I believe you're referring to the Chung's probability theorem, also known as Chung's lemma. However, I think you might be looking for the Chung-Fuchs theorem or more specifically, the probability density function (pdf) related to Chung's work.
Here, I couldn't find or assume well known standard Chung distribution.
However, I assume you are looking for , which doesn't exist; I suggest **F Chung - type Distribution.'
