Simply put: The scholar owns the paper by virtue of having created it. Now,
your question may have been: What should the scholar do if he fears that the
others who will see it might steal it? In this case, the creator might want
to secure a formal copyright by registering it with the Copyright Office of
the United States. (If outside the U.S., consult the laws of the
appropriate country.) The Copyright Office accepts formal registrations of
works that are published and those that are not. (There are different
forms, but that's a technicality which you can resolve when it comes time to
select the appropriate form.) With the registration form and fee, the
claimant will enclose one or two copies of the work. There will now be a
legally-recognized, date-fixed record of the creator having claimed his
ownership of this work.
(The email address I gave won't work unless you make an obvious deletion.)