Anomalous Rings in the DELPHI Barrel RICH 9

1. Anomalous Rings in the DELPHI Barrel RICH 9 12 June 2013 Vassili Perepelitsa ITEP, Moscow/IFIC, Valencia

2. Agenda • Addressing some questions of the previous meeting • Study of topology 2 background with real events a) background rings b) events with multiple anomalous rings • Test of standard rings with developed proto-MC • Conclusion

3. Agenda • Addressing some questions of the previous meeting • Study of topology 2 background with real events a) background rings b) events with multiple anomalous rings • Test of standard rings with developed proto-MC • Conclusion

4. Standard rings • Liquid radiator: Rmax = 667 mrad Upper limit for R at DST production: 750 mrad • Gas radiator: Rmax = 62-63 mrad Upper limit for R at DST production: 102 mrad

5. Peculiar event 88336:1338 • Invisible tracks (?) • producing very strong response in corresponding drift tubes • but without HPS showers • however with a tachyon kinematics justifying the track invisibility • Why are the HPC showers absent? Another tachyon specimen, effect of the angular momentum conservation for high velocity tachyons, or just a background?

8. Gas ring of a radius of 1080 mrad Full pattern

9. Gas ring of a radius of 1080 mrad Without sector 20

10. Gas ring of a radius of 970 mrad

14. A method to study the background to topology 2 with real data events • The di-muon event sample does not have the same background characteristics as two-electron event sample. • Just take two-electron events and look for anomalous rings in them with the same tools as in the main analysis. • Number of events, candidates to topology 2, scanned in the main analysis, is about 550; scan at least the same number of two-electron events in order to estimate the level of all possible backgrounds. • At the moment about 300 two-electron events were scanned; 4 events satisfying all the criteria for tachyonic candidates were found, all of them pertaining to topology 3.

15. Jacobian Rings

16. Liquid Ring ``reflected” in gas radiator detector

17. Moderate background rings(probability to be composed of random hits is (1-10)% BG probability = 5% BG probability = 6%

18. Prominent Background Rings(probability to be composed of random hits is below 1%) • Expected ring number: 1 to 6 • Found: 2 (or more?)

22. A prominent background ring(probability to be composed of random hits is below 1%)

23. Standard Ring in the same event

28. Events with multiple anomalous rings(combined probability to be composedof random hits < 0.1%) • Expected: < 0.6 • Found: 4 (will be shown in the order of increasing beauty)

30. No dE/dx available

35. Standard Liquid Ring

36. 1st Liquid Anomalous Ring, R=735 mr

37. 2nd Liquid Anomalous Ring, R=1015 mr

38. Gas Radiator Patterns

39. Standard Gas Ring

40. 1st Gas Anomalous ring, R = 865 mr(corresponding to Liquid radius 1034 mr)

41. 2nd Gas Anomalous Ring, R = 322 mr (corresponding to Liquid radius 727 mr)

42. cleaned region

43. 2nd Gas Anomalous Ring, cleaned

44. Results of kinematic fit (1C-fit) • Numberofconstraintequations: 4 + 2 = 6 • Unknowns: μ, perec, pt1, pt2, qquartz • Fit results (χ² = 0.02): μ = (6.1 ± 2.3) GeV/c² pt1 = (8.1 ± 3.0) GeV/c pt2 = (18.6 ± 7.3) GeV/c perec = (58.1 ± 16.1) GeV/c qquartz = (3.8 ± 4.7) GeV/c Ringradii,measured: Liq1 = (1015±20) mr, Liq2 = (715±10) mr after fit: 1034 mr 727 mr Gas1 = (864±20) mr; Gas2=(322±10) mr (not changed after fit)

48. positive

50. 4 arguments in favour of a double structure of the track: 1. Double dE/dx 2. Visible indication for the track splitting 3. Two OD track elements (see below, slide 56) 4. Charge conservation argument dE/dx = 3.76±0.81