Hanbury-Brown–Twiss correlation functions and radii from event-by-event hydrodynamics

Abstract

HoTCoffeeh (Hanbury Brown-Twiss Correlation f unctions and radii f rom event-by-event hydrodynamics) is a new computational tool which determines Hanbury Brown-Twiss (HBT) charged pion (π + ) correlation functions and radii for event-by-event (EBE) hydrodynamics with fluctuating initial conditions in terms of Cooper-Frye integrals, including resonance decay contributions. In this paper, we review the basic formalism for computing the HBT correlation functions and radii with resonance decay contributions included, and discuss our implementation of this formalism in the form of HoTCoffeeh. This tool may be easily integrated with other numerical packages (e.g., [1]) for the purpose of simulating the evolution of heavy-ion collisions and thereby extracting predictions for heavy-ion observables.

The Shape of the Correlation Function

“…We generated 1,000 events of 0 − 10% Au+Au collisions at 200𝐴 GeV with freeze-out temperature 120 MeV and 𝜂/𝑠 = 0.08. To compute the HBT correlation function we used the HoTCoffeeh code [11], which directly evaluates Cooper-Frye integrals over the freeze-out surface on an event-by-event basis.…”

Hanbury Brown--Twiss Interferometry and Collectivity in Small Systems

“…The correlation functions ( 2)-( 3) can be similarly evaluated in terms of Cooper-Frye-like integrals over the freeze-out surface [49]. In this case, the correlation function ( 2) is first evaluated on a fixed grid of points in q, K T , and the transverse pair momentum angle Φ K .…”

The Shape of the Correlation Function

“…For this study we generated 1,000 events of 0 − 10% Au+Au collisions at 200A GeV with a freeze-out temperature T f o = 120 MeV and η/s = 0.08. To compute the HBT correlation function we used the HoTCoffeeh code [10], which directly evaluates Cooper-Frye integrals over the freeze-out surface on an event-by-event basis. Thanks to that we can calculate correlation functions with negligible uncertainties.…”