Eur. Phys. J. A (2019) 55: 78
https://doi.org/10.1140/epja/i2019-12755-9

Regular Article - Theoretical Physics

Quasi equilibrium state of expanding quantum fields and two-pion Bose-Einstein correlations in pp collisions at the LHC

Bogolyubov Institute for Theoretical Physics, Metrolohichna 14b, 03143, Kiev, Ukraine

^* e-mail: akkelin@bitp.kiev.ua

Received: 12 December 2018
Accepted: 8 April 2019
Published online: 23 May 2019

Abstract

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.