PROGRAM SUMMARY
Title of program:
rhad
Catalogue identifier:
ADRT
Ref. in CPC:
153(2003)244
Distribution format: tar gzip file
Operating system: Alpha, Linux, Solaris
Number of lines in distributed program, including test data, etc:
5574
Keywords:
Hadronic R-ratio, Perturbative QCD, Electron-positron annihilation,
Running and decoupling of alphas, Elementary particle physics.
Programming language used: Fortran
Nature of physical problem:
The hadronic R-ratio R(s) is a fundamental quantity in high energy
physics. It is defined as the ratio of the inclusive cross section
sigma(e+e- -> hadrons) and the point cross section
sigmapt = 4 pi alpha**2/(3s). It is well-defined both from the
experimental and the theoretical side. R(s) belongs to the few physical
quantities for which high-order perturbative calculations have been
performed (partial results up to order alphas**4 exist!). Mass effects
from real and virtual quarks, the evolution of the MSbar parameters, in
particular in the presence of thresholds, and other subtleties lead to
fairly complex results in high orders. Thus it is important to provide
a comprehensive collection of formulas in order to make them available
to non-experts.
Method of solution:
rhad is a compilation of all currently available perturbative QCD
corrections to the quantity R(s). Several options are provided which
allow for a flexible use. In addition, rhad contains routines which
perform the running and decoupling of the strong coupling constant.
Thus only the center-of-mass energy has to be provided in order to
determine R(s).
Restrictions:
The applicability of rhad is restricted to the perturbative energy
regions and does not cover the narrow and broad resonances.
Typical running time:
The typical runtime is of the order of fractions of a second.