230 research outputs found
A non-Abelian Black Ring
We construct a supersymmetric black ring solution of SU(2) N=1, d=5
Super-Einstein-Yang-Mills (SEYM) theory by adding a distorted BPST instanton to
an Abelian black ring solution of the same theory. The change cannot be
observed from spatial infinity: neither the mass, nor the angular momenta or
the values of the scalars at infinity differ from those of the Abelian ring.
The entropy is, however, sensitive to the presence of the non-Abelian
instanton, and it is smaller than that of the Abelian ring, in analogy to what
happens in the supersymmetric coloured black holes recently constructed in the
same theory and in N=2, d=4 SEYM. By taking the limit in which the two angular
momenta become equal we derive a non-Abelian generalization of the BMPV
rotating black-hole solution.Comment: 19 pages, no figure
N=2 Einstein-Yang-Mills' static two-center solutions
We construct bona fide one- and two-center supersymmetric solutions to N=2,
d=4 supergravity coupled to SU(2) non-Abelian vector multiplets. The solutions
describe black holes and global monopoles alone or in equilibrium with each
other and exhibit non-Abelian hairs of different kinds.Comment: 46 pages, 1 figure; v2 references adde
Non-Abelian black holes in string theory
We study a family of 5-dimensional non-Abelian black holes that can be
obtained by adding an instanton field to the well-known D1D5W Abelian black
holes. Naively, the non-Abelian fields seem to contribute to the black-hole
entropy but not to the mass due to their rapid fall-off at spatial infinity. By
uplifting the 5-dimensional supergravity solution to 10-dimensional Heterotic
Supergravity first and then dualizing it into a Type-I Supergravity solution,
we show that the non-Abelian fields are associated to D5-branes dissolved into
the D9-branes (dual to the Heterotic "gauge 5-branes") and that their
associated RR charge does not, in fact, contribute to the entropy, which only
depends on the number16 pages of D-strings and D5 branes and the momentum along
the D-strings, as in the Abelian case. These "dissolved" or "gauge" D5-branes
do contribute to the mass in the expected form. The correct interpretation of
the 5-dimensional charges in terms of the string-theory objects solves the
non-Abelian hair puzzle, allowing for the microscopic accounting of the
entropy. We discuss the validity of the solution when alpha prime corrections
are taken into account.Comment: Latex 2e file, 21 pages. A full appendix on alpha prime corrections
and the corresponding discussions have been added. The conclusions have
suffered minor changes. Version accepted in JHE
Unimodular cosmology and the weight of energy
Some models are presented in which the strength of the gravitational coupling
of the potential energy relative to the same coupling for the kinetic energy
is, in a precise sense, adjustable. The gauge symmetry of these models consists
of those coordinate changes with unit jacobian.Comment: LaTeX, 23 pages, conclusions expanded. Two paragraphs and a new
reference adde
An efficient and scalable platform for java source code analysis using overlaid graph representations
© 2013 IEEE. Although source code programs are commonly written as textual information, they enclose syntactic and semantic information that is usually represented as graphs. This information is used for many different purposes, such as static program analysis, advanced code search, coding guideline checking, software metrics computation, and extraction of semantic and syntactic information to create predictive models. Most of the existing systems that provide these kinds of services are designed ad hoc for the particular purpose they are aimed at. For this reason, we created ProgQuery, a platform to allow users to write their own Java program analyses in a declarative fashion, using graph representations. We modify the Java compiler to compute seven syntactic and semantic representations, and store them in a Neo4j graph database. Such representations are overlaid, meaning that syntactic and semantic nodes of the different graphs are interconnected to allow combining different kinds of information in the queries/analyses. We evaluate ProgQuery and compare it to the related systems. Our platform outperforms the other systems in analysis time, and scales better to program sizes and analysis complexity. Moreover, the queries coded show that ProgQuery is more expressive than the other approaches. The additional information stored by ProgQuery increases the database size and associated insertion time, but these increases are significantly lower than the query/analysis performance gains obtained.Spanish Department of Science, Innovation and Universities under Project RTI2018-099235-B-I00
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