4,319 research outputs found
Interface Conformal Anomalies
We consider two conformal field theories (CFTs) glued together
along a codimension one conformal interface. The conformal anomaly of such a
system contains both bulk and interface contributions. In a curved-space setup,
we compute the heat kernel coefficients and interface central charges in free
theories. The results are consistent with the known boundary CFT data via the
folding trick. In , two interface invariants generally allowed as
anomalies turn out to have vanishing interface charges. These missing
invariants are constructed from components with odd parity with respect to
flipping the orientation of the defect. We conjecture that all invariants
constructed from components with odd parity may have vanishing coefficient for
symmetric interfaces, even in the case of interacting interface CFT.Comment: 14 pp; v2: clarifications added, introduction expande
Programmable quantum state discriminators with simple programs
We describe a class of programmable devices that can discriminate between two
quantum states. We consider two cases. In the first, both states are unknown.
One copy of each of the unknown states is provided as input, or program, for
the two program registers, and the data state, which is guaranteed to be
prepared in one of the program states, is fed into the data register of the
device. This device will then tell us, in an optimal way, which of the
templates stored in the program registers the data state matches. In the second
case, we know one of the states while the other is unknown. One copy of the
unknown state is fed into the single program register, and the data state which
is guaranteed to be prepared in either the program state or the known state, is
fed into the data register. The device will then tell us, again optimally,
whether the data state matches the template or is the known state. We determine
two types of optimal devices. The first performs discrimination with minimum
error, the second performs optimal unambiguous discrimination. In all cases we
first treat the simpler problem of only one copy of the data state and then
generalize the treatment to n copies. In comparison to other works we find that
providing n > 1 copies of the data state yields higher success probabilities
than providing n > 1 copies of the program states.Comment: 17 pages, 5 figure
Betti numbers for numerical semigroup rings
We survey results related to the magnitude of the Betti numbers of numerical
semigroup rings and of their tangent cones.Comment: 22 pages; v2: updated references. To appear in Multigraded Algebra
and Applications (V. Ene, E. Miller Eds.
Pieri resolutions for classical groups
We generalize the constructions of Eisenbud, Fl{\o}ystad, and Weyman for
equivariant minimal free resolutions over the general linear group, and we
construct equivariant resolutions over the orthogonal and symplectic groups. We
also conjecture and provide some partial results for the existence of an
equivariant analogue of Boij-S\"oderberg decompositions for Betti tables, which
were proven to exist in the non-equivariant setting by Eisenbud and Schreyer.
Many examples are given.Comment: 40 pages, no figures; v2: corrections to sections 2.2, 3.1, 3.3, and
some typos; v3: important corrections to sections 2.2, 2.3 and Prop. 4.9
added, plus other minor corrections; v4: added assumptions to Theorem 3.6 and
updated its proof; v5: Older versions misrepresented Peter Olver's results.
See "New in this version" at the end of the introduction for more detail
A good leaf order on simplicial trees
Using the existence of a good leaf in every simplicial tree, we order the
facets of a simplicial tree in order to find combinatorial information about
the Betti numbers of its facet ideal. Applications include an Eliahou-Kervaire
splitting of the ideal, as well as a refinement of a recursive formula of H\`a
and Van Tuyl for computing the graded Betti numbers of simplicial trees.Comment: 17 pages, to appear; Connections Between Algebra and Geometry,
Birkhauser volume (2013
Quark-Gluon Plasma/Black Hole duality from Gauge/Gravity Correspondence
The Quark-Gluon Plasma (QGP) is the QCD phase of matter expected to be formed
at small proper-times in the collision of heavy-ions at high energy.
Experimental observations seem to favor a strongly coupled QCD plasma with the
hydrodynamic properties of a quasi-perfect fluid, i.e. rapid thermalization (or
isotropization) and small viscosity. The theoretical investigation of such
properties is not obvious, due to the the strong coupling. The Gauge/Gravity
correspondence provides a stimulating framework to explore the strong coupling
regime of gauge theories using the dual string description. After a brief
introduction to Gauge/Gravity duality, and among various existing studies, we
focus on challenging problems of QGP hydrodynamics, such as viscosity and
thermalization, in terms of gravitational duals of both the static and
relativistically evolving plasma. We show how a Black Hole geometry arises
naturally from the dual properties of a nearly perfect fluid and explore the
lessons and prospects one may draw for actual heavy ion collisions from the
Gauge/Gravity duality approach.Comment: 6 pages, 4 figures, invited talk at the EPS HEP 2007 Conference,
Manchester (UK), and at the ``Deuxiemes rencontres PQG-France'', Etretat
(2007); reference adde
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