We used radio observations of the neighbor galaxy M31 in order to put constraints on the dark matter particle mass and annihilation cross section. Dark matter annihilation in M31 halo produces highly energetic leptons, which emit synchrotron radiation on radio frequencies in the galactic magnetic field. We predicted expected radio fluxes for the two annihilation channels: ! b b and ! þ . We the...

Graph games with an annihilation rule, as introduced by Conway, Fraenkel and Yesha, are studied under the midre play rule for progressively finite graphs that satisfy a condition on the reversibility of non-terminal Sprague-Grundy zeros to Spragu+Grundy ones. Two general theorems on the Spragu+Grundy zeros and ones are given, followed by two theorems characterizing the set of P-positions under ...

Creation and annihilation operators are used in many-body quantum physics because they provide a less awkward notation than symmetrized or antisymmetrized wave functions, and a convenient language for perturbation theory, etc. These notes are not intended to give anything but an introduction. For a much more extended discussion see books on many-body theory, such as Fetter and Walecka, Quantum ...

We investigate experimentally the interaction of two-dimensional solitary beams in photorefractive strontium barium niobate crystal. We show that simultaneous collision of many solitons can result in complete annihilation of some of them. This effect depends on the relative phases of the solitons and may be useful for application in the formation of multiport waveguide junctions.

Top quark pair production close to threshold at a next linear col-lider is discussed, with special focus on the influence of rescattering corrections. Numerical results are shown for the differential cross-section, i.e. the momentum distribution and the forward backward asymmetry, and for moments of the angular distribution of leptons arising from the semileptonic top quark decay.

The problem of ballistically controlled annihilation is revisited for general initial velocity distributions and an arbitrary dimension. An analytical derivation of the hierarchy equations obeyed by the reduced distributions is given, and a scaling analysis of the corresponding spatially homogeneous system is performed. This approach points to the relevance of the nonlinear Boltzmann equation f...