# Transformation of auxiliary field

1. Sep 27, 2013

### rbwang1225

In West's book "Introduction to Strings and Branes", page 2, I don't understand why the auxiliary field e transformed as e'($\tau'$)d$\tau'$=e($\tau$)d$\tau$.

Last edited: Sep 27, 2013
2. Sep 29, 2013

### Korybut

By construction :-)

You impose several conditions on your action and then get how auxilary fields should transform. Just like with YM gauge field, you want gauge invarianceand from this you get transformation law