# Event Generators

**twoPionGen**
A Monte Carlo event generator for the process %$\bar{p} p \rightarrow \pi^+\pi^-$%,
when both the proton target and the antiproton beam are unpolarized, is described.
The kinematic region covers the antiproton momentum range
from 0.79GeV to 12.0GeV, in the LAB frame.
For the low energy regime, the parametrization of the cross section
is based on a Legendre polynomial fit to data from the (antiproton beam)
CERN 28GeV proton synchroton.
For the high energy regime, the recent predictions by J. van de Wiele and S. Ong
based on a Regge Theory approach were used.
The generator is a useful first tool to study pion production at PANDA.

The generator is part of the current "trunk" version of PANDA ROOT.

Full documentation for the event generator can be found

here

**twoLeptonGen**
A Monte Carlo event generator for the process %$\bar{p} p \rightarrow l^+l^-$%,
with %$l=e,\mu$% or %$\tau$%, when both the proton target and the antiproton beam
are unpolarized, is described. The input cross section is a leading order calculation
with a massive lepton in the final state. The generator is a useful first tool to study
lepton production at PANDA.

The generator is part of the current "trunk" version of PANDA ROOT.

Full documentation for the event generator can be found

here

**The %$\bar{p} p \rightarrow l^+l^-$% %$(l=e,\mu,\tau)$% and %$\bar{p} p \rightarrow \pi^+\pi^-$% cross section**
We describe the differential cross section
for the processes %$\bar{p} p \rightarrow l^+l^-$%, with %$l=e,\mu$% or %$\tau$%,
and %$\bar{p} p \rightarrow \pi^+\pi^-$%, when both the proton target
and the antiproton beam and the antiproton beam are unpolarized.
For lepton production, the cross section is a leading order calculation
with a massive lepton in the final state. For pion production,
the parametrization of the cross section in the low energy regime
is based on a Legendre polynomial fit to data from the (antiproton beam)
CERN 28GeV proton synchroton, whereas in the high energy regime
the recent predictions by J. van de Wiele and S. Ong
based on a Regge Theory approach were used.
A computer code to perform integration of both the lepton and pion
cross section in a user-defined kinematic region is also described.

Full documentation can be found

here.

A tar (gziped) file with the computer code to perform numerical integration
of both the lepton and pion cross section can be found

here.

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