Baryons, hadrons, and non-zero-mass leptons {fermion}| have half-integer spins, with Fermi-Dirac statistics. No two fermions can have same quantum numbers. Fermion energy quanta always have same units. Same-type fermions are indistinguishable. For example, all electrons are exactly alike. Fermions and bosons account for all particles.
statistics
Bosons and fermions with the same quantum numbers are exactly the same, so two different photons or electrons with the same quantum numbers are exactly the same. Because they have no relativistic effects on each other, bosons have symmetric wave functions: f(b+) = f(b-), where b+ has spin +1 and b- has spin -1. Different bosons can have the same state, because bosons do not attract or repel each other by relativistic effects. Their changing fields are symmetrical and cancel. Because they have relativistic effects on each other, fermions have anti-symmetric wave functions: f(e+) = -f(e-), where e+ has spin +1/2 and e- has spin -1/2. For two fermions, wavefunction is anti-symmetric for fermion exchange: f(e+,e-) = -f(e-,e+). For helium atoms (with two electrons in lowest orbital), with no time changes, the ground-state wavefunction is anti-symmetric, but the main (zero-order) wavefunction is symmetric, so the spin wavefunction is anti-symmetric. Electrons with same spin cannot be in same state (Pauli exclusion principle), because f(e+,e+) = -f(e+,e+) can be true only if f(e+,e+) = 0. Different fermions have different states, because fermions repel each other by relativistic effects. Changing electric fields induce magnetic fields that affect moving electric charges. Their changing fields are anti-symmetrical and do not cancel.
Protons, neutrons, and over 100 other particles {baryon}|, such as lambda, sigma, delta, cascade, omega, and upsilon, share properties. Baryons have baryon number 1, while other particles have baryon number 0. Baryons have three quarks.
Particles {hyperon} similar to protons and neutrons can have higher masses. Hyperons have masses 2 to 10 times proton mass. Hyperons have charge -1, 0, +1, or +2. Hyperons have spin 1/2 or 3/2. Hyperons have lifetime 10^-23 to 10^-10 seconds. Hyperons have three quarks and are baryons.
Particles {neutron}| similar to protons in mass have no charge. Neutron has three quarks, two down and one up. Free neutrons have lifetime 1000 seconds before they decay to proton. Neutrons in atoms are stable, because, in nuclei, strong nuclear force lowers neutron energy, so neutrons do not decay.
The main and lowest-energy baryon {proton}| is mainly in atomic nuclei. Proton has three quarks, two up and one down. Proton mass is 10^-24 grams. Protons have infinite lifetime. However, if superweak nuclear force exists, lifetime is 10^31 years.
Electrons and similar fermions {lepton}| share properties.
size
Leptons have diameter 10^-15 centimeter. Leptons have no internal structure, at least down to 10^-16 centimeter. Quantum electrodynamics requires leptons to be points.
forces
Weak nuclear force affects leptons, but strong nuclear force does not affect them. They have no color charge. Weak nuclear force causes one-quarter of lepton mass.
charge
Electron, muon, and tau particle leptons have charge -1 unit. Neutrinos have charge 0 units. Charge causes part of lepton mass. Lepton charge is sum of infinite negative charge, surrounded by positive-charge cloud induced by negative charge.
lifetime
Electrons cannot decay to smaller particles, so electrons have infinite lifetime.
isospin
Electrons, muons, and taus have weak-isospin third component -1/2, while all neutrinos have +1/2.
quarks
Quarks and leptons are similar. Both are point-like, pair, and have six types.
Negatively charged particles {electron}| rapidly orbit atomic nuclei at varying distances. Electron mass is 10^-27 grams or 0.511 MeV. Electron charge is -1. Lifetime is infinite. Protons equal electrons in neutral atoms. Electrons travel 10^-14 meters in 10^-8 seconds in one orbit.
Leptons {muon}| can be more massive than electrons. They can be in particles caused by cosmic rays hitting upper atmosphere. Muons have masses 204 times electron mass or 106 MeV. Lifetime is 2.2 x 10^-6 seconds, because muon can decay to electron. Muons have electric charge -1. Muon has associated neutrino. Muon has weak-isospin third component -1/2.
Atoms can have muons instead of electrons. Collisions can make two muons {dimuon event} or three muons {trimuon event}. These collisions demonstrate charmed particles and heavy leptons.
Leptons {neutrino}| can have almost no mass, zero charge, and half-integer spin.
types
Electrons {electron neutrino}, muons {muon neutrino}, and taus {tau neutrino} have neutrinos {flavor, neutrino}. Electron neutrinos have masses less than 54000 times electron mass. Muon neutrinos have masses less than 367 times muon mass. Tau neutrinos have masses less than 58 times tau mass. Neutrinos can change into each other, if neutrino mass is greater than 1 eV. Interaction with surrounding matter and energy causes neutrino masses to oscillate from electron to muon to tau neutrinos as they travel.
mass
Fewer neutrinos than expected come from Sun, because they have mass.
forces
Neutrinos do not feel strong force or electromagnetic force, only weak force and gravity. Neutrinos have two orthogonal linear-polarization states at 180-degree angle. Perhaps, weak force does not affect a possible fourth neutrino type {sterile neutrino}.
interactions
Because they have little mass and no charge, neutrinos pass through matter with few interactions. 10^12 neutrinos pass through people each second, because Sun radiation is 10% neutrinos.
antineutrino
Antineutrinos have one-third neutrino cross-sectional area.
