Naturally Small Seesaw Neutrino Mass with No New Physics Beyond the TeV Scale

If there is no new physics beyond the TeV energy scale, such as in a theory of large extra dimensions, the smallness of the seesaw neutrino mass, i.e., m(nu) = m(2)(D)/m(N), cannot be explained by a very large m(N). In contrast to previous attempts to find an alternative mechanism for a small m(nu), I show how a solution may be obtained in a simple extension of the standard model, without using any ingredient supplied by the large extra dimensions. It is also experimentally testable at future accelerators.