effect of muon misalignments on muon p t resolution and on the search for z' ssm → µ + µ -...
TRANSCRIPT
Effect of muon misalignments Effect of muon misalignments
on muon pon muon pTT resolution and on resolution and on
the search for Z'the search for Z'SSM SSM → µ→ µ++µµ--
using 7 TeV MC samplesusing 7 TeV MC samples
Samir Guragain, Marcus Hohlmann Florida Tech
Exotica meetingThesis endorsement
August 3, 2010
CMS AN-2010/064CMS AN-2010/064
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 2
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 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
Endorsed by EXO resonances convener, Meenakshi Narain
OverviewOverview• 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 analysisAugust 3, 2010 3Exotica 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 Alignment scenarios and corresponding global tagscorresponding 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)
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 4
Thanks to Jim Pivarski
MC samples and MC samples and event selectionevent selection
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 5
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
Resolution study for 3 alignment scenarios Resolution study for 3 alignment scenarios using 1.2 TeV Zusing 1.2 TeV Z′′ MC sample at MC sample at √s = 7TeV√s = 7TeV
August 3, 2010 6Exotica meeting (Thesis endorsement), S. Guragain
Muon Momentum resolution (endcap)
for 3 misalignment scenarios with
MZ′ = 1.2 TeV at 7 TeV CM energy
Z'SSM → µ+ µ- analysis
Summary: resolutions for 3 alignmentsSummary: resolutions for 3 alignmentsand different Zand different Z′′ mass with mass with √s=7TeV & 10TeV√s=7TeV & 10TeV
August 3, 2010 7Exotica meeting (Thesis endorsement), S. Guragain
50 pb-1 alignment scenario is validated.
Systematics study:Systematics study:Muon endcap alignment Muon endcap alignment
Method:
1.Muon Endcap was misaligned with respect to ideal or startup muon geometry.
2.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 (φZ
CMS) 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 ∆φZ
CMS]
3. The analysis code was re-run over the resulting biased MC data set for each misalignment.
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 8
ppTT resolution vs. resolution vs. ηηIdeal alignement & with 2mm BiasIdeal alignement & with 2mm Bias
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 9
2 TeV Z′ Sample
2 TeV Z′ Sample
No systematic bias applied to the Barrel and Tracker-only
Ideal alignment
Ideal alignment + 2mm shift of muon endcaps
Comparison: pComparison: pTT resolution resolution
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 10
• 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
Ideal alignment + 2mm shift of muon endcap
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 11
Alignment Systematics Study: Alignment Systematics Study: Bias on ideal Endcap positionsBias on ideal Endcap positions
Alignment Systematics Study: Alignment Systematics Study: Bias on startup Endcap positionsBias on startup Endcap positions
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 12
Asymmetric results
MC Mass SpectraMC Mass Spectra
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 13
Ideal alignment(MC_31X_V5)
50 pb -1 alignment (50PBMU31X_V1)
Startup alignment(STARTUP31X_V4)
Generated and reconstructed dimuon mass with 3 alignment scenarios
MZ′ = 1.2 TeV
Better aligned detector narrows the signal peak; eg from startup to 50 pb -1
ZZ′ ′ Mass Reach AnalysisMass Reach Analysis
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 14
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.
Reconstructed Mass fits: Reconstructed Mass fits: Significance with 200pbSignificance with 200pb-1-1
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 15
Likelihood-ratio estimator has been used to evaluate the significance
STARTUP align.
MZ′ = 1.2 TeV & 200pb-1
MZ′ = 1.2 TeV & 200pb-1
50 pb -1 align.
Signal significance vs. Signal significance vs. LLintint
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 16
Variation of signal significance for MZ′ = 1.0 TeV/c2 and 1.2 TeV/c2 for different alignments and integrated luminosities.
Int. luminosity for 5Int. luminosity for 5σσ
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 17
Estimated data required for the expected Z′ signal with 5σ
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 18
Negligible effect
ZZ′ signal significance with ′ signal significance with misaligned muon endcaps onlymisaligned muon endcaps only
Mass spectra & Signal significance Mass spectra & Signal significance with 7 TeV official MC samples*with 7 TeV official MC samples*
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 19
STARTUP Alignment
MZ’ =1000 GeV/c2MZ’ = 1250 GeV/c2
STARTUP Alignment
MZ′ = 1000 GeV/c2
STARTUP align.
MZ′ = 1250 GeV/c2
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)Comparisons (I)
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 20
MZ′ = 1000 GeV/c2
STARTUP align.(START3X_V26)
Privately generated samples Official samples
MZ′ = 1000 GeV/c2
STARTUP align.(STARTUP31X_V4)
Full interference (Z ′ /Z/γ ) sampleSTARTUP (randomly misaligned chamber positions with an RMS)
Z′ signal onlyMC generated STARTUP (running Reference-Target algorithm)
500 pseudo-experiments with Lint = 200 pb-1 each
Comparisons (II)Comparisons (II)
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 21
Signal significance vs. Lint Int. luminosity for 5σ
Compatible results
7 TeV collision data analysis7 TeV collision data analysisDatasets: (pre-ICHEP 2010)
1. /MinimumBias/Commisioning10-CS_Onia-Jun14thSkim_v1/RAW-RECO– Run range 131511-135802, 135740 events
2. /Mu/Run2010A-CS_Onia-jun14thSkim_v1/RAW-RECO– Run range 135821-137436, 79833 events
3. /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
1. Two opposite sign muons with pT > 1 GeV/c (Std. 20 GeV/c)
2. Isolation Σ track pT (ΔR < 0.3 ) < 10 GeV/c
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 22
Dimuon mass spectraDimuon mass spectra
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 23
Z
J/ψ
Events
ConclusionsConclusions• 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)
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain 24
Seeking Ph.D. thesis endorsement: Seeking Ph.D. thesis endorsement: CMS AN-2010/064 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
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
August 3, 2010 Exotica meeting (Thesis endorsement), S. Guragain
Summary • Published the note on iCMS and circulated it to the exotica resonances group through the hypernews on 9th Julyhttps://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. thesisIn-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, andCollision 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
25
Backup slideBackup slideOfficial 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
August 3, 2010 26Exotica meeting (Thesis endorsement), S. Guragain
These signal mass points are chosen because of my earlier work and results obtained with privately generated samples.