general ewk meeting 20-01-09 christopher rogan california institute of technology

General EWK Meeting 20-01-09

Christopher Rogan

California Institute of Technology

V+jets m/e studies with 21X: Status and plans

forMarcella Bona, Emanuele Di Marco, Ran Feldesh,

Joseph D. Lykken, Paolo Meridiani, C.R., Chiara Rovelli, Maurizio Pierini, Ilaria Segoni, Maria Spiropulu, Thiago

Tomei, Lukas Vanelderen, Marco Zanetti

◉ goal of the analyses: ◎ candle with the Z mass: validate e and reconstruction ◎ application examples:◍ MC tuning with the dN/dnjets and dN/dpT(Z)◍ check and correction of MET◍ ratios good for start-up: systematics cancel

◉ references for 16X analyses:◎ CMS notes◉ Z+jets & W+jets Alpgen Validation: CMS AN-2008/091◉ Z(ee)+jets Candle Analysis: CMS AN-2008/092◉ Z()+jets Candle Analysis: CMS AN-2008/095◉ W(e)/Z(ee)+jets Ratio Analysis: CMS AN-2008/096◉ W()/Z()+jets Ratio Analysis: CMS AN-2008/105◎ previous EWK talks on 16X analysis:◉ summary by M.Pierini Nov 11th 2008◉ note release: E. Di Marco, C. Rogan, and I. Segoni: Oct 17th 2008◎ V+jets talks:◉ e and analyses: I. Segoni and M.Zanetti: Nov 14th 2008◉ selection: M. Bona: Nov 28th 2008

Christopher Rogan - EWK Meeting 20-01-09 3

V+j so far

◉ samples: 2.1.X and Fall09◎ signals, other Z/W decays andtt events: MADGRAPH◎ QCD: “InclusiveMu15” sample (muon enriched QCD)

◉ general strategy for the analyses◎ single non isolated muon trigger◎ muon selection: optimization in the next slides◎ Z mass window [60, 120] GeV/c2

◎ closest-to-the-leading-muon PV selection◎ jet clustering (calo jets and track jets: SisCone with 0.5) with E/pT and cuts (30/15 GeV and 3/2.4, respectively)◎ 2D maximum likelihood fit: Z mass and sin(angleMET, MHT) for Z+jets; transverse mass and sin(angleTS-jet)◎ floating the shape parameters for low jet multiplicities and fixing for the high multiplicities◎ sPlots for verify shapes on data

◉ muon selection in 16X◎ only global muons◎ pT > 15 GeV/c◎ vertex variables and isolation variables

simultaneous optimization:◉ vertex variables:xy/(xy) and z(-PV)◉ isolation variables: tracking isolation i pi

T/pT

ECAL isolation R<0.35 ETECAL

HCAL isolation R<0.5 ETHCAL

◍ extensive study to select thevariables and to establish theoptimization procedure:done in 16X and now repeated

in 21X production, the PV is displaced in x so we can calculate the distance wrt the PV but the error is calculated wrt (0,0,0) :so we started looking at xy better for the electrons that have typically poorer tracking resolution about the same discrimination for muons (wrt the significance)

in 21X production, the PV is displaced in x so we can calculate the distance wrt the PV but the error is calculated wrt (0,0,0) so we started looking at: xy better for the electrons that have typically poorer tracking resolution about the same discrimination for muons (wrt the significance)

Hcal isolation:H0 excluded and zero suppression introduced

Hcal isolation:H0 excluded and zero suppression introduced


Cut variables

i piT/p

T R<0.35 ETECAL

R<0.5 ETHCAL

z(-PV) xy

Christopher Rogan - VecBos + jets 15-01-09 7

Optimization on the W selection

Optimize the Punzi Significance:

Consider all backgrounds and scan over all cut values simultaneously, with rates normalized to 100 pb-1

Consider only events in ML fit ‘signal region’


Optimization scans requiring:

R<0.35 ETECAL

R<0.5 ETHCAL

i piT/p

T <0.15

<2.25 GeV<2.8 GeV


xy(PV)z(-PV)

Optimization scans requiring:

<0.11 cm <0.005 cm


Optimized cut values

0.0045 0.0045 0.0045 0.005 (n.a.)

