In particle physics, a massless particle is an elementary particle whose invariant mass is zero. At present the only confirmed massless particle is the...

Higgs mechanism, a way for some particles to acquire mass. All fundamental particles known at the time should be massless at very high energies, but fully...

massive particle refers to a massful particle which has real non-zero rest mass (such as baryonic matter), the counter-part to the term massless particle. According...

that, if a massless spin-2 particle is discovered, it must be the graviton. Supersymmetric theories predict the existence of more particles, none of which...

The spin of a particle may be used to define a handedness, or helicity, for that particle, which, in the case of a massless particle, is the same as...

discrete. For a massive particle of spin S, the eigenvalues of helicity are S, S − 1, S − 2, ..., −S.: 12  For massless particles, not all of spin eigenvalues...

a massive particle, By evaluating the norm of the four-momentum of the system. This method applies to both massive and massless particles, and can be...

physics, a subatomic particle is a particle smaller than an atom. According to the Standard Model of particle physics, a subatomic particle can be either a...

In the physical sciences, a particle (or corpuscule in older texts) is a small localized object which can be described by several physical or chemical...

including dark matter), mostly photons and other massless force carriers. The Standard Model of particle physics contains 12 flavors of elementary fermions...