733 research outputs found
A Monte Carlo study of the three-states antiferromagnetic Potts model in two dimensions
Using Monte Carlo methods the author studies the two-dimensional three-stages Potts model with antiferromagnetic nearest neighbours and ferromagnetic next-nearest neighbours couplings on a square lattice. The author focuses on the case with only antiferromagnetic coupling; from the analysis of the data gathered, there is evidence that this system shows critical behaviour only at T=0
Deflected Anomaly Mediation and Neutralino Dark Matter
We study the phenomenology of the neutralino dark matter in the so called
deflected anomaly mediation scenario. This scheme is obtained from the minimal
anomaly mediated scenario by introducing a gauge mediated sector with
messenger fields. Unlike the former scheme the latter has no tachyons. We find
that the neutralino is still the LSP in a wide region of the parameter space:
it is essentially a pure bino in the scenario with while it can also be
a pure higgsino for . This is very different from the naive anomaly
mediated scenario which predicts a wino like neutralino. Moreover we do not
find any tachyonic scalars in this scheme. After computing the relic density
(considering all the possible coannihilations) we find that there are regions
in the parameter space with values compatible with the latest WMAP results with
no need to consider moduli fields that decay in the early universe.Comment: 23 pages, 6 figures, submitted to Phys. Rev.
On the Stability of a Stringy Black Hole
We study the stability under perturbations of a charged four dimensional
stringy black hole arising from gauging a previously studied WZW model. We find
that the black hole is stable only in the extremal case .Comment: 14 pages + 1 figure (not included but available on request
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