211 research outputs found
Particle Dark Matter Physics: An Update
This write--up gives a rather elementary introduction into particle physics
aspects of the cosmological Dark Matter puzzle. A fairly comprehensive list of
possible candidates is given; in each case the production mechanism and
possible ways to detect them (if any) are described. I then describe detection
of the in my view most promising candidates, weakly interacting massive
particles or WIMPs, in slightly more detail. The main emphasis will be on
recent developments.Comment: Invited talk at the 5th Workshop on Particle Physics Phenomenology,
Pune, India, January 1998; 21 pages, LaTeX with equation.st
Neutralino Annihilation into a Photon and a Z boson
A full one-loop calculation of neutralino S-wave annihilation into the
final state is performed in the minimal supersymmetric extension of
the Standard Model. This process, like the similar one with two photons in the
final state, may be of importance for the indirect detection of supersymmetric
dark matter through the very narrow ray line that would result from
neutralino annihilations in the galactic halo.
We give the complete analytical formulas for this loop-induced process and
treat the case of a pure Higgsino as a first application of our expressions.
Predictions for the gamma line flux are given for the halo model which is of
the form suggested by Kravtsov et al. and for the profile proposed by Navarro,
Frenk and White.
For heavy neutralinos, the lines from and would have
indistiguishable energy in a realistic detector, making the fluxes add and
facilitating discovery. For lighter neutralinos, the positions and relative
strengths of the two lines would give valuable information on the nature of the
supersymmetric dark matter particles.Comment: 19 pages, LaTeX, 6 eps figures. Some formulas corrected, improved
discussion of halo models, results and conclusions unchanged. Version to
appear in Phys. Rev.
Bremsstrahlung Suppression due to the LPM and Dielectric Effects in a Variety of Materials
The cross section for bremsstrahlung from highly relativistic particles is
suppressed due to interference caused by multiple scattering in dense media,
and due to photon interactions with the electrons in all materials. We present
here a detailed study of bremsstrahlung production of 200 keV to 500 MeV
photons from 8 and 25 GeV electrons traversing a variety of target materials.
For most targets, we observe the expected suppressions to a good accuracy. We
observe that finite thickness effects are important for thin targets.Comment: 52 pages, 13 figures (incorporated in the revtex LaTeX file
Beside the Seaside. The archaeology of the twentieth-century English seaside holiday experience: a phenomenological context.
A recent survey commissioned by English Heritage highlights the rich cultural history of the traditional English seaside resort (Brodie and Winter 2007). Emerging in the eighteenth century, these towns grew in significance before the advent of cheaper continental holidays in the 1960s signalled their demise. Nevertheless they retain an affectionate place within English social memory, and are in their own right distinctive maritime communities. Using an archaeological case study and a broadly phenomenological approach this contribution analyses the experience of the resort holiday through reference to place, space and materiality. Further, it seeks to situate the English seaside resort, as a functionally distinctive post-medieval urban and maritime phenomenon, within a global context of the archaeology of tourism
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