This page describes the Monte Carlo event generators which we feel are best-suited for the LCD study. Linear collider physics studies need to take account of many properties of the initial and final states, include smearing of the center-of-mass energy by beamstrahlung and initial state radiation, polarization of the initial beams, and propagation of polarization correlations to the final state. We believe that it is preferable to use generators that contain this level of detail, hopefully also in a manner that is straightforward to use. For this reason, we are using as our main generator the program PANDORA by Michael Peskin. Events from PANDORA can be processed with PYTHIA and TAUOLA to include final state gluon showering, fragmentation, and tau decays. This is done automatically by the package PANDORA_PYTHIA, by Masako Iwasaki. Instructions downloading and using these programs can be found by following the links above.
The remainder of this page discusses:
Note for experimentalist:: Some detector simulators decay V0 particles during the detector simulation. If you use such simulator, you must stop the decay of such particles in the generator level. For example, if you want to use GISMO, you need to stop the decay of L0, K0-short, K0-long, S-, S+, X0, X-, W- particles in the generator level. (But If you want to use LCD FastMC, you need to decay them. Because LCD FastMC does not decay any particles.)
The 2.1 version of PANDORA (Sept. 00) handles the following Standard Model
processes:
All processes are simulated with parameterized beam distributions and
initial-state radiation, and with full account of polarization at the parton
level. Cross section formula are given at the tree level only.
A modified program for e+e- -> t tbar allows input of general production
and decay form factors. The simulation of the Higgs boson allows input of
arbitrary partial widths for 10 possible decay modes.
Supersymmetry processes are simulated by the program ISAJET. Effects of
beamstrahlung, ISR, and polarization effects are included in ISAJET 7.42 and
above. For further information, see the ISAJET manual.
Supersymmetry reactions, without account for beam polarization, are also
included in recent versions of PYTHIA.
For processes not simulated by PANDORA but which are included in PYTHIA,
beamstrahlung can be added using the program
Though PANDORA does include finite widths for W, Z, and t, it does not
correctly simulate multi-parton final states in which these particles are far
from mass shell. This requires a dedicated multi-parton event generator. A
number of these are available In principle, a multi-parton generator put into the format of a PANDORA process can make use of
PANDORA's the beam simulation. For further details, see
the PANDORA documentation.
Hard gamma-gamma processes can be treated by PANDORA and
Please send comments on these pages to Masako Iwasaki and/or Michael Peskin.
Status of PANDORA
Simulation of supersymmetry
Simulation of additional physics processes
Simulation of 4- and 6-parton backgrounds
Simulation of two-photon backgrounds
World-Wide LC Study