validation of dc3 fully simulated w→eν samples (nlo, reconstructed in 11.0.42) laura gilbert...

Validation of DC3 fully Validation of DC3 fully simulated Wsimulated W→→eeνν samples samples (NLO, reconstructed in 11.0.42)(NLO, reconstructed in 11.0.42)

Laura Gilbert 01/08/06

WW→→eeνν from MC@NLO, full simfrom MC@NLO, full sim Original sample submitted for generation in Original sample submitted for generation in

December, some of the one million December, some of the one million WW→→ee--νν now fully now fully simulated on the grid, in batches of 10k events.simulated on the grid, in batches of 10k events.

47800 events available (using CBNTs)47800 events available (using CBNTs) Lepton generator level filter efficiency (10Gev, |Lepton generator level filter efficiency (10Gev, |ηη|<2.7) was |<2.7) was

~63.3%~63.3% Generated cross section is 8.4nb (cf. 30nb for Generated cross section is 8.4nb (cf. 30nb for WW→→ll--νν: TDR). : TDR).

Luminosity for 10k events is 1.9pbLuminosity for 10k events is 1.9pb-1-1.. Cuts applied at any stage are listed on top right of slide.Cuts applied at any stage are listed on top right of slide. ALL truth plots are normalised to weighting of simulated data ALL truth plots are normalised to weighting of simulated data

EXCEPT multiplicity plots.EXCEPT multiplicity plots.

ELECTRONSELECTRONS

- truth- full

sim

Sanity plots: multiplicitySanity plots: multiplicity

Electron Selection CutsElectron Selection Cuts

At least one electron with transverse energy > At least one electron with transverse energy > 25GeV. (Use ET rather than pT since brem 25GeV. (Use ET rather than pT since brem recovery not properly implemented yet0recovery not properly implemented yet0

Electron candidate has at least one associated Electron candidate has at least one associated track matched (exclude photons)track matched (exclude photons)

ηη < 2.4. This cuts out dubious candidates at < 2.4. This cuts out dubious candidates at the end of the electromagnetic calorimeter.the end of the electromagnetic calorimeter.

IsEM flag = 0, electron isolation cut. This IsEM flag = 0, electron isolation cut. This should now be tuned correctly but I need to should now be tuned correctly but I need to look into the bitwise cuts in more detail to look into the bitwise cuts in more detail to check.check.

ELECTRONSELECTRONS

- truth- full

sim

Sanity plots: multiplicity of electrons that pass Sanity plots: multiplicity of electrons that pass selection cutsselection cuts

Cuts: ET(ele) > 25GeV At least one

track matched IsEM=0 η(ele) < 2.4

Almost always only one electron

candidate per event passes cuts.

ELECTRONSELECTRONSCuts:

ET(ele) > 25GeV At least one

track matched IsEM=0 η(ele) < 2.4Checking cuts with truth info:Checking cuts with truth info:

- before cuts- after cuts

Initially tracks of candiadates entered into egamma container include kaons, pions, muons. After cuts only electrons remain.

ELECTRONSELECTRONSSanity plots: phiSanity plots: phi

- truth- full

sim



ELECTRONSELECTRONSSanity plots: etaSanity plots: eta

- truth- full

sim



ELECTRONSELECTRONSIdentifying electrons with their partner in Identifying electrons with their partner in truth containers, matching (truth containers, matching (ηη,,φφ) space) space::

22 )()( TTR

If (ΔR<0.1) match is found



ELECTRONSELECTRONSSanity plots: ETSanity plots: ET

- truth- full

sim



ELECTRONSELECTRONSDifference between simulated and truth ET Difference between simulated and truth ET distributions:distributions:

No overall difference between simulated and truth ET shapes!

PROBLEM?



ELECTRONSELECTRONSElectron ET resolution: (sim-truth)/truth for Electron ET resolution: (sim-truth)/truth for matched sim:truth electron pairs.matched sim:truth electron pairs.

Cuts: ET(ele) > 25GeV At least one track

matched IsEM=0 η(ele) < 2.4 ΔR<0.1

(matching sim to truth)

Resolution looks roughly ok though…

ELECTRONS ELECTRONS "Wrong sign" electrons found from associated "Wrong sign" electrons found from associated track q/p, AFTER cuts:track q/p, AFTER cuts:

Wrong sign

Correct sign

*PROBLEM*



ELECTRONSELECTRONSET distribution of "wrong sign" electron ET distribution of "wrong sign" electron candidates:candidates:

- +ve charge electrons (from track q/p)

- all electron candidates (for shape comparison)



ELECTRONSELECTRONSConsider truth information: just cut on ET > 25GeVConsider truth information: just cut on ET > 25GeV

- before cuts- after cuts

There are positrons present in egamma truth, but none pass ET cut.

Cuts: ET (ele truth)

> 25GeV

ELECTRONSELECTRONS

What are the wrong sign electrons?What are the wrong sign electrons? Not generated positronsNot generated positrons Don't have high pT tracks, so probably Don't have high pT tracks, so probably

not electrons mis-reconstructed.not electrons mis-reconstructed. Possibly wrong track-cluster Possibly wrong track-cluster

combinations. Needs further combinations. Needs further investigation.investigation.



ELECTRON ISSUESELECTRON ISSUES

E over p always 0! → needs to be fixed in future.

Where do the "positrons" come from?

Need to look into IsEM flags in detail.

Further investigation needed:

ELECTRON JETSELECTRON JETS

W Transverse mass plots look fishy if I apply W Transverse mass plots look fishy if I apply exclusions on events containing jets with exclusions on events containing jets with ET>30GeV.ET>30GeV.

Therefore many jets come from electrons.Therefore many jets come from electrons.

Identify and exclude these electron jets. Identify and exclude these electron jets.

Can only be one on jets with Can only be one on jets with ηη<2.5 to make <2.5 to make electron matching possible.electron matching possible.

(Jets reconstructed using cone algorithm with R<0.7, see (Jets reconstructed using cone algorithm with R<0.7, see later)later)

ELECTRON JETSELECTRON JETSCuts:


track matched IsEM=0 Jet η < 2.5

22 )()( jetejeteR

Identify jets with electrons if ΔR<0.7

- truth- full

sim

Matching electrons and jets in (Matching electrons and jets in (ηη,,φφ) space:) space:

Log scale→



track matched IsEM=0 Jet η < 2.4

Jets are corrected to have more energy than electron candidates so -ve values more likely to be a match.

Trying to match energy as well as (η,φ) distribution (no cut made):

- truth- full

sim

Matching electrons and jets in energy:Matching electrons and jets in energy:



track matched IsEM=0 Jet η < 2.4A closer look at electron-jet A closer look at electron-jet ΔΔR and R and

energy distributions: simulationenergy distributions: simulation

Smattering of events

here




energy distributions: truthenergy distributions: truth

no events here




energy distributions: (truth - simulation)energy distributions: (truth - simulation)

This is the normalised difference of the last two plots!

ΔR

Energy difference (MeV)

Truth - simulated

JETSJETSCuts:

ΔR (e-jet) > 0.7 Jet η < 2.4

Looking at all jets which have not been matched Looking at all jets which have not been matched with electrons: ie. Jets which are isolated from with electrons: ie. Jets which are isolated from electron candidates by at least 0.7 in (electron candidates by at least 0.7 in (ηη,,φφ).).

Still looking at jets with Still looking at jets with ηη<2.4 for accurate <2.4 for accurate electron matching.electron matching.

There are three available clustering algorithms:There are three available clustering algorithms: Kt alorithm: apparently unsuitable for low pT jets.Kt alorithm: apparently unsuitable for low pT jets. Cone algorithm with R<0.4. Discounted as produces Cone algorithm with R<0.4. Discounted as produces

very low statistics (few jets reconstructed)very low statistics (few jets reconstructed) Cone algorithm with R<0.7. Use this.Cone algorithm with R<0.7. Use this.

JETSJETSSanity plots: multiplicity before any selection:Sanity plots: multiplicity before any selection:

- truth- full

sim

JETSJETSCuts:

ΔR (e-jet) > 0.7 Jet η < 2.4

Sanity plots: multiplicity after electron/jet Sanity plots: multiplicity after electