As already discussed in the blog a bit (see also the comments there linking to newer posts), Q2A offers not only tags as a means to characterize question, there is also built in the possibility to define and use broader categories (and subcategories) to organize questions. The category (and subcategory) can be choosen too, when asking a question.
For now, from the earlier discussions we came up with the following broad first level categories:
- Q&A: intended to contain all general (graduate level upward) physics questions, some kind of a revival of TP.SE with a slightly broadened scope
- Reviews: this is intended to review and discuss specific papers as suggested here
- Open Problems: for questions that are still open to active research
- Meta: for discussions about the site itself
- Chat: for longer physics discussions and things of interest to the community, that do not exactly fit into the format of the Q&A or Reviews sections
These broad categories can be further subdivided into subcategories. For the Main category we have from the blog discussions about what topics should be allowed on PhysicsOverflow
- Theoretical Physics
- Phenomenology
- Experimental Physics
- Astronomy
- Mathematics
- SE.Imported (imported questions from living SE sites, see also this community moderation question)
- SE.TP (the questions imported from the closed Theoretical Physics SE site.
Meta is currently subdivided into the categories
- Community Moderation
- Discussion
- Support
- Bug
- Feature Request
- SE.Imported (not sure how important this is)
- SE.TP.Meta (former TP.SE users in particular might like this)
If I understand the sophisticated refereeing suggestion right, the Reviews category might be subdivided into ArXiv categories, and concerning Vixra I dont know (how important will non-mainstream be here anyway?)
Update
Take these discussions into account, I have removed the non-mainstream category for now
Update2
The for PhysicsOverflow relevant ArXiv categories are now mapped in a one-to-one correspondance to sub-categories of the Reviews section, such that we presently have
- astro-ph
- cond-mat
- gr-qc
- hep-ex
- hep-lat
- hep-ph
- hep-th
- math-ph
- nlin
- nucl-ex
- nucl-th
- physics
- quant-ph