Post on 19-Jan-2021
• Main points of today’s lecture:– Charmonium etc.– fragmentation– weak interactions
• Main points of last lecture:– e++e- scattering, baryon
production and color– Color
• quark color• gluon color• color wavefunctions• hadron color
Physics 492 Lecture 34
In Charmonium
• We consider the bound state:cc
Where:
Except for F0, this is analogous to positronium.
The resulting spectrum
• Solving the Schrodinger equation:
Jπ = 0- 1+ 1- 0+ 1+ 2+ 2- 2-
Comparison to Positronium
• The systems are qualitatively similar.
Light quark pairs?
Fragmentation?
• What happens when energetic pairs are created.? qq
at large distances
Example
• consider the creation of an energetic pair.
cc
Weak interactions
• Examples of weak interactions:
Structure of weak decays
• Let’s consider microscopic behavior:
when there is a
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Looking ahead
#
Beta decay, double beta decay.
• two neutrino double beta decay
• Main points of today’s lecture:– Weak interactions and;
• double beta decay• lepton number
conservation in vertices• W, Z bozons• quarks
• Main points of last lecture:– Charmonium etc.– fragmentation– weak interactions– leptons
Physics 492 Lecture 35
Beta decay, double beta decay.
• two neutrino double beta decay
Beta decay, double beta decay.
• two neutrino double beta decay
0 Neutrino Double beta decayFor a Majorana neutrino, the difference between neutrino and antineutrino
is mainly the orientation of the spin relative to the momentum
neglecting orientation of s and p.
Double beta decay
• Present situation
can change orientation of p relative to s by a large Lorentz boost opposite to the direction of p
Lepton number conservation?
• What does experiment say about lepton number conservation? – are the muon and electron neutrinos different?
Other examples of Lepton number conservation.
W bosons
• W mass
• Vertex rules involving W’s
Things that do not occur at vertices• Focus on behavior at short times.
Quarks and quark flavors
• The rules governing quark flavor conservation are more complex:
Quark decay