Scientists have observed a unique particle that moves easily one way, yet resists at 90 degrees. These semi-Dirac fermions were observed using their energy signature in a topological metal. Particles ...

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 quasiparticle, ...

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 a ...