Under U.S. copyright law, as soon as a work is fixed in a tangible form, you as the author immediately have certain exclusive copyrights:
- The right to reproduce copies of your work in any format;
- The right to prepare derivative works, or adaptations of your work, including translations, revised editions, etc.;
- The right to distribute new copies of your work;
- The right to display your work publicly.
When your paper is accepted for publication, many publishers will ask you to sign a standard publishing agreement which transfers all copyrights in the work to the publisher. That may not be necessary, nor to your advantage.