Fermions are just one of the basic categories of particles, and almost all of them are Dirac, meaning they have a complementary and distinctive antiparticle—think electron and positron.

For the first time, scientists have observed a collection of particles, also known as a quasiparticle, that's massless when moving one direction but has mass in the other direction. The ...

Strange particles that have mass when moving one direction but no mass when moving in another were first theorised more than a decade ago. Now, these mass-shifting particles have been glimpsed in ...

The scientists compared the behavior of the particles within the material to a train traveling on a network of tracks. In some directions, this train can move extremely fast, as if it had no weight.

Mathematicians at the Universities of York, Munich and Cardiff have identified a unique property of quantum mechanical particles – they can move in the opposite way to the direction in which they are ...