Observations of annihilation radiation in the Galaxy are briefly reviewed. We summarize astrophysical mechanisms leading to positron production and recent estimates for production rates from nova and su-pernova nucleosynthesis in the Galaxy. The physical processes involved in the production of annihilation radiation in the interstellar medium are described. These include positron thermalization...

We present a proposal for testing the prediction of non-equilibrium quantum field theory below the Schwinger limit. The proposed experiments should be able to detect a measurable number of gamma rays resulting from the annihilation of pairs in the focal spot of two opposing high intensity laser beams. We discuss the dependence of the expected number of gamma rays with the laser parameters and c...

We present the Model-Agnostic Dark Halo Analysis Tool (MADHAT), a numerical tool which implements Fermi-LAT data-driven, model-independent analysis of gamma-ray emission from dwarf satellite galaxies and galaxy candidates due to dark matter annihilation, decay, or other nonstandard unknown astrophysics. This efficiently provides statistical upper bounds on number observed photons in excess expe...

We consider a BMN operator with one scalar, φ and one vector, DμZ, impurity field and compute the anomalous dimension both at planar and torus levels. This mixed operator corresponds to a string state with two creation operators which belong to different SO(4) sectors of the background. The anomalous dimension at both levels is found to be the same as the scalar impurity BMN operator. At planar...

Vibrational Feshbach resonances are dominant features of positron annihilation for incident positron energies in the range of the molecular vibrations. Studies in relatively small molecules are described that elucidate the role of intramolecular vibrational energy redistribution into near-resonant multimode states, and the subsequent coupling of these modes to the positron continuum, in suppres...

A simple method to calculate the total annihilation cross section of massive cold relics is presented. Exact expressions for arel, brel, and crel of σvrel = arel + brelv 2 rel + crelv 4 rel are obtained from simple derivatives of the squared annihilation amplitude. Three examples are given. In one example, the computed annihilation cross section of massive Dirac neutrinos confirms recent correc...

Enhanced positron annihilation on polyatomic molecules is a long-standing and complex problem. We report the results of calculations of resonant positron annihilation on methyl halides. A free parameter of our theory is the positron binding energy. A comparison with energy-resolved annihilation rates measured for CH3F, CH3Cl, and CH3Br [L. D. Barnes, Phys. Rev. A 74, 012706 (2006)10.1103/PhysRe...

Assuming that ρ -mesons exist in a quark-gluon plasma at temperatures close to the QCD phase transition, we calculate the dilepton production rate from q-q̄ annihilation via a ρ -meson state using Vector Meson Dominance. The result is compared to the rates from direct q-q̄ annihilation and from π-π annihilation. Furthermore we discuss the suppression of low mass dileptons if the quarks assume an ...