We present a model of weak scale dark matter (DM) where the thermal DM density is set by the lepton asymmetry due to the presence of higher dimension lepton violating operators. In these models there is generically a separation between the annihilation cross section responsible for the relic abundance (through lepton violating operators) and the annihilation cross section that is relevant for t...

We found new current-field equations including charge creation-annihilation fields. Although it is difficult to treat creation and annihilation of charge pairs for Maxwell’s equations, the new equations easily treat them. The equations cause the confinement of charge creation and annihilation centers, which means the charge conservation for this model. The equations can treat not only electroma...

Context. We investigate the deposition of energy and momentum due to the annihilation of neutrinos (ν) and antineutrinos (¯ ν) in the vicinity of steady, axisymmetric accretion tori around stellar-mass black holes (BHs). This process is widely considered as an energy source for driving ultrarelativistic outflows with the potential to produce gamma-ray bursts. Aims. We analyze the influence of g...

We know that when an electron, a matter particle, collides with positron, antimatter they annihilate each other as the energy in two particles is carried away by real photons to conserve energy. The same phenomenon occurs all annihilates equal quantity of antimatter. In case charged like proton and antiproton, their opposite charges cancel while neutral neutron antineutron, spins cancel. cases,...

We argue that WIMP dark matter can annihilate via long-lived “WIMPonium” bound states in reasonable particle physics models of dark matter (DM). WIMPonium bound states can occur at or near threshold leading to substantial enhancements in the DM annihilation rate, closely related to the Sommerfeld effect. Large “boost factor” amplifications in the annihilation rate can thus occur without large d...

Energetic positrons propagating along low index directions in a crystal interact strongly with the periodic array of atoms via a process known as channeling. The trajectories of such channeled positrons can be manipulated to sample di€erent spatial regions in the crystal. Here we report the ®rst observations of channeling e€ects on in̄ight annihilation radiation from positrons traversing a thin ...