492 research outputs found
Weak convergence of Vervaat and Vervaat Error processes of long-range dependent sequences
Following Cs\"{o}rg\H{o}, Szyszkowicz and Wang (Ann. Statist. {\bf 34},
(2006), 1013--1044) we consider a long range dependent linear sequence. We
prove weak convergence of the uniform Vervaat and the uniform Vervaat error
processes, extending their results to distributions with unbounded support and
removing normality assumption
Reduction principles for quantile and Bahadur-Kiefer processes of long-range dependent linear sequences
In this paper we consider quantile and Bahadur-Kiefer processes for long
range dependent linear sequences. These processes, unlike in previous studies,
are considered on the whole interval . As it is well-known, quantile
processes can have very erratic behavior on the tails. We overcome this problem
by considering these processes with appropriate weight functions. In this way
we conclude strong approximations that yield some remarkable phenomena that are
not shared with i.i.d. sequences, including weak convergence of the
Bahadur-Kiefer processes, a different pointwise behavior of the general and
uniform Bahadur-Kiefer processes, and a somewhat "strange" behavior of the
general quantile process.Comment: Preprint. The final version will appear in Probability Theory and
Related Field
Lepton interferometry in relativistic heavy ion collisions - a case study
We propose intensity interferometry with identical lepton pairs as an
efficient tool for the estimation of the source size of the expanding hot zone
produced in relativistic heavy ion collisions. This can act as a complementary
method to two photon interferometry. The correlation function of two electrons
with the same helicity has been evaluated for RHIC energies. The thermal shift
of the rho meson mass has negligible effects on the HBT radii.Comment: 5 pages and 2 figure
Reduced-bias estimator of the Conditional Tail Expectation of heavy-tailed distributions
International audienceSeveral risk measures have been proposed in the literature. In this paper, we focus on the estimation of the Conditional Tail Expectation (CTE). Its asymptotic normality has been first established in the literature under the classical assumption that the second moment of the loss variable is finite, this condition being very restrictive in practical applications. Such a result has been extended by Necir {\it et al.} (2010) in the case of infinite second moment. In this framework, we propose a reduced-bias estimator of the CTE. We illustrate the efficiency of our approach on a small simulation study and a real data analysis
Modified Boltzmann Transport Equation and Freeze Out
We study Freeze Out process in high energy heavy ion reaction. The
description of the process is based on the Boltzmann Transport Equation (BTE).
We point out the basic limitations of the BTE approach and introduce Modified
BTE. The Freeze Out dynamics is presented in the 4-dimensional space-time in a
layer of finite thickness, and we employ Modified BTE for the realistic Freeze
Out description.Comment: 9 pages, 2 figure
Low Freeze-out Temperature and High Collective Velocities in Relativistic Heavy-Ion Collisions
On the basis of a nine-parameter expanding source model that includes special
relativity, quantum statistics, resonance decays, and freeze-out on a realistic
hypersurface in spacetime, we analyze in detail invariant pi+, pi-, K+, and K-
one-particle multiplicity distributions and pi+ and K+ two-particle
correlations in nearly central collisions of Si + Au at a laboratory bombarding
energy per nucleon of 14.6 GeV/c. By considering separately the one-particle
data and the correlation data, we find that the central baryon density, nuclear
temperature, transverse collective velocity, longitudinal collective velocity,
and source velocity are determined primarily by one-particle multiplicity
distributions and that the transverse radius, longitudinal proper time, width
in proper time, and pion incoherence fraction are determined primarily by
two-particle correlations. By considering separately the pion data and the kaon
data, we find that although the pion freeze-out occurs somewhat later than the
kaon freeze-out, the 99% confidence-level error bars associated with the two
freeze-outs overlap. These and other detailed studies confirm our earlier
conclusion based on the simultaneous consideration of the pion and kaon
one-particle and correlation data that the freeze-out temperature is less than
100 MeV and that both the longitudinal and transverse collective
