1,238 research outputs found
Zooming in on local level statistics by supersymmetric extension of free probability
We consider unitary ensembles of Hermitian NxN matrices H with a confining
potential NV where V is analytic and uniformly convex. From work by
Zinn-Justin, Collins, and Guionnet and Maida it is known that the large-N limit
of the characteristic function for a finite-rank Fourier variable K is
determined by the Voiculescu R-transform, a key object in free probability
theory. Going beyond these results, we argue that the same holds true when the
finite-rank operator K has the form that is required by the Wegner-Efetov
supersymmetry method of integration over commuting and anti-commuting
variables. This insight leads to a potent new technique for the study of local
statistics, e.g., level correlations. We illustrate the new technique by
demonstrating universality in a random matrix model of stochastic scattering.Comment: 38 pages, 3 figures, published version, minor changes in Section
Experimental Tests of Quantum Chromodynamics in High-p_⊥ Jet Production in 200-GeV/c Hadron-Proton Collisions
Data on inclusive jet production in the transverse-momentum (p_⊥) range 0-8 GeV/c for 200-GeV/c p, π^-, π^+, K^-, K^+, and p incident on a hydrogen target are presented. The jet cross section is fully corrected for losses and biases, and compared with the predictions of a model based on quantum chromodynamics. Both the absolute cross section and the inclusive charged-particle distributions inside and outside the jet are in qualitative agreement with the model
Observation of the Production of Jets of Particles at High Transverse Momentum and Comparison with Inclusive Single-Particle Reactions
Data are presented on production by 200-GeV/c hadrons incident on beryllium of both single particles and jets (groups of particles) with high p_T (transverse momentum). The experiment was performed in a wide-aperture multiparticle spectrometer at Fermilab. The jet and single-particle cross sections have a similar shape from p_T=3 to 5 GeV/c but the jet cross section is over two orders of magnitude larger. The distributions of charged-particle momenta show striking similarities to those observed in lepton-induced processes
Jets Produced in π^-, π^+, and Proton Interactions at 200 GeV on Hydrogen and Aluminum Targets
This paper presents results from an experiment on the production of jets (groups of particles) with high p_⊥ produced in 200-GeV/c interactions. Results are presented on the comparison of jet cross sections on aluminum and hydrogen targets. The jet fragmentation distributions are also examined. Both the cross section and the jet structure are found to depend strongly on the beam and target types
Measurement of Forward Jets Produced in High-Transverse-Momentum Hadron-Proton Collisions
A measurement of charged-particle production is reported for the forward region in events triggered by high-transverse-momentum (p⊥) jets and single particles. The momentum distributions of forward-going particles are observed to scale in a simple p⊥-dependent longitudinal variable. Forward-going (beam) jets are observed to be tilted away from the original direction by an amount which agrees with muon-pair data when interpreted in a parton (quantum-chromodynamics) model
Factorization and Scaling in Hadronic Diffraction
In standard Regge theory with a pomeron intercept a(0)=1+\epsilon, the
contribution of the tripe-pomeron amplitude to the t=0 differential cross
section for single diffraction dissociation has the form d\sigma/dM^2(t=0) \sim
s^{2\epsilon}/(M^2)^{1+\epsilon}. For \epsilon>0, this form, which is based on
factorization, does not scale with energy. From an analysis of p-p and p-pbar
data from fixed target to collider energies, we find that such scaling actually
holds, signaling a breakdown of factorization. Phenomenologically, this result
can be obtained from a scaling law in diffraction, which is embedded in the
hypothesis of pomeron flux renormalization introduced to unitarize the triple
pomeron amplitude.Comment: 39 pages, Latex, 16 figure
Genetic, serological and biochemical characterization of Leishmania tropica from foci in northern Palestine and discovery of zymodeme MON-307
Background
Many cases of cutaneous leishmaniasis (CL) have been recorded in the Jenin District based on their clinical appearance. Here, their parasites have been characterized in depth.
