The Pluto++ Event Generator.

Abstract

Pluto is a Monte-Carlo event generator designed for hadronic interactions from Pion production threshold to intermediate energies of a few GeV per nucleon, as well as for studies of heavy ion reactions. The package is entirely based on ROOT, without the need of additional packages, and uses the embedded C++ interpreter of ROOT to control the event production. The generation of events based on a single reaction chain and the storage of the resulting particle objects can be done with a few lines of a ROOT-macro. However, the complete control of the package can be taken over by the steering macro and user-defined models may be added without a recompilation of the framework. Multi-reaction cocktails can be facilitated as well using either mass-dependent or user-defined static branching ratios. The included physics uses resonance production with mass-dependent Breit-Wigner sampling. The calculation of partial and total widths for resonances producing unstable particles is performed recursively in a coupled-channel approach. Here, particular attention is paid to the electromagnetic decays, motivated by the physics program of HADES. The thermal model supports 2-component thermal distributions, longitudinal broadening, radial blast, direct and elliptic flow, and impact-parameter sampled multiplicities. The interface allows angular distribution models (e.g. for the primary meson emission) to be attached by the user as well as descriptions of multi-particle correlations using decay chain templates. The exchange of mass sampling or momentum generation models is also possible. The first feature allows for consistent coupled-channel calculations, needed for a correct description of hadronic interactions. For elementary reactions, angular distribution models for selected channels are already part of the framework, based on parameterizations of existing data. This report gives an overview of the design of the package, the included models and the user interface.

Virtual Photon Measurements with the HADES at GSI

“…Virtual Photon Measurements with the HADES at GSI Jan-Hendrik Otto To reveal eventual fireball medium contributions to the reconstructed spectrum of dielectrons, simulations of the relevant hadronic sources are performed utilizing the software package Pluto [9] (see fig. 5).…”

Impact of the Coulomb field on charged-pion spectra in few-GeV heavy-ion collisions

“…In order to illustrate the effect of a Coulomb field on the kinematic distributions of charged pions, we have used the event generator Pluto [34] to simulate thermal spectra of all three pion species, π + π 0 , and π − . To do that, the Pluto code was modified to include the Coulomb potential, basically by implementing Eqs.…”

“…Right side: Simulated center-of-mass rapidity distributions of π − (blue), π + (red) and π 0 (black); the lower panel shows the ratio to π 0 . The Pluto [34] simulation was done with a common set of parameters for all pion charges (T 1 = 50 MeV, T 2 = 90 MeV, f = 0.95, V c = 15 MeV, T p = 130 MeV, and angular distribution coefficient A 2 = 0.54/0.60/0.66 for π + /π 0 /π − , respectively).…”

Studies of Deuteron Breakup Reactions in Deuteron–Deuteron Collisions at 160 MeV with BINA

“…Therefore, semi-inclusive correlations between the energies of the two outgoing protons from the breakup have been investigated within the Wall acceptance. The correlations were drawn for the coplanar configurations of the two protons and compared to the results of simulations performed with the use of the Pluto++ event generator [60], see Fig. 12.…”