Copyright typically only applies to expressions of an idea, not the idea itself. You cannot copyright the observation that the sky is blue, but you can copyright a poem describing this circumstance in a certain language.
In this particular instance, a scientific theory is not copyrightable, but a paper describing said theory definitely is. Sci-Hub is in hot water precisely because copyright on papers is a thing.
If you wanted to exercise ownership rights on a theory itself, your best bet would be patent law. Patents apply to ideas, but only within the realm of making actual objects. Abstract ideas like scientific theories are usually not patentable, except for the realm of software. Software patents typically cover algorithms and thus mathematical concepts, and since software is a way for mathematical principles to enter commerce, it's probably your only way. (This is also why software patents are so controversial: It's the closest thing to "denying others access to an idea" that we have in our current system of law.)
In this particular instance, a scientific theory is not copyrightable, but a paper describing said theory definitely is. Sci-Hub is in hot water precisely because copyright on papers is a thing.
If you wanted to exercise ownership rights on a theory itself, your best bet would be patent law. Patents apply to ideas, but only within the realm of making actual objects. Abstract ideas like scientific theories are usually not patentable, except for the realm of software. Software patents typically cover algorithms and thus mathematical concepts, and since software is a way for mathematical principles to enter commerce, it's probably your only way. (This is also why software patents are so controversial: It's the closest thing to "denying others access to an idea" that we have in our current system of law.)
Disclaimer: IANAL either.