Sartre 1 is an event generator for exclusive diffractive vector meson production and DVCS in ep and eA collisions based on the dipole model. It describes the process: e p → e' p' V and e A → e' A' V where V = J/ψ, φ, ρ, γ. Sartre is not a stand-alone program but a set of C++ classes and C functions that form the API. The heart of Sartre is an implementation of the bSat and bCGC dipole models. We extended the models to also describe eA collisions making Sartre the first generator to describe this class of processes. Saturation is introduced in the bSat model through an exponential term in the scattering amplitude. In order to study the impact of saturation on the production cross-section we also construct a non-saturated version of the bSat model, bNonSat, by linearizing the dipole cross-section.
Sartre was developed at Brookhaven National Laboratory for studies of electron-ion collisions at future facilities such as EIC (eRHIC/JLEIC) and LHeC.
The latest stable version is Sartre 1.20 (tag release-1.20). Although this was planned to be the last version of Sartre 1, some important features are currently being added. One is the addition of a new set of bSat and bNonSat parameters derived from fits to the latest HERA data, the other is the inclusion of UPC capabilities.
Version 2 is a long term project with the objective to add inclusive event generation. This will be a major re-write.
The latest version (svn trunk) is not fully tested and we urge users to stick to the latest tagged releases.
Sartre is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation. This program is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. See the GNU General Public License for more details.