Electron antiparticles {positron}| have +1 charge.
Leptons {tau particle}| {tauon} [found in 1975] can be heavier than muons. Tau particles have masses 3519 times electron mass or 1.78 GeV. Electric charge is -1. Lifetime is 0.3 x 10^-12 seconds, because tau can decay to electron. Tau has associated neutrino.
Baryons have units {quark}|. Quarks have no internal structure, have diameter 10^-15 meters, and feel all forces.
types
Up quark has lowest mass, 2 MeV, one-ninth proton mass and nine times electron mass.
Down quark is slightly heavier, 5 MeV, 14 times electron mass.
Strange quark has one-third proton mass, 95 MeV, 1.5 times muon mass. Strange quark is 20 times bigger than up or down quark. Strange quarks are in kaons.
Charmed quark has 1.5 times proton mass, 1.25 GeV, 15 times muon mass. Charmed quarks are in J (psi) particles.
Bottom quark has one-third proton mass, 4.2 GeV, 2.7 times tau mass. Bottom quark is 600 times bigger than up or down quark. Bottom quarks are in B mesons.
Top quark [1995] has 1.5 times proton mass, 171 GeV, 99 times tau mass. Top quark has same mass as osmium.
flavor
Quarks have six flavors: upness, downness, strangeness, charm, topness, and bottomness.
charge
Up, charmed, and top quarks have charge +2/3. Down, strange, and bottom quarks have charge -1/3. The weak interaction has a quantum number T (weak isopin), which has three components. The third component T3 is conserved in all weak interactions (weak isospin conservation law) and in all interactions.
Fermions have spin 1/2. If spin direction and the direction of motion are the same, fermion helicity is right-handed, and spin is counterclockwise +1/2. If spin direction and the direction of motion are the opposite, fermion helicity is left-handed, and spin is clockwise -1/2. Massless particles move at light speed, so all observers see the same helicity. Observers can move faster than massive particles, so such observers see helicity change.
Particles have transformations, some of which (chiral transformations) can be different for left-handed or right-handed particle properties. For example, left-handed fermions have weak interactions, but right-handed fermions do not. Most transformations (vector transformations) are the same for both left-handed and right-handed properties.
Transformations can be symmetric or anti-symmetric, with parity even or odd, respectively. Most transformations involving left-handed and right-handed conserve parity (chiral symmetry), but weak interactions do not.
Left-handed fermions have spin -1/2, have negative chirality, have T = 1/2, are doublets with T3 = +1/2 or -1/2, and so have weak interactions. Right-handed fermions have spin +1/2, have positive chirality, have T = 0, are singlets with T3 = 0, and so never have weak interactions.
Electromagnetism and the weak interaction interact (electroweak). Electromagnetism has electric charges. The weak interaction has gauge bosons W+, W-, and W0. The electroweak interaction has a weak hypercharge Yw that generates the U(1) group of the electroweak gauge group SU(2)xU(1). The (unobservable) gauge boson W0 interacts with weak hypercharge Yw to make (observable) Z gauge boson and photon. For left-handed quarks, Yw = +1/3 or -1/3. [In grand unified theories, weak hypercharge depends on the conserved X-charge and on baryon number minus lepton number: Yw = (5 * (B - L) - X) / 2.]
To make interactions renormalizable, a group of interactions must cancel all asymmetries (anomaly cancellation). The weak interaction has both charge and parity asymmetry, and does not conserve charge or parity, but the electroweak interaction cancels all asymmetries and conserves charge-parity-time (CPT conservation) together ['t Hooft and Veltman, 1972]. This requires that electric charge Q be related to weak isospin T3 and weak hypercharge Yw: Q = T3 + Yw / 2. For left-handed quarks, T3 = +1/2 or -1/2, and Yw = +1/3 or -1/3, so Q = +2/3 or -1/3.
isospin
Quarks are fermions. Up, charmed, and top quarks have weak-isospin third component +1/2. Down, strange, and bottom quarks have weak-isospin third component -1/2. Quarks have no right-handed weak-isospin components.
pairs
Six quarks have three pairs: up and down {up quark} {down quark}, strange and charmed {strange quark} {charmed quark}, and top and bottom {top quark} {bottom quark}.
lifetime
Up quark has infinite lifetime, because it cannot decay to anything. Other quarks can decay to lower-mass quarks. For quark pairs, one can change to the other by emitting W particle or Z particle.
distance
After distance, strong nuclear force stays constant with distance. Inside distance, quarks move freely. After distance, quarks have constant force between them, so they cannot separate. Quarks must be in mesons or baryons. Strong nuclear force makes quarks orbit in shells at relativistic speed.
Perhaps, empty space superconducts color charge and can contain color-charge flux as discrete quanta. Strings between particles are fundamental with derived fields, as in string theory, or color-charge field is fundamental with derived space structure, as in quantum chromodynamics.
leptons
Quarks and leptons are similar. Both are point-like, pair, and have six types.
neutron magnetic moment
Quarks can explain the magnetic moment that zero-charge neutrons have, because quarks have charges.
Quarks have property that uses red, green, or blue {color charge}| to show how they combine to make baryons and mesons, which have no color.
Quark types have one of six properties {flavor, quark}|: upness, downness, strangeness, charm, topness, and bottomness.
5-Physics-Matter-Particle-Subatomic
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Date Modified: 2022.0225