effect of muon misalignments on muon p t resolution and on the search for z' ssm → µ + µ -...

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


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

MZ′SSM = 1.2 TeV using 7 TeV MC samples


EXO-Resonances 06/11/10 Effect of muon misalignments on muon pT 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












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)


Thanks to Jim Pivarski

MC samples and MC samples and event selectionevent 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

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


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.


ppTT resolution vs. resolution vs. ηηIdeal alignement & with 2mm BiasIdeal alignement & with 2mm Bias


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


• 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


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


Asymmetric results

MC Mass SpectraMC Mass Spectra


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


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


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


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


Estimated data required for the expected Z′ signal with 5σ


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*


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)


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)


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


Dimuon mass spectraDimuon mass spectra


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)


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


Muon POG WG 08/20/09 Status of alignment systematics study


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

MZ′SSM = 1.2 TeV using 7 TeV MC samples


EXO-Resonances 06/11/10 Effect of muon misalignments on muon pT resolution and on the search for Z' → μ+ μ−


EXO-Resonances 06/25/10 Update on search for Z' →μ+ μ− (2)


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


These signal mass points are chosen because of my earlier work and results obtained with privately generated samples.

effect of muon misalignments on muon p t resolution and on the search for z' ssm → µ + µ -...

Documents

muon alignment

z http

alignment systematics

z analysis http

z search http

alignment studies

ideal alignment scenario

different alignment