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[Licence| Download | New Version Template] aepr_v1_0.tar.gz(1526 Kbytes)
Manuscript Title: HELAC-Onia: an automatic matrix element generator for heavy quarkonium physics
Authors: Hua-Sheng Shao
Program title: HELAC-Onia.
Catalogue identifier: AEPR_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 184(2013)2562
Programming language: Fortran 90.
Computer: Any.
Operating system: Windows, Unix.
Keywords: Quarkonium helicity amplitudes, NRQCD, Dyson-Schwinger equations, Off-shell currents.
Classification: 4.4, 11.1, 11.2, 11.5.

Nature of problem:
An important way to explore the law of the nature is to investigate the heavy quarkonium physics at B factories and hadron colliders. However, its production mechanism is still unclear, though NRQCD can explain its decay mechanism in a sufficiently satisfactory manner. The substantial K-factor in heavy quarkonium production processes also implies that the associated production of quarkonium and a relatively large number of particles may play a crucial role in unveiling its production mechanism.

Solution method:
A labor-saving and efficient way is to make the tedious amplitudes calculation automatic. Based on a recursive algorithm derived from the Dyson-Schwinger equations, the goal of automatic calculation of heavy quarkonium helicity amplitudes in NRQCD has been acheived. Inheriting from the virtues of the recursion relations with the lower computational cost compared to the traditional Feynman-diagram based method, the multi-leg processes ( with or without multi-quarkonia up to P-wave states) at colliders are also accessible.

Additional comments:
This is an Open Access program

Running time:
It depends on the process that is to be calculated. However, typically, for all of the tested processes, they take from several minutes to tens of minutes.