The
Standard Model of Physics
By Evan Jones and Karis Schneider
Click a particle to
continue: Quarks are in pink, Leptons
are in green and Force Carriers
are in blue
Quarks
Quarks are a fundamental building block of matter. They come in 6 different types, or flavors: up, down, charm, strange, top and bottom. Quarks form in groups of either two or three to form mesons and baryons, respectively. Mesons are particles consisting of a quark and a non-annihilatory anti-quark. For example, a pion (a particle formed by comsic rays in the upper atmosphere) consists of an up quark and an anti-down quark. Baryons are particles consisting of three quarks together.
Color
Color is a property given to quarks to help explain the bonding forces between quarks in particles. The problem first came up when physicists were stumped by the Ω- particle. The Ω- particle consists of three strange quarks. According to Pauli's exclusion principle, no two identical particles can occupy the same energy level. In the Ω- particle, one strange quark must spin in the positive direction, and one must spin in the opposite direction in order for both of them to occupy the same energy level. The problem is that the third strange quark cannot spin in either direction, causing a discrepancy. Thus color was devised to differentiate the different quarks from each other so that they were different and could therefore occupy the same energy level.
Three colors exist: Red, Blue and Green. All three mutually attract, allowing for baryons to occur when three quarks of different color group together. Three anti-colors exist as well: anti-red, anti-blue and anti-green. Red and Anti-Red attract, as do Blue and Anti-Blue and Green and Anti-Green. This is what causes Mesons to occur. In the case of the pion, the up quark is a color, while the anti-down is the corresponding anti-color. We cannot tell what color it actually is, but it does not really matter.
Quark Confinement
The up quark has a charge of +2/3. It is one of most common quarks along with the down quark.
The up quark combines with other quarks to create baryons. Baryons with 3 up or down quarks are nucleons (N). Baryons with 2 up or down quarks are Lambdas (Λ) or Sigmas (Σ). Baryons with 1 up or down quark are Xi (Ξ). Baryons with no up or down quarks are Omegas (Ω).
Down Quark
The down quark has a charge of -1/3. It is one of the most common quarks along with the up quark. See up quark for list of baryons formed by down quarks.
Charm Quark
It was theorized when a meson called the J/Psi particle was discovered in 1974. It had a mass of over 3 times the mass of a proton, which means that it needed something heavier than just up or down quarks. This particle was the first example of a particle with the chram quark. The lightest meson with a charm quark is a D meson.
Strange Quark
The name strange came from an incident in 1947 when a proton hit a nucleus and lived longer than expected. The new particle was named the <>Λ0
Top Quark
In 1995, at the Fermilab Tevatron, proton and antiproton collisions yielded many candidates for the already proposed top quark. The detectors found tons of decayed particles which in turn had decayed from a W boson and a bottom quark, which are the result of the decay of the top quark created in an top anti-top pair. The mass of the top quark was found to be 180 times larger than the mass of a proton, and twice as heavy as the next heaviest fundamental particle, the Z0 boson.
Bottom Quark
In 1977, Leon Lederman found extra mass in a decay of a proton and a platinum/copper nucleus which was called the Upsilon meson. The Upsilon meson is composed of a bottom anti-bottom pair. This was the first sighting of the bottom quark.
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Leptons
Leptons are fundamental particles that are not made of quarks and are unaffected by the strong color force.
Electron
The electron was discovered by J.J. Thomson in 1897. It has a charge of -1. It has a spin of 1/2. It is the smallest non-neutrino lepton with a mass of .511 MeV/c^2
Muon
Muons are produced in cosmic rays in the upper atmosphere in the decay of pions. They were discovered in cloud chambers by J.C. Street and E.C. Stevenson. The muon is approximately 200x times bigger than the electron. The muon is an unstable particle and has a mean lifetime of 2.2x10-6 seconds. After its existence, it decays into an electron, a muon neutrino and an anti-electron neutrino
Tau
Electron Neutrino
Neutrinos were discovered due to a descrepency in the Conservation of Momentum during neutron decay. They have negligible mass, and there is one kind of neutrino for ever other lepton particle. Therefore, there are three types of neutrinos, the electron neutrino, the muon neutrino, and the tau neutrino.
Muon Neutrino
See Electron Neutrino.
Tau Neutrino
See Electron Neutrino.
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Force Carriers
Photon
Photons are the force carrier particles for the electromagnetic force. This force binds molecules together, and is the second strongest force. Light is composed of photons.
Gluon
The strong force is carried by gluons, which binds quarks together. This keeps the protons and the neutrons in the nucleus despite their repulsion.
Z and W Bosons
These force carrier particles are assosicated with the weak force, which is responsible for nuclear decay. For example, beta decay releases a proton, a neutron, and a w boson. This boson can further decay to an electron neutrino and an electon.
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Quarks are a fundamental building block of matter. They come in 6 different types, or flavors: up, down, charm, strange, top and bottom. Quarks form in groups of either two or three to form mesons and baryons, respectively. Mesons are particles consisting of a quark and a non-annihilatory anti-quark. For example, a pion (a particle formed by comsic rays in the upper atmosphere) consists of an up quark and an anti-down quark. Baryons are particles consisting of three quarks together.
