460 research outputs found
Recrystallization at grain boundaries in deformed copper bicrystals
The role of specific grain boundaries in the nucleation of recrystallization textures is demonstrated by experiments on copper bicrystals. It is deduced that the major part of the recrystallized grains that have nucleated at the grain boundary can be traced back to having nucleated in {100} <001>, {210}<001> or {210}<120> orientations. These orientations do not exist in the bicrystals after deformation but can easily be accounted for by the <112>-slip nucleation mechanism proposed by Verbraak. X-ray strain measurements support this conclusion. Finally, on the basis of the observation of near-CSL misorientation relationships between deformed matrix and recrystallized grains, a suggestion is made for a more general nucleation mechanism
Interaction between Kondo impurities in a quantum corral
We calculate the spectral densities for two impurities inside an elliptical
quantum corral using exact diagonalization in the relevant Hilbert subspace and
embedding into the rest of the system. For one impurity, the space and energy
dependence of the change in differential conductance observed
in the quantum mirage experiment is reproduced. In presence of another
impurity, is very sensitive to the hybridization between
impurity and bulk. The impurities are correlated ferromagnetically between
them. A hopping eV between impurities destroy the Kondo
resonance.Comment: 4 pages, 4 figure
A new derivation of Luscher F-term and fluctuations around the giant magnon
15 pages, no figures; v2: added assumption on diagonal scattering and a section on generalizations; v3: minor changes, version accepted for publication in JHEPIn this paper we give a new derivation of the generalized Luscher F-term formula from a summation over quadratic fluctuations around a given soliton. The result is very general providing that S-matrix is diagonal and is valid for arbitrary dispersion relation. We then apply this formalism to compute the leading finite size corrections to the giant magnon dispersion relation coming from quantum fluctuations.Peer reviewe
Universal geometric approach to uncertainty, entropy and information
It is shown that for any ensemble, whether classical or quantum, continuous
or discrete, there is only one measure of the "volume" of the ensemble that is
compatible with several basic geometric postulates. This volume measure is thus
a preferred and universal choice for characterising the inherent spread,
dispersion, localisation, etc, of the ensemble. Remarkably, this unique
"ensemble volume" is a simple function of the ensemble entropy, and hence
provides a new geometric characterisation of the latter quantity. Applications
include unified, volume-based derivations of the Holevo and Shannon bounds in
quantum and classical information theory; a precise geometric interpretation of
thermodynamic entropy for equilibrium ensembles; a geometric derivation of
semi-classical uncertainty relations; a new means for defining classical and
quantum localization for arbitrary evolution processes; a geometric
interpretation of relative entropy; and a new proposed definition for the
spot-size of an optical beam. Advantages of the ensemble volume over other
measures of localization (root-mean-square deviation, Renyi entropies, and
inverse participation ratio) are discussed.Comment: Latex, 38 pages + 2 figures; p(\alpha)->1/|T| in Eq. (72) [Eq. (A10)
of published version
Precision Pion-Proton Elastic Differential Cross Sections at Energies Spanning the Delta Resonance
A precision measurement of absolute pi+p and pi-p elastic differential cross
sections at incident pion laboratory kinetic energies from T_pi= 141.15 to
267.3 MeV is described. Data were obtained detecting the scattered pion and
recoil proton in coincidence at 12 laboratory pion angles from 55 to 155
degrees for pi+p, and six angles from 60 to 155 degrees for pi-p. Single arm
measurements were also obtained for pi+p energies up to 218.1 MeV, with the
scattered pi+ detected at six angles from 20 to 70 degrees. A flat-walled,
super-cooled liquid hydrogen target as well as solid CH2 targets were used. The
data are characterized by small uncertainties, ~1-2% statistical and ~1-1.5%
normalization. The reliability of the cross section results was ensured by
carrying out the measurements under a variety of experimental conditions to
identify and quantify the sources of instrumental uncertainty. Our lowest and
highest energy data are consistent with overlapping results from TRIUMF and
LAMPF. In general, the Virginia Polytechnic Institute SM95 partial wave
analysis solution describes our data well, but the older Karlsruhe-Helsinki PWA
solution KH80 does not.Comment: 39 pages, 22 figures (some with quality reduced to satisfy ArXiv
requirements. Contact M.M. Pavan for originals). Submitted to Physical Review
The all loop AdS4/CFT3 Bethe ansatz
We propose a set of Bethe equations yielding the full asymptotic spectrum of
the AdS4/CFT3 duality proposed in arXiv:0806.1218 to all orders in the t'Hooft
coupling. These equations interpolate between the 2-loop Bethe ansatz of
Minahan and Zarembo arXiv:0806.3951 and the string algebraic curve of
arXiv:0807.0437. The several SU(2|2) symmetries of the theory seem to highly
constrain the form of the Bethe equations up to a dressing factor whose form we
also conjecture.Comment: References added. Factor of 2 in the discussion of the (generalized)
scaling function fixe
The Fueling and Evolution of AGN: Internal and External Triggers
In this chapter, I review the fueling and evolution of active galactic nuclei
(AGN) under the influence of internal and external triggers, namely intrinsic
properties of host galaxies (morphological or Hubble type, color, presence of
bars and other non-axisymmetric features, etc) and external factors such as
environment and interactions. The most daunting challenge in fueling AGN is
arguably the angular momentum problem as even matter located at a radius of a
few hundred pc must lose more than 99.99 % of its specific angular momentum
before it is fit for consumption by a BH. I review mass accretion rates,
angular momentum requirements, the effectiveness of different fueling
mechanisms, and the growth and mass density of black BHs at different epochs. I
discuss connections between the nuclear and larger-scale properties of AGN,
both locally and at intermediate redshifts, outlining some recent results from
the GEMS and GOODS HST surveys.Comment: Invited Review Chapter to appear in LNP Volume on "AGN Physics on All
Scales", Chapter 6, in press. 40 pages, 12 figures. Typo in Eq 5 correcte
Pediatric inflammatory bowel disease clinical innovations meeting of the Crohn's and colitis foundation: Charting the future of pediatric IBD
The Crohn's & Colitis Foundation has facilitated transformational research in pediatric inflammatory bowel disease (IBD), through the RISK and PROTECT studies, that has laid the groundwork for a comprehensive understanding of molecular mechanisms of disease and predictors of therapeutic response in children. Despite these advances, children have lacked timely and informed access to the latest therapeutic advancements in IBD. The Crohn's & Colitis Foundation convened a Pediatric Resource Organization for Kids with Inflammatory Intestinal Diseases (PRO-KIIDS) Clinical Innovations Meeting at the inaugural Crohn's and Colitis Congress in January 2018 to devise how to advance the care of children with IBD. The working group selected 2 priorities: (1) accelerating therapies to children with IBD and (2) stimulating investigator-initiated research while fostering sustainable collaboration; and proposed 2 actions: (a) the convening of a task force to specifically address how to accelerate pharmacotherapies to children with IBD and (b) the funding of a multicenter clinical and translational research study that incorporates the building of critical research infrastructure
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
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