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 ...

A careful investigation of 1/mb power suppressed effects is crucial for enhancing predictive power of the QCD factorization approach to charmless B decays. It is instructive to systematically investigate the 1/mb effects from soft and hard gluon exchanges, in addition to annihilation topology in the charmless B decays. In this work we try to give a systematic discussion on impact of such soft a...

When exposed to excess light illumination photosynthetic organisms switch into a photoprotective quenched state where the excess energy is safely dissipated as heat. When these processes are investigated by means of ultrafast spectroscopy, the experimentalist is faced with the unnatural process of singlet–singlet annihilation which often makes the interpretation of the results very complicated....