Help! I need to disallow a specific query string

[Hissingsid]

Hi,

Due to an error in the PPC search engine concerned, Google has indexed a redirecting URL from this particular PPC search engine. This redirects to my home page and includes a query string which I added on the search engine so I could track the clicks.

I want to remove this URL from the index and wonder if I can disallow it like this.

User-agent: googlebot
Disallow:?widgets

If not any suggestions would be much appreciated. I'm concerned that this thing might be seen as dupe content.

Many thanks in advance.

Sid