velocities--which are anti-correlated with the temperature--are substantial. We
also discuss the flaws in several previous analyses that yielded a much higher
freeze-out temperature of approximately 140 MeV for both this reaction and
other reactions involving heavier projectiles and/or higher bombarding
energies.Comment: 14 pages. RevTeX 3.1. Submitted to Physical Review C. PostScript
version available at http://t2.lanl.gov/publications/publications.html or at
ftp://t2.lanl.gov/pub/publications/lf
Resonance contributions to HBT correlation radii
We study the effect of resonance decays on intensity interferometry for heavy
ion collisions. Collective expansion of the source leads to a dependence of the
two-particle correlation function on the pair momentum K. This opens the
possibility to reconstruct the dynamics of the source from the K-dependence of
the measured HBT radii. Here we address the question to what extent resonance
decays can fake such a flow signal. Within a simple parametrization for the
emission function we present a comprehensive analysis of the interplay of flow
and resonance decays on the one- and two-particle spectra. We discuss in detail
the non-Gaussian features of the correlation function introduced by long-lived
resonances and the resulting problems in extracting meaningful HBT radii. We
propose to define them in terms of the second order q-moments of the correlator
C(q, K). We show that this yields a more reliable characterisation of the
correlator in terms of its width and the correlation strength `lambda' than
other commonly used fit procedures. The normalized fourth-order q-moments
(kurtosis) provide a quantitative measure for the non-Gaussian features of the
correlator. At least for the class of models studied here, the kurtosis helps
separating effects from expansion flow and resonance decays, and provides the
cleanest signal to distinguish between scenarios with and without transverse
flow.Comment: 23 pages, twocolumn RevTeX, 12 eps-figures included, minor changes
following referee comment
Fluctuations of the Initial Conditions and the Continuous Emission in Hydrodynamic Description of Two-Pion Interferometry
Within hydrodynamic approach, we study the Bose-Einstein correlation of
identical pions by taking into account both event-by-event fluctuating initial
conditions and continuous pion emission during the whole development of the hot
and dense matter formed in high-energy collisions. Considerable deviations
occur, compared to the usual hydro calculations with smooth initial conditions
and a sudden freeze-out on a well defined hypersurface. Comparison with data at
RHIC shows that, despite rather rough approximation we used here, this
description can give account of the dependence of and and
improves considerably the one for with respect to the usual version.Comment: 5 pages, 4 figure
Quark-Gluon Plasma Fireball
Lattice-QCD results provide an opportunity to model, and extrapolate to
finite baryon density, the properties of the quark-gluon plasma (QGP). Upon
fixing the scale of the thermal coupling constant and vacuum energy to the
lattice data, the properties of resulting QGP equations of state (EoS) are
developed. We show that the physical properties of the dense matter fireball
formed in heavy ion collision experiments at CERN-SPS are well described by the
QGP-EoS we presented. We also estimate the properties of the fireball formed in
early stages of nuclear collision, and argue that QGP formation must be
expected down to 40A GeV in central Pb--Pb interactions.Comment: 10 pages, 9 postscript figures, 1 table, uses revtex, V3: introduced
difference between n_f and n_s; fireball restframe energy corrected,
references added. Publisched version in press Phys. Rev.
Two-Particle Correlations in Relativistic Heavy-Ion Collisions
Two-particle momentum correlations between pairs of identical particles
produced in relativistic heavy-ion reactions can be analyzed to extract the
space-time structure of the collision fireball. We review recent progress in
the application of this method, based on newly developed theoretical tools and
new high-quality data from heavy-ion collision experiments. Implications for
our understanding of the collision dynamics and for the search for the
quark-gluon plasma are discussed.Comment: 44 pages, LaTeX, 11 Figures, uses special style files (included),
prepared for Ann. Rev. Nucl. Part. Sci. 49 (1999). Error in Chapt. 1
corrected and a few references adde
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