Abstract :
The LanHEP program for Feynman rules generation in momentum representation is presented. LanHEP input is the Lagrangian written in the compact form close to the one used in publications. In particular, the Lagrangian terms can be written with summation over indices of space-time or gauge symmetries and using special symbols for complicated expressions, such as covariant derivative and strength tensor for gauge fields. The output is a set of Feynman rules in terms of physical fields and independent parameters. This output can be written in LATEX format and in the form of CompHEP model files, which allows one to start calculations of processes in the new physical model. Although this work could be done basically by hand, in some cases of extended gauge models it is hardly possible in practice because of the very large size of algebraic expressions. The program allows one to introduce into CompHEP new gauge models and anomalous effective Lagrangian terms.
