The document discusses hadrons, which are particles that experience the strong force. Hadrons include protons and neutrons, which make up normal matter, as well as other unstable particles that decay within fractions of a second. Physicists study these unstable hadrons because their properties helped reveal that protons and neutrons are made up of even smaller particles called quarks, allowing scientists to better understand the structure of matter at the subatomic level. The document outlines the different groups of hadrons and introduces the quark model developed in the 1960s to explain the characteristics of hadrons in terms of arrangements of quarks.

1. The Family of Hadrons
Nat Sci 1
January 18, 2008

2. • Strong force
• Hadrons- Definition
• Groups of hadrons
• Quarks

3. The Strong Force
• A short-range force that attracts
protons and neutrons together
• Holds the nucleus together

4. Hadrons
• The family of particles that feel the
strong force
• Includes protons and neutrons

5. Hadrons
• Except the protons and neutrons, all
the hadrons are very unstable and
decay within a hundredth of a second
and do not form part of normal matter.

6. So why are they useful to
physicists??

7. …it’s because…
• the existence and properties of the
other hadrons allowed physicists to
develop the quark model and
understand the structure of protons
and neutrons!!!

8. Hadrons
• Gell-Mann and Ne’eman tried to
simplify the picture by putting the
hadrons into family tables like
Mendeleev’s Periodic Table to look for
patterns which they could then explain
using more fundamental particles.

9. Groups of Hadrons
• Mesons- with spin 0
• Baryons- with spin ½ or 3/2

10. Quarks
• In the 1960s, Gell-Mann and Zweig
suggested that all hadrons, including
protons and neutrons, are made from
smaller particles called quarks.
• They explained the different properties
of all the hadrons in terms of different
arrangements of quarks.

11. Quarks
• They are unusual due to the fact that
they have a fractional electric charge,
unlike protons and electrons.
• There are three generations of quarks.

12. THANK YOU!!!