621 research outputs found
Observation of interspecies Feshbach resonances in an ultracold Rb-Cs mixture
We report on the observation of interspecies Feshbach resonances in an
ultracold, optically trapped mixture of Rb and Cs atoms. In a magnetic field
range up to 300 G we find 23 interspecies Feshbach resonances in the lowest
spin channel and 2 resonances in a higher channel of the mixture. The
extraordinarily rich Feshbach spectrum suggests the importance of different
partial waves in both the open and closed channels of the scattering problem
along with higher-order coupling mechanisms. Our results provide, on one hand,
fundamental experimental input to characterize the Rb-Cs scattering properties
and, on the other hand, identify possible starting points for the association
of ultracold heteronuclear RbCs molecules.Comment: 7 pages, 3 figures, 1 tabl
Supersymmetric Charged Clouds in AdS_5
We consider supersymmetric holographic flows that involve background gauge
fields dual to chemical potentials in the boundary field theory. We use a
consistent truncation of gauged N=8 supergravity in five dimensions and we give
a complete analysis of the supersymmetry conditions for a large family of
flows. We examine how the well-known supersymmetric flow between two fixed
points is modified by the presence of the chemical potentials and this yields a
new, completely smooth, solution that interpolates between two global AdS
spaces of different radii and with different values of the chemical potential.
We also examine some black-hole-like singular flows and a new
non-supersymmetric black hole solution. We comment on the interpretation of our
new solutions in terms of giant gravitons and discuss the implications of our
work for finding black-hole solutions in AdS geometries.Comment: 31 pages, 6 figures; minor corrections, updated reference
Experimental Evidence for Efimov Quantum States
Three interacting particles form a system which is well known for its complex
physical behavior. A landmark theoretical result in few-body quantum physics is
Efimov's prediction of a universal set of weakly bound trimer states appearing
for three identical bosons with a resonant two-body interaction. Surprisingly,
these states even exist in the absence of a corresponding two-body bound state
and their precise nature is largely independent of the particular type of the
two-body interaction potential. Efimov's scenario has attracted great interest
in many areas of physics; an experimental test however has not been achieved.
We report the observation of an Efimov resonance in an ultracold thermal gas of
cesium atoms. The resonance occurs in the range of large negative two-body
scattering lengths and arises from the coupling of three free atoms to an
Efimov trimer. We observe its signature as a giant three-body recombination
loss when the strength of the two-body interaction is varied near a Feshbach
resonance. This resonance develops into a continuum resonance at non-zero
collision energies, and we observe a shift of the resonance position as a
function of temperature. We also report on a minimum in the recombination loss
for positive scattering lengths, indicating destructive interference of decay
pathways. Our results confirm central theoretical predictions of Efimov physics
and represent a starting point from which to explore the universal properties
of resonantly interacting few-body systems.Comment: 8 pages, 4 figures, Proceedings of ICAP-2006 (Innsbruck
Recommended from our members
Tensile properties of Fe-3Mn-0Âż6/0Âż7C steels sintered in semiclosed containers in dry hydrogen, nitrogen and mixtures thereof
Ye
Supergravity Instabilities of Non-Supersymmetric Quantum Critical Points
Motivated by the recent use of certain consistent truncations of M-theory to
study condensed matter physics using holographic techniques, we study the
SU(3)-invariant sector of four-dimensional, N=8 gauged supergravity and compute
the complete scalar spectrum at each of the five non-trivial critical points.
