35 research outputs found
Charge dynamics effects in conductance through a large semi-open quantum dot
Fano lineshapes in resonant transmission in a quantum dot imply interference
between localized and extended states. The influence of the charge accumulated
at the localized levels, which screens the external gate voltage acting on the
conduction channel is investigated. The modified Fano q parameter and the
resonant conduction is derived starting from a microscopic Hamiltonian. The
latest experiments on "charge sensing" and ``Coulomb modified Fano sensing ``
compare well with the results of the present model.Comment: 5 pages, 4 figures, RevTex styl
A search for AdS5 X S2 IIB supergravity solutions dual to N = 2 SCFTs
We present a systematic search for Type IIB supergravity solutions whose
spacetimes include AdS5 and S2 factors, which would be candidate duals to N = 2
four-dimensional Superconformal field theories. The candidate solutions encode
the SU(2) R-symmetry geometrically on the S2 and an additional Killing vector
generates the U(1) R-symmetry. By analysing the Killing spinor equations we
show that no such solutions exist. This suggests that, if Type IIB backgrounds
dual to N = 2 SCFTs exist, the SU(2) R-symmetry is realised non-geometrically.
Finally, we also show that, in the context of both N = 1 and N = 2 Type IIB
backgrounds with an AdS5 factor, the only candidate U(1) R-symmetry Killing
vector directions are the ones that appear for generic values of the Killing
spinors; no further Killing vectors exist for special values of the Killing
spinors.Comment: 22 pages,typos corrected, references added, published versio
The effectiveness of relativistic invariance in AdS(3)
We use relativistic invariance to investigate two aspects of integrable AdS3 string theory. Firstly, we write down the all-loop TBA equations for the massless sector of the theory with R-R flux, using the recently discovered hidden relativistic symmetry. Secondly, for the low-energy relativistic limit of the theory with NS-NS flux we write down the S matrix, dressing factors and TBA. We find that the integrable system coincides with a restriction to AdS3 of the relativistic q-deformed AdS5 theory. We also comment on the relativistic limit of the small-k NS-NS theory
Towards the All-Loop Worldsheet S Matrix for AdS3 Ă S3 Ă T4
We obtain the all-loop worldsheet S matrix for fundamental excitations on AdS3 Ă S3 Ă T4 by studying the off-shell symmetry algebra of the superspace action in light cone gauge. The massless modes, unaccounted for in earlier works, are automatically included in our treatment. Their exact dispersion relation is found to be nonrelativistic, of giant-magnon form, and their scattering is naturally well defined. This opens the way to a complete investigation of AdS3/CFT2 integrability
Quantum Spectral Curve for AdS(3)/CFT2: a proposal
We conjecture the Quantum Spectral Curve equations for string theory on AdS3 Ă S3 Ă T4 with RR charge and its CFT2 dual. We show that in the large-length regime, under additional mild assumptions, the QSC reproduces the Asymptotic Bethe Ansatz equations for the massive sector of the theory, including the exact dressing phases found in the literature. The structure of the QSC shares many similarities with the previously known AdS5 and AdS4 cases, but contains a critical new feature â the branch cuts are no longer quadratic. Nevertheless, we show that much of the QSC analysis can be suitably generalised producing a self-consistent system of equations. While further tests are necessary, particularly outside the massive sector, the simplicity and self-consistency of our construction suggests the completeness of the QSC
Gravitational Couplings of D-branes and O-planes
An explicit calculation is performed to check all the tangent bundle gravitational couplings of Dirichlet branes and Orientifold planes by scattering gravitons with a form Ramond-Ramond potential in the world-volume of a -brane. The structure of the D-brane Wess-Zumino term in the world-volume action is confirmed, while a different O-plane Wess-Zumino action is obtained
Non-BPS States and Heterotic - Type I' Duality
There are two families of non-BPS bi-spinors in the perturbative spectrum of
the nine dimensional heterotic string charged under the gauge group
. The relation between these perturbative non-BPS states
and certain non-perturbative non-BPS D-brane states of the dual type I
theory is exhibited. The relevant branes include a \Zop_2 charged non-BPS
D-string, and a bound state of such a D-string with a fundamental string. The
domains of stability of these states as well as their decay products in both
theories are determined and shown to agree with the duality map.Comment: 19 pages, LaTe
Dressing phases of AdS3/CFT2
We determine the all-loop dressing phases of the AdS3/CFT2 integrable system related to type IIB string theory on AdS3ĂS3ĂT4 by solving the recently found crossing relations and studying their singularity structure. The two resulting phases present a novel structure with respect to the ones appearing in AdS5/CFT4 and AdS4/CFT3. In the strongly coupled regime, their leading order reduces to the universal ArutyunovâFrolovâStaudacher phase as expected. We also compute their subleading order and compare it with recent one-loop perturbative results and comment on their weak-coupling expansion
Landau-Lifshitz sigma-models, fermions and the AdS/CFT correspondence
We define Landau-Lifshitz sigma models on general coset space , with
a maximal stability sub-group of . These are non-relativistic models that
have -valued N\"other charges, local invariance and are classically
integrable. Using this definition, we construct the
Landau-Lifshitz sigma-model. This sigma model describes the thermodynamic limit
of the spin-chain Hamiltonian obtained from the complete one-loop dilatation
operator of the N=4 super Yang-Mills (SYM) theory. In the second part of the
paper, we identify a number of consistent truncations of the Type IIB
Green-Schwarz action on whose field content consists of two
real bosons and 4,8 or 16 real fermions. We show that -symmetry acts
trivially in these sub-sectors. In the context of the large spin limit of the
AdS/CFT correspondence, we map the Lagrangians of these sub-sectors to
corresponding truncations of the Landau-Lifshitz
sigma-model.Comment: 42 page