gammaLoss

Tables, example configurations, analysis code and data for the gammaLoss thermal photon module of C-SCAPE (thermal photon emission from the QGP and hadron gas, and reabsorption of thermal and jet photons in the medium).

The module itself lives in C-SCAPE (src/photons). This repository holds what it needs at run time and what is used to run and analyze photon simulations.

Installation

From the C-SCAPE external_packages directory:

./get_gammaLoss.sh

This clones the repository into external_packages/gammaLoss. Then build C-SCAPE with ROOT (MathMore is required for the photon modules):

cd build
cmake .. -DUSE_ROOT=ON -DUSE_MUSIC=ON -DUSE_ISS=ON
make -j

The MUSIC examples need MUSIC and iSS (get_music.sh, get_iSS.sh); the config/photon runs with an afterburner also need SMASH (-DUSE_SMASH=ON).

With the repository present, the analysis programs in analysis/ are built as well.

Contents

directory	contents
tables/	Rapp HRG photon rate and pion/kaon chemical potential tables used by the hadron gas rate (<hadronGasTablePath>, default ../external_packages/gammaLoss/tables)
config/	example user XMLs: jetscape_user_gamma_brick.xml (PhotonGun in a static brick), jetscape_user_gamma_MUSIC.xml (PhotonGun and thermal photons in Trento + MUSIC with iSS freeze-out) and jetscape_user_gamma_jet_absorption.xml (Pythia QCD jets and prompt photons with MATTER energy loss in Trento + MUSIC, showing absorption of hard and shower photons with an enhanced absFactor)
config/photon/	run configurations for AuAu 200 GeV and PbPb 2.76 TeV (0-20%, 20-40%), pp references, brick and rate tests, and the MUSIC input file
analysis/	C++ analysis of the final state output: AuAu200GammaAnalysis, PbPb2760GammaAnalysis, PP200GammaAnalysis, PP2760GammaAnalysis
data/	experimental photon and hadron spectra and v2 (PHENIX, STAR, ALICE) used by the analysis
python/	plotting, comparison and slurm submission scripts

Run the examples from the C-SCAPE build directory, for example

./runJetscape ../external_packages/gammaLoss/config/jetscape_user_gamma_brick.xml

The analysis programs also run from build and read the data from ../external_packages/gammaLoss/data.

Photon status codes

All photons are written directly to the final state hadron output by gammaLoss; jet photons are not passed to hadronization.

pstat	meaning
22	hard / prompt photon from the hard process
23	photon radiated in the jet shower (e.g. MATTER)
24	thermal photon emitted by the QGP
25	thermal photon emitted by the hadron resonance gas
negative	absorbed in the medium, only written with <writeAbsorbed>1

Hadrons from SMASH carry status 27.

Notes on the configurations

The configurations were converted from the X-SCAPE-COMP cparker/gamma branch:

• gammaLoss moved from <Eloss> into its own <Photons> block after the medium; gammaLoss_on and hydro2D were removed.
• only_photons was dropped since photons no longer go through hadronization; for photon-only runs simply leave out <JetHadronization> (configurations that used only_photons=1 have no such block).
• Configurations without gammaLoss (pp references and hadron runs) have a <Photons> block with emission and reabsorption off, so hard and shower photons are still labeled 22 and 23.
• min_bias (one hard process per binary collision) is not available in C-SCAPE and was removed from hydro/PbPb2760/20-40/hadrons.xml.
• Paths into the code are relative to the C-SCAPE build directory. Output paths (outputFilename) and the pp baselines read by the analysis still point to /scratch/user/cameron.parker/projects/runs, and the python scripts assume the checkout is at /scratch/user/cameron.parker/projects/C-SCAPE-COMP-gamma.
• The iSS configurations use the default ../external_packages/iSS/iSS_parameters.dat.