We demonstrate that the smaller SU(4)^- sector is equivalent to a consistent
truncation studied recently by various authors and find that the critical point
in this sector, which has been proposed as the ground state of a holographic
superconductor, is unstable due to a family of scalars that violate the
Breitenlohner-Freedman bound. We also derive the origin of this instability in
eleven dimensions and comment on the generalization to other embeddings of this
critical point which involve arbitrary Sasaki-Einstein seven manifolds. In the
spirit of a resurging interest in consistent truncations, we present a formal
treatment of the SU(3)-invariant sector as a U(1)xU(1) gauged N=2 supergravity
theory coupled to one hypermultiplet.Comment: 46 page
Holographic Renormalization Group Flows: The View from Ten Dimensions
The holographic description of supersymmetric RG flows in supergravity is
considered from both the five-dimensional and ten-dimensional perspectives. An
N=1* flow of N=4 super-Yang Mills is considered in detail, and the infra-red
limit is studied in terms of IIB supergravity in ten dimensions. Depending on
the vevs and the direction of approach to the core, the supergravity solution
can be interpreted in terms of either 5-branes or 7-branes. Generally, it is
shown that it is essential to use the ten-dimensional description in order to
study the infra-red asymptotics in supergravity.Comment: Talk presented at the Second Gursey Memmorial Conference; 14 pages;
Latex; IOP Macro
Constructing Lifshitz solutions from AdS
Under general assumptions, we show that a gravitational theory in d+1
dimensions admitting an AdS solution can be reduced to a d-dimensional theory
containing a Lifshitz solution with dynamical exponent z=2. Working in a d=4,
N=2 supergravity setup, we prove that if the AdS background is N=2
supersymmetric, then the Lifshitz geometry preserves 1/4 of the supercharges,
and we construct the corresponding Killing spinors. We illustrate these results
in examples from supersymmetric consistent truncations of type IIB
supergravity, enhancing the class of known 4-dimensional Lifshitz solutions of
string theory. As a byproduct, we find a new AdS4 x S1 x T(1,1) solution of
type IIB.Comment: 29 pages, no figures; v2 minor corrections, a reference adde
Holographic RG Flows and Universal Structures on the Coulomb Branch of N=2 Supersymmetric Large n Gauge Theory
We report on our results of D3-brane probing a large class of generalised
type IIB supergravity solutions presented very recently in the literature. The
structure of the solutions is controlled by a single non-linear differential
equation. These solutions correspond to renormalisation group flows from pure
N=4 supersymmetric gauge theory to an N=2 gauge theory with a massive adjoint
scalar. The gauge group is SU(n) with n large. After presenting the general
result, we focus on one of the new solutions, solving for the specific
coordinates needed to display the explicit metric on the moduli space. We
obtain an appropriately holomorphic result for the coupling. We look for the
singular locus, and interestingly, the final result again manifests itself in
terms of a square root branch cut on the complex plane, as previously found for
a set of solutions for which the details are very different. This, together
with the existence of the single simple non-linear differential equation, is
further evidence in support of an earlier suggestion that there is a very
simple model --perhaps a matrix model with relation to the Calogero-Moser
integrable system-- underlying this gauge theory physics.Comment: 14 pages, LaTeX, 1 figur
Gravity duals to deformed SYM theories and Generalized Complex Geometry
We analyze the supersymmetry conditions for a class of SU(2) structure
backgrounds of Type IIB supergravity, corresponding to a specific ansatz for
the supersymmetry parameters. These backgrounds are relevant for the AdS/CFT
correspondence since they are suitable to describe mass deformations or
beta-deformations of four-dimensional superconformal gauge theories. Using
Generalized Complex Geometry we show that these geometries are characterized by
a closed nowhere-vanishing vector field and a modified fundamental form which
is also closed. The vector field encodes the information about the
superpotential and the type of deformation - mass or beta respectively. We also
show that the Pilch-Warner solution dual to a mass-deformation of N =4 Super
Yang-Mills and the Lunin-Maldacena beta-deformation of the same background fall
in our class of solutions.Comment: LaTex, 29 page
Holographic dual of the Eguchi-Kawai mechanism
archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2014-40, UUITP-03-14, QMUL-PH-14-08 slaccitation: %%CITATION = ARXIV:1404.0225;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2014-40, UUITP-03-14, QMUL-PH-14-08 slaccitation: %%CITATION = ARXIV:1404.0225;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2014-40, UUITP-03-14, QMUL-PH-14-08 slaccitation: %%CITATION = ARXIV:1404.0225;%%The work of K.Z. was supported by
the ERC advanced grant No 341222, by the Marie Curie network GATIS of the European
Unionâs FP7 Programme under REA Grant Agreement No 317089, and by the Swedish
Research Council (VR) grant 2013-4329. DY acknowledges NORDITA where this work
was begun, during his time as a NORDITA fellow
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