1. Stavebné kamene tohto sveta
Trenčín,
Stavebné kamene tohto sveta
Ivan Melo

2. 2

3. Rutherfordov experiment 1908 - 1913

4. Od atómov ku kvarkom 4

5. Fermióny

6. Bozóny

7. Antičastice

8. Čo lepí základné kamene do štruktúr?
….sily

9. Sila mení hybnosť

10. Sila zodpovedá za vznik a zánik častíc

11. Štyri základné sily 11

12. Predpoveď

13. Predpoveď výsledku merania nie je jednoznačná

21. W and Z decays
Higgs decay events:
H ZZ e+e-e+e-
H ZZ e+e-μ+μ-
H ZZ μ+μ-μ+μ-
H γγ

22. Higgs production

23. Higgs decay

24. Discovery of Higgs-like particle
H → l+l-l+l-

25. Žilina,
Z bozóny na LHC
Ivan Melo

26. Z bozón je produkovaný minimálne 4 spôsobmi:
1. q antiq → Z (q = u alebo d)
2. g q → Z q (g = gluon)
3. q antiq → Z g
4. g g → q antiq Z

31. Kritériá pre Z bozón Z eventy vs pozadie
● chýbajúca priečna energia ETMiss < 25 GeV
● elektrón-pozitrón alebo mión-antimión IZOLOVANÉ od
jetov
● priečna hybnosť leptónov > 25 GeV
● l+l- musia pochádzať z jednej zrážky (vylúčiť pile-up)
● l+l- sú zvyčajne kolineárne v priečnej rovine, ale NEMUSIA
byť
Z eventy vs pozadie

32. How many peaks are there in the mass plot?
Where is the Z peak? What is the mass of the Z boson?
What do the other peaks mean?
Where is the ZZ peak in the plot? Why that mass?
What is the ratio of electrons to muons? Is it close to what we should expect?
What is the W+/W- ratio? What should it be?

33. How many peaks are there in the mass plot?
J/ψ bound state c/anti c, 3.1 GeV, l+l %
ϒ bound state b/anti b GeV, l+l %
Z mediator of weak interaction, GeV, l+l %
ZZ H Higgs boson, 126 GeV decays to ZZ -> 4 l %
The rest are not peaks, just B fluctuations or analysis errors
Where is the Z peak? What is the mass of the Z boson?
What do the other peaks mean?
Where is the ZZ peak in the plot? Why that mass?
Mass Z + mass Z > mass H ??? (one Z is „virtual“)
What is the ratio of electrons to muons? Is it close to what we should expect?
1 … because both W and Z decay democratically into e/mu

34. What is the W+/W- ratio? What should it be?
R = W+/W- > 1

35. In the videoconference, studenta might ask questions like
Why are the widths or heights or numbers of peaks different from one Institute to the next?
Why do different Institutes get different ratios? How did they identify electrons or muons or W candidates or Z candidates or zoo events? How did they measure charge for W candidates?
Now that the Tevatron is shut down, what do you do at Fermilab?
Is it boring at CERN when the LHC is not running?
Why did you become a physicist?
...and better questions which only students can create.