It is known that particles with rest mass cannot travel at the speed of light. Can we also say that particles that travel at subliminal velocity, like these OAM photons do, have mass? It has been demonstrated  that these beams can be thought as made of photons that posses intrinsic OAM, and can be seen as 1/2 spin particles. We know that all fermions which are 1/2 spin particles have mass. At first I thought that it was straight forward that they have mass, but then I've realised this may not be a general opinion and I've decided to ask. http://physicsworld.com/cws/article...ngular-momentum-are-the-latest-twist-on-light .