I have found the perfect adviser for my dissertation. He’s well known in the field, we work well together and he’s genuinely interested in my work. The problem is, I found out that he’s published one of my chapters from my dissertation as an article in a leading journal in the field without discussing it with me or including my name as a co-author. What should I do?
Let’s look at your claim that the chapter is yours. Did your adviser suggest your project, or at least give you the broad outlines of the questions that you could explore? If you answered yes to either of these questions, then you and your adviser worked as a team on this chapter. I don’t mean to suggest that it isn’t unpleasant to see your work published word for word without attribution, but at least you’ve been published (and in a leading journal, no less) even if no one else knows it is your work.
Now, is it unethical for the professor to publish without attaching your name? Yes. Has this risen to the level of plagiarism? Probably. But that doesn’t matter, because you’re a graduate student and even if your claim is believed, you will forever be remembered only as that graduate student that was somehow implicated in a plagiarism scandal that brought down another Great Man of Science.
No matter what, work hard to keep your relationship with your graduate adviser cordial. There’s a lot riding on this relationship; you will need good reference letters, whether it’s for your next position, a fellowship, or something else. Don’t put those at risk.