Search results for "Correlations"
showing 10 items of 181 documents
Multiplicity fluctuations in one- And two-dimensional angular intervals compared with analytic QCD calculations
1999
Multiplicity fluctuations in rings around the jet axis and in off-axis cones have been measured by the DELPHI collaboration in $e^+e^-$ annihilations into hadrons at LEP energies. The measurements are compared with analytical perturbative QCD calculations for the corresponding multiparton system, using the concept of Local Parton Hadron Duality. Some qualitative features are confirmed by the data but substantial quantitative deviations are observed.
Measurement of correlations between pions from different W's in e+e- → W+W- events
1997
Correlations between pions from different W's in e(+)e(-) --> W+W- events are studied using data collected by the DELPHI detector at LEP running at a centre-of-mass energy of 172 GeV in 1996. At the present level of statistics, no enhancement of the correlation function above that expected from a pair of uncorrelated W's is observed at small values of the four-momentum difference of the pions. (C) 1997 Published by Elsevier Science B.V.
Low-diffusion Xe-He gas mixtures for rare-event detection: electroluminescence yield
2020
[EN] High pressure xenon Time Projection Chambers (TPC) based on secondary scintillation (electroluminescence) signal amplification are being proposed for rare event detection such as directional dark matter, double electron capture and double beta decay detection. The discrimination of the rare event through the topological signature of primary ionisation trails is a major asset for this type of TPC when compared to single liquid or double-phase TPCs, limited mainly by the high electron diffusion in pure xenon. Helium admixtures with xenon can be an attractive solution to reduce the electron diffu- sion significantly, improving the discrimination efficiency of these optical TPCs. We have m…
Nuclear charge radii of 62−80Zn and their dependence on cross-shell proton excitations
2019
Nuclear charge radii of 62−80Zn have been determined using collinear laser spectroscopy of bunched ion beams at CERN-ISOLDE. The subtle variations of observed charge radii, both within one isotope and along the full range of neutron numbers, are found to be well described in terms of the proton excitations across the Z=28 shell gap, as predicted by large-scale shell model calculations. It comprehensively explains the changes in isomer-to-ground state mean square charge radii of 69−79Zn, the inversion of the odd-even staggering around N=40 and the odd-even staggering systematics of the Zn charge radii. With two protons above Z=28, the observed charge radii of the Zn isotopic chain show a cum…
Azimuthal harmonics of color fields in a high energy nucleus
2015
Recent experimental results have revealed a surprisingly rich structure of multiparticle azimuthal correlations in high energy proton-nucleus collisions. Final state collective effects can be responsible for many of the observed effects, but it has recently been argued that a part of these correlations are present already in the wavefunctions of the colliding particles. We evaluate the momentum space 2-particle cumulant azimuthal anisotropy coefficients v_n{2}, n=2,3,4 from fundamental representation Wilson line distributions describing the high energy nucleus. These would correspond to the flow coefficients in very forward proton nucleus scattering. We find significant differences beteen W…
Multiplicity dependence of jet-like two-particle correlation structures in p–Pb collisions at √sNN =5.02 TeV
2015
Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p–Pb collisions at a nucleon–nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7 < pT,assoc < pT,trig < 5.0 GeV/c is examined, to include correlations induced by jets originating from low momentum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range |η| < 0.9. The near-side long-range pseudorapidity correlations observed in high-multiplicity p–Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remov…
Jet-like correlations with neutral pion triggers in pp and central Pb–Pb collisions at 2.76 TeV
2016
We present measurements of two-particle correlations with neutral pion trigger particles of transverse momenta 8>pT trig>16 GeV/c and associated charged particles of 0.5>pT assoc>10 GeV/c versus the azimuthal angle difference Δφ at midrapidity in pp and central Pb–Pb collisions at √sNN=2.76 TeV with ALICE. The new measurements exploit associated charged hadrons down to 0.5 GeV/c, which significantly extends our previous measurement that only used charged hadrons above 3 GeV/c. After subtracting the contributions of the flow background, v2 to v5, the per-trigger yields are extracted for |Δφ|>0.7 on the near and for |Δφ−π|>1.1 on the away side. The ratio of per-trigger yields in Pb–Pb to thos…
Systematic studies of correlations between different order flow harmonics in Pb-Pb collisions at √sNN = 2.76 TeV
2018
The correlations between event-by-event fluctuations of anisotropic flow harmonic amplitudes have been measured in Pb-Pb collisions at √ s NN = 2.76 TeV with the ALICE detector at the Large Hadron Collider. The results are reported in terms of multiparticle correlation observables dubbed symmetric cumulants. These observables are robust against biases originating from nonflow effects. The centrality dependence of correlations between the higher order harmonics (the quadrangular v 4 and pentagonal v 5 flow) and the lower order harmonics (the elliptic v 2 and triangular v 3 flow) is presented. The transverse momentum dependences of correlations between v 3 and v 2 and between v 4 and v 2 are …
Zymographic detection and clinical correlations of MMP-2 and MMP-9 in breast cancer sera.
2004
Matrix metalloproteinases, in particular the gelatinases MMP-2 and MMP-9, have received great attention in recent years as putative tumour markers for clinical applications. The main reason for the observed interest is their easy detection in body fluids. Moreover, recent evidence has shown multiple functions of MMPs, rather than simply degrading ECM, which include the mobilisation of growth factors and processing of surface molecules. Several authors have reported increased levels of MMPs in a number of cancers, but clinical correlations in breast cancer are still fragmentary. Thus, the aim of the present research was to investigate the activity levels of circulating gelatinases in the ser…
Study of dimuon production in photon-photon collisions and measurement of QED photon structure functions at LEP
2001
Muon pair production in the process e+e- -> e+e-mu+mu- is studied using the data taken at LEP1 (sqrt(s) \simeq m_Z) with the DELPHI detector during the years 1992-1995. The corresponding integrated luminosity is 138.5 pb^{-1}. The QED predictions have been tested over the whole Q^2 range accessible at LEP1 (from several GeV^2/c^4 to several hundred GeV^2/c^4) by comparing experimental distributions with distributions resulting from Monte Carlo simulations using various generators. Selected events are used to extract the leptonic photon structure function F_2^\gamma. Azimuthal correlations are used to obtain information on additional structure functions, F_A^\gamma and F_B^\gamma, which orig…