Phenomenology of dark matter and mirror fermions from a left-right mirror model with singlet scalar

We investigate a left-right mirror model with SU(3)c×SU(2)L×SU(2)R×U(1)Y and a discrete Z2 symmetry, which introduces mirror fields that are copies of the standard model fields. The mirror fields have the opposite chirality to their standard model counterpart fields. We also introduce singlet scalars as dark matter. The new interaction between dark matter, standard model fermions, and mirror fermions can account for dark matter abundance, charged lepton flavor violation, lepton anomalous magnetic moment, and flavor changing neutral current. We demonstrated that if we choose dark matter annihilation into muon as the dominant annihilation channel for leptophilic dark matter, both the observed dark matter abundance and the observed discrepancy between theory and experiment in the muon anomalous magnetic moment can be explained without contradicting the bound derived from charged lepton flavor violating processes. We briefly discuss how mirror fermions will be produced at the future linear collider, as mirror fermions can interact with neutral gauge bosons in this model. Finally, we discuss the lightest mirror neutrino decay mechanism, which will be highly abundant if stable.

Lepton dark matter portal in the inert Zee model

The inert Zee model is an extension of the Zee model for neutrino masses. This new model explains the dark matter relic abundance, generates a one-loop neutrino masses and forbids tree-level Higgs-mediated flavor changing neutral currents. Although the dark matter phenomenology of the model is similar to that of the inert doublet model, the presence of new vector-like fermions opens the lepton portal as a new dark matter annihilation channel. We study the impact of this new portal in the low-mass regime and show the parameter space allowed by direct and indirect searches of dark matter. Remarkably, the region for [Formula: see text] GeV is recovered for [Formula: see text]. We also show that future experiments like LZ and DARWIN could probe a large region of the parameter space of the model.

Resonant annihilation and production of high-energy electron-positron pairs in an external electromagnetic field

A resonant process of annihilation and production of high-energy electron-positron pairs in an external electromagnetic field is studied theoretically. This process is the annihilation channel of an electron-positron scattering. It is shown that the resonance in an external electromagnetic field is possible only when the certain combination of electron and positron initial energies is more than threshold energy. Also, the angle between initial electron and initial positron momenta directions must be small and satisfy the resonant conditions. This angle is determined by the high-energy of the initial pair and the threshold energy. An emerging electron-positron pair also flies out in a narrow cone along the direction of the initial pair and must be ultrarelativistic. For each fixed angle, energies of the final electron and positron can take from one to two values. It is shown that the resonant differential cross section can significantly exceed the corresponding Bhabha cross section without an external field.

Constraints to Dark Matter Annihilation from High-Latitude HAWC Unidentified Sources

The Λ CDM cosmological framework predicts the existence of thousands of subhalos in our own Galaxy not massive enough to retain baryons and become visible. Yet, some of them may outshine in gamma rays provided that the dark matter is made of weakly interacting massive particles (WIMPs), which would self-annihilate and would appear as unidentified gamma-ray sources (unIDs) in gamma-ray catalogs. Indeed, unIDs have proven to be competitive targets for dark matter searches with gamma rays. In this work, we focus on the three high-latitude ( | b | ≥ 10 ) sources present in the 2HWC catalog of the High Altitude Water Cherenkov (HAWC) observatory with no clear associations at other wavelengths. Indeed, only one of these sources, 2HWC J1040+308, is found to be above the HAWC detection threshold when considering 760 days of data, i.e., a factor 1.5 more exposure time than in the original 2HWC catalog. Other gamma-ray instruments, such as Fermi-LAT or VERITAS at lower energies, do not detect the source. Also, this unID is reported as spatially extended, making it even more interesting in a dark matter search context. While waiting for more data that may shed further light on the nature of this source, we set competitive upper limits on the annihilation cross section by comparing this HAWC unID to expectations based on state-of-the-art N-body cosmological simulations of the Galactic subhalo population. We find these constraints to be particularly competitive for heavy WIMPs, i.e., masses above ∼25 (40) TeV in the case of the b b ¯ ( τ + τ − ) annihilation channel, reaching velocity-averaged cross section values of 2 × 10 − 25 ( 5 × 10 − 25 ) cm 3 ·s − 1 . Although far from testing the thermal relic cross section value, the obtained limits are independent and nicely complementary to those from radically different DM analyses and targets, demonstrating once again the high potential of this DM search approach.

Non-thermal radio emission from dark matter annihilation processes in simulated Coma like galaxy clusters

Taking secondary particles produced from dark matter (DM) annihilation process to the origin of the extended diffuse radio emission observed in galaxy clusters, we studied both their morphology and radio spectral profile using simulated Coma like galaxy clusters. We have considered a neutralino annihilation channel dominated by $b\overline b $ species with a branching ratio of 1 and neutralino mass of 35 GeV with annihilation cross-section of 1×10-26 cm3 s-1. The radio emission maps produced for the two simulated galaxy clusters which are based on the MUsic SImulation of galaxy Clusters (MUSIC) dataset reveal the observed radio halo morphology showing radio emission both from the central regions of the cluster and substructures lying out off cluster centre. The flux density curve is in a good agreement for ν ≤ 2 GHz with the obsevational values for the Coma cluster of galaxies showing a small deviation at higher frequencies.

Effect of turbulent reacceleration on electrons produced by dark matter annihilation in the Coma cluster

ABSTRACT In this paper, we study the effect of reacceleration provided by turbulences on electrons produced by dark matter (DM) annihilation in the Coma cluster. We use a simplified phenomenological model to describe the effect of the turbulences, and explore a limited subset of three possible DM models for neutralino particles with different mass and annihilation channel. We find that, for values of the annihilation cross-section of the order of the upper limits found with Fermi–LAT measurements in astrophysical objects, and for conservative values of the boosting factor due to DM substructures, the reacceleration due to turbulences can enhance the radio emission produced by DM-originated electrons up to the level of the observed flux of the radio halo in Coma, for moderate reacceleration intensity in relatively short times. Therefore, we conclude that, even if it is not possible to distinguish between the fits obtained in this paper because of the scattering present in the radio flux data, the electrons produced by DM annihilation can be possible seed electrons for the reacceleration, as well as secondary electrons of hadronic origin. A possible discriminant between these two classes of models is the flux produced in the gamma ray band, which in the case of DM-originated electrons should be more than two orders of magnitude smaller than the present Fermi–LAT upper limits, whereas in the hadronic case the expected gamma ray flux should be close to the value of present upper limits.