Weinberg-Witten Theorem

The Weinberg-Witten Theorem, proved by Steven Weinberg and Edward Witten, is a result of relativistic quantum field theory stating that massless particles of spin greater than one half cannot carry a Lorentz-covariant current, and massless particles of spin greater than one cannot carry a Lorentz-covariant stress-energy tensor, whether the particle is elementary or composite. Because the graviton has spin two, the theorem is usually interpreted as ruling out any composite graviton arising within an ordinary relativistic quantum field theory.