Color
Color is a property given to quarks to help explain the bonding forces between quarks in particles. The problem first came up when physicists were stumped by the Ω- particle. The Ω- particle consists of three strange quarks. According to Pauli's exclusion principle, no two identical particles can occupy the same energy level. In the Ω- particle, one strange quark must spin in the positive direction, and one must spin in the opposite direction in order for both of them to occupy the same energy level. The problem is that the third strange quark cannot spin in either direction, causing a discrepancy. Thus color was devised to differentiate the different quarks from each other so that they were different and could therefore occupy the same energy level.
Three colors exist: Red, Blue and Green. All three mutually attract, allowing for baryons to occur when three quarks of different color group together. Three anti-colors exist as well: anti-red, anti-blue and anti-green. Red and Anti-Red attract, as do Blue and Anti-Blue and Green and Anti-Green. This is what causes Mesons to occur. In the case of the pion, the up quark is a color, while the anti-down is the corresponding anti-color. We cannot tell what color it actually is, but it does not really matter.
Quark Confinement
Quark
confinement is the principle that individual quarks cannot be isolated
from one another. This is beacuse the strong force, unlike the other
three forces actually increases in strength over distance, so in order
for a quark to be infinitely far away from another quark, infinite
energy is required. Infinite energy is obviously far greater than the
energy needed to create a new quark pair. So when the quarks get far
enough apart, a new quark pair will have emerged.
The up quark has a charge of +2/3. It is one of most common quarks along with the down quark.
The up quark combines with other quarks to create baryons. Baryons with 3 up or down quarks are nucleons (N). Baryons with 2 up or down quarks are Lambdas (Λ) or Sigmas (Σ). Baryons with 1 up or down quark are Xi (Ξ). Baryons with no up or down quarks are Omegas (Ω).
Down Quark
The down quark has a charge of -1/3. It is one of the most common quarks along with the up quark. See up quark for list of baryons formed by down quarks.
Charm Quark
It was theorized when a meson called the J/Psi particle was discovered in 1974. It had a mass of over 3 times the mass of a proton, which means that it needed something heavier than just up or down quarks. This particle was the first example of a particle with the chram quark. The lightest meson with a charm quark is a D meson.
Strange Quark
The name strange came from an incident in 1947 when a proton hit a nucleus and lived longer than expected. The new particle was named the <>Λ0
Top Quark
In 1995, at the Fermilab Tevatron, proton and antiproton collisions yielded many candidates for the already proposed top quark. The detectors found tons of decayed particles which in turn had decayed from a W boson and a bottom quark, which are the result of the decay of the top quark created in an top anti-top pair. The mass of the top quark was found to be 180 times larger than the mass of a proton, and twice as heavy as the next heaviest fundamental particle, the Z0 boson.
Bottom Quark
In 1977, Leon Lederman found extra mass in a decay of a proton and a platinum/copper nucleus which was called the Upsilon meson. The Upsilon meson is composed of a bottom anti-bottom pair. This was the first sighting of the bottom quark.
Back To Top
Leptons
Leptons are fundamental particles that are not made of quarks and are unaffected by the strong color force.
Electron
The electron was discovered by J.J. Thomson in 1897. It has a charge of -1. It has a spin of 1/2. It is the smallest non-neutrino lepton with a mass of .511 MeV/c^2
Muon
Muons are produced in cosmic rays in the upper atmosphere in the decay of pions. They were discovered in cloud chambers by J.C. Street and E.C. Stevenson. The muon is approximately 200x times bigger than the electron. The muon is an unstable particle and has a mean lifetime of 2.2x10-6 seconds. After its existence, it decays into an electron, a muon neutrino and an anti-electron neutrino
Tau particles were
discovered with detectors in electron-positron collisions. They have an
extrememly short mean life span of 2.96 x 10^-13 seconds. Tau
particles decay into a lepton and the corresponding neutrino, a tau
neutrino. They
are much larger than the normal electron; in fact, they are 3,490 times
bigger(Mass of 1777 MeV/c^2).
•
Electron Neutrino
Neutrinos were discovered due to a descrepency in the Conservation of Momentum during neutron decay. They have negligible mass, and there is one kind of neutrino for ever other lepton particle. Therefore, there are three types of neutrinos, the electron neutrino, the muon neutrino, and the tau neutrino.
Muon Neutrino
See Electron Neutrino.
Tau Neutrino
See Electron Neutrino.
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Force Carriers
Photon
Photons are the force carrier particles for the electromagnetic force. This force binds molecules together, and is the second strongest force. Light is composed of photons.
Gluon
The strong force is carried by gluons, which binds quarks together. This keeps the protons and the neutrons in the nucleus despite their repulsion.
Z and W Bosons
These force carrier particles are assosicated with the weak force, which is responsible for nuclear decay. For example, beta decay releases a proton, a neutron, and a w boson. This boson can further decay to an electron neutrino and an electon.
Back To Top