8,597 research outputs found
Continuous distributions of D3-branes and gauged supergravity
States on the Coulomb branch of N=4 super-Yang-Mills theory are studied from
the point of view of gauged supergravity in five dimensions. These
supersymmetric solutions provide examples of consistent truncation from type
IIB supergravity in ten dimensions. A mass gap for states created by local
operators and perfect screening for external quarks arise in the supergravity
approximation. We offer an interpretation of these surprising features in terms
of ensembles of brane distributions.Comment: 19 pages, two figures, latex. v2: reference added, small corrections.
v3: corrected unbounded spectrum erro
Renormalization Group Flows from Holography--Supersymmetry and a c-Theorem
We obtain first order equations that determine a supersymmetric kink solution
in five-dimensional N=8 gauged supergravity. The kink interpolates between an
exterior anti-de Sitter region with maximal supersymmetry and an interior
anti-de Sitter region with one quarter of the maximal supersymmetry. One eighth
of supersymmetry is preserved by the kink as a whole. We interpret it as
describing the renormalization group flow in N=4 super-Yang-Mills theory broken
to an N=1 theory by the addition of a mass term for one of the three adjoint
chiral superfields. A detailed correspondence is obtained between fields of
bulk supergravity in the interior anti-de Sitter region and composite operators
of the infrared field theory. We also point out that the truncation used to
find the reduced symmetry critical point can be extended to obtain a new N=4
gauged supergravity theory holographically dual to a sector of N=2 gauge
theories based on quiver diagrams.
We consider more general kink geometries and construct a c-function that is
positive and monotonic if a weak energy condition holds in the bulk gravity
theory. For even-dimensional boundaries, the c-function coincides with the
trace anomaly coefficients of the holographically related field theory in
limits where conformal invariance is recovered.Comment: 56 pages, three figures, harvmac. v2: improved referencing, corrected
discussion of energy conditions. v3: one more reference fixe
THE PARAPAPIO SPECIES OF STERKFONTEIN, TRANSVAAL, SOUTH AFRICA
The premolar and molar dimensions of the Parapapio specimens hitherto described
from the South African lower Pleistocene deposits at Sterkfontein have been
re-examined. The relatively minor sexual dimorphism in these teeth (except P3 length)
was confirmed. 103 new cercopithecoid specimens from Sterkfontein were tentatively
assigned to the 3 previously described Parapapio spp. from that site. The new and old
samples of each species were compared and then pooled. Analysis of this new enlarged
sample, and also the newly available distribution data of Parapapio from other South
African deposits, both tend to support the validity of 3 Parapapio spp., P. jonesi, P.
broomi and P. whitei, at Sterkfontein.Wenner-Gren Foundation for
Anthropological Researc
Inclusive charged-current neutrino-nucleus reactions calculated with the relativistic quasiparticle random phase approximation
Inclusive neutrino-nucleus cross sections are calculated using a consistent
relativistic mean-field theoretical framework. The weak lepton-hadron
interaction is expressed in the standard current-current form, the nuclear
ground state is described with the relativistic Hartree-Bogoliubov model, and
the relevant transitions to excited nuclear states are calculated in the
relativistic quasiparticle random phase approximation. Illustrative test
calculations are performed for charged-current neutrino reactions on C,
O, Fe, and Pb, and results compared with previous studies
and available data. Using the experimental neutrino fluxes, the averaged cross
sections are evaluated for nuclei of interest for neutrino detectors. We
analyze the total neutrino-nucleus cross sections, and the evolution of the
contribution of the different multipole excitations as a function of neutrino
energy. The cross sections for reactions of supernova neutrinos on O and
Pb target nuclei are analyzed as functions of the temperature and
chemical potential.Comment: 28 pages, 8 figures, 2 tables, submitted to Phys. Rev.
High magnetic field superconducting properties of Nb3Sn films Final report
High magnetic field superconducting properties of niobium stannide films and shielding characterictics of stannide layer
Topological Quantum Computing with Only One Mobile Quasiparticle
In a topological quantum computer, universal quantum computation is performed
by dragging quasiparticle excitations of certain two dimensional systems around
each other to form braids of their world lines in 2+1 dimensional space-time.
In this paper we show that any such quantum computation that can be done by
braiding identical quasiparticles can also be done by moving a single
quasiparticle around n-1 other identical quasiparticles whose positions remain
fixed.Comment: 4 pages, 5 figure
The B Neutrino Spectrum
Knowledge of the energy spectrum of B neutrinos is an important
ingredient for interpreting experiments that detect energetic neutrinos from
the Sun. The neutrino spectrum deviates from the allowed approximation because
of the broad alpha-unstable Be final state and recoil order corrections to
the beta decay. We have measured the total energy of the alpha particles
emitted following the beta decay of B. The measured spectrum is
inconsistent with some previous measurements, in particular with a recent
experiment of comparable precision. The beta decay strength function for the
transition from B to the accessible excitation energies in Be is fit to
the alpha energy spectrum using the R-matrix approach. Both the positron and
neutrino energy spectra, corrected for recoil order effects, are constructed
from the strength function. The positron spectrum is in good agreement with a
previous direct measurement. The neutrino spectrum disagrees with previous
experiments, particularly for neutrino energies above 12 MeV.Comment: 15 pages, 13 figures, 4 tables, submitted to Phys. Rev. C, typos
correcte
Holographic Normal Ordering and Multi-particle States in the AdS/CFT Correspondence
The general correlator of composite operators of N=4 supersymmetric gauge
field theory is divergent. We introduce a means for renormalizing these
correlators by adding a boundary theory on the AdS space correcting for the
divergences. Such renormalizations are not equivalent to the standard normal
ordering of current algebras in two dimensions. The correlators contain contact
terms that contribute to the OPE; we relate them diagrammatically to
correlation functions of compound composite operators dual to multi-particle
states.Comment: 18 pages, one equation corr., further comments and refs. adde
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