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Manuscript Title: The evaluation of the volume of the phase space of n particles.
Authors: K. Kajantie, V. Karimaki
Program title: RN
Catalogue identifier: AAUB_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 2(1971)207
Programming language: Fortran.
Computer: BURROUGHS 6500.
Operating system: UNSPECIFIED.
RAM: 1K words
Word size: 48
Keywords: Elementary, Particle physics, Multiparticle Production, Phase space, Statistical model, Central limit theorem, Steepest descent method, High energy.
Classification: 11.2.

Nature of problem:
In multiparticle production reactions of large multiplicity, n, a rough approximation to reality is to assume that the reaction probability is proportional to the volume of the phase space. At lower multiplicities the situation is complicated by the limitations in transverse momenta and by other more detailed dynamical effects. Similar remarks apply to the calculation of all quantities expressible in terms of phase space volumes: mass spectra, one-particle spectra, etc. The phase space distribution gives a kind of background to these, which then is modified by dynamical effects.

Solution method:
An approximation based on the saddle point method is used.

Restrictions:
The total multiplicity n is taken to be less than 100, but this limit is easy to change.

Running time:
For n~~10, the time needed to calculate one value of the phase space integral is about 0.1 s for computers like CDC 6500 or Burroughs 6500.