1. Liang Shang, Henan Normal University IHEP 2016.06.14
Explanation of the ATLAS Z-peaked excess
in the NMSSM
Liang Shang, Henan Normal University
IHEP

2. I Monte Carlo simulation in collider physics
1. Why do we need to do MC simulation?
2. How to do MC simulation in collider physics?
3. Which kind of work can MC simulation do?
II Work: Explanation of the ATLAS Z-peaked excess in the NMSSM
1. The ATLAS experimental report for Z-peaked excess
2. The explanation of the Z-peaked excess
III Introduction: Implement New Analysis into CheckMATE
1. Why do we use CheckMATE for analysis?
2. Information putting into CheckMATE
3. Easiest to do one task oneself
IV Summary

3. I Monte Carlo simulation
in collider physics

4. 1.Why do we need to do MC simulation?
Theory Experiment
𝜎𝐿𝜖=𝑁

5. 1.Why do we need to do MC simulation?
Monte Carlo methods (or Monte Carlo experiments) are a broad class of computational algorithms that rely on repeated random sampling to obtain numerical results. Monte Carlo methods are mainly used in three distinct problem classes: optimization, numerical integration, and generating draws from a probability distribution.

6. 2.How to do MC simulation in collider physics?
a. PDF
CTEQ6L1, …
b. Hard scattering
MadGraph/MadEvent, SHERPA, …
c. Parton Shower
Hadronization
PYTHIA
d. Detector
Delphes, PGS, GEANT4, …
FastJet
MG/FR School, Beijing, May 22-26, 2013, Johan Alwall

7. a. PDF b. Hard scattering c. Parton Shower Hadronization d. Detector
CTEQ6L1, …
b. Hard scattering
MadGraph/MadEvent, SHERPA, …
c. Parton Shower
Hadronization
PYTHIA
d. Detector
Delphes, PGS, GEANT4, …
FastJet

8. a. PDF b. Hard scattering c. Parton Shower Hadronization d. Detector
CTEQ6L1, …
b. Hard scattering
MadGraph/MadEvent, SHERPA, …
c. Parton Shower
Hadronization
PYTHIA
d. Detector
Delphes, PGS, GEANT4, …
FastJet

9. a. PDF b. Hard scattering c. Parton Shower Hadronization d. Detector
CTEQ6L1, …
b. Hard scattering
MadGraph/MadEvent, SHERPA, …
c. Parton Shower
Hadronization
PYTHIA
d. Detector
Delphes, PGS, GEANT4, …
FastJet

10. a. PDF b. Hard scattering c. Parton Shower Hadronization d. Detector
CTEQ6L1
b. Hard scattering
MadGraph/MadEvent, SHERPA, …
c. Parton Shower
Hadronization
PYTHIA
d. Detector
Delphes, PGS, GEANT4, …
FastJet

11. 3. Which kind of work can MC simulation do?
arXiv:

12. 3. Which kind of work can MC simulation do?
arXiv:

13. 3. Which kind of work can MC simulation do?
arXiv:

14. 3. Which kind of work can MC simulation do?

15. II Example-- Work Explanation of the ATLAS Z-peaked excess
in the NMSSM
arXiv:

16. arXiv:

17. 1. The ATLAS report
general gauge mediation models

19. Event selection

20. Result
3.0σ

21. The ATLAS Z-peaked excess
29.6 12
= 18.4

22. End of the Story? ATLAS: Excess! 2~6 Jets +MET : Null!q
2~6 Jets +MET : Null!
Multi-Jets +MET : Null!

23. Not GGM! Multi-Jets +MET : Null! 2~6 Jets +MET 0 GeV for GGM
Z-peaked Excess in GGM

24. 3. Explanation
( 𝑊 , 𝐻 𝑢 , 𝐻 𝑑 )
( 𝑊 , 𝐻 𝑢 , 𝐻 𝑑 )

25. Work flow Fastjet MadGraph/MadEvent Pythia Delphes Parton Level Event
Hardron Level Event
Detector Level Event
CheckMATE
arXiv:
.root

26. CheckMATE

27. The explanation in NMSSM
By gluino pair production

28. III CheckMATE --Add New Analysis into CheckMATE

29. CheckMATE
Authors: Manuel Drees, Herbi Dreiner, Jong Soo Kim, Daniel Schmeier, Jamie Tattersall, Krzysztof Rolbiecki

30. 1.Why do we use CheckMATE for analysis?
Analysis frame: in analysis frame Focus on how to add cuts
1. Final objects:
“Loose”, “Tight”, “Medium” electron in ATLAS
“Combined” and “Segment-tagged”, “Combined+Segment-tagged” muon in ATLAS
2. kinematical variables
“ 𝑀 𝑇 ”
“ 𝑀 𝑇2 ”
“ 𝑀 𝑇2 W ”
3. Root integrated
TLorentzVector class: Δ𝜙= 𝜙 1 − 𝜙 2 , Δ𝑅= Δ 𝜙 2 +Δ 𝜂 2 , vector1.M(vector2)
Histogramming
Statistical functions
4. Helper functions
CountSignalEvent: trigger CheckMATE evaluation
filterPhaseSpace: simplify basic cuts - avoid multiple loops!
Ref: arXiv: , arXiv:

31. 2.Information putting into CheckMATE
1. Author and analysis card information
1. Analysis Name, c.m.s, luminosity
2. Author name,
2.Properties of Final States
Isolation criteria for lepton
Jet clustering algorithm
B-jet tagging efficiency
3. Information of Signal regions
Signal name
Observed number of events, SM expectation and associated error
Questions and Answered
by ./AnalysisManager
4. Information of cuts
Basic cut
Cut for phase space: Pt and eta
Isolation condition and Overlap removal
Event selection cutting
M, HT, …
C++
Initialize()
Finalize()
Analyze()

32. A atlas_zpeak 3. Example：ATLAS Z-peak Excess 1. ./AnalysisManager 2.
arXiv: and 2. A
3. The description for the new analysis
atlas_zpeak

33. arXiv: 1503.03290 General Information
4. Name of Signal Region and events’ number
arXiv:
General Information

34. 1. Information for isolation criteria
Track
400MeV
DR=0.3
PT < 16%

35. 2. Information for jets’ construction
PT>20GeV

36. 3. Information for b-jets
yes 60

38. initialize(): initialize variables and open files, etc.
Success!
4. Information of cuts
Basic cut
Cut for phase space: Pt and eta
Isolation condition and Overlap removal condition
Event selection cutting
M, HT, …
C++
initialize(): initialize variables and open files, etc.
finalize(): free pointers and close file, etc.
analyze(): core
atlas_zpeak.cc

39. 1. Type of lepton and cuts for phase space

40. 2. Overlap Removal

41. 3. Isolation Condition

42. Event selection – example: M()

43. Add new Analysis into CheckMATE
Ref:

44. SUMMARY I Monte Carlo simulation in collider physics
1. Why do we need to do MC simulation?
Monte Carlo simulation studies of physics processes at colliders
2. How to do MC simulation in collider physics?
MadGraph/MadEvent, Pythia, Delphes, Root, CheckMATE, …
3. Which kind of work can MC simulation do?
Constraint, Prediction, Improve, Explanation
II Work: Explanation of the ATLAS Z-peaked excess by gluino pair
in the NMSSM
1. The ATLAS experimental report for Z-peaked excess
Process, identification, selection, results
2. The explanation of the Z-peaked excess
𝑚 𝑔 =750𝐺𝑒𝑉, 𝑚 𝜒 =650𝐺𝑒𝑉, 𝑚 𝜒 =565𝐺𝑒𝑉 can explain at 1.3𝜎
III Introduction: Implement new analysis into CheckMATE
1. Why do we use CheckMATE for analysis?
Final objects, kinematical variables, Root integrated, Helper functions
2. Information putting into CheckMATE
Questions and Answered, analysis code in C++
3. Easiest to do one task oneself
Atlas_zpeak

45. We ARE JUST ON THE WAY
Thank you.

47. 2.How to do MC simulation in collider physics?
MET

48. arXiv:

49. 2.How to do MC simulation in collider physics?
arXiv:
arXiv:

52. Why do we need to do MC simulation?

53. 1. Brief introduction of SUSY
( 𝐵 , 𝑊 3 , 𝐻 𝑢 0 , 𝐻 𝑑 0 )
( 𝜒 1 0 , 𝜒 2 0 , 𝜒 3 0 , 𝜒 )
MET SM
MSSM
𝑊 𝐻 +
𝜒 𝜒 2 +

54. Result
arXiv:

55. By squark pair production

56. Conclusion