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Changes in version 6.1:

The move from JETSET 7.4 and PYTHIA 5.7 to PYTHIA 6.1 was a major one. For reasons of space, individual points are therefore not listed separately below, but only the main ones. The PYTHIA web page contains complete update notes, where all changes are documented by topic and subversion.

The main new features of PYTHIA 6.1, either present from the beginning or added later on, include:

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PYTHIA and JETSET have been merged.
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All real variables are declared in double precision.
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The internal mapping of particle codes has changed.
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The supersymmetric process machinery of SPYTHIA has been included and further improved, with several new processes.
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Many new processes of beyond-the-Standard-Model physics, in areas such as technicolor and doubly-charged Higgs bosons.
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An expanded description of QCD processes in virtual-photon interactions, combined with a new machinery for the flux of virtual photons from leptons.
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Initial-state parton showers are matched to the next-to-leading order matrix elements for gauge boson production.
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Final-state parton showers are matched to a number of different first-order matrix elements for gluon emission, including full mass dependence.
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The hadronization description of low-mass strings has been improved, with consequences especially for heavy-flavour production.
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An alternative baryon production model has been introduced.
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Colour rearrangement is included as a new option, and several alternative Bose-Einstein descriptions are added.


next up previous contents
Next: Changes in version 6.2: Up: Update History Previous: Versions before 6.1:   Contents
Stephen Mrenna 2007-10-30