2,193 research outputs found
Different fractal properties of positive and negative returns
We perform an analysis of fractal properties of the positive and the negative
changes of the German DAX30 index separately using Multifractal Detrended
Fluctuation Analysis (MFDFA). By calculating the singularity spectra
we show that returns of both signs reveal multiscaling. Curiously,
these spectra display a significant difference in the scaling properties of
returns with opposite sign. The negative price changes are ruled by stronger
temporal correlations than the positive ones, what is manifested by larger
values of the corresponding H\"{o}lder exponents. As regards the properties of
dominant trends, a bear market is more persistent than the bull market
irrespective of the sign of fluctuations.Comment: presented at FENS2007 conference, 8 pages, 4 Fig
Jet quenching in relativistic heavy ion collisions
Parton propagation in dense nuclear matter results in elastic, inelastic and
coherent multiple soft scattering with the in-medium color charges. Such
scattering leads to calculable modifications of the hadron production cross
section that is evaluated in the framework of the perturbative QCD
factorization approach. Final state medium-induced gluon bremsstrahlung is
arguably the most efficient way of suppressing large transverse momentum
particle production in nucleus-nucleus collisions. The observed hadronic
attenuation, known as jet quenching, can be related to the properties of the
medium, such as density and temperature, and carries valuable information about
the early stages of heavy ion reactions. Non-Abelian energy loss in the
quark-gluon plasma can be studied in much greater detail through the
modification of the two particle back-to-back correlations. Perturbative
calculations give good description of the redistribution of the lost energy in
lower transverse momentum particles and predict significant increase of the
correlation width of away-side di-hadrons. In contrast, energy loss in cold
nuclear matter was found to be small but for large values of Feynman-x is
expected to complement the dynamical higher twist shadowing in experimentally
observable forward rapidity hadron suppression.Comment: Invited plenary talk at the V-th international conference on the
physics and astrophysics of the quark-gluon plasma. 8 pages, 4 figure
Quantitative features of multifractal subtleties in time series
Based on the Multifractal Detrended Fluctuation Analysis (MFDFA) and on the
Wavelet Transform Modulus Maxima (WTMM) methods we investigate the origin of
multifractality in the time series. Series fluctuating according to a qGaussian
distribution, both uncorrelated and correlated in time, are used. For the
uncorrelated series at the border (q=5/3) between the Gaussian and the Levy
basins of attraction asymptotically we find a phase-like transition between
monofractal and bifractal characteristics. This indicates that these may solely
be the specific nonlinear temporal correlations that organize the series into a
genuine multifractal hierarchy. For analyzing various features of
multifractality due to such correlations, we use the model series generated
from the binomial cascade as well as empirical series. Then, within the
temporal ranges of well developed power-law correlations we find a fast
convergence in all multifractal measures. Besides of its practical significance
this fact may reflect another manifestation of a conjectured q-generalized
Central Limit Theorem
Measurement of the Low-Energy Antideuteron Inelastic Cross Section
In this Letter, we report the first measurement of the inelastic cross section for antideuteron-nucleus interactions at low particle momenta, covering a range of 0.3 = 17.4 and 31.8 is obtained. The measured inelastic cross section points to a possible excess with respect to the Glauber model parametrization used in GEANT4 in the lowest momentum interval of 0.3Peer reviewe
Measurement of nuclear effects on ψ(2S) production in p-Pb collisions at sNN−−−√ = 8.16 TeV
Inclusive psi(2S) production is measured in p-Pb collisions at the centre-of-mass energy per nucleon-nucleon pair root s(NN) = 8.16 TeV, using the ALICE detector at the CERN LHC. The production of psi(2S) is studied at forward (2.03<y(cms)Peer reviewe
J/psi production as a function of charged-particle multiplicity in p-Pb collisions at root s(NN)=8.16 TeV
Inclusive J/psi yields and average transverse momenta in p-Pb collisions at a center-of-mass energy per nucleon pairs root s(NN) = 8.16 TeV are measured as a function of the charged-particle pseudorapidity density with ALICE. The J/psi mesons are reconstructed at forward (2.03<y(cms)Peer reviewe
Constraining the Chiral Magnetic Effect with charge-dependent azimuthal correlations in Pb-Pb collisions at root s(NN)=2.76 and 5.02 TeV
Systematic studies of charge-dependent two- and three-particle correlations in Pb-Pb collisions at root s(NN) = 2.76 and 5.02 TeV used to probe the Chiral Magnetic Effect (CME) are presented. These measurements are performed for charged particles in the pseudorapidity (eta) and transverse momentum (p(T)) ranges |eta| and gamma(1, - 3) = . The results are used to estimate the contribution of background effects, associated with local charge conservation coupled to anisotropic flow modulations, to measurements of the CME. A blast-wave parametrisation that incorporates local charge conservation tuned to reproduce the centrality dependent background effects is not able to fully describe the measured gamma(1,1). Finally, the charge and centrality dependence of mixed-harmonics three-particle correlations, of the form gamma(1, 2) = , which are insensitive to the CME signal, verify again that background contributions dominate the measurement of gamma(1,1).Peer reviewe
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