The Nobel Prize in Physics 2004

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The Nobel Prize in Physics 2004
"for the discovery of asymptotic freedom in the
theory of the strong interaction
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• Interactions of Forces in Nature

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fundamental particles
?

• electron
• proton
• neutron

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fundamental particles
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hadrons

• not fundamental
• made up of even smallerparticles, quarks
• 3 different generations of quarks

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The Origin of Quarks

• The theory behind quarks was first suggested
  by physicists Murray Gell-Mann and George Zweig,
  who found they could explain the properties of
  many particles by considering them to be composed
  of these elementary quarks. The name quark comes
  from "three quarks for Muster Mark", a phrase in
  James Joyce's Finnegans Wake. According to The
  American Heritage Dictionary of the English
  Language Fourth Edition, the word quark as used
  by Joyce is the standard English verb quark,
  meaning "to caw, croak." The reference to three
  quarks in Joyce's phrase caught Gell-Mann's
  attention as particularly suggestive of the
  particle's circumstances.

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hadrons

• the combination of these 6 types of quarks make
  up hundreds of hadrons
• 1st generation quarks (up/down)found in the
  proton and the neutron, the nucleons of normal
  matter
• other quarks are found in experiments, not in
  daily life

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1st generation quarks
updowndown
upupdown
proton
neutron
2/3 2/3 -1/3 1
-1/3- 1/3 2/3 0
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binding the nucleus

• the nucleus of helium contains two protons which
  are both positively charged. they should repel
  each other but they do not. why?

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the strong force

• an attractive force
• has an effect over a very short range(10-15 m,
  about the size of the nucleus)
• leptons dont feel this force, but particles in
  the quark family do.

strongnuclear force
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Strong Force and Color Charge
In 1965 Moo-Young Han and Yoichiro Nambu
suggested quarks possess color.

•  

Color is also called color charge.Like colors
repel. Unlike attract. Color-AntiColorattractio
n is stronger.Blue-AntiBluestronger
thanBlue-Red, forexample
The "color" attribute is not traditional
colorthe name is somewhat arbitrary, and
almostas whimsical as the names of the quarks.
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Quark-Containing Particles are White

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  Pi-mesons contain only two quarks.
  
  For example

Protons and neutrons contain three quarks
Anti-red minus red,   is white
Protons and neutrons each  contain a  red, blue,
and green quark.
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The Strong Force

• Gross and Wilczek and independently Politzer
  made the key discovery of how the "strong" force
  works to bind the constituent elements, called
  quarks, of protons and neutrons (the particles
  that make up the nucleus of atoms). The other
  three forces of nature--electromagnetism, the
  weak force (responsible for radioactive decay),
  and gravity all diminish in strength with
  distance. They discovered that the strong force
  grows stronger with distance.

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Asymptotic Freedom

• This discovery called "asymptotic freedom"
  means that attempts to pull the quarks inside
  protons and neutrons apart increase the strength
  of the force binding them.

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Infra-red Slavery

• The flip side of "asymptotic freedom" has been
  described as "infra-red slavery." Since the force
  that binds quarks inside protons and neutrons
  grows stronger with distance, protons and
  neutrons can't be dismantled into constituent
  quarks. This part of the Gross-Wilczek discovery
  is called "confinement."

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