Project 1 To be delivered 4. February 2015 1.
State whether the following processes are allowed or not. Classify them according to the underlying interaction and draw the corresponding Feynman graphs. 2.  For each particle decay, indicate the lifetime and the branching ratio. 3.  What conservation laws, invariance principles, or other mechanisms account for the suppressing or forbidding of some processes. 4.  Why are processes 1, 4, 7 and 8 rather special? Justify and tell more. 1.
1. e+e− → qqg
2. γγ → e+e−
3. e+e− → γγγγγ
4. pp → l +l − X
5. τ + → µ +ν µν τ
6. K − p → Ω− K + K 0
7. ν ee− → ν ee−
8. pp → l +l −l +l − X
9. e+e− → Z 0 H
10. e+e− → W +W −γ
11. e+e− → ZZγ
12. gg → H → γγ
13. e+e− → ννγγ
14. gg → ttH
15. e+e− → Υ(4s) → B 0 B 0
16. gg → ggg
17. e+e− → qqggg
18. ep → cc + X
19. K 0 ↔ K 0
20. e+e− → Z 0 bb
1.
2.
3.
Start by introducing the CKM matrix and the role of the W boson 1.
Explain how 3 of the matrix elements are measured experimentally. Discuss top-­‐quark producEon in electron-­‐positron, proton-­‐proton and proton-­‐anEproton collisions 1.  Consider single top and top-­‐anE-­‐top 2.  Feynman graphs? How does the top decay – 1.  Feynman diagram(s) 4.
2.  How is top idenEfied experimentally? 1.  Consider all possible categories of final states 2.  Find an ATLAS display of a top candidate and describe/comment it. 3.  What is special with the top quark compared to b-­‐quark and c-­‐quark? 1.  Consider theoreEcal and experimental aspects EsEmate the branching raEos of top quark decays t → b + cs ;
t → b + τ +ν τ
1.
Apply the gauge principle to Quantum Chromo-­‐Dynamics Go through all steps in detail 2.  Derive the QCD Lagrangian 3.  Compare to QED 1.
2.
What about involving weak interactions? No need to do all steps in detail. 2.  Optional: all steps. 1.