134 research outputs found
Review of AdS/CFT Integrability, Chapter III.2: Exact world-sheet S-matrix
We review the derivation of the S-matrix for planar N=4 supersymmetric
Yang-Mills theory and type IIB superstring theory on an AdS5xS5 background.
After deriving the S-matrix for the su(2) and su(3) sectors at the one-loop
level based on coordinate Bethe ansatz, we show how su(2|2) symmetry leads to
the exact asymptotic S-matrix up to an overall scalar function. We then briefly
review the spectrum of bound states by relating these states to simple poles of
the S-matrix. Finally, we review the derivation of the asymptotic Bethe
equations, which can be used to determine the asymptotic multiparticle
spectrum.Comment: 20 pages, see also overview article arXiv:1012.3982, v2: references
to other chapters updated, v3: references added and minor change
Reflecting Magnon Bound States
In N=4 super Yang-Mills spin chain, we compute reflection amplitudes of
magnon bound-state off giant graviton. We first compute the reflection
amplitude off Y=0 brane boundary and compare it with the scattering amplitude
between two magnon bound-states in the bulk. We find that analytic structure of
the two amplitudes are intimately related each other: the boundary reflection
amplitude is a square-root of the bulk scattering amplitude. Using such
relation as a guide and taking known results at weak and strong coupling limits
as inputs, we find the reflection amplitude of an elementary magnon off Z=0
giant graviton boundary. The reflection phase factor is shown to solve crossing
and unitarity relations. We then compute the reflection amplitude of magnon
bound-state off the Z=0 brane boundary and observe that its analytic structures
are again intimately related to the bulk scattering and the Y=0 boundary
reflection amplitudes. We also take dyonic giant magnon limit of these
reflection amplitudes and confirm that their phase-shifts agree completely with
string worldsheet computations based on complex sine-Gordon soliton scattering.Comment: cover+15 pages, 2 figures; v2. minor changes, references added; v3.
further minor change
Probing Universality in the Gravity Duals of N=1 SYM by gamma-deformations
Recently, a one-parameter deformation of the Maldacena-Nunez dual of the N=1
SYM theory was constructed in hep-th/0505100. According to the Lunin-Maldacena
conjecture, the background is dual to pure N=1 SYM in the IR coupled to a KK
sector whose dynamics is altered by a dipole deformation that is proportional
to the deformation parameter gamma. Thus, the deformation serves to identify
the aspects of the gravity backgrounds that bear the effects of the KK sector,
hence non-universal in the dual gauge theory. We make this idea concrete by
studying a Penrose limit of the deformed MN theory. We obtain an exactly
solvable pp-wave that is conjectured to describe the IR dynamics of KK-hadrons
in the field theory. The spectrum, the thermal partition function and the
Hagedorn temperature are calculated. The Hagedorn temperature turns out to be
independent of the deformation parameter.Comment: 29 pages, 1 figure, refs. added, typos corrected, v3: discussion
extended and modified v4: discussion section modified, typos corrceted, v5:
referencing correcte
Metastable vacua and geometric deformations
We study the geometric interpretation of metastable vacua for systems of D3
branes at non isolated toric deformable singularities. Using the L^{aba}
examples, we investigate the relations between the field theoretic susy
breaking and restoration and the complex deformations of the CY singularities.Comment: Minor corrections, references added, published in JHE
Study of the temperature distribution in Si nanowires under microscopic laser beam excitation
The use of laser beams as excitation sources for the characterization of semiconductor nanowires (NWs) is largely extended. Raman spectroscopy and photoluminescence (PL) are currently applied to the study of NWs. However, NWs are systems with poor thermal conductivity and poor heat dissipation, which result in unintentional heating under the excitation with a focused laser beam with microscopic size, as those usually used in microRaman and microPL experiments. On the other hand, the NWs have subwavelength diameter, which changes the optical absorption with respect to the absorption in bulk materials. Furthermore, the NW diameter is smaller than the laser beam spot, which means that the optical power absorbed by the NW depends on its position inside the laser beam spot. A detailed analysis of the interaction between a microscopic focused laser beam and semiconductor NWs is necessary for the understanding of the experiments involving laser beam excitation of NWs. We present in this work a numerical analysis of the thermal transport in Si NWs, where the heat source is the laser energy locally absorbed by the NW. This analysis takes account of the optical absorption, the thermal conductivity, the dimensions, diameter and length of the NWs, and the immersion medium. Both free standing and heat-sunk NWs are considered. Also, the temperature distribution in ensembles of NWs is discussed. This analysis intends to constitute a tool for the understanding of the thermal phenomena induced by laser beams in semiconductor NWs
Magnetic, orbital and charge ordering in the electron-doped manganites
The three dimensional perovskite manganites in the range of hole-doping are studied in detail using a double exchange model with degenerate
orbitals including intra- and inter-orbital correlations and near-neighbour
Coulomb repulsion. We show that such a model captures the observed phase
diagram and orbital-ordering in the intermediate to large band-width regime. It
is argued that the Jahn-Teller effect, considered to be crucial for the region
, does not play a major role in this region, particularly for systems
with moderate to large band-width. The anisotropic hopping across the
degenerate orbitals are crucial in understanding the ground state phases
of this region, an observation emphasized earlier by Brink and Khomskii. Based
on calculations using a realistic limit of finite Hund's coupling, we show that
the inclusion of interactions stabilizes th e C-phase, the antiferromagnetic
metallic A-phase moves closer to while th e ferromagnetic phase shrinks
in agreement with recent observations. The charge ordering close to and
the effect of reduction of band-width are also outlined. The effect of disorder
and the possibility of inhomogeneous mixture of competing states have been
discussed.Comment: 42 pages, 16 figure
Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.
BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362
Mechanisms of allergen-specific immunotherapy for allergic rhinitis and food allergies
10.1042/BSR20200256Bioscience Reports404BSR2020025
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