Status Report of electron response in φ crack

1. Status Report of electron response in φ crack Universiry of Rochester Yeonsei Chung, Geumbong Yu

2. For study • 1 million MC(Z→ee) used →Zewkae: Pythia MC with min bias events • Data set of bhel0d (high pt electron): 454 files read(~48G) • Eta towers, 19~32, used for both of electron and track. • For electron, tight central electron cut used except Et cut. • Cut strategy is to have clean Z sample by every possile tight cut.

3. Track selection • Track pt > 20 GeV • Opposite charge to electron’s • E/p<2.0 • Had/Em<0.05 • No other track within 0.4 cone of track. • All energy used in cut is 2x2 Cal energy. • To make similar condition of track with electron, raise track pt cut to 20 GeV. Footnote: we found the electron Et>25 GeV cut make bias in comparing E/p distribution of track and electron(higher E/p of electron than track). Therefore we tried to apply pt>20GeV to both of el and track.

4. Z mass To reconstruct Z we used 2x2 Cal data and track momentum for 4-vector of track. Emobject used for electron 4-vector. Monte Carlo Data 2x2 Cal E Track Mom

5. Zmass Selected Zmass 80< MZ < 100 2x2 Cal E Track Mom. used Black : overall dist. Blue : |rphi|<0.9 Green : |rphi|>=0.9 Data in dot trk |rphi|<0.9 In the case of Cal data, Z mass are strongly affected by hit position of phi since we lost energy in crack. But if we use track momentum for 4-vector of track, the shape is not changed by Relative phi position. trk |rphi|>=0.9 Crack region

6. Zmass Black : overall dist. Blue : |rphi|<0.9 Green : |rphi|>=0.9 Data in dot Compare events in |rphi|>=0.9 of track with |rphi|<0.9. Obviously there’s mismatch in Zmass with Cal E.

7. Selected Zmass with Cal Eafter 80<M(Z,trk)<100 cut Monte Carlo Data In addition to the M(Ztrk) mass cut, we require |rphi|<0.8 of electron to reduce possible background on electron leg. overall dist. Trk |rphi|<0.9 Trk |rphi|>=0.9

8. E/p We have seen the E/p dist. of crack region (either electron of track) is different from non-crack area. Black : overall dist. Blue : |rphi|<0.9 Green : |rphi|>=0.9 Data in dot Single Tower Cal energy Track Momentum Electron Track

9. Electron Track E/p Black : overall dist. Blue : |rphi|<0.9 Green : |rphi|>0.9 Data in dot Does the high E/p distribution mean background on electron leg?

10. Combined Zmass in el crack Blue : |rphi|<0.9 Green : |rphi|>0.9 Data in dot

11. Had/Em(track) 2x2 Had Cal Energy 2x2 EM Cal Energy Black : overall dist. Blue : |rphi|<0.9 Green : |rphi|>=0.9 Data in dot Tight central electron cut including sliding Had/Em cut already was applied to electron leg. To have track cut, we plotted normalized Had/Em dist. Had/Em on track less than 0.05 selected to have clean Z sample.

12. Had/Em Data shows sharper Had/Em in low but more fluctuation in high region. Black : overall dist. Blue : |rphi|<0.9 Green : |rphi|>=0.9 Data in dot

13. Events in rel. position Rel. phi Rel. eta Monte Carlo Data Electron We have flat relative phi distribution of track without requiring em object Track

14. E/p vs rel. phi & rel. eta Rel. phi Rel. eta Monte Carlo Data Electron Track

15. E/p vs rel. phi & rel. eta Rel. phi Rel. eta Monte Carlo Data Electron Just blowup of Previous page Have correction on Cal Data? Track

16. E/p vs. rel. phi & rel. eta Emobject E/p variable shows flat distribution after correction but we don’t have no way to see how track response change. Rel. phi Rel. eta

17. Cal energy distribution in phi Monte Carlo Data Electron Track

18. Cal energy distribution in eta Monte Carlo Data Electron Track

19. Summary • To study crack response properly, we had to use track momentum instead of Cal energy for clean Z sample. • We used pt>20 cut for both of electron and track to make a fair comparision of E/p profile. • There’s a discrepancy between MC and data in phi, electron and track in eta. It needs to be understood.