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...

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

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...

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...

oscillations Massive particle – bradyon, aka tardyon Massless particle – luxon Retrocausality Tachyonic antitelephone Virtual particle Wheeler–Feynman absorber...

continuous spin particle (CSP), sometimes called an infinite spin particle, is a massless particle never observed before in nature. This particle is one of...

electromagnetism. Massless particles and field perturbations, such as gravitational waves, also travel at speed c in vacuum. Such particles and waves travel...

 bosons have mass while photons are massless was a major obstacle in developing electroweak theory. These particles are accurately described by an SU(2)...

Wave-particle duality is the concept in quantum mechanics that quantum entities exhibit particle or wave properties according to the experimental circumstances...

In particle physics, a fermion is a subatomic particle that follows Fermi–Dirac statistics. Fermions have a half-odd-integer spin (spin ⁠1/2⁠, spin ⁠3/2⁠...

In particle physics, a boson (/ˈboʊzɒn/ /ˈboʊsɒn/) is a subatomic particle whose spin quantum number has an integer value (0, 1, 2, ...). Bosons form...

gauge bosons are described mathematically by field equations for massless particles. Otherwise, the mass terms add non-zero additional terms to the Lagrangian...

(or combination of particles) that act as if they have both rest mass and volume. However it does not include massless particles such as photons, or...

is much smaller than that of the other known elementary particles (excluding massless particles). The weak force has a very short range, the gravitational...

inertial frames of reference. Massless particles such as photons have zero invariant mass, but massless free particles have both momentum and energy....

{\frac {2\pi \hbar ^{2}}{mk_{\mathrm {B} }T}}}.} For massless (or highly relativistic) particles, the thermal wavelength is defined as λ t h = h c 2 π...

traveled by massive particles), and is usually taken to be equal to it. For lightlike (or null) orbits (which are traveled by massless particles such as the photon)...

be given in this article. For both massive and massless particles in a box, the states of a particle are enumerated by a set of quantum numbers [nx,...

The tau (τ), also called the tau lepton, tau particle, tauon or tau electron, is an elementary particle similar to the electron, with negative electric...

expected to be massless. All bosons have an integer quantum spin (0 and 1) and can have the same quantum state. Most aforementioned particles have corresponding...

is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are...

direction) have zero invariant mass and are referred to as massless. A physical object or particle moving faster than the speed of light would have space-like...

responsible for interactions between electrically charged particles. The photon is massless and is described by the theory of quantum electrodynamics...

such as the scalar or vector mesons. If their current quarks were massless particles, it could make the chiral symmetry exact and thus the Goldstone theorem...