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Inclusive SUSY Reach of CMS during Early LHC Running in the Jets + MET + N Leptons topologyPowerPoint Presentation

Inclusive SUSY Reach of CMS during Early LHC Running in the Jets + MET + N Leptons topology

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### Inclusive SUSY Reach of CMS during Early LHC Running in the Jets + MET + N Leptons topology

Bobby Scurlock

Darin Acosta

Richard Cavanaugh

University of Florida

Overview

- Motivation
- Phase 1 : Prelude
- Establish “full-chain”
- Verify CMS Note 98-073 with “full-chain”

- Phase 2 : Main emphasis
- Study systematic effects on reach
- Establish reach scenarios

- Phase 3
- Write contributions for Physics TDR
- Defend PhD !

Our Interest

- Extend earlier Florida JetMET BSM analysis efforts from CDF to CMS
- Collaborate with other CMS members:
- Florida Colleagues on SS 2μ Inclusive SUSY Reach Analysis:
- A.Drozdetski, Y.Pakhotin, P.Bartalini, D.Acosta, G.Mitselmakher

- JetMET Group:
- Haifeng Pi, Arno Heister, Rob Harris, et al.

- UF SUSY/BSM Theorists:
- P. Ramond, R. Field, and K. Matchev

- Florida Colleagues on SS 2μ Inclusive SUSY Reach Analysis:
- Focus on early (~10 fb-1) LHC physics
- Establish realistic reach expectations
- Study systematic effects
- Consider “What if…” scenarios

- Probe quasi-model-independent reaches

- Establish realistic reach expectations

Earlier CMS Work

Abdullin & Charles (CMS Note 98-073)

- Used Fast Sim. (CMSJET) of CMS detector
- Established reasonable criteria for signal selection & background rejection, and sensible expectations for signal & background distributions
- Studied some simple systematics
- Signal & Background variations
- Pile-up effects

- QCD background was (remains) a serious challenge

- DAQ TDR
Gives idea of Level-1 Trigger and HLT requirements for good efficiency for SUSY events over several representative points in mSUGRA space

What if…

…we assume a well understood detector?

- 0 leptons + Jets + MET has most significant reach

…we assume, e.g., that calorimeter responses are not well understood?

- Would n muons + Jets + MET be more significant?
- If so, at what level of jet energy scale uncertainty?

Abdullin & Charles

(CMS Note 98-073)

Establish “full-chain” analysis

CMKIN 3+

OSCAR 3+

ORCA 8+

Develop RootMaker

Defining our own currently

Investigating JetMET ntuple

Run on Digis (baseline)

Run on DSTs (when stable)

“Full-chain” important for systematic studies !

Modify physics process

Perturb detector response

Change reconstruction

RecCollections

minbias

DST

Digis,Assocs

Stream

signal

Phase 1 : Analysis set-upOSCAR

CMKIN

Simulation

Generation

MCinfo,G4 Vtx, Tk

SimHits

HEPEVTNtuple

MC generator

Production

ORCA

Analysis or Calibration

Reconstruction

Digitization

RecReader

SimReader

RecReader

Histo/Tree

Histo/Tree

RecColl, Digis

Histo/Tree

Digis

Histo/Tree

RecColl, Digis

User

Production

RootMaker

Tree

Phase 1 : Digi Datasets - Signal

Need more signal !

Phase-1 : Digi Datasets – EW Background

Z+jets lagging a bit !

Phase 1 : Confirm Abdullin & Charles

- Examine distributions after full simulation:
- Jet multiplicity, ET, ETMiss, Δφ(ETjet1, ETMiss), etc…

- Simple optimised cut set based on significance = Ns / √(Ns+Nb)
- Try/use initial selection criteria from Abdullin & Charles

- Produce preliminary expected reach in m0 vs m1/2 plane
- 10 fb-1
- 100 fb-1

- Ultimately, would like to limit number of cut sets used, by carving out regions in mSUGRA space rather than optimizing cuts for each particular point – this reduces systematics…

N = (εSσS + εBσB) L

Estimate uncertainties in cross-section σB

Treat QCD differently from EW

K-Factors

Guess at uncertainties in Luminosity L

Estimate uncertainties in efficiencies εS , εB

MC statistics

Detector Effects

Reconstruction Effects

JetMET

Muon

Electron

Theory

Examine uncertainties on backgrounds in control regions

Phase 2 : Systematics: The main emphasis of this workPhase 2 : Systematics – Triggers

- Jet Corrections at L1?
- Trigger Efficiencies:
- Jet+ETMiss
- Muons
- Electrons
- Inclusive SUSY

Phase 2 : Systematics – Reconstruction of Physics Objects

- Jets:
- E/HCAL Calibration
- Tracking Uncertainties
- ET vs. h

- ETMiss:
- Calibration
- Fake Rates
- Azimuthal Isolation

- Muons
- B-Field
- Detector Alignment
- Brem

- Electrons
- B-Field
- ECAL Calibration
- Brem

Phase 2 : Significance Estimator

- Estimate reach at 95% CL using likelihood
- Include systematic effects via convolution

Likelihood for SUSY Signal hypothesis, given Experimental Data and assuming knowledge of Standard Model Background

Systematic Gaussian PDFs

Statistical Poisson PDF

Phase 2 : Quasi-model-independent studies

- “What if…” mSUGRA is not the SUSY breaking model realised in Nature?
- Investigate more model independent approaches for setting reaches
- Physical squark and gluino masses
- Cross-section x BRs
- Validate against several different SUSY models at generator level

mSUGRA parameter sweeps

Estimates of systematic effects which are otherwise to costly

Investigate Distributions of Physics Objects:

JetMET:

ET of leading jet, ET of next leading jet, MET of event, Jet multiplicity, etc…

Muons:

PT of leading muon, PT of next leading muon, Muon isolation, etc…

Electron:

ET of leading electron, ET of next leading electron, Electron isolation, etc...

Phase 2 : FAMOSSynergy with Inclusive SS 2μ SUSY Reach

- Authors:
- Alexei Drozdetski (see today’s talk), Yuriy Pakhotin, Paolo Bartalini, Darin Acosta, Guenakh Mitselmakher

- Many systematics are the same (or similar) for both analyses
- Division of labor
- Agree on a common Root Tree

- Etc…

Conclusions

- Interested in conducting inclusive SUSY search in the Jets + MET + Leptons topology to establish realistic reach expectations
- In process of mastering analysis chain and crating analysis tools
- Will conduct sanity checks against previous studies
- Consider various “What if …” scenarios, and systematic effects
- Would like to evolve to a model independent study

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