In particle physics, a generation is a division of the elementary particles. Between generations, particles differ only by their mass and flavor; all interactions and quantum numbers are identical. There are three generations according to the Standard Model of particle physics. Thousands of particles explode from the collision point of two relativistic (100 GeV per ion) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ... In particle physics, an elementary particle is a particle of which other, larger particles are composed. ... Unsolved problems in physics: What causes anything to have mass? The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. Mass is the property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... In particle physics, flavor is a property of a fermion that identifies it, a label that specifies the name of the particle. ... A fundamental interaction is a mechanism by which particles interact with each other, and which cannot be explained by another more fundamental interaction. ... A quantum number describes the energies of electrons in atoms. ... The Standard Model of Fundamental Particles and Interactions For the Standard Model in Cryptography, see Standard Model (cryptography). ...

Each generation is divided into two leptons and two quarks. The two leptons may be divided into one with electric charge −1 (electron-like) and one neutral (neutrino); the two quarks may be divided into one with charge −1/3 (down-type) and one with charge +2/3 (up-type). In physics, a particle is a lepton if it has a spin of 1/2 and does not experience the strong nuclear force. ... These are the six flavors of quarks and their most likely decay modes. ... Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ...

The first generation consists of the electron, electron neutrino and the down and up quarks.

The second generation consists of the muon, muon neutrino and the strange and charm quarks.

The third generation consists of the tau lepton, tau neutrino and the bottom and top quarks.

Each member of a higher generation has greater mass than the corresponding particle of the previous generation. For example: the first-generation electron has a mass of only 0.511 MeV, the second-generation muon has a mass of 106 MeV, and the third-generation tau lepton has a mass of 1777 MeV (almost twice as heavy as a proton). e- redirects here. ... The neutrino is an elementary particle. ... The down quark is a first-generation quark with a charge of -(1/3)e. ... The up quark is a first-generation quark with a charge of +(2/3)e. ... The muon (from the letter mu (μ)--used to represent it) is an elementary particle with negative electric charge and a spin of 1/2. ... The neutrino is an elementary particle. ... For other uses of this term, see: Quark (disambiguation) 1974 discovery photograph of a possible charmed baryon, now identified as the Σc++ In particle physics, the quarks are subatomic particles thought to be elemental and indivisible. ... The charm quark is a second-generation quark with a charge of +(2/3)e. ... The tau lepton (often called the tau or occasionally the tauon) is a negatively charged elementary particle with a lifetime of 3×10−13 seconds and a high mass of 1777 MeV (compared to 939 MeV for protons and 0. ... The neutrino is an elementary particle. ... The bottom quark is a third-generation quark with a charge of -(1/3)e. ... The top quark is the third-generation up-type quark with a charge of +(2/3)e. ... An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt. ...

All ordinary atoms are made of particles from the first generation. Electrons surround a nucleus made of protons and neutrons, which contain up and down quarks. The second and third generations of charged particles do not occur in normal matter and are only seen in extremely high-energy environments. Neutrinos of all generations stream throughout the universe but rarely interact with normal matter. Properties In chemistry and physics, an atom (Greek ἄτομος or átomos meaning indivisible) is the smallest particle still characterizing a chemical element. ... A semi-accurate depiction of the helium atom. ... // Properties [1][2] In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... This article or section does not adequately cite its references or sources. ...

Possibility of a fourth generation

Within the Standard Model, fourth and further generations have been ruled out by theoretical considerations. Some of these are based on the subtle modifications of precision electroweak observables that extra generations would induce; such modifications are strongly disfavored by measurements. Furthermore, a fourth generation with a light neutrino (one with a mass less than about 40 GeV) has been ruled out by measurements of the widths of the Z boson (LEP, CERN)^{[citation needed]}. Nonetheless, searches at high-energy colliders for particles from a fourth generation continue, but as yet no evidence has been observed. The Standard Model of Fundamental Particles and Interactions For the Standard Model in Cryptography, see Standard Model (cryptography). ... In physics, the W and Z bosons are the elementary particles that mediate the weak nuclear force. ... The Large Electron-Positron Collider (usually called LEP for short. ... CERN logo The Organisation européenne pour la recherche nucléaire (English: European Organization for Nuclear Research), commonly known as CERN, pronounced (or in French), is the worlds largest particle physics laboratory, situated just northwest of Geneva on the border between France and Switzerland. ...