Squeezed correlations ofϕmeson pairs for hydrodynamic sources in high-energy heavy-ion collisions

Abstract

In the hot and dense hadronic sources formed in high-energy heavy-ion collisions, the particle interactions in medium might lead to a squeezed back-to-back correlation (BBC) of boson-antiboson pairs. We calculate the BBC functions of φφ for sources evolving hydrodynamically in (2 + 1) dimensions and with longitudinal boost invariance. The BBC functions for hydrodynamic sources exhibit oscillations as a function of the particle momentum because the temporal distributions of hydrodynamic sources have sharp falls to 0 at large evolving times. The dependences of the BBC functions on the directions of the particle momentum are investigated. For transverse anisotropic sources, the BBC functions are minimum when the azimuthal angles of the particles reach 0. The BBC functions increase with decreasing absolute value of the particle pseudorapidity. The oscillations and the dependences on the particle azimuthal angle and pseudorapidity are the significant signatures for detecting the BBC in high-energy heavy-ion collisions.

Predictions for squeezed back-to-back correlations of $$\phi \phi $$ ϕ ϕ and $$K^+K^-$$ K + K - in high-energy heavy-ion collisions by event-by-event hydrodynamics

“…In the calculations of the BBC functions in this work, the total event number N E for each kind of heavy-ion collision is 2000, and the space-time rapidity of source is taken to be |η| ≤ 1. Unlike the oscillations appearing in the BBC functions for the hydrodynamic sources with Gaussian distributions of initial-energy density [10], the BBC functions for the hydrodynamic sources with FIC vary smoothly with respect to the particle momentum. This is because the oscillations in the single-event BBC functions are canceled each other in the BBC functions averaged over event-by-event calculations for many events.…”

“…So the BBC function C(k, −k) is sensitive to the temporal distribution of the freeze-out points [2,[8][9][10][11]. Recent research [10] indicates that the BBC functions for the hydrodynamic sources with Gaussian initialenergy distributions exhibit oscillations as a function of the particle momentum because of the sharp falls of temporal freeze-out distributions at long times. Investigating the BBC behavior and predicting its effect in high-energy heavy-ion collisions based on more realistic models is of great interest [10].…”

“…Recent research [10] indicates that the BBC functions for the hydrodynamic sources with Gaussian initialenergy distributions exhibit oscillations as a function of the particle momentum because of the sharp falls of temporal freeze-out distributions at long times. Investigating the BBC behavior and predicting its effect in high-energy heavy-ion collisions based on more realistic models is of great interest [10]. In this work, we investigate the BBC functions for the hydrodynamic sources with event-by-event fluctuating initial conditions (FIC).…”

“…For hydrodynamic sources, with the formula derived by Makhlin and Sinyukov [6,7], the chaotic and squeezed ampli-tudes can be expressed as [2,[8][9][10]]…”

“…The local quantities, c k 1 ,k 2 , s k 1 ,k 2 , and n k 1 ,k 2 are the coefficients of the Bogoliubov transformation and boson distribution associated with the particle pair (see in Ref. [10]). …”