Methods
Leishmanial parasites isolated from 12 human cases of CL from the Jenin District were cultured as promastigotes, whose DNA was extracted. The ITS1 sequence and the 7SL RNA gene were analysed as was the kinetoplast minicircle DNA (kDNA) sequence. Excreted factor (EF) serotyping and multilocus enzyme electrophoresis (MLEE) were also applied.
Results
This extensive characterization identified the strains as Leishmania tropica of two very distinct sub-types that parallel the two sub-groups discerned by multilocus microsatellite typing (MLMT) done previously. A high degree of congruity was displayed among the results generated by the different analytical methods that had examined various cellular components and exposed intra-specific heterogeneity among the 12 strains.
Three of the ten strains subjected to MLEE constituted a new zymodeme, zymodeme MON-307, and seven belonged to the known zymodeme MON-137. Ten of the 15 enzymes in the profile of zymodeme MON-307 displayed different electrophoretic mobilities compared with the enzyme profile of the zymodeme MON-137. The closest profile to that of zymodeme MON-307 was that of the zymodeme MON-76 known from Syria.
Strains of the zymodeme MON-307 were EF sub-serotype A2 and those of the zymodeme MON-137 were either A9 or A9B4. The sub-serotype B4 component appears, so far, to be unique to some strains of L. tropica of zymodeme MON-137. Strains of the zymodeme MON-137 displayed a distinctive fragment of 417 bp that was absent in those of zymodeme MON-307 when their kDNA was digested with the endonuclease RsaI. kDNA-RFLP after digestion with the endonuclease MboI facilitated a further level of differentiation that partially coincided with the geographical distribution of the human cases from which the strains came.
Conclusions
The Palestinian strains that were assigned to different genetic groups differed in their MLEE profiles and their EF types. A new zymodeme, zymodeme MON-307 was discovered that seems to be unique to the northern part of the Palestinian West Bank. What seemed to be a straight forward classical situation of L. tropica causing anthroponotic CL in the Jenin District might be a more complex situation, owing to the presence of two separate sub-types of L. tropica that, possibly, indicates two separate transmission cycles involving two separate types of phlebotomine sand fly vector
The von Neumann Hierarchy for Correlation Operators of Quantum Many-Particle Systems
The Cauchy problem for the von Neumann hierarchy of nonlinear equations is
investigated. One describes the evolution of all possible states of quantum
many-particle systems by the correlation operators. A solution of such
nonlinear equations is constructed in the form of an expansion over particle
clusters whose evolution is described by the corresponding order cumulant
(semi-invariant) of evolution operators for the von Neumann equations. For the
initial data from the space of sequences of trace class operators the existence
of a strong and a weak solution of the Cauchy problem is proved. We discuss the
relationships of this solution both with the -particle statistical
operators, which are solutions of the BBGKY hierarchy, and with the
-particle correlation operators of quantum systems.Comment: 26 page
R & D for collider beauty physics at the LHC
We propose an R&D program for the development of a Beauty trigger and innovative elements of the associated spectrometer. A series of short test runs is proposed at the SPS p-pbar Collider with the minimal spectrometer which will allow a credible B signal to be obtained in an invariant mass spectrum of reconstructed B mesons. The program builds on the success of the recent collider run of the P238 Collaboration, in which clean signals from beam-beam interactions were observed in a large silicon strip microvertex detector running 1.5 mm from the circulating beams. A continuing successful R&D program of the type proposed could ultimately lead to a collider experiment at the LHC to study CP Violation and rare B decays
Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV
The t t-bar production cross section (sigma[t t-bar]) is measured in
proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS
experiment, corresponding to an integrated luminosity of 2.3 inverse
femtobarns. The measurement is performed in events with two leptons (electrons
or muons) in the final state, at least two jets identified as jets originating
from b quarks, and the presence of an imbalance in transverse momentum. The
measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/-
2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction
of the standard model.Comment: Replaced with published version. Included journal reference and DO
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