the story of quarks the first two, then three…eventually 6…quarks or partons
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The Story of Quarks the first two, then three…eventually 6…quarks or partons all hadrons made up of quarks to “explain” their quantum numbers …partons to describe their scattering behavior. bubble chamber recordings all “strange” particlesmade in association with each other - PowerPoint PPT PresentationTRANSCRIPT
The Story of Quarksthe first two, then three…eventually 6…quarks or partons
all hadrons made up of quarks to “explain” their quantum numbers
…partons to describe their scattering behavior
bubble chamber recordings
all “strange” particlesmade in association
with each other
…they come in pairs
invent a new “charge,”
strange charge
that is conserved
…see how the Λ got its name
Fig 46-11a, p.1528
Discovery of the Omega-
the octets of the Eightfold Way…
spin = ½ = ↑↑↓ spin = 0 = ↑↓
B=1 baryons, “nucleon-like” B=0, mesons, “generalized pions”
bary = heavy, > 1 GeV meso = medium weight, 0.1 -0.5 GeV
Q = charge, S = strangeness
really nonets and decuplets
the excited nucleon, the Δ++ resonance…width lifetime
the hunt for the omega minus…spin = 3/2 = ↑↑↑ B=1 …the decuplet
family of 4 excited → nucleons
doubly charged ↓
Ω-
some examples:
all conceivable combinations of quark & antiquark found…and nothing else
all conceivable combinations of 3 quark found…and nothing extra
in the end, 6 quarks discovered…the t (top) only a few years ago
we study the point-like electron with point-like neutrinos
W+
-1/3
+2/3
probing the quarks with point-like neutrino
…behave identically as electrons
individual current quarks inside composite particle scatter
remaining mystery…the problem of mass:
if you scatter quarks with electrons or neutrinos, you get mu ~ 5 MeV, md ~ 7 MeV, …the vast majority of the momentum is carried by gluons!
naively dividing the rest mass of the composite particles among quark constituents, you get much different rest energies: