The Standard Model - Briefly

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    Beginning with J.J. Thomson's discovery of the electron in 1897, have discovered a large number of subatomic particles, the great majority of them unstable, by examining the debris from ever more potent particle-on-particle collisions. From their knowledge of those particles and of those particles' decays, physicists, led by Murray Gell-Mann (1929 Sep 15 - ?) And Yuval Ne'eman (1925 May 14 - 2006 Apr 26), have inferred the existence of a small set comprising the most fundamental particles of them all. That set, which we call the Standard Model, consists of three families of four particles each, which make up all matter, and a handful of particles representing the forces that make matter do interesting things. In this essay I offer a brief outline of the Standard Model by reviewing what physicists know about the particles that comprise it.

Fermions

    Named for the Italian physicist Enrico Fermi (1901 Sep 29 - 1954 Nov 28), this class of particles contains all of and only those fundamental particles that carry one-half unit of spin (and thus obey Pauli's exclusion principle), the particles that make up matter. The fermions fall into three families (epsilon, mu, and tau) that each contain four particles - two quarks and two leptons. I have left the antimatter counterparts of these particles implicit.

Epsilon

    Also known as Generation 1, this family consists of the up quark, the down quark, the electron, and the electron neutrino. We have for their basic properties

 

particle

electric charge

mass

up quark

+2/3 e

3 Mev

down quark

-1/3 e

6 Mev

electron

-e

0.511 Mev

electron neutrino

0

0

(Fig. 1)

    1. The up quark provides almost half of the mass of the ordinary matter in the Universe. The 3 Mev listed on the table applies to the bare quark, which can never exist as such, so it gives us merely an estimate. When it participates in a baryon, such as a proton (two up quarks and a down quark), it contributes 363 Mev to the mass of the combination and when it participates in a meson it contributes 310 Mev.

    2. The down quark provides most of the other half of the mass of the ordinary matter in the Universe. The 6 Mev listed on the table applies to the bare quark, as with the up quark. When it participates in a baryon, such as a neutron (two down quarks and an up quark), it contributes, like the up quark, 363 Mev to the mass of the combination and when it participates in a meson it contributes 310 Mev.

    3. The electron exists as the lightest particle carrying an electric charge. It participates in ordinary matter as the main carrier of electric currents (what Maxwell called free electricity) and as the cloud that neutralizes the positive electricity of the atomic nucleus and thereby gives the atom its chemical properties.

    4. The electron neutrino exists as something like the ghost of an electron. It seems to consist of nothing more than the spirit of electronity, presumably for the sake of upholding a conservation law. In any process that creates or annihilates an electron or a positron a neutrino or an antineutrino must appear or vanish.

Mu

    Also known as Generation 2, this family consists of the charm quark, the strange quark, the muon (also known as the mu meson), and the mu neutrino. We have for the basic properties of those particles

 

particle

electric charge

mass

charm quark

+2/3 e

1250 Mev

strange quark

-1/3 e

95 Mev

muon

-e

106 Mev

mu neutrino

0

0

(Fig 2)

    1. The charm quark exists as something like a heavier version of the up quark, one that carries a dose of the spirit of muonity. As with the up quark, the given mass represents an estimate of what the bare quark would ponder. When it participates in hadrons (baryons and mesons) it contributes about 1500 Mev to the mass of the combination.

    2. The strange quark exists as a heavier, muonity-infused version of the down quark. When it participates in a baryon it adds 538 Mev to the baryon's mass and when it participates in a meson it adds 483 Mev to the meson's mass.

    3. The muon (originally the mu meson) exists as something like a heavy electron imbued with the spirit of muonity. With a half-life of 2.197 microseconds, a muon decays into an electron, an electron antineutrino, and a mu neutrino. The muon itself comes primarily from the decays of pions and kaons.

    4. The mu neutrino exists as the pure spirit of muonity. Without mass or electric charge, the mu neutrino exists, presumably, for the sake of a conservation law.

Tau

    Also known as Generation 3, this family consists of the top quark, the bottom quark, the tau particle (or tauon), and the tau neutrino. We sum up the basic properties of these particles as

 

particle

electric charge

mass

top quark

+2/3 e

171 Gev

down quark

-1/3 e

4.2 Gev

tauon

-e

1.78 Gev

tau neutrino

0

0

(Fig. 3)

    1. The top quark exists as something like a heavy version of the charm quark imbued with the spirit of tauonity. When it participates in a hadron it adds 23 Gev (23,000 Mev) to the mass of the combination.

    2. The bottom quark exists as a heavier, tauonity-infused strange quark. When it participates in a hadron it adds 4.7 Gev of mass to the combination.

    3. The tau particle (or tauon) exists as something like a heavy muon imbued with the spirit of tauonity. With a half-life of 0.33 millionth of a microsecond, the tauon decays into a) an electron, an electron antineutrino, and a tau neutrino, b) a muon, a mu antineutrino, and a tau neutrino, or c) a rho meson and a tau neutrino.

    4. The tau neutrino exists as the pure spirit of tauonity. With no mass or electric charge, it seems to exist solely to uphold a conservation law.

Bosons

    Named for the Indian physicist Satyendra Nath Bose (1894 Jan 01 - 1974 Feb 04), this class of particles contains all of and only those fundamental particles that carry one unit of spin. These particles represent the forces that make matter do interesting things. The fundamental bosons consist of the photon, the W and Z vector bosons, and the gluon.

Photon

    The well-known particle of light represents the electromagnetic force. Manifest in light the photon is a quantized vibration of the electromagnetic field while the field itself (in the physicists= conception) consists of virtual photons emanating from, passing among, and exerting force upon any and all electrically charged particles. The photon has zero mass (and thus moves at the speed of light) and no charge of any kind.

Z Boson

    With a mass of 91 Gev and zero electric charge, the Z boson mediates weak interactions that change the identities of particles. The weak force, which comes manifest primarily in radioactive decays, affects only quarks and leptons, acting on a kind of charge that some physicists call flavor.

W+/W- Bosons

    Pondering 80.4 Gev and carrying one unit of positive or negative electric charge, the W+ and W- bosons mediate weak interactions that change particle flavor and electric charge. Except for interacting with other electrically charged particles via the electromagnetic force, these bosons affect only quarks and leptons.

Gluons

    With zero mass, zero electric charge, and zero flavor, gluons mediate the chromodynamic force, which is one component of the strong force. Eight kinds of gluons carry the various combinations of basic color (red, green, and blue) and anti-color (anti-red=cyan, anti-green=magenta, and anti-blue=yellow) and act only on quarks and other gluons.

    Physicists also identify the other component of the strong force as the residual strong interaction, which involves mesons interacting with hadrons. This is the force that holds protons and neutrons together in an atomic nucleus.

○ ○ ○

    I have not included the graviton and the Higgs boson in this overview because to this date (2010 Jan 20) physicists have no evidence that those particles actually exist. For the same reason I have also not included the hypothetical supersymmetric partners of the fundamental particles.

    If the Map of Physics stands fully true to Reality, then we can deduce the Standard Model in all its features from primitive axioms or theorems. I have dedicated this section to the search for those propositions and that deduction.

habg

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