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STARlight
STARlight is a Monte Carlo that simulates two-photon and photon-Pomeron interactions between relativistic nuclei and protons. It produces a variety of final states. For two-photons, it simulates lepton pairs and a variety of mesons. A list of available channels may be found here. For photonuclear interactions, it models coherent and incoherent vector mesons production. A list of available channels may be found here.
A write-up of the code has been published recently:
- S.R. Klein, J. Nystrand, J. Seger, Y. Gorbunov, J. Butterworth, Comp. Phys. Comm. 212 (2017) 258.
More details on the physics behind STARlight can be found in these publications:
- S.R. Klein, J. Nystrand, Phys. Rev. C 60 (1999)
014903 (coherent vector meson production).
- A.J. Baltz, S.R. Klein, J. Nystrand Phys. Rev. Lett. 89 (2002) 012301
(vector meson production accompanied by exchange of additional photons leading to nuclear break up).
- S.R. Klein, J. Nystrand, Phys. Rev. Lett. 92 (2004) 142003 (photoproduction of vector mesons in pp collisions).
- A.J. Baltz, Y. Gorbunov, S.R. Klein, J. Nystrand, Phys. Rev. C 80 (2009) 044902 (two-photon interactions).
The review article
C.A. Bertulani, S.R. Klein, J. Nystrand, Ann. Rev. Nucl. Part. Sci. 55 (2005) 271
provides more general information on the physics of ultra-peripheral collisions.
To install & run STARlight in a *nix based environment, follow these steps(README):
- Download the package from the tracker on the left sidebar or from here. The version in the example might be outdated.
- wget 'https://starlight.hepforge.org/downloads?f=starlight_r300.tar'
- mv 'downloads?f=starlight_r300.tar' starlight_r300.tar
- tar xvf starlight_r300.tar
- Alternatively, one may obtain the latest version via svn---no longer the case--will update to new phab link.
- svn co http://starlight.hepforge.org/svn/trunk
- Change to the installation directory of your choice
- mkdir /home/my/installation/dir
- cd /home/my/installation/dir
- Setup the compilation with cmake
- Compile with (g)make
- Setup the input file, slight.in, for your simluation needs
- cp /path/to/trunk/config/slight.in .
- vim slight.in
- Run
- ./starlight >& output.txt&
- Interpreting the output
- For more information and special scenarios, such as running with PYTHIA or DPMJET, consult the README files located in trunk/
Two-Photon Channels
| Particle | Jetset ID
| e+e- pair | 11
| µ+µ- pair | 13
| τ+τ- pair | 15
| τ+τ- pair, polarized decay | 10015*
| ρ0 pair | 33
| a2(1320) decayed by PYTHIA | 115
| η decayed by PYTHIA | 221
| f2(1270) decayed by PYTHIA | 225
| η' decayed by PYTHIA | 331
| f2(1525) → K+K-(50%),K0K̄0(50%) | 335
| ηc decayed by PYTHIA | 441
| f0(980) decayed by PYTHIA | 9010221
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Vector Meson Channels
| Particle | Jetset ID
| ρ0 → π+π- | 113
| ρ0 → π+π- and direct π+π- production, including the interference. | 913
| ω → π+π- | 223
| φ → K+K- | 333
| J/Ψ → e+e- | 443011
| J/Ψ → µ+µ- | 443013
| Ψ(2S) → e+e- | 444011
| Ψ(2S) → µ+µ- | 444013
| Υ(1S) → e+e- | 553011
| Υ(1S) → µ+µ- | 553013
| Υ(2S) → e+e- | 554011
| Υ(2S) → µ+µ- | 554013
| Υ(3S) → e+e- | 555011
| Υ(3S) → µ+µ- | 555013
| ρ' → π+π-π+π- | 999
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Reading the output
For each event, a summary line is printed, with the follwing format
EVENT: n ntracks nvertices ,
where n is the event number (starting with 1), ntracks is the number of tracks in the event, and nvertices is the number of vertices in the event (STARlight does not currently produce events with more than one vertex).
This is followed by a line describing the vertex, of the format
VERTEX: x y z t nv nproc nparent ndaughters ,
where x, y, z and t are the 4-vector components of the vertex location, nv is the vertex number, nproc is a number intended to represent physical process (always set to 0), nparent is the track number of parent track (0 for primary vertex) and ndaughters is the number of daughter tracks from this vertex.
This is followed by a series of lines describing each of the daughter tracks emanating from this vertex. Each track line has the format
TRACK: GPID px py py nev ntr stopv PDGPID ,
where GPID is the Geant particle id code, px, py and pz are the three vector components of the track's momentum, nev is the event number, ntr is the number of this track within the vertex (starting with 0), stopv is the vertex number where track ends (0 if track does not terminate within the event), and PDGPID is the Monte Carlo particle ID code endorsed by the Particle Data Group.
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