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Azimuthal distribution of diffractive pions in DIS

Azimuthal distribution of diffractive pions in DIS. Richard Polifka, Charles University, Prague 8. - 9.12.2005, Antverpen. motivation. Study of diffractive DIS of non resonant di pions in invariant mass range 1.1 – 3 GeV (between  and J/ Ψ )

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Azimuthal distribution of diffractive pions in DIS

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  1. Azimuthal distribution of diffractive pions in DIS Richard Polifka, Charles University, Prague 8. - 9.12.2005, Antverpen

  2. motivation • Study of diffractive DIS of non resonant di pions in invariant mass range 1.1 – 3 GeV (between  and J/Ψ) • Looking at angular distribution of pion and lepton plane in gamma-p CMS to distinguish between 2 gluon exchange model and pomeron exchange model

  3. motivation Pi+ Picture 2. Schematic diagram of 2 gluon exchange Pi- Pion plane Picture 1. Definition of pion and lepton plane

  4. sources • DATA – 99/00, still using only 00 • MC – rapgap inclusive diffraction at medium Q2 from Tinne Anthonis for 99/00 • Pomeron uds – 12 500/1 500 000 • Pomeron c – 0/500 000 • Meson – 350/3 000 000 => Pomeron uds

  5. basic cuts • Q2 = < 3.5,100> GeV2 • Run Quality < 3 • Ybjörken=< 0.05 , 0.7 > • | ZVTX | < 35 cm • E-Pz =< 35, 70> GeV • Good electron cuts: only 1 electon in elmg candidates, E in SpaCal > 8 GeV, RSpaCal > 9.1 cm, excluded some runs because of unfunctional clusters…

  6. pion cuts • Based on Light VM Finder by X. Janssen and C. Gwilliam • 2 opposite charged tracks in central region coming from primary vertex • Pt > 0.1 GeV •  = < 20° , 160° > • No neutral particle with E > 0.4 GeV in Lar or SpaCal

  7. diffractive and noise cuts • Usually MAX < 3.2, but here not needed • Xpom < 0.04 • Invariant Mass =<1.1 , 3 > GeV • No noise in PRT • In first 2 plates of Forward Muon Detector allowed some noise

  8. comparison of data & mc • 12 500 mc x 776 data events => big error for data, my mc more or less describe data => look into mc to see what’s happening • weighting with L4 and L5 weights ( standard HAT vars)

  9. looking into hadron & parton level to see what in the event is going on Good event record Background event record

  10. realisation • Comparing several variables and trying to find some, which can on detector level distinguish between good and background events • Not much differencies

  11. comparison of good and background events

  12. comparison of good and background events

  13. E – Pz > 50 GeV Ionisation < 2.3

  14. effects ( from 776 data events) => 626 events left

  15. comparison of data before (old) and after cuts (new)

  16. comparison of data and monte carlo

  17. comparison of data and monte carlo

  18. subtriggers s0 is on in only 24%, s61 in 100% cases 146 from 626 !!

  19. outlook • Too small statistics => idea of cone in SpaCal ( no need to exclude whole SpaCal, many good events with radiated gamma) • Cut on s0 = true would brutally decrease statistics => ? • Add data 99 • Put data and mc in better agreement

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