# Delete Particles

## General

In some cases it might be necessary to remove some degrees particles which are initially defined from the model. This is for instance the case if particles are much heavier than the considered energy scale. In order to do that, these particles can be added to the list

`DeleteParticles={List of fields}`

There are some remarks necessary

- SARAH does not integrate out the fields, i.e. it does not derive higher dimensional operators when removing the degrees of freedom
- SARAH deletes these particles only from the Lagrangian and in all subsequent calculations (vertices, masses, loop corrections), but includes them for instance in the RGE calculation.

### Example

To delete the right-handed neutrinos (called `v`

in the following) from the low energy Lagrangian in seesaw I models, it is sufficient to put

`DeleteParticles={v};`