318 research outputs found
Dyons in N=4 Gauged Supergravity
We study monopole and dyon solutions to the equations of motion of the
bosonic sector of N = 4 gauged supergravity in four dimensional space-time. A
static, spherically symmetric ansatz for the metric, gauge fields, dilaton and
axion leads to soliton solutions which, in the electrically charged case, have
compact spatial sections. Both analytical and numerical results for the
solutions are presented.Comment: 12 pages, 7 figures. Minor changes, references adde
On spin chains and field theories
We point out that the existence of global symmetries in a field theory is not
an essential ingredient in its relation with an integrable model. We describe
an obvious construction which, given an integrable spin chain, yields a field
theory whose 1-loop scale transformations are generated by the spin chain
Hamiltonian. We also identify a necessary condition for a given field theory to
be related to an integrable spin chain.
As an example, we describe an anisotropic and parity-breaking generalization
of the XXZ Heisenberg spin chain and its associated field theory. The system
has no nonabelian global symmetries and generally does not admit a
supersymmetric extension without the introduction of more propagating bosonic
fields. For the case of a 2-state chain we find the spectrum and the
eigenstates. For certain values of its coupling constants the field theory
associated to this general type of chain is the bosonic sector of the
Leigh-Strassler deformation of N=4 SYM theory.Comment: 22 pages, Latex; v2. typos correcte
Rotating nonuniform black string solutions
We explore via linearized perturbation theory the Gregory-Laflamme
instability of rotating black strings with equal magnitude angular momenta. Our
results indicate that the Gregory-Laflamme instability persists up to
extremality for all even dimensions between six and fourteen. We construct
rotating nonuniform black strings with two equal magnitude angular momenta in
six dimensions. We see a first indication for the occurrence of a topology
changing transition, associated with such rotating nonuniform black strings.
Charged nonuniform black string configurations in heterotic string theory are
also constructed by employing a solution generation technique.Comment: 36 pages, 10 figures, final versio
Mesoscopic Stern-Gerlach device to polarize spin currents
Spin preparation and spin detection are fundamental problems in spintronics
and in several solid state proposals for quantum information processing. Here
we propose the mesoscopic equivalent of an optical polarizing beam splitter
(PBS). This interferometric device uses non-dispersive phases (Aharonov-Bohm
and Rashba) in order to separate spin up and spin down carriers into distinct
outputs and thus it is analogous to a Stern-Gerlach apparatus. It can be used
both as a spin preparation device and as a spin measuring device by converting
spin into charge (orbital) degrees of freedom. An important feature of the
proposed spin polarizer is that no ferromagnetic contacts are used.Comment: Updated to the published versio
Classical Yang-Mills Black hole hair in anti-de Sitter space
The properties of hairy black holes in Einstein–Yang–Mills (EYM) theory are reviewed, focusing on spherically symmetric solutions. In particular, in asymptotically anti-de Sitter space (adS) stable black hole hair is known to exist for frak su(2) EYM. We review recent work in which it is shown that stable hair also exists in frak su(N) EYM for arbitrary N, so that there is no upper limit on how much stable hair a black hole in adS can possess
Gauge-string duality for superconformal deformations of N=4 Super Yang-Mills theory
We analyze in detail the relation between an exactly marginal deformation of
N=4 SYM - the Leigh-Strassler or ``beta-deformation'' - and its string theory
dual (recently constructed in hep-th/0502086) by comparing energies of
semiclassical strings to anomalous dimensions of gauge-theory operators in the
two-scalar sector. We stress the existence of integrable structures on the two
sides of the duality. In particular, we argue that the integrability of strings
in AdS_5 x S^5 implies the integrability of the deformed world sheet theory
with real deformation parameter. We compare the fast string limit of the
worldsheet action in the sector with two angular momenta with the continuum
limit of the coherent state action of an anisotropic XXZ spin chain describing
the one-loop anomalous dimensions of the corresponding operators and find a
remarkable agreement for all values of the deformation parameter. We discuss
some of the properties of the Bethe Ansatz for this spin chain, solve the Bethe
equations for small number of excitations and comment on higher loop properties
of the dilatation operator. With the goal of going beyond the leading order in
the 't Hooft expansion we derive the analog of the Bethe equations on the
string-theory side, and show that they coincide with the thermodynamic limit of
the Bethe equations for the spin chain. We also compute the 1/J corrections to
the anomalous dimensions of operators with large R-charge (corresponding to
strings with angular momentum J) and match them to the 1-loop corrections to
the fast string energies. Our results suggest that the impressive agreement
between the gauge theory and semiclassical strings in AdS_5 x S^5 is part of a
larger picture underlying the gauge/gravity duality.Comment: 50 pages, Latex; v2:typos corrected, references added, clarifications
in sec 8 and Appendix A, a discussion of a rational solution added in section
4.2; v3: minor corrections to coefficients in eq. 2.5, 5.2 and appendix A;
v4: minor misprints correcte
Supramolecular architecture of [AsPh2Br2]2[(Br3)−…(Br2)…(Br3)−] obtained by bromination of (AsPh2)2S
Bromination of (AsPh2)2S leads to cleavage of the sulfide bridge to give AsPh2Br when 1 mol of bromine is used but with 2 mols the product is the polybromide, [AsPh2Br2]2[Br8], containing the previously unknown [AsPh2Br2]+ cation and a rare [(Br3)−…(Br2)…(Br3)−] ensemble whose short (yet not covalent) Br2…Br3 contacts have previously supported tentative description as an octabromide Br82− anion. X-ray crystallography shows that the compound has a three dimensional supramolecular structure based on cooperativity of weak intermolecular Csingle bondH…π, Csingle bondH…Br hydrogen bonds and secondary Br…Br interactions in the solid state. The electronic structure and the stability of the [AsPh2Br2]2[Br8] are rationalized using DFT and HF calculations and molecular orbital considerations
Yang-Mills Correlation Functions from Integrable Spin Chains
The relation between the dilatation operator of N=4 Yang-Mills theory and
integrable spin chains makes it possible to compute the one-loop anomalous
dimensions of all operators in the theory. In this paper we show how to apply
the technology of integrable spin chains to the calculation of Yang-Mills
correlation functions by expressing them in terms of matrix elements of spin
operators on the corresponding spin chain. We illustrate this method with
several examples in the SU(2) sector described by the XXX_1/2 chain.Comment: 27 pages, 3 figures, harvma
Spinning strings at one-loop in AdS_4 x P^3
We analyze the folded spinning string in AdS_4 x P^3 with spin S in AdS_4 and
angular momentum J in P^3. We calculate the one-loop correction to its energy
in the scaling limit of both ln S and J large with their ratio kept fixed. This
result should correspond to the first subleading strong coupling correction to
the anomalous dimension of operators of the type Tr(D^S(Y^\dagger Y)^J) in the
dual N=6 Chern-Simons-matter theory. Our result appears to depart from the
predictions for the generalized scaling function found from the all-loop Bethe
equations conjectured for this AdS_4/CFT_3 duality. We comment on the possible
origin of this difference.Comment: 24 pages; v2: References added and typos correcte
Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS
We present the results of a search for new, heavy particles that decay at a
significant distance from their production point into a final state containing
charged hadrons in association with a high-momentum muon. The search is
conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV
and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS
detector operating at the Large Hadron Collider. Production of such particles
is expected in various scenarios of physics beyond the standard model. We
observe no signal and place limits on the production cross-section of
supersymmetric particles in an R-parity-violating scenario as a function of the
neutralino lifetime. Limits are presented for different squark and neutralino
masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final
version to appear in Physics Letters
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