Samir Guragain , Marcus Hohlmann Florida Tech

1. Effect of muon misalignments on muon pT resolution and on the search for Z'SSM → µ+µ-using 7 TeV MC samples Samir Guragain, Marcus Hohlmann Florida Tech • Exotica meeting • Thesis endorsement • August 3, 2010

2. CMS AN-2010/064 From the beginning to the final results of the note, they were presented at the following meetings: TeVMu 07/23/09 Preliminary work & plans on studying alignment systematics http://indico.cern.ch/contributionDisplay.py?contribId=0&confId=64916 Muon POG WG 08/20/09 Status of alignment systematics study http://indico.cern.ch/contributionDisplay.py?contribId=0&sessionId=1&confId=66502 Muon Alignment 09/18/09 Alignment studies for Z′→μ+ μ− search http://indico.cern.ch/contributionDisplay.py?contribId=6&confId=68513 EXO-MU 10/15/09 Alignment Systematics Study http://indico.cern.ch/contributionDisplay.py?contribId=3&confId=70813 EXO-MU 10/29/09 Updates on Alignment systematics http://indico.cern.ch/contributionDisplay.py?contribId=0&confId=72297 EXO-MU 11/12/09 Update on Alignment Systematicswrt Ideal Alignment http://indico.cern.ch/contributionDisplay.py?contribId=3&confId=73809 MU align 11/20/09 Alignment systematicsw.r.t. ideal alignment scenario http://indico.cern.ch/contributionDisplay.py?contribId=6&confId=74620 EXO-MU 01/28/10 Updates on resolution from Z'→μ+ μ− analysis http://indico.cern.ch/contributionDisplay.py?contribId=5&confId=82293 EXO-MU 03/11/10 First Results from Mass Reach Analysis for MZ′SSM= 1.2 TeV using 7 TeV MC samples http://indico.cern.ch/contributionDisplay.py?contribId=7&confId=87444 EXO-Resonances 06/11/10 Effect of muon misalignments on muon pT resolution and on the search for Z′→μ+ μ− http://indico.cern.ch/contributionDisplay.py?contribId=7&confId=97968 EXO-Resonances 06/25/10 Update on search for Z'→ μ+ μ− (2) http://indico.cern.ch/contributionDisplay.py?contribId=5&confId=99443 Endorsed by EXO resonances convener, Meenakshi Narain Exotica meeting (Thesis endorsement), S. Guragain

3. Overview • 50K event samples for Z′SSM & Drell-Yan at √s=7 TeV with 3 different alignment scenarios using CMSSW_3_1_X • The effect of muon misalignment on transverse momentum resolution for muons and the dimuon mass resolution for various scenarios • Z′ Mass Reach analysis for MZ′SSM= 1.0 TeV/c2 & 1.2 TeV/c2 • Mass spectra w.r.t. different alignment scenarios • Generated vs. reconstructed (Global) • Signal Significance with different Muon+Tracker alignments and integrated luminosities • Signal Significance with different Muon Endcap misalignment systematics • Comparison of results with official MC samples • My first look at the collision data and dimuon data analysis All analysis is performed with the “Zprime2muAnalysis” (no PATTuple) package [Thanks to Jordan Tucker, UCLA group, and Piotr Traczyk] Exotica meeting (Thesis endorsement), S. Guragain

4. Alignment scenarios and corresponding global tags • IDEAL (MC_31X_V5) : Ideal geometry of the detector • STARTUP (STARTUP31X_V4): Based on CRAFT 2008 and 2009 data analysis for early phase and produced by randomly misaligning chambers with an RMS consistent with cross-checks Uncertainty in chamber positions: 0.05 cm – 0.60 cm in (x,y,z) & 0.3 mrad – 2.3 mrad in (φx,φy,φz) • 50 pb-1 (50PBMU31X_V1) : Assuming an alignment with tracks using 50 pb-1 data and produced by running the Reference-Target algorithm on MC samples Uncertainty in chambers: 0.05 cm – 0.18 cm (x,y,z) & 0.3 mrad – 0.6 mrad (φx,φy,φz) Tracker misalignment scenarios in startup and 50 pb-1 are the same and based on CRAFT 2008 (tag TrackerCRAFTScenario310_mc) Thanks to Jim Pivarski Exotica meeting (Thesis endorsement), S. Guragain

5. MC samples and event selection MC samples • Z′ signal samples with full Z′/Z/γ interference for MZ′SSM=1.0 TeV/c2, 1.2 TeV/c2, 1.3 TeV/c2, and 2.0 TeV/c2 • Drell-Yan samples, one in the mass region (>500 GeV/c2) around the Z′ mass and another at lower mass(>200 GeV/c2) Event selection: • At least a pair of oppositely charged muons • pT of each muon track in a pair > 20 GeV/c • Isolated muons: Σ track pT (ΔR < 0.3) < 10 GeV/c Exotica meeting (Thesis endorsement), S. Guragain

6. Resolution study for 3 alignment scenarios using 1.2 TeV Z′ MC sample at √s = 7TeV Muon Momentum resolution (endcap) for 3 misalignment scenarios with MZ′ = 1.2 TeV at 7 TeV CM energy Z'SSM → µ+ µ- analysis Exotica meeting (Thesis endorsement), S. Guragain

7. Summary: resolutions for 3 alignmentsand different Z′ mass with √s=7TeV & 10TeV 50 pb-1 alignment scenario is validated. Exotica meeting (Thesis endorsement), S. Guragain

8. Systematics study:Muon endcap alignment Method: • Muon Endcap was misaligned with respect to ideal or startup muon geometry. • A signal sample (MZ′=1.2TeV/c2 or 2.0TeV/c2) was fully reconstructed. • The sample was reconstructed with a customized global tag by inputting a modified SQLite file, with a bias for the position(XCMS, YCMS, ZCMS) up to 2 mm or a bias on rotation (φZCMS) up to 0.5 mrad of muon endcap stations together or individual ME stations. [For comparison: Current startup ME disk misalignments are 0.5 - 1.0 mm in (∆x, ∆y, ∆z) & 0.1 mrad in ∆φZCMS] 3. The analysis code was re-run over the resulting biased MC data set for each misalignment. Exotica meeting (Thesis endorsement), S. Guragain

9. pT resolution vs. ηIdeal alignement & with 2mm Bias Ideal alignment 2 TeV Z′ Sample 2 TeV Z′ Sample No systematic bias applied to the Barrel and Tracker-only Ideal alignment + 2mm shift of muon endcaps Exotica meeting (Thesis endorsement), S. Guragain

10. Comparison: pT resolution Ideal alignment + 2mm shift of muon endcap • Up to 200 GeV/c, no significant change due to bias but changes at higher pT • Muon alignment becomes prominent at higher pT in all scenarios • Demonstrates tracker-only does not change, as expected with or without bias on endcap stations Exotica meeting (Thesis endorsement), S. Guragain

11. Alignment Systematics Study: Bias on ideal Endcap positions Exotica meeting (Thesis endorsement), S. Guragain

12. Alignment Systematics Study: Bias on startup Endcap positions Asymmetric results Exotica meeting (Thesis endorsement), S. Guragain

13. MC Mass Spectra Generated and reconstructed dimuon mass with 3 alignment scenarios Ideal alignment (MC_31X_V5) 50 pb -1 alignment (50PBMU31X_V1) MZ′ = 1.2 TeV Startup alignment (STARTUP31X_V4) Better aligned detector narrows the signal peak; eg from startup to 50 pb -1 Exotica meeting (Thesis endorsement), S. Guragain

14. Z′ Mass Reach Analysis Z′ signal sample with full Z′/Z/γ interference, reconstructed with startup alignment ; and the background samples, one in the mass region (> 500 GeV/c2) around the Z′ mass and the other at lower mass (>200 GeV/c2). For the analysis, the reconstructed background sample is the weighted sum of these 2 background datasets. Exotica meeting (Thesis endorsement), S. Guragain

15. Reconstructed Mass fits: Significance with 200pb-1 Likelihood-ratio estimator has been used to evaluate the significance STARTUP align. 50 pb -1 align. MZ′ = 1.2 TeV & 200pb-1 MZ′ = 1.2 TeV & 200pb-1 Exotica meeting (Thesis endorsement), S. Guragain

16. Signal significance vs. Lint Variation of signal significance for MZ′ = 1.0 TeV/c2 and 1.2 TeV/c2 for different alignments and integrated luminosities. Exotica meeting (Thesis endorsement), S. Guragain

17. Int. luminosity for 5σ Estimated data required for the expected Z′ signal with 5σ Exotica meeting (Thesis endorsement), S. Guragain

18. Z′ signal significance with misaligned muon endcaps only Negligible effect Exotica meeting (Thesis endorsement), S. Guragain

19. Mass spectra & Signal significance with 7 TeV official MC samples* Following the convener’s request at the June 11 resonance meeting, we have also analyzed recent Z′ and DY official MC samples * Samples on backup slide STARTUP Alignment STARTUP Alignment MZ’ = 1250 GeV/c2 MZ’ =1000 GeV/c2 Signal significance MZ′ = 1250 GeV/c2 STARTUP align. MZ′ = 1000 GeV/c2 STARTUP align. Exotica meeting (Thesis endorsement), S. Guragain

20. Comparisons (I) 500 pseudo-experiments with Lint = 200 pb-1 each Official samples Privately generated samples MZ′ = 1000 GeV/c2 STARTUP align. (START3X_V26) MZ′ = 1000 GeV/c2 STARTUP align. (STARTUP31X_V4) Z′ signal only MC generated STARTUP (running Reference-Target algorithm) Full interference (Z ′ /Z/γ ) sample STARTUP (randomly misaligned chamber positions with an RMS) Exotica meeting (Thesis endorsement), S. Guragain

21. Comparisons (II) Signal significance vs. Lint Int. luminosity for 5σ Compatible results Exotica meeting (Thesis endorsement), S. Guragain

22. 7 TeV collision data analysis Datasets: (pre-ICHEP 2010) • /MinimumBias/Commisioning10-CS_Onia-Jun14thSkim_v1/RAW-RECO • Run range 131511-135802, 135740 events • /Mu/Run2010A-CS_Onia-jun14thSkim_v1/RAW-RECO • Run range 135821-137436, 79833 events • /Mu/Run2010A-PromptReco-v4/RECO • Run range 137437-140399 (July 19), Event selections: • Official good runs & lumisections certified from DQM group (Cert_132440-140399_7TeV_StreamExpress_Collisions10_JSON.txt) • Scraping filter to remove monster events (beam background rejection requiring ≥ 25% of high purity tracks • Primary vertex (not fake) with at least 4 tracks (ndof ≥ 4) with |Z| ≤ 15 cm && position.Rho ≤ 2 cm • Two opposite sign muons with pT > 1 GeV/c (Std. 20 GeV/c) • Isolation Σ track pT (ΔR < 0.3 ) < 10 GeV/c Exotica meeting (Thesis endorsement), S. Guragain

23. Dimuon mass spectra J/ψ Events Z Exotica meeting (Thesis endorsement), S. Guragain

24. Conclusions • Samples for MZ′ = 1.0 TeV, 1.2 TeV, 1.3 TeV, & 2 TeV and Drell-Yan at √s=7 TeV with the ideal, startup & 50 pb-1 alignment scenarios are generated, analyzed and published in CMS Database Bookkeeping System [hosted by FLTECH T3]. • The transverse momentum (pT) resolutions and dimuon mass resolutions are studied for various scenarios with the aforementioned samples. Typical dimuon mass resolutions are ~3% for ideal (MC), 6% for 50 pb-1 & 10% for startup. • The muon pT resolution in Endcaps is sensitive to the disk misalignment in position as well as rotation and the resolution is quantified for various misalignment scenarios. • Simulation results for discovery potential for MZ′SSM= 1.0 TeV & 1.2 TeV with different muon alignments and integrated luminosities are studied. • Effect of muon (mis)alignment on mass spectra • Expect to observe the Z′ (M = 1.2 TeV) with 5σ significance at √s=7 TeV and integrated luminosity of 250pb-1 with the 50pb-1 alignment or better • Negligible effect of muon endcap (only) misalignments upto 2 mm in translation or 0.5 mrad in rotation on Z′ signal significance Analyzed 7 TeV official MC samples, compared Z′ signal significances, and found compatible results. Looked and analyzed 7 TeV collision data (dimuon) up to run 140399 (July 19, 2010) Exotica meeting (Thesis endorsement), S. Guragain

25. Seeking Ph.D. thesis endorsement: CMS AN-2010/064 • Summary • Published the note on iCMS and circulated it to the exotica resonances group through the hypernews on 9th July • https://hypernews.cern.ch/HyperNews/CMS/get/exotica-resonances/13.html • Endorsed by the EXO resonances convener • Seek endorsement of work documented in the note for my Ph.D. thesis • In-progress Writing thesis“Muon Endcap alignment for CMS experiment and its effect on the search for Z′ in the dimuon channel at LHC” • Main contents of my thesis: • CRAFT paper results (Muon alignment), CMS AN-2010/064, and • Collision data (dimuon) analysis, data taken through July 19 (250-300 nb-1) • Plan Finalize my dissertation and defend at Florida Tech by September 10, 2010 From the beginning to the final results of the note: TeVMu 07/23/09 Preliminary work & plans on studying alignment systematics http://indico.cern.ch/contributionDisplay.py?contribId=0&confId=64916 Muon POG WG 08/20/09 Status of alignment systematics study http://indico.cern.ch/contributionDisplay.py?contribId=0&sessionId=1&confId=66502 Muon Alignment 09/18/09 Alignment studies for Z′ →μ+ μ− search http://indico.cern.ch/contributionDisplay.py?contribId=6&confId=68513 EXO-MU 10/15/09 Alignment Systematics Study http://indico.cern.ch/contributionDisplay.py?contribId=3&confId=70813 EXO-MU 10/29/09 Updates on Alignment systematics http://indico.cern.ch/contributionDisplay.py?contribId=0&confId=72297 EXO-MU 11/12/09 Update on Alignment Systematics wrt Ideal Alignment http://indico.cern.ch/contributionDisplay.py?contribId=3&confId=73809 MU align 11/20/09 Alignment systematics w.r.t. ideal alignment scenario http://indico.cern.ch/contributionDisplay.py?contribId=6&confId=74620 EXO-MU 01/28/10 Updates on resolution from Z‘→ μ+ μ− analysis http://indico.cern.ch/contributionDisplay.py?contribId=5&confId=82293 EXO-MU 03/11/10 First Results from Mass Reach Analysis for MZ′SSM = 1.2 TeV using 7 TeV MC samples http://indico.cern.ch/contributionDisplay.py?contribId=7&confId=87444 EXO-Resonances 06/11/10 Effect of muon misalignments on muon pT resolution and on the search for Z' → μ+ μ− http://indico.cern.ch/contributionDisplay.py?contribId=7&confId=97968 EXO-Resonances 06/25/10 Update on search for Z' →μ+ μ− (2) http://indico.cern.ch/contributionDisplay.py?contribId=5&confId=99443 Exotica meeting (Thesis endorsement), S. Guragain

26. Backup slide Official MC samples: Z′ Mass Reach analysis for MZ′SSM= 1 TeV/c2 & 1.25 TeV/c2 • Mass spectra • Z′ Signal Significance Data selection: Official 7 TeV MC samples: • ZprimeSSMToMuMu_M-X_7TeV-pythia6/Spring10-START3X_V26-v1/GEN-SIM-RECO • X = 500, 750, 1000, 1250, 1500, 1750 • DYToMuMu_M-Y_7TeV-pythia6/Spring10-START3X_V26-v2/GEN-SIM-RECO • Y = 120, 200, 500, 800 These samples are reconstructed with MC-generated STARTUP alignment scenario and using CMSSW_3_5_6 Event selection: • Two opposite sign muons with pT > 20 GeV/c • Isolation Σ track pT (ΔR < 0.3 ) < 10 GeV/c These signal mass points are chosen because of my earlier work and results obtained with privately generated samples. Exotica meeting (Thesis endorsement), S. Guragain