Download Plasma = a fluid of free charged particles

Plasma = a fluid of free charged particles
Maxwell’s eqn’s:
+ Newton’s laws Î Magnetohydrodynamics
(MHD)
“Frozen in” fields:
•
•
•
Field lines and charged particles move together.
Takes energy to squish field lines closer together
Takes energy to stretch field lines.
The Sun’s magnetic field
Charged particles
in magnetic field
feel Lorenz force:
Magnetic
Field Lines
Force
B (mag field)
velocity
X-ray flare movie
http://farside.ph.utexas.edu/teaching/plasma/lectures/node60.html
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The History of the Universe
Nucleosynthesis
Planck
Galaxy
of H, He, Li
time
Formation
Decoupling
Inflation
of CMB
Now
Hot
Cool
High density
Low density
Interactions
Four forces in Nature
1 Gravity
3 Weak Interaction
Newton
Beta (radioactive) decay
Muon decay
Time scales: 10-12 ~ 103 sec
2 Electromagnetism
Faraday
4 Strong Interaction
Hold nuclei together
Particle collision
Time scales: 10-23 sec
(These slides compliments of Prof. Yuan)
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Leptons
• Don’t feel the strong force
• Integer or Zero charge
• Flavours:
e−
“electron”
(1897)
In atoms
(1937)
First seen in Cosmic Ray
(1975)
Seen at SLAC
(0.511 MeV)
µ−
“Muon”
(206 me)
τ−
“Tau”
(17 mµ)
νe
( Stanford Linear Accelerator Center)
“electron neutrino”
(1956)
Pauli’s explanation of Beta Decay (1930)
Mass
νµ
“Muon neutrino”
(1962)
ντ
ν e < 3 eV
ν µ < 0.19 MeV
“Tau neutrino”
(2000)
ν τ < 18.2 MeV
Quarks
• Feel the strong force
• Fractionally charged
 2 
 3 
Q=
 × Proton charge
− 1 3 
• Constituents of neutron and proton
(udd)
( )
u
d
• Flavors:
u
d
s
c
b
t
(uud)
“up”
“down”
“up”
“down”
“strange”
“charmed”
“bottom”
“top”
Baryon
A strongly interacting particle that is
composed of quarks and has a spin
that is an integer multiple of ħ
(e.g., a quark, neutron, or proton).
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The Standard Model of Particle Physics
™ Matter fields (make up all visible matter in the universe)
ƒ Fermions (Spin 1/2)
Lepton
(
No Strong
Interaction
Quarks
(q)
)
u
 
 d L
νe 
 −
e L
νµ 
 −
µ L
ντ 
 −
τ L
eR−
µ −R
τ−R
u
 
 d L
c c c
     
 s L  s L  s L
u
 
 d L
t 
 
 b L
t
 
 b L
t
 
 b L
uR uR uR
c R c R cR
tR tR tR
dR dR dR
sR sR sR
bR bR bR
14444444244444443
3 families
ƒ Scalar (Spin 0)
Higgs Boson
( Not yet found! )
( From Higgs Mechanism
Spontaneous Symmetry Breaking)
The Standard Model of Particle Physics
™ Interactions ( mediated by interchanging Gauge Bosons, spin-1 force carrier )
1) Electromagnetic Interaction (QED)
Photon
(massless)
2) Strong Interaction (QCD)
Gluon
(massless)
(1979)
3) Weak Interaction
W + , W − and
(
Z Gauge Bosons
massive M W = 80.4 GeV
M Z = 91.187 GeV
In SM, the Mass of W-boson, either W
±
(1983)
1 GeV = 109 eV
)
or Z , arises from the
Higgs Mechanism
( Without it, Gauge Bosons have to be massless from gauge principle.)
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“Freezing out” of the four forces:
Theory of
Everything
Grand
Unified
Theory
• Massless gauge bosons.
• Many additional
massive particles
(dark matter candidates)
• Quarks
• Massive gauge bosons
• Leptons
• Gluons
• Photons
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