Long ago, as a new researcher to an established field, I submitted a paper to the leading journal, with the first time experimental observation of a weak but theoretically predicted quantum transition. The paper was rejected by the reviewer, a professor and leading specialist in the field, claiming my observation was impossible. I did not resubmit the paper elsewhere. I have discovered that this same reviewer and his group published a later paper claiming to have observed the same transition first, which I had submitted.
What are my options for handling this situation?