaining freedom in this model, making it highly predictive. We provide a comprehensive analysis of this scenario, identifying a viable range of dark matter masses between approximately 10 and 100 MeV, which falls entirely within the projected sensitivity of several accelerator-based experiments, including NA62, NA64μ, M^{3}, and DUNE. Furthermore, portions of this mass range predict contributions to ΔN_{eff} which could ameliorate the tension between early and late time measurements of the Hubble constant, and which could be tested by stage 4 CMB experiments.

What If Planet 9 Is a Primordial Black Hole?

We highlight that the anomalous orbits of trans-Neptunian objects (TNOs) and an excess in microlensing events in the 5-year Optical Gravitational Lensing Experiment data set can be simultaneously explained by a new population of astrophysical bodies with mass several times that of the Earth (M_{⊕}). We take these objects to be primordial black holes (PBHs) and point out the orbits of TNOs would be altered if one of these PBHs was captured by the Solar System, inline with the Planet 9 hypothesis. Capture of a free floating planet is a leading explanation for the origin of Planet 9, and we show that the probability of capturing a PBH instead is comparable. The observational constraints on a PBH in the outer Solar System significantly differ from the case of a new ninth planet. This scenario could be confirmed through annihilation signals from the dark matter microhalo around the PBH.