268 research outputs found
Higher Order Bose-Einstein Correlations test the Gaussian Density Matrix Approach
A multiparticle system produced by a large number of independent sources is
described by a gaussian density matrix W. All theoretical approach to
Bose-Einstein Correlatios Cn in high energy physics use this form for W. One of
the most salient consequences of this form is the fact that all higher order
(n>2) moments of the current distribution can be expressed in terms of the
first two. We test this property by comparing the data on C2(Q^2), C3(Q^2) and
C4(Q^2) from pion-p and K-p reactions at 250 GeV/c with the predictions of a
general quantum statistical space-time approach. Even a simplified version of
such approach can account for the data. Previous attempts along these lines,
which did not use the space-time approach, met with difficulties.Comment: 17 pages (including one Table) and 2 figures. To appear in Physics
Letters B (PLB 13397
The Bose-Einstein correlation function from a Quantum Field Theory point of view
We show that a recently proposed derivation of Bose-Einstein correlations
(BEC) by means of a specific version of thermal Quantum Field Theory (QFT),
supplemented by operator-field evolution of the Langevin type, allows for a
deeper understanding of the possible coherent behaviour of the emitting source
and a clear identification of the origin of the observed shape of the BEC
function . Previous conjectures in this matter obtained by other
approaches are confirmed and have received complementary explanation.Comment: Some misprints corrected. To be publishe in Phys. Rev.
Dynamical Properties of Heavy-Ion Collisions from the Photon-Photon Intensity Correlations
We consider here the bremsstrahlung emission of photons at low and
intermediate energies of the projectile. and derive
expressions more general than previous results obtained by Neuhauser which were
limited to the case of isotropic systems. We find that the two-photon
correlation function strongly depends not only on the space-time properties of
the collision region but also on the dynamics of the proton-neutron scattering
process in nuclear matter. As a consequence of polarisation correlations it
turns out that for a purely chaotic source the intercept of the correlation
function of photons can reach the value (as compared with the maximum value
for isotropic systems). Furthermore even for ``hard" photons () the maximum of the correlation function can reach the value of in
contrast with the value of derived by Neuhauser for this case. The
formulae obtained in this paper which include also the possible presence of a
coherent component can be used as a basis for a systematic analysis of photon
intensity-interferometry experiments.Comment: 12 pages, LaTeX, DMR-THEP-93-2/
Hydrodynamical Beam Jets in High Energy Hadronic Collisions
A study of hadronic data up to TEVATRON energies in terms of relativistic
hydrodynamics indicates an extended 1-dimensional stage of the expansion which
suggests a jet like behaviour of the fireball along the collision axis.Comment: 3 pages (1 page of figures) ,(LATEX), GSI-93-2
Production of a chaotic squeezed state from a ``pion liquid" and overbunching of identical pion correlations
It is shown that a one to one correspondence between quantum fields in two
different "phases" as might be realized for pions produced from a "hadron
liquid" leads to squeezed states. The single and double inclusive cross
sections for at chaotic superposition of such states are calculated. The
correlation of identical pions is overbunched in comparison with canonical
Bose-Einstein correlations.Comment: Latex File, 6 page
pi-/pi+ ratio in heavy ions collisions: Coulomb effect or chemical equilibration?
We calculate the pi-/pi+ ratio for Pb+Pb at CERN/SPS energies and for Au+Au
at BNL/AGS energies using a (3+1) dimensional hydrodynamical model. Without
consideration of Coulomb effect an enhancement of this ratio at low mt is found
compatible with that observed in these experiments. Our calculations are based
on previous (3+1) dimensional hydrodynamical simulations (HYLANDER), which
described many other aspects of experimental data. In this model the observed
enhancement is a consequence of baryon and strangeness conservation and of
chemical equilibration of the system and is caused by the decay of produced
hyperons, which leads to a difference in the total number of positive and
negative pions as well. Based on the same approach, we also present results for
the pi-/pi+ ratio for S+S (CERN/SPS) collisions, where we find a similar
effect. The absence of the enhancement of the pi-/pi+ ratio in the S+S data
presented by the NA44 Collaboration, if confirmed, could indicate that chemical
equilibration has not yet been estabilished in this reaction.Comment: 8 pages and 2 figures, submmited to Phys. Lett. B. This reviewed
version (Nov.29,1996) contains more details about the model simulated
efficiency considering the experimental detection conditions. Other small
modifications were mad
The Fractal Properties of the Source and BEC
Using simple space-time implementation of the random cascade model we
investigate numerically influence of the possible fractal structure of the
emitting source on Bose-Einstein correlations between identical particles. The
results are then discussed in terms of the non-extensive Tsallis statistics.Comment: LaTeX file and 2 PS files with figures, 8 pages altogether. Talk
presented at the 12th Indian Summer School "Relativistic Heavy Ion Physics,
Prague, Czech Republic, 30 August-3 Sept. 1999; to be published in Czech J.
Phys. (1999). Some typos correcte
Thermal photon production in heavy ion collisions
Using a three-dimensional hydrodynamic simulation of the collision and an
equation of state containing a first order phase transition to the quark-gluon
plasma, we study thermal photon production for collisions at
AGeV and for collisions at AGeV. We obtain
surprisingly high rates of thermal photons even at the lower energy, suggesting
that, contrary to what was expected so far, photon production may be an
interesting topic for experimental search also at the Alternating Gradient
Synchrotron. When applied to the reaction at AGeV, our model can
reproduce preliminary data obtained by the WA80 Collaboration without having to
postulate the existence of an extremely long-lived mixed phase as was recently
proposed.Comment: 9 pages, figures are uudecoded compressed and tare
Bounds for Bose-Einstein Correlation Functions
Bounds for the correlation functions of identical bosons are discussed for
the general case of a Gaussian density matrix. In particular, for a purely
chaotic system the two-particle correlation function must always be greater
than one. On the other hand, in the presence of a coherent component the
correlation function may take values below unity. The experimental situation is
briefly discussed.Comment: 7 pages, LaTeX, DMR-THEP-93-5/
Hydrodynamical analysis of single inclusive spectra and Bose-Einstein correlations for at 160 AGeV
We present the first analysis of preliminary data for at 160
using 3+1-dimensional relativistic hydrodynamics. We find excellent agreement
with the rapidity spectra of negative hadrons and the correlation measurements.
The data indicates a large amount of stopping; of the invariant energy
of the collision is thermalized and of the baryons are contained in the
central fireball. Within our model this implies that a quark-gluon-plasma of
lifetime 3.4 was formed.Comment: 13 pages, 5 Postscript figures (attached to this file as compressed
and uuencoded Postscript file
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