How to handle dislike of/lack-of-interest in sub-specialty of research area I am a PhD student studying in a field that I enjoy. Furthermore, I enjoy the area within the field that I am specializing in. However, my specialty generally has two major application arenas, which in some ways are disjoint. I came to the program knowing I would be working in one of them, sub-specialty A, despite having no prior experience in it. I did have experience in the other, sub-specialty B, but the faculty in my department who work in sub-specialty B either didn't have openings or didn't see me as a fit for their group (i.e. they didn't support my application).

I arrived planning to give sub-specialty A a fair shake, as I honestly knew little about it and for all I knew I'd enjoy it. After a semester, I am finding it hard to stay interested in the research, and this feeling is compounded by the frustration of feeling like I have to start over in the field. It's also tough watching my peers work on problems of sub-specialty B that I find so much more interesting than my work in sub-specialty A.

I know a PhD is the start, not the end, of a career, and that what you do during it is not what you have to do for the rest of your life, but, that being said, I do have to spend 4-6 years working with this material.

How does one handle this sort of situation? Is it appropriate to bring up my concerns with my adviser? Could trying to bring in a co-adviser from sub-specialty B be a feasible way to bridge the gap between the sub-specialties? (NOTE: It's worth mentioning that this is literally the only problem I am having with my PhD; the school is great, the cohort is great, and my adviser is great) Have other people been in these circumstances? If so, what did you do about it?
How does one handle this sort of situation? Is it appropriate to bring up my concerns with my adviser? 


YES. That is exactly how one handles this sort of situation. 

Try something like the following:


  I knew coming in that I'd be working on A, and I thought I'd enjoy it. But after a semester, I'm feeling.... How do you suggest I move forward?


and see where that gets you. 


  Should I wait until I've published a first-author paper in this sub-specialty first, so that I can veritably say that I have definitely given it a shot? 


If you believe you've given it a fair shot, there's no reason to wait to voice these concerns (in a professional manner). There's no "milestone" at which point you can say "I definitely don't enjoy this area" - there will always be more things to try. The reason to speak to your advisor is that he may be able to advise you on what to try next.