How do you ask a professor for possibility of publication

[Choppy]

If a student is published in a field where they don't intend to actually do graduate work, the admissions committee will certainly like that more than a student who did no research at all, but significantly less than a student who has experience in the field they plan to write a dissertation in.

Perhaps this is a semantics argument, but I disagree with "significantly less" and later with "disservice."

I would agree that it can look better if you have exerience in the field you plan to go into, but you also have to keep in mind that incoming grad students don't always know which field they want to pursue. I sure didn't. And I don't think it's realistic to expect an admissions committee to place a lot of weight on that as a factor for entrance (although I'm sure the exact weight varies from school to school).

Undergraduate students work for professors for lots of reasons. It could be that they like a particular professor or feel that they can learn more in one lab over another. Maybe they know grad students in a particular lab. Maybe they win a scholarship that requires they work in a particular field. Maybe at first, the choice is random. Maybe there aren't any jobs available in the field they dearly want to pursue and so they chose the next best thing. And yes, the possibility of getting credit for the work is also a factor.

The assumtion that students are penalized for not doing work as an undergraduate in the field they plan to pursue graduate work in is inconsistent with my experience.

 

[j93]

There was no assumption that someone who doesn't publish will work harder, just that someone only interested in publishing will be much more transparent than someone only interested in doing physics. And the letter of recommendation will carry much more weight than a second (or fourth) authored publication.

Youre still making the same assumption because a letter of recommendation is written about your work for a supervisor and the quality of that work and any future work. This is orthogonal to whether one is published or not. There is no reason to believe that if you work hard for a professor that is likely to publish you won't get as good a letter as working hard for a professor that doesn't not publish as often.
Im assuming youre dropping the he will drop out argument.

I also agree with Choppy's points.