Z 0 ->ee Analysis

1. Z0->ee Analysis ByDenis O. Damazio (BNL) (06/28/2004) Presented by Srini Rajagopalan

2. Introduction • Z0->ee analysis can be used for EM calibration studies. • Z0->ee may be used for simulation, reconstruction and physics performance evaluation. • Z0->ee is also suggested as a parton-parton luminosity monitor. (also W+/-). • Needs to understand trigger and Reconstruction efficiencies. D.O. Damazio (BNL) “egamma Workshop”

3. Framework • The following analysis was performed using the Reconstruction in Offline software version 7.2.0. • Data set from Z0->ee run 002513 (dc1). DICE cut |eta| < 2.7 and a e+/- Pt cut of 17 GeV (300K events initially produced reduced to 149K). • The ~300 roottuple files produced by reconstruction are parsed and produce reduced data sets for different environments (truth, iPat, xKalman, clusters, Jets, L1 Trigger and general Rec). • Such special roottuples are parsed to produce the pictures. D.O. Damazio (BNL) “egamma Workshop”

4. Truth Analysis (Z0) • Truth is checked for the inclusivity of the data sample. • Z0 Pt and Mass (fitted by Breit-Wigner curve. D.O. Damazio (BNL) “egamma Workshop”

5. Truth Analysis (e+/-) • The electron cuts (in Pt and Eta) can be easily spotted. D.O. Damazio (BNL) “egamma Workshop”

6. Reconstructed Clusters • The Pt distribution of the clusters with eg_IsEM=0 is similar to truth. • IsEM clusters have smaller leakage. D.O. Damazio (BNL) “egamma Workshop”

7. Reconstructed Clusters • E over p. • EM clusters eta (showing the cracks). D.O. Damazio (BNL) “egamma Workshop”

8. Reconstructed e+/- • To evaluate the rec. performance, clusters away from truth electrons are discarded. • For different distances Delta Pt is calculated. D.O. Damazio (BNL) “egamma Workshop”

9. Reconstructed e+/- • For different Pt Ranges, the Delta Pt between Truth and Rec is measured. Calorimeter resolution is worst for small Pt. D.O. Damazio (BNL) “egamma Workshop”

10. Reconstruction (Z0) • Z0 features are reconstructed from the e+/- analysis. • Z0 Mass and Pt for truth and rec. D.O. Damazio (BNL) “egamma Workshop”

11. Reconstruction (Z0) • Z0 P and Eta distribution for truth and Rec. • P suffers from small reconstruction losses. D.O. Damazio (BNL) “egamma Workshop”

12. L1Trigger • Trigger ROIs Pt. • 2 = 2EM(10) • 6 = 2EM(10)+1EM(20) D.O. Damazio (BNL) “egamma Workshop”

13. Conclusions & Future Steps • Upgrade Analysis to Offline Software version 8.2.0 (Python stuff). This work has already been started however, some reconstruction packages do not work (tracks and trigger). • Look at DC2 preproduction files (used by Fabiola). Same problem as above. • Start to use the AODs in order to add flexibility to the analysis (with Ketevi Assamagan's help). • Start a deeper analysis of LVL1 and LVL2 efficiencies (with Steve Armstrong's help). • Expand to other data sets. Pile-up?! Background?! D.O. Damazio (BNL) “egamma Workshop”

14. Web Pages • The latest results about this run and others being still analysed can be found at the following URL. http://www.usatlas.bnl.gov/~damazio/log/ • Comments and Suggestions are very welcome. • The ROOT code can also be distributed. D.O. Damazio (BNL) “egamma Workshop”