2,206 research outputs found
Disappearance of Squeezed Back-to-Back Correlations - a new signal of hadron freeze-out from a supercooled Quark Gluon Plasma
We briefly discuss four different possible types of transitions from quark to
hadronic matter and their characteristic signatures in terms of correlations.
We also highlight the effects arising from mass modification of hadrons in hot
and dense hadronic matter, as well as their quantum statistical consequences:
the appearance of squeezed quantum states and the associated experimental
signatures, i.e., the back-to-back correlations of particle - anti-particle
pairs. We briefly review the theoretical results of these squeezed quanta,
generated by in-medium modified masses, starting from the first indication of
the existence of surprising particle - anti-particle correlations, and ending
by considering the effects of chiral dynamics on these correlation patterns. A
prerequisite for such a signature is the experimental verification that these
theoretically predicted back-to-back correlation of particle anti-particle
pairs are, in fact, observable in high energy heavy ion reactions. Therefore,
the experimental observation of back-to-back correlations in high energy heavy
ion reactions would be a unique signature, proving the existence of in-medium
mass modification of hadronic states. On the other hand, their disappearance at
some threshold centrality or collision energy would indicate that the hadron
formation mechanism would have qualitatively changed: asymptotic hadrons above
such a threshold are not formed from medium modified hadrons anymore, but
rather by new degrees of freedom characterizing the medium. Furthermore, the
disappearance of the squeezed BBC could also serve as a signature of a sudden,
non-equilibrium hadronization scenario from a supercooled quark-gluon plasma
phase.Comment: 12 pages, 3 figures. Presented at 2nd Workshop on Particle
Correlation and Femtoscopy (WPCF 2006), Sao Paulo, Brazil, 9-11 Sep 2006.
Brazilian Journal of Physics (2007) in pres
Stable Bose-Einstein correlations
The shape of Bose-Einstein (or HBT) correlation functions is determined for
the case when particles are emitted from a stable source, obtained after
convolutions of large number of elementary random processes. The two-particle
correlation function is shown to have a {\it stretched exponential} shape,
characterized by the L\'evy index of stability and the
scale parameter . The normal, Gaussian shape corresponds to a particular
case, when is selected. The asymmetry parameter of the stable
source, is shown to be proportional to the angle, measured by the
normalized three-particle cumulant correlations.Comment: 7 pages, no figures, invited talk of T. Csorgo at the 2nd Warsaw
Meeting on Particle Correlations and Resonances in HIC, see
http://hirg.if.pw.edu.pl/en/meeting/oct2003/talks/csorgo/Csorgo.pp
Bose-Einstein or HBT correlations and the anomalous dimension of QCD
Bose-Einstein (or HBT) correlation functions are evaluated for the fractal
structure of QCD jets. These correlation functions have a stretched exponential
(or Levy-stable) form. The anomalous dimension of QCD determines the Levy index
of stability, thus the running coupling constant of QCD becomes measurable with
the help of two-particle Bose-Einstein correlation functions. These
considerations are tested on NA22 and UA1 two-pion correlation data.Comment: 8 pages, 5 figures, presented by T. Csorgo at the XXXIV International
Symposium on Multiparticle Dynamics, Sonoma County, California, USA, July
2004, to appear in Acta Physica Polonica
Bose-Einstein or HBT correlation signature of a second order QCD phase transition
For particles emerging from a second order QCD phase transition, we show that
a recently introduced shape parameter of the Bose-Einstein correlation
function, the Levy index of stability equals to the correlation exponent - one
of the critical exponents that characterize the behavior of the matter in the
vicinity of the second order phase transition point. Hence the shape of the
Bose-Einstein / HBT correlation functions, when measured as a function of
bombarding energy and centrality in various heavy ion reactions, can be
utilized to locate experimentally the second order phase transition and the
critical end point of the first order phase transition line in QCD.Comment: 8 pages, talk given by T. Csorgo at the Workshop on Particle
Correlations and Femtoscopy 2005, Kromeriz, Czech Republic, August 200
Squeezed Fermions at Relativistic Heavy Ion Colliders
Large back-to-back correlations of observable fermion -- anti-fermion pairs
are predicted to appear, if the mass of the fermions is modified in a
thermalized medium. The back-to-back correlations of protons and anti-protons
are experimentally observable in ultra-relativistic heavy ion collisions,
similarly to the Andreev reflection of electrons off the boundary of a
superconductor. While quantum statistics suppresses the probability of
observing pairs of fermions with nearby momenta, the fermionic back-to-back
correlations are positive and of similar strength to bosonic back-to-back
correlations.Comment: LaTeX, ReVTeX 12 pages, uses epsf.sty, 2 eps figures, improved
presentatio
Back-to-Back Correlations for Finite Expanding Fireballs
Back-to-Back Correlations of particle-antiparticle pairs are related to the
in-medium mass-modification and squeezing of the quanta involved. They are
predicted to appear when hot and dense hadronic matter is formed in high energy
nucleus-nucleus collisions. The survival and magnitude of the Back-to-Back
Correlations of boson-antiboson pairs generated by in-medium mass modifications
are studied here in the case of a thermalized, finite-sized, spherically
symmetric expanding medium. We show that the BBC signal indeed survives the
finite-time emission, as well as the expansion and flow effects, with
sufficient intensity to be observed at RHIC.Comment: 24 pages, 4 figure
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