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unscientific
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Homework Statement
(a) What are their vertex and propagator factors?
(b) Find the value of R.
(c) Explain the peaks at 3, 10 and 100 GeV.
Homework Equations
The Attempt at a Solution
Part (a)
They have the same propagator factor ##\frac{1}{P \cdot P}##.
Vertex factor for muon production is ##(1)(-1)g_{EM}^2 = -g_{EM}^2##.
Vertex factor for hadron production is ##\sum -q^2##.
Part (b)
In the rage of 2GeV to 20GeV, types of quarks produced: u,d,s,c,b.
[tex]R = 3 \times \frac{e^2\left( -\frac{4}{9} -\frac{1}{9} - \frac{1}{9} - \frac{4}{9} - \frac{1}{9} \right)}{-e^2} = \frac{11}{3}[/tex]
Factor of 3 comes from the 3 colours, R, G and B.
Part (c)
Masses of quarks: u, d ~ ##10^{-3} GeV##, s~ ##0.1GeV##, c~##1 GeV##, b~##4eV##, t~##170GeV##.
Peak at 3GeV comes from production of charmed quarks.
Peak at 10GeV comes from production of bottom quarks.
Peak at 100GeV comes from production of top quarks.