0.005 0.005

0.11 0.11 0.1 0.11 (0.08)

0.1 0.11

4.5 4.5 3.1 4.0 (6.0)

4.1 2.82.8

2.0 2.0 2.0 2.5 (1.6)

2.75 2.25

0.11 0.11 0.11 0.2 (0.11)

0.2 0.15

Values used

Values used

Calo jets Track jets


Optimized cut values

Values

used

Values

used

0.15 0.2 0.2 0.11 0.11 0.11

2.25 2.75 2.5 2.0 2.0 2.0

2.8 2.5 4.5 4.0 2.5 4.5 4.5

0.11 0.1 0.11 0.1 0.11 0.11

0.0055 0.005 0.005 0.0045 0.0045 0.0045

Calo jets Track jets


Changing muon pt cut

W selection


Changing muon pt cut

Z selection


Analysis strategy

Common requirements:

Single non isolated HLT trigger (HLT_Ele15_LW_L1R)pixel-match GSF electron reconstruction

electron identification*electron isolation*

electron - PV compatibilitycalo-jet clustering (SisCone, ΔR=0.5)

electron(s) from W(Z) cleaning from calo-jetsjet counting

W-specific requirements:

exactly 1 electron (against Z+j)Z mass veto (decouple W+j dataset

from Z+j)MET > 20 GeV (against QCD)

mT(W) > 30 GeV (against QCD)

Z-specific requirements:

≥2 electrons (against W+j)Z mass range (decouple Z+j dataset

from W+j)

yields and ratio determination:Maximum Likelihood fit

efficiency correction of yields, if needed

* for Z, asymmetric id+iso


why re-iteration with 2.1.X ?

electron reconstruction details changed w.r.t. 1.6.X. (i.e. CSA07)

tracker material changedsome electron identification related to tracker - ECAL match can be changed

among others, H/E definition changed

pre-shower is excluded

HO is excluded and zero-suppression in HCAL has been introduced

H/E is affected

HCAL isolation is affected

PV is displaced in x w.r.t. (0,0,0)

In this iteration, possibly no new variables w.r.t. the ones used in CSA07 analysis are used. Various new quantities have been developed and released, will be tested in W+j/Z+j @ next round

Disclaimer!


Electron identification

We use the set of variables from egamma POG, with selection depending on electron classification (based on fbrem)

we compare 2.1.X - 1.6.X and re-optimize selection for golden / showering both barrel and endcap

this defines the W electron and the first Z electron (i.e. tight) loose egamma identification on the other (asymmetric ID)

tracker-ECAL

match

ECAL-HCAL match

ECAL cluster shapes


Efficiency of ele - id

Cuts optimized simultaneously to maximize W signal significance against QCD

QCD e.m. enriched + b,c→electrons used

the optimization is driven by W+j. For Z+j, the highest pT electron is identified with the same criteria to allow efficiency cancelation in Wj/Zjthe ID of the second is based on the same variables, but looser

selection ε(CSA07) ε(Summer08)- 93.7 +/- 0.1 95.7 +/- 0.1-*- s9s25: 95.7 +/- 0.1 95.9 +/- 0.1-*- deta: 97.6 +/- 0.1 91.2 +/- 0.1-*- dphiIn: 98.4 +/- 0.1 98.6 +/- 0.1-*- sigmaEtaEta: 93.5 +/- 0.1 96.5 +/- 0.1-*- eOverPout: 93.7 +/- 0.1 99.2 +/- 0.1-*- total eID: 75.5 +/- 0.2 79.0 +/- 0.2

Single electron efficiency on W+≥0j

The optimized cuts

egamma loose


S and B yields (W+j)

yields, normalized in 100 pb-1, up to electron definition.

large stat error


S and B yields (Z+j)

yields, normalized in 100 pb-1, up to electron definition


m(e+e-) lineshapes

Cruijff = Gaussian + exp tails for signal, parabola for inclusive bkg

≥1 jet ≥2 jet ≥3 jet

Z+

jets

(M

AD

GR

APH

)tt

+je

ts (

MA

DG

RA

PH

)

consistent parameters for signal lineshape as a function of jet multiplicity


mT(W) lineshapes

Cafu = Crystal ball + Gaussian with same mean

≥1 jet

≥2 jet

W+jets tt+jets Z+jets QCD

decreasing importance


slope correction

Yields uncorrected Yields efficiency-corrected

W+

jZ

+j

e-Slope=7.5±1.2

e-Slope=6.8±0.5

e-Slope=6.9±1.1

e-Slope=6.8±0.5

W/Z = 1.09±0.20 W/Z = 1.01±0.19⇒ eff changes the slope, but effect on double ratio is within

