This paper is a review of low-energy positron interactions with atoms and molecules. Processes of interest include elastic scattering, electronic and vibrational excitation, ionization, positronium formation and annihilation. An overview is presented of the currently available theoretical and experimental techniques to study these phenomena, including the use of trap-based positron beam sources...

It has been proposed that during the formation of the first generation stars there might be a “dark star” phase in which the power of the star comes from dark matter annihilation. The adiabatic contraction process to form the dark star would result in a highly concentrated density profile of the host halo at the same time, which may give enhanced indirect detection signals of dark matter. In th...

We estimate the ux of cosmic-ray antiprotons expected from the annihilation of neutralinos in the galactic halo. The antiproton signal may ooer an important alternative detection scheme in the case that neutralino annihilation proceeds mainly to the two-gluon nal state.

We establish a useful identity for intertwining a creation or annihilation operator with the heat kernel of a self-interacting bosonic field theory. I Background Consider creation operators a(f) and annihilation operators a(h), both linear in their respective test functions f, h ∈ L(R, dx), acting on the Fock Hilbert space H, and satisfying the canonical commutation relations [a(h), a(f)] = 〈

If Weakly Interacting Massive Particles (WIMPs) are the Dark Matter in the Galaxy, they can be detected directly in nuclear-recoil experiments or indirectly by observing their annihilation products. Limits obtained by the two techniques can be compared but this comparison requires some hypothesis about the WIMPs cross sections on nuclei and their annihilation branching ratios into neutrinos.

ABSTRACT: We investigate the dynamics of monopole annihilation by the LangackerPi mechanism. We find that considerations of causality, flux-tube energetics and the friction from Aharonov-Bohm scattering suggest that the monopole annihilation is most efficient if electromagnetism is spontaneously broken at the lowest temperature (Tem ≈ 106 GeV) consistent with not having the monopoles dominate t...

Positron annihilation radiation from the Galaxy has been observed by the OSSE, SMM and TGRS instruments. Improved spectral modeling of OSSE observations has allowed studies of the distribution of both positron annihilation radiation components, the narrow line emission at 511 keV and the positronium continuum emission. The results derived for each individual annihilation component are then comp...

We investigate the kinetics of systems in which particles of one species undergo binary fragmentation and pair annihilation. In the latter, non-linear process, fragments react at collision to produce an inert species, causing loss of mass. We analyse these systems in the reaction-limited regime by solving a continuous model within the mean-field approximation. The rate of fragmentation, for a p...

The neutralino, the lightest stable supersymmetric particle, is a strong theoretical candidate for the missing astronomical ”dark matter”. Depending on their annihilation cross section, relic neutralinos from early formation of the Universe trapped in orbits around massive objects may currently be annihilating at measurable rates. The Minimal Supersymmetric extension of the Standard Model predi...

A rigorous QCD analysis of the inclusive annihilation decay rates of heavy quarkonium states is presented. The effective-field-theory framework of nonrelativistic QCD is used to separate the short-distance scale of annihilation, which is set by the heavy quark massM , from the longer-distance scales assoOn leave from Dept. of Physics and Astronomy, Northwestern University, Evanston, IL 60208.