Elegent - old version

This page describes an old version of Elegent (used up to CMSSW 4.2.4). For the up-to-date version, see CompElegent.

Generates p-p and ap-p elastic scattering events according to one of the available hadronic and Coulomb-interference models.

Hadronic models

• Islam et al. According to Int.J.Mod.Phys.A21:1-42,2006. Tags islam_bfkl (for the BFKL/hard pomeron version) or islam_cgc (for the color-glass-condensate version).
• Petrov, Predazzi, Prokudin. According to Eur.Phys.J.C28:525-533,2003. There are two versions implemented - with 2 pomerons (tag ppp2) and with 3 pomerons (tag ppp3).
• Bourrely, Soffer, Wu. According to Eur.Phys.J.C28:97-105, 2003. Tag bsw.
• Block, Halzen. According to Phys.Rev.D60:054024,1999. Tag bh.
• Jenkovszky et al. According to arXiv:1105.1202 (2011). Tag jenkovszky.
• simple exponential, tag exp.

Coulomb-interference models

• West-Yennie, see Phys.Rev.172:1413-1422,1968. Tag WY.
• Kundrát-Lokajíček, see e.g. Z.Phys.C63:619-630,1994. Tag KL.

Besides those, the Elegent recognizes these tags

• PH to neglect the Coulomb-interference and take a hadronic model only and
• PC to take only the Coulomb amplitude and neglect hadronic scattering.

ElegentCDFBuilder

Before the actual event generation, one has to calculate CDFs (cumulative distribution functions) for the energy of interest. They're stored in ROOT files under the Elegent/data directory. It is very likely that all files you need, would be already there. If not, you can use python/ElegentCDFBuilder_cfg.py to do it yourself.

Naming schemes

The CDF ROOT files follow this convention

<E>_<|t|_min>_<|t|_max>_<number of sampling points>.root

where E stands for beam energy in GeV (i.e. half of cms energy) and t_min and t_max are the boundaries of supported t-range in GeV^2.

For ElegentSource, the CDF choice is in the form

<coulomb-interaction tag>/<hadronic-model tag>

for example KL/ppp3.

The recommended usage of ElegentSource

As for every energy there is one preferred/default ROOT file with CDFs, the ElegentSource_cfi.py includes function ElegentDefaultFileName(energy) which returns the default filename for the given energy (string parameter). Hence a recommended usage is a follows

energy = "3500"
...
import IOMC.Elegent.ElegentSource_cfi
process.generator = IOMC.Elegent.ElegentSource_cfi.generator
process.generator.fileName = IOMC.Elegent.ElegentSource_cfi.ElegentDefaultFileName(energy)
process.generator.verbosity = ...
...

ElegentCalculateDetails

ElegentCalculateDetails is a plugin that can take any of the ROOT files in the data directory and calculate some more detailed quantities like B(t), rho(t), etc. These would be stored in a file with .details.root extension.

makePlots.asy

makePlots.asy is an Asymptote script take takes the .root and .details.root files and coverts them into a PDF with a standard set of plots.

-- JanKaspar - 23-Oct-2009