1,339 research outputs found
Dilaton black holes with a cosmological term
The properties of static spherically symmetric black holes, which carry
electric and magnetic charges, and which are coupled to the dilaton in the
presence of a cosmological term (Liouville-type potential, or cosmological
constant) are reviewed.Comment: 20 pages, phyzzx, v2 contains expanded introduction, additional
references etc to coincide with published versio
Multi-scalar black holes with contingent primary hair: Mechanics and stability
We generalize a class of magnetically charged black holes holes non-minimally
coupled to two scalar fields previously found by one of us [gr-qc/9910041] to
the case of multiple scalar fields. The black holes possess a novel type of
primary scalar hair, which we call a contingent primary hair: although the
solutions possess degrees of freedom which are not completely determined by the
other charges of the theory, the charges necessarily vanish in the absence of
the magnetic monopole. Only one constraint relates the black hole mass to the
magnetic charge and scalar charges of the theory. We obtain a Smarr-type
thermodynamic relation, and the first law of black hole thermodynamics for the
system. We further explicitly show in the two-scalar-field case that, contrary
to the case of many other hairy black holes, the black hole solutions are
stable to radial perturbations.Comment: 10 pages, RevTeX4, 6 figures, graphicx. v2: Substantial new sections
and results added from authors' joint unpublished manuscript dated 2000,
doubling the length of the paper. v3: references added. v4: Small additions
(extra figures etc) to agree with published versio
Specht Polytopes and Specht Matroids
The generators of the classical Specht module satisfy intricate relations. We
introduce the Specht matroid, which keeps track of these relations, and the
Specht polytope, which also keeps track of convexity relations. We establish
basic facts about the Specht polytope, for example, that the symmetric group
acts transitively on its vertices and irreducibly on its ambient real vector
space. A similar construction builds a matroid and polytope for a tensor
product of Specht modules, giving "Kronecker matroids" and "Kronecker
polytopes" instead of the usual Kronecker coefficients. We dub this process of
upgrading numbers to matroids and polytopes "matroidification," giving two more
examples. In the course of describing these objects, we also give an elementary
account of the construction of Specht modules different from the standard one.
Finally, we provide code to compute with Specht matroids and their Chow rings.Comment: 32 pages, 5 figure
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