7,222 research outputs found
Einstein-AdS action, renormalized volume/area and holographic Rényi entropies
Indexación: Scopus.The authors thank D.E. Díaz, P. Sundell and A. Waldron for interesting discussions. C.A. is a Universidad Andres Bello (UNAB) Ph.D. Scholarship holder, and his work is supported by Dirección General de Investigación (DGI-UNAB). This work is funded in part by FONDECYT Grants No. 1170765 “Boundary dynamics in anti-de Sitter gravity and gauge/gravity duality ” and No. 3180620 “Entanglement Entropy and AdS gravity ”, and CONICYT Grant DPI 20140115.We exhibit the equivalence between the renormalized volume of asymptotically anti-de Sitter (AAdS) Einstein manifolds in four and six dimensions, and their renormalized Euclidean bulk gravity actions. The action is that of Einstein gravity, where the renormalization is achieved through the addition of a single topological term. We generalize this equivalence, proposing an explicit form for the renormalized volume of higher even-dimensional AAdS Einstein manifolds. We also show that evaluating the renormalized bulk gravity action on the conically singular manifold of the replica trick results in an action principle that corresponds to the renormalized volume of the regular part of the bulk, plus the renormalized area of a codimension-2 cosmic brane whose tension is related to the replica index. Renormalized Rényi entropy of odd-dimensional holographic CFTs can thus be obtained from the renormalized area of the brane with finite tension, including the effects of its backreaction on the bulk geometry. The area computation corresponds to an extremization problem for an enclosing surface that extends to the AdS boundary, where the newly defined renormalized volume is considered. © 2018, The Author(s).https://link.springer.com/article/10.1007%2FJHEP08%282018%2913
Evidence of strong dynamic core excitation in C resonant break-up
The resonant break-up of C on protons measured at RIKEN [Phys. Lett. B
660, 320 (2008)] is analyzed in terms of a valence-core model for C
including possible core excitations. The analysis of the angular distribution
of a prominent peak appearing in the relative-energy spectrum could be well
described with this model and is consistent with the previous assignment of
for this state. Inclusion of core-excitation effects are found to be
essential to give the correct magnitude of the cross section for this state. By
contrast, the calculation assuming an inert C core is found to largely
underestimate the data.Comment: 5 pages, 2 figures, to be submitte
Momentum distributions and spectroscopic factors of doubly-closed shell nuclei in correlated basis function theory
The momentum distributions, natural orbits, spectroscopic factors and
quasi-hole
wave functions of the C12, O16, Ca40, Ca48, and Pb208 doubly closed shell
nuclei, have been calculated in the framework of the Correlated Basis Function
theory, by using the Fermi hypernetted chain resummation techniques. The
calculations have been done by using the realistic Argonne v8' nucleon-nucleon
potential, together with the Urbana IX three-body interaction. Operator
dependent correlations, which consider channels up to the tensor ones, have
been
used. We found noticeable effects produced by the correlations. For high
momentum values, the momentum distributions show large enhancements with
respect to the independent particle model results. Natural orbits occupation
numbers are depleted by about the 10\% with respect to the independent particle
model values. The effects of the correlations on the spectroscopic factors are
larger on the more deeply bound states.Comment: Modified version of the previous paper (there are new figures). The
paper has been accepted for publication in Physical Review
Unexpected Magnetism of Small Silver Clusters
The ground-state electronic, structural, and magnetic properties of small
silver clusters, Ag (2n22), have been studied using a linear
combination of atomic Gaussian-type orbitals within the density functional
theory. The results show that the silver atoms, which are diamagnetic in bulk
environment, can be magnetic when they are grouped together in clusters. The
Ag cluster with icosahedral symmetry has the highest magnetic moment per
atom among the studied silver clusters. The cluster symmetry and the reduced
coordination number specific of small clusters reveal as a fundamental factor
for the onset of the magnetism.Comment: 4 pages, 4 figure
Interacting Particles and Strings in Path and Surface Representations
Non-relativistic charged particles and strings coupled with abelian gauge
fields are quantized in a geometric representation that generalizes the Loop
Representation. We consider three models: the string in self-interaction
through a Kalb-Ramond field in four dimensions, the topological interaction of
two particles due to a BF term in 2+1 dimensions, and the string-particle
interaction mediated by a BF term in 3+1 dimensions. In the first case one
finds that a consistent "surface-representation" can be built provided that the
coupling constant is quantized. The geometrical setting that arises corresponds
to a generalized version of the Faraday's lines picture: quantum states are
labeled by the shape of the string, from which emanate "Faraday`s surfaces". In
the other models, the topological interaction can also be described by
geometrical means. It is shown that the open-path (or open-surface) dependence
carried by the wave functional in these models can be eliminated through an
unitary transformation, except by a remaining dependence on the boundary of the
path (or surface). These feature is closely related to the presence of
anomalous statistics in the 2+1 model, and to a generalized "anyonic behavior"
of the string in the other case.Comment: RevTeX 4, 28 page
The Galactic O-Star Spectroscopic Survey (GOSSS). II. Bright Southern Stars
We present the second installment of GOSSS, a massive spectroscopic survey of
Galactic O stars, based on new homogeneous, high signal-to-noise ratio, R ~
2500 digital observations from both hemispheres selected from the Galactic
O-Star Catalog (GOSC). In this paper we include bright stars and other objects
drawn mostly from the first version of GOSC, all of them south of delta = -20
degrees, for a total number of 258 O stars. We also revise the northern sample
of paper I to provide the full list of spectroscopically classified Galactic O
stars complete to B = 8, bringing the total number of published GOSSS stars to
448. Extensive sequences of exceptional objects are given, including the early
Of/WN, O Iafpe, Ofc, ON/OC, Onfp, Of?p, and Oe types, as well as
double/triple-lined spectroscopic binaries. The new spectral subtype O9.2 is
also discussed. The magnitude and spatial distributions of the observed sample
are analyzed. We also present new results from OWN, a multi-epoch
high-resolution spectroscopic survey coordinated with GOSSS that is assembling
the largest sample of Galactic spectroscopic massive binaries ever attained.
The OWN data combined with additional information on spectroscopic and visual
binaries from the literature indicate that only a very small fraction (if any)
of the stars with masses above 15-20 M_Sol are born as single systems. In the
future we will publish the rest of the GOSSS survey, which is expected to
include over 1000 Galactic O stars.Comment: 110 pages, 16 figures, accepted for publication in ApJS. Some figures
have low quality due to arXiv file size limitations, alternative version
available at http://jmaiz.iaa.es/files/Sotaetal14.pd
Spectroscopic and photometric analysis of the early-type spectroscopic binary HD 161853 in the centre of an H II region
We study the O-type star HD 161853, which has been noted as a probable
double-lined spectroscopic binary system. We secured high-resolution spectra of
HD 161853 during the past nine years. We separated the two components in the
system and measured their respective radial velocities for the first time. We
confirm that HD 161853 is an 1 Ma old binary system consisting of an O8 V
star ( M) and a B1--3 V star ( M) at about 1.3 kpc. From the radial velocity curve, we measure an
orbital period = 2.667650.00001 d and an eccentricity =
0.1210.007. Its -band light curve is constant within 0.014 mag and does
not display eclipses, from which we impose a maximum orbital inclination
deg. HD 161853 is probably associated with an H II region and a poorly
investigated very young open cluster. In addition, we detect a compact emission
region at 50 arcsec to HD 161853 in 22m-WISE and 24m-Spitzer images,
which may be identified as a dust wave piled up by the radiation pressure of
the massive binary system.Comment: 5 pages, 4 figures, to appear in A&
A Geometric Approach to Massive p-form Duality
Massive theories of abelian p-forms are quantized in a generalized
path-representation that leads to a description of the phase space in terms of
a pair of dual non-local operators analogous to the Wilson Loop and the 't
Hooft disorder operators. Special atention is devoted to the study of the
duality between the Topologically Massive and the Self-Dual models in 2+1
dimensions. It is shown that these models share a geometric representation in
which just one non local operator suffices to describe the observables.Comment: 26 pages, LaTeX. The discussion about the equivalence between the
Proca model and two seldual models, with opposite spins, was eliminated.
Typos correcte
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