84 research outputs found
Quantum canonical ensemble and correlation femtoscopy at fixed multiplicities
Identical particle correlations at fixed multiplicity are considered by means
of quantum canonical ensemble of finite systems. We calculate one-particle
momentum spectra and two-particle Bose-Einstein correlation functions in the
ideal gas by using a recurrence relation for the partition function. Within
such a model we investigate the validity of the thermal Wick's theorem and its
applicability for decomposition of the two-particle distribution function. The
dependence of the Bose-Einstein correlation parameters on the average momentum
of the particle pair is also investigated. Specifically, we present the
analytical formulas that allow one to estimate the effect of suppressing the
correlation functions in a finite canonical system. The results can be used for
the femtoscopy analysis of the A+A and p+p collisions with selected (fixed)
multiplicity.Comment: 20 pages, 1 figur
Quasi equilibrium state of expanding quantum fields and two-pion Bose-Einstein correlations in collisions at the LHC
We argue that the two-particle momentum correlation functions of
high-multiplicity collisions at the LHC provide a signal for a ground
state structure of a quasi equilibrium state of the longitudinally
boost-invariant expanding quantum field which lies in the future light cone of
a collision. The physical picture is that pions are produced by the expanding
quantum emitter with two different scales approximately attributed to the
expanding ideal gas in local equilibrium state and ground-state condensate.
Specifically, we show that the effect of suppressing the two-particle
Bose-Einstein momentum correlation functions increases with increasing
transverse momentum of a like-sign pion pair due to different
momentum-dependence of the corresponding particle emission regions.Comment: 20 pages, accepted for publicatio
Sudden freeze-out vs continuous emission: duality in hydro-kinetic approach to A+A collisions
The problem of spectra formation in hydrodynamic approach to A+A collisions
is discussed. It is analyzed in terms of the two different objects:
distribution and emission functions. We show that though the process of
particle liberation, described by the emission function, is, usually,
continuous in time, the observable spectra can be also expressed by means of
the Landau/Cooper-Frye prescription. We argue that such an approximate duality
results from some symmetry properties that systems in A+A collisions reach to
the end of hydrodynamic evolution and reduction of the collision rate at post
hydrodynamic stageComment: 6 pages, talk presented by S.V. Akkelin during the 3rd Budapest
Winter School on Heavy Ion Physics, Dec. 8-11, 2003, Budapest, Hungar
On final conditions in high energy heavy ion collisions
Motivated by the recent experimental observations, we discuss the freeze-out
properties of the fireball created in central heavy ion collisions. We find
that the freeze-out conditions, like temperature, velocity gradient near center
of the fireball, are similar for different colliding systems and beam energies.
This means that the transverse flow is stronger in the collisions of heavy
nuclei than that of the light ones.Comment: 10 pages, 1 figure, 1 tabl
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