CalcHEP tutorial

In order to get on with CalcHEP, we'll see two examples one sightly more complicated than the other. Hopefully, by the end of this tutorial, you'll be able to use pretty every function of CalcHEP.

A simple leptonic process

Let's start with a simple process and try to compute matrix elements using CalcHEP. In this section, we'll study:

ee → μμττ

The process will be studied in the standard model framework.

Preparing HEPMDB

First, connect to HEPMDB and go in the Calculate section. In the left panel, in the CalcHEP section, check whether the Standard Model (CKM=1) line appears. If not, in the CalcHEP menu, choose Import model. When you find the line Standard Model (CKM=1) for CalcHEP (it should be the model 43), select it and click Select. The model should now be accessible in your environment.

This model is the complete standard model without CKM matrix. As a consequence, it is lighter and in situation where quarks' flavours don't matter, it gives the same results as the standard model.

The batch file

Select the model and select Edit Full Batch File in the CalcHEP menu. A new window will appear. You will be able to edit the batch file which is the file describing the process of interest.