Recent measurements of very low-energy (p L < 100 MeV/c) ¯ p annihilation on light nuclei reveal apparent suppression of annihilation upon increasing the atomic charge Z and mass number A. Using ¯ p-nucleus optical potentials V opt , fitted to ¯ p-atom energy-shifts and-widths, we resolve this suppression as due to the strong effective repulsion produced by the very absorptive V opt. The low-en...

Recent measurements of very low-energy (p L < 100 MeV/c) ¯ p annihilation on light nuclei reveal apparent suppression of annihilation upon increasing the atomic charge Z and mass number A. Using ¯ p-nucleus optical potentials V opt , fitted to ¯ p-atom energy-shifts and-widths, we resolve this suppression as due to the strong effective repulsion produced by the very absorptive V opt. The low-en...

The central engine that drives gamma ray burst (GRB) explosions may derive from the ability of electrons/positrons and nucleons to tap into the momentum and energy from the large neutrino luminosity emitted by an accretion disk surrounding a black hole. This transfer of momentum and energy occurs due to neutrino absorption, scattering, and annihilation and the non-spherical geometry of the sour...

The behavior of the positron- 2 gamma annihilation rate on an atomic target near the positronium (Ps) formation threshold is determined. When the positron energy epsilon approaches the threshold epsilon(thr) from below, the effective number of electrons contributing to the annihilation, Z(eff), grows as Z(eff) approximately A/square root of [epsilon(thr)-epsilon], where A is related to the size...

We give perturbative predictions for the distribution of the C-parameter event shape variable in e + e − annihilation, including resummation of large logarithms in the two-jet (small-C) region, matched to next-to-leading order results. We also estimate the leading non-perturbative power correction and make a preliminary comparison with experimental data.

Role of ∆ exchange for p¯ p annihilation into two-pion and three-pion channels Abstract p¯ p annihilation into two pions and three pions is studied in a baryon-exchange model. Annihilation diagrams involving nucleon as well as ∆-resonance exchanges are included consistently in the two-and three-pion channels. Effects from the initial-state interaction are fully taken into account. A comparison ...

The neglected annihilation contributions in the Wilson loop formalism of Eichten and Feinberg are defined and calculated. An annihilation time scale is introduced to discriminate the glueball contributions from true annihilation contributions to isoscalar-pseudoscalar meson states. In this formalism, it is found that there is no mixing between two quarkonium states with different quark masses t...

We use classical/large N c (number of colors) QCD to study nucleon–antinucleon annihilation at rest. We include pion, rho and omega fields in the classical dynamics, starting from the nonlinear sigma model. We begin with a spherical blob of pionic matter with zero baryon number and energy of twice the nucleon mass. This evolves according to the classical dynamics to pion and vector meson fields...

Large deviation functions for an exactly solvable lattice gas model of diffusing particles on a ring, subject to pair annihilation and creation, are obtained analytically using exact free-fermion techniques. Our findings for the large deviation function for the current are compared to recent results of Appert-Rolland et al. [Phys. Rev. E 78, 021122 (2008)] for diffusive systems with conserved p...