GLISSANDO 3: GLauber Initial-State Simulation AND mOre, ver. 3

Abstract

We present ver. 3 of GLISSANDO, a versatile Monte-Carlo generator for Glauber-like models of the initial stages of ultra-relativistic heavy-ion collisions. The present version incorporates the wounded parton model, which is phenomenologically successful in reproducing multiplicities of particle production at the RHIC and the LHC. Within this model, one can study the nucleon substructure fluctuation effects, recently explored in p-A collisions. In addition, the code includes the possibility of investigating collisions of light nuclei, such as 3 He and 3 H, or the α-clustered 7,9 Be, 12 C, and 16 O, where the deformation of the intrinsic wave function influences the transverse shape of the initial state. The current version, being down-compatible, retains the functionality of the previous releases, such as incorporation of various variants of Glauber-like models, a smooth N N inelasticity profile in the impact parameter obtained from a parametrization of experimental data, fluctuating strength of the entropy deposition, or realistic nuclear distributions of heavy nuclei with deformation. The code can provide output in the format containing the event-by-event source location, which may be further used in modeling the intermediate evolution phase, e.g., with hydrodynamics or transport models. The interface is simplified, such that in the control input file the user may supply only the very basic information, such as the collision energy, the mass numbers of the colliding nuclei, and the model type. GLISSANDO 3 is integrated with the CERN ROOT platform. The package includes numerous illustrative and useful ROOT scripts to compute and plot various results. PROGRAM SUMMARYProgram Title: GLISSANDO 3 ver. 3.42 Licensing provisions: CC By 4.0 Programming language: C++ with the ROOT libraries Nature of problem: The code implements in a versatile way the Glauber modeling of the initial stages of ultra-relativistic nuclear collisions, including the wounded nucleon and wounded quark models, with possible admixture of binary collisions. A state-of-the art inelastic nucleon-nucleon collision profile is implemented. A statistical distribution of the strength of the sources can be overlaid. The α clustered structure of light nuclei is built in.Solution method: Monte-Carlo simulation of nuclear collisions, analyzed off-line with numerous ROOT scripts. The software allows for a straightforward event-by-event analysis of eccentricity coefficients and their correlations, size fluctuations, or multiplicity distributions. Additional comments including Restrictions and Unusual features:The input may consist only of the model type, the mass numbers of the nuclei and the collision energy. The output can also be used as initial conditions for further hydrodynamic studies.

Self-similarity in Fluctuations and Clustering of Multiplicities

“…For the simulation of nucleus-nucleus collisions in the framework of Glauber Monte Carlo, we have used an accordingly adopted GLISSANDO package [17]. The parameters of the particle production were adjusted by fitting of experimental data.…”

Investigating high energy proton proton collisions with a multi-phase transport model approach based on PYTHIA8 initial conditions

“…The results shown in this work are obtained with σ cc = 25.2 mb, which reproduces the inelastic pp cross section at √ s = 13 TeV [69]. It must be emphasized that the constituent quark picture used in our current approach is different from an initial state quark participant Glauber Monte Carlo model [71]. We first take the interacting nucleon collision geometries provided by PYTHIA/Angantyr for pp and then assign the produced particle transverse positions using the colliding quark spatial conditions as an afterburner to account for the event by event sub-nucleon fluctuations.…”

“…The previous method gives a smooth initial transverse spatial condition but may underestimate the fluctuations in the proton matter distribution. We also introduce a Glauber Monte Carlo type method considering the event by event subnucleon level fluctuations based on the constituent quark picture [68][69][70][71]. By assuming that a proton can carry three constituent quarks, the interaction of two protons can be extended to the participant quark geometries within the Glauber model framework.…”

Further developments of a multi-phase transport model for relativistic nuclear collisions

“…where z is along the beam directions. In the second way, the initial transverse spatial condition including event-byevent sub-nucleon fluctuations is generated with a Glauber Monte Carlo method based on the constituent quark picture [236, [239][240][241][242][243]. By modeling the proton as three constituent quarks, the interaction of two protons can be interpreted as collisions between the constituent quarks from each incoming proton within the Glauber model framework [241,244].…”