Introduction to Q

2. We are made of particles and so is
everything else in the universe! We know
now that just four kinds of building blocks
are needed to account for all of ordinary
matter. These particles are called:

3. The name "quark" was taken by Murray Gell-
Mann from the book "Finnegan's Wake" by
James Joyce. The line "Three quarks for Muster
Mark..." appears in the fanciful book. Gell-
Mann received the 1969 Nobel Prize for his
work in classifying elementary particles.

5. As we go to higher energy
particle collisions:
1) Wavelength probe is smaller
 see finer detail
2) Can produce more massive
objects, via E=mc2
Today, high energy accelerators produce
energetic beams which allow us to probe
matter at its most fundamental level

7. Quark Date Where
Mass
[GeV/c2]
Comment
up,
down
- -
~0.005,
~0.010
Constituents of hadrons, most
prominently, proton and
neutrons.
strange 1947 - ~0.2 discovered in cosmic rays
charm 1974
SLAC/
BNL
~1.5
Discovered simultaneously in
both pp and e+e- collisions.
bottom 1977
Fermi-
lab
~4.5
Discovered in collisions of
protons on nuclei
top 1995
Fermi-
lab
~175 Discovered in pp collisions
Notice the units of mass !!!
SLAC = Stanford Linear Accelerator
BNL = Brookhaven National LabProton mass = 0.938 [GeV/c2]

8.  6 different kinds of quarks.
 Matter is composed mainly
of up quarks and down quarks
bound in the nuclei of atoms.
 The masses vary dramatically
(from ~0.005 to 175 [GeV/c2])
 The heavier quarks are not
stable, and decay to lighter quarks
quite rapidly

9. 1.25 miles
Main Injector
Tevatron
Experimental areas
Top Quark
discovered
here at FNAL
in 1995.

10. ~ 6 ft

11. • Pros
–Explains zoo of hadrons economically
–Verified by high energy electron scattering
experiments
• Cons
–Isolated quarks have never been seen
–No explanation for qqq=baryon & qq =
meson rule
–Problems with Pauli exclusion principle

12. Thanks …