uncertainty

Preliminary


slope correction

Yields uncorrected Yields efficiency-corrected

W+

jZ

+j

W/Z = 0.91±0.05⇒ eff changes the slope, but effect on double ratio is within

uncertainty

e-Slope=7.32±0.09 e-Slope=6.82±0.08

e-Slope=8.0±0.4 e-Slope=7.4±0.3

W/Z = 0.93±0.04

Preliminary


◉ for the candle analysis:◎ we start from the optimization values obtained for the ratio in the W selection

we can afford to loosen the cut to increase efficiency◉ muon pT > 10 GeV/c◉ vertex variables:xy <0.02 cm z(-PV) <0.15 cm◉ isolation: i pi

T/pT <0.30 (on the second leg)

Preliminary


Preliminary

≥1jet ≥1jet

Background


≥1jet ≥2jet

≥3jet ≥4jet

Signal


≥1jet ≥2jet

≥3jet ≥4jet

Background


≥1jet ≥2jet

≥3jet ≥4jet

Signal


≥1jet ≥2jet

≥3jet ≥4jet

Background


◉ for the electron candle analysis:

we can afford to loosen the cut to increase efficiency◉ electron pT > 10 GeV/c◉ loose electron ID on both legs◉ Best Z candidate choice (highest pt electrons)◉ vertex variables:xy <0.04 cm z(-PV) <0.12 cm◉ isolation: i pi

T/pT <0.15 (on both legs)

Preliminary


≥1jet

≥2jet

≥1jet

≥2jet

Signal


≥1jet

≥2jet

≥1jet

≥2jet

Background


EXTRA SLIDES


Madgraph/Alpgen Production changes

For tt+j parton pt 20, matched at 30 MADGRAPH – KT MLM matching

x-section 317pb @ 10 TeV, x-section 750 pb @ 14 TeV Parton pt 70, matched at 20 GeV, ALPGEN –MLM (old, IC) Matching

x-sec 450 pb @14 TeV – if 20 GeV parton pt x-sec 754 pb@14 TeV,

x-section 270 pb@ 10 TeV [15% compared to MAD, MAD>ALPGEN but different scales, PDFs see below]

Scale (m_top)^2 at MADGRAPH Scale (M_T)^2=sum(m_top^2+P_T^2) ALPGEN

Lower Q^2 pushes the cross section up (MAD>ALPG) (10%)PDF CTEQ6L NLO and corresponding a_s change in MADGRPAHPDF CTEQ5L LO ALPGEN

NLO PDF pushes x-section up (MAD>ALPG) (10%)


Comparison of isolation variables: CSA07 - FALL08


Comparison of vertex variables: CSA07 - FALL08

significance


◉ isolation variables: tracking isolation normalized: i pi

T/pT

ECAL isolation: R<0.35 ETECAL

HCAL isolation: R<0.5 ETHCAL

tracking isolation: tracks within R < 0.5◈ at least 5 associated hits◈ |z(track-PV)| < 0.1 cm◈ |xy/(xy)| < 5◈ 500 MeV/c < pT < 500 GeV/c

ECAL isolation: EM calotowers in the 0.35 cone around the energy is not subtracted

HCAL isolation: hadronic calotowers in the 0.5 cone


W selection efficienciesPreliminary


Z selection efficienciesPreliminary


Eseed/Pout

Major point: track pout estimation depends by the tracker material knowledge

barrel endcap


Δηvtx

GSF-track - ECAL supercluster matchlarger tails for non-showering

non-showering endcap bumps for η>0, η<0: tilt changed in the geometry?

barrel endcap


ΔΦvtx

GSF-track - ECAL supercluster match

barrel endcap


H/E

CSA07: H/E = sum(H rechits) / supercluster energy in cone ΔR=0.1

no HCAL zero-suppression

Summer08: H/E = max (H rechit / basic cluster ), the H rechit is the one above the ECAL basic cluster

HCAL zero - suppression

barrel endcap


s9/s25

Cluster shape variable

barrel endcap


σηη

Cluster shape variable (cluster width)changed thresholds?

barrel endcap


Optimization scan requiring:

z(-PV) xy(PV)

R<0.35 ETECAL i pi

T/pT R<0.5 ET

HCAL


R<0.35 ETECAL i pi

T/pT R<0.5 ET

HCAL

z(-PV) xy(PV)



Optimization

Some comments: Currently we are not including a sphericity cut or MET cut in the

optimization (we will include this once I finish the W MET calibration using the Z candle)

As a result, we are cutting more tightly on these five variables relative to what we will do when including MET or sphericity - I anticipate that the signal efficiency will go up with

Ultimately, we will also do the optimization in the signal region of the ‘angular variable’ which we use in the fit - we can’t do this until we have the W MET calibration.

Hence these are probably not the ‘final’ values, but they demonstrate the procedure/philosophy of the optimization


what looks different

Most of the electron ID variables looks very similar to CSA07. (see backup)

larger differences in: H/E, σηη H/E: definition changed, was H/E in a cone ΔR=0.1, now is Hover-

ECALseed/Eseed

σηη: noise threshold for covariance matrix calculation changed (w0=4.2 → 4.7): expected larger width

H/Ebarrel

σηη

barrel


what’s looks different: Δηvtx

double peak for golden (i.e. when the super-cluster = 1 basic cluster) in the endcap

peak>(<)0 for η<(>)0

true also evaluating Δη=ηclus-ηgenele

it is a cluster problem

difference 1.6.X - 2.1.X:2.1.X has not the preshower: the cluster position (depth in crystal) accounts for it with a parameter

hypothesis check. In 3.0.X preshower is backthe double peak disappears

ηcl

us-

ηg

en

ele

η

Δηvtx(3.0.X)


electron isolation

Comparison of the variables used in the CSA07 notesTraker: sum(pT

tracks)/pTele , with internal cone veto

internal cone veto found to be good and robust

external cone ΔR=0.4: all similar, chosen the intermediate one

ECAL: sum(ET5x5 crystals-ET

super-cluster)/ETsuper-cluster in a cone

ΔR=0.4

electron footprint ETsuper-cluster not optimal, move to

rechits isolation soon

HCAL: sum(ETrechits)/ET

super-cluster in a cone ΔR=0.4

ECAL rechits

removal

tracker veto cone

See summary from M. Le Bourgeois: http://indico.cern.ch/contributionDisplay.py?contribId=4&confId=43146


isolation: distributions

tracker ECAL

HCAL isolation ε(CSA07)

ε(Summer08)-*- tracker: 91.8 +/- 0.4 89.025 +/- 0.2-*- ECAL: 90.3 +/- 0.4 94.748 +/- 0.2-*- HCAL: 93.6 +/- 0.4 91.989 +/- 0.2


vertexing variables

Used to suppress events not coming from Primary Vertex (PV):

dz = zele-zPV

dxy = distance in transverse plane w.r.t. PV

RMS=210μm RMS=66μm


jet multiplicity dependency (1)

efficiency variations in different multiplicities change the slope V+(n-1)j / V+(n)j

but mostly cancels out in double ratio W+nj / Z+nj (W ele and 1st ele of Z have the same selection) Z+jets: no variations at all

re-e

stim

ate

on F

all0

8 s

am

ple

s w

ith H

LT


jet multiplicity dependency (2)

W+jets: 2% drop at each added jet

re-e

stim

ate

on F

all0

8 s

am

ple

s w

ith H

LT


maximum likelihood fit

signal, backgrounds yields extracted on data with extended, maximum likelihood fit

for Z+≥1jet also Z lineshape parameters extracted on data

Z+jets:1dim fit: P=PDF(mee)

W+jets:1dim fit: P=PDF(mT

W)

Ni=signal and backgrounds yields Z+jets: i=signal, tt W+jets: i=signal, tt+QCD, Z+jets

total number of eventsentering the fit

(i.e. extended likelihood)


Tracking Isolation i piT/p

T

comparisonwrt the jet bin


ECAL Isolation R<0.35 ETECAL



HCAL Isolation R<0.5 ETHCAL



vertex variable: z(-PV)



vertex variable: xy



W selection results

Calo jetsPreliminary

16X numbers: CAVEATdifferent cutsand different energy!


W selection results

Track jetsPreliminary


Z selection results

Calo jetsPreliminary

16X numbers: CAVEATdifferent cutsand different energy!


Z selection results

Track jetsPreliminary


W slopes

Calo jets


W slopes

Track jets


Z slopes

Calo jets


Z slopes

Track jets


Calo jets

Track jets


W/Z Ratio

general ewk meeting 20-01-09 christopher rogan california institute of technology

Documents

z jets transverse mass

zee jets candle analysis

zmm jets candle analysis

wenzee jets ratio analysis

wmnzmm jets ratio analysis

general ewk meeting

electron isolation

data muon selection