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#
Nuclear Physics
Colloquium

Venue: Physics Building, Max-von-Laue-Str. 1, PHYS 02.116

Time: Thursday, December 05, 4:30pm (s.t.)

Contact: hees@itp.uni-frankfurt.de

# Particle momentum spectra and correlations
from quasi equilibrium state of expanding quantum fields

## Sergii Akkelin (Bogolyubov Institute for
Theoretical Physics, Kiev)

In this talk I discuss particle momentum
spectra and correlations from a quasi equilibrium state of the
longitudinally boost-invariant expanding quantum field which is locally
restricted to the light cone with beginning at the $t = z = 0$ plane of
the Minkowski spacetime manifold. I show that the lowest energy eigenstate
of the corresponding quasi equilibrium statistical operator does not
coincide with the Minkowski vacuum. Then, I demonstrate results of
calculations of one- and two-particle momentum spectra in an exactly
solvable model of non-interacting scalar field. The physical picture which
follows from these results is that particles are produced by the emitter
with two different scales approximately attributed to the expanding ideal
gas in the local equilibrium state and to the highly entangled (squeezed)
state (condensate) of correlated pairs of particles. Signals of
particle production from such a condensate can be detected if the rate of
matter expansion is high, and if the effect of rescatterings for produced
particles is small. I suggest that recent experimental observations of the
suppression of two-pion Bose-Einstein momentum correlations in the
high-multiplicity pp collisions at the LHC can be associated with the
ground-state condensate contribution to particle momentum spectra and
correlations.

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