Effect of muon misalignments on muon p T 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

CMS AN-2010/064 August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain2 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 Muon POG WG 08/20/09 Status of alignment systematics study =66502 Muon Alignment 09/18/09 Alignment studies for Z′→μ + μ − search EXO-MU 10/15/09 Alignment Systematics Study EXO-MU 10/29/09 Updates on Alignment systematics EXO-MU 11/12/09 Update on Alignment Systematics wrt Ideal Alignment MU align 11/20/09 Alignment systematics w.r.t. ideal alignment scenario EXO-MU 01/28/10 Updates on resolution from Z'→μ + μ − analysis EXO-MU 03/11/10 First Results from Mass Reach Analysis for M Z′ SSM = 1.2 TeV using 7 TeV MC samples EXO-Resonances 06/11/10 Effect of muon misalignments on muon p T resolution and on the search for Z′→ μ + μ − EXO-Resonances 06/25/10 Update on search for Z'→ μ + μ − (2) Endorsed by EXO resonances convener, Meenakshi Narain

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 M Z′ SSM = 1.0 TeV/c 2 & 1.2 TeV/c 2 –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 August 3, 20103Exotica meeting (Thesis endorsement), S. Guragain All analysis is performed with the “Zprime2muAnalysis” (no PATTuple) package [Thanks to Jordan Tucker, UCLA group, and Piotr Traczyk]

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 (φ x,φ y,φ z ) 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 (φ x,φ y,φ z ) Tracker misalignment scenarios in startup and 50 pb -1 are the same and based on CRAFT 2008 (tag TrackerCRAFTScenario310_mc) August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain4 Thanks to Jim Pivarski

MC samples and event selection August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain5 MC samples Z′ signal samples with full Z′/Z/γ interference for M Z′ SSM =1.0 TeV/c 2, 1.2 TeV/c 2, 1.3 TeV/c 2, and 2.0 TeV/c 2 Drell-Yan samples, one in the mass region (>500 GeV/c 2 ) around the Z′ mass and another at lower mass(>200 GeV/c 2 ) Event selection: At least a pair of oppositely charged muons p T of each muon track in a pair > 20 GeV/c Isolated muons: Σ track p T (ΔR < 0.3) < 10 GeV/c

Resolution study for 3 alignment scenarios using 1.2 TeV Z′ MC sample at √s = 7TeV August 3, 20106Exotica meeting (Thesis endorsement), S. Guragain Muon Momentum resolution (endcap) for 3 misalignment scenarios with M Z′ = 1.2 TeV at 7 TeV CM energy Z' SSM → µ + µ - analysis

Summary: resolutions for 3 alignments and different Z′ mass with √s=7TeV & 10TeV August 3, 20107Exotica meeting (Thesis endorsement), S. Guragain 50 pb -1 alignment scenario is validated.

Systematics study: Muon endcap alignment Method: 1.Muon Endcap was misaligned with respect to ideal or startup muon geometry. 2.A signal sample (M Z′ =1.2TeV/c 2 or 2.0TeV/c 2 ) was fully reconstructed. –The sample was reconstructed with a customized global tag by inputting a modified SQLite file, with a bias for the position(X CMS, Y CMS, Z CMS ) up to 2 mm or a bias on rotation (φ Z CMS ) up to 0.5 mrad of muon endcap stations together or individual ME stations. [For comparison: Current startup ME disk misalignments are mm in (∆x, ∆y, ∆z) & 0.1 mrad in ∆φ Z CMS ] 3. The analysis code was re-run over the resulting biased MC data set for each misalignment. August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain8

p T resolution vs. η Ideal alignement & with 2mm Bias August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain9 2 TeV Z′ Sample No systematic bias applied to the Barrel and Tracker- only Ideal alignment Ideal alignment + 2mm shift of muon endcaps

Comparison: p T resolution August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain10 Up to 200 GeV/c, no significant change due to bias but changes at higher p T Muon alignment becomes prominent at higher p T in all scenarios Demonstrates tracker-only does not change, as expected with or without bias on endcap stations Ideal alignment + 2mm shift of muon endcap

August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain11 Alignment Systematics Study: Bias on ideal Endcap positions

Alignment Systematics Study: Bias on startup Endcap positions August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain12 Asymmetric results

MC Mass Spectra August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain13 Ideal alignment (MC_31X_V5) 50 pb -1 alignment (50PBMU31X_V1) Startup alignment (STARTUP31X_V4) Generated and reconstructed dimuon mass with 3 alignment scenarios M Z′ = 1.2 TeV Better aligned detector narrows the signal peak; eg from startup to 50 pb -1

Z′ Mass Reach Analysis August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain14 Z′ signal sample with full Z′/Z/γ interference, reconstructed with startup alignment ; and the background samples, one in the mass region (> 500 GeV/c 2 ) around the Z′ mass and the other at lower mass (>200 GeV/c 2 ). For the analysis, the reconstructed background sample is the weighted sum of these 2 background datasets.

Reconstructed Mass fits: Significance with 200pb -1 August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain15 Likelihood-ratio estimator has been used to evaluate the significance STARTUP align. M Z′ = 1.2 TeV & 200pb -1 M Z′ = 1.2 TeV & 200pb pb -1 align.

Signal significance vs. L int August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain16 Variation of signal significance for M Z′ = 1.0 TeV/c 2 and 1.2 TeV/c 2 for different alignments and integrated luminosities.

Int. luminosity for 5σ August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain17 Estimated data required for the expected Z′ signal with 5σ

August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain18 Negligible effect Z′ signal significance with misaligned muon endcaps only

Mass spectra & Signal significance with 7 TeV official MC samples* August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain19 STARTUP Alignment M Z’ =1000 GeV/c 2 M Z’ = 1250 GeV/c 2 STARTUP Alignment M Z′ = 1000 GeV/c 2 STARTUP align. M Z′ = 1250 GeV/c 2 STARTUP align. * Samples on backup slide Signal significance Following the convener’s request at the June 11 resonance meeting, we have also analyzed recent Z′ and DY official MC samples

Comparisons (I) August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain20 M Z′ = 1000 GeV/c 2 STARTUP align. (START3X_V26) Privately generated samplesOfficial samples M Z′ = 1000 GeV/c 2 STARTUP align. (STARTUP31X_V4) Full interference (Z ′ /Z/γ ) sample STARTUP (randomly misaligned chamber positions with an RMS) Z′ signal only MC generated STARTUP (running Reference-Target algorithm) 500 pseudo-experiments with L int = 200 pb -1 each

Comparisons (II) August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain21 Signal significance vs. L int Int. luminosity for 5σ Compatible results

7 TeV collision data analysis Datasets: (pre-ICHEP 2010) 1./MinimumBias/Commisioning10-CS_Onia-Jun14thSkim_v1/RAW-RECO –Run range , events 2./Mu/Run2010A-CS_Onia-jun14thSkim_v1/RAW-RECO –Run range , events 3./Mu/Run2010A-PromptReco-v4/RECO –Run range (July 19), Event selections: Official good runs & lumisections certified from DQM group (Cert_ _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 p T > 1 GeV/c (Std. 20 GeV/c) Isolation Σ track p T (ΔR < 0.3 ) < 10 GeV/c August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain22

Dimuon mass spectra August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain23 Z J/ψ Events

Conclusions Samples for M Z′ = 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 (p T ) 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 p T 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 M Z′ 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 (July 19, 2010) August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain24

Seeking Ph.D. thesis endorsement: CMS AN-2010/064 From the beginning to the final results of the note: TeVMu 07/23/09 Preliminary work & plans on studying alignment systematics Muon POG WG 08/20/09 Status of alignment systematics study =66502 Muon Alignment 09/18/09 Alignment studies for Z′ →μ + μ − search EXO-MU 10/15/09 Alignment Systematics Study EXO-MU 10/29/09 Updates on Alignment systematics EXO-MU 11/12/09 Update on Alignment Systematics wrt Ideal Alignment MU align 11/20/09 Alignment systematics w.r.t. ideal alignment scenario EXO-MU 01/28/10 Updates on resolution from Z‘→ μ + μ − analysis EXO-MU 03/11/10 First Results from Mass Reach Analysis for M Z′ SSM = 1.2 TeV using 7 TeV MC samples EXO-Resonances 06/11/10 Effect of muon misalignments on muon p T resolution and on the search for Z' → μ + μ − EXO-Resonances 06/25/10 Update on search for Z' →μ + μ − (2) August 3, 2010Exotica meeting (Thesis endorsement), S. Guragain Summary Published the note on iCMS and circulated it to the exotica resonances group through the hypernews on 9 th July S/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 ( nb -1 ) Plan Finalize my dissertation and defend at Florida Tech by September 10,

Backup slide Official MC samples: Z′ Mass Reach analysis for M Z′ SSM = 1 TeV/c 2 & 1.25 TeV/c 2 –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 p T > 20 GeV/c Isolation Σ track p T (ΔR < 0.3 ) < 10 GeV/c August 3, Exotica meeting (Thesis endorsement), S. Guragain These signal mass points are chosen because of my earlier work and results obtained with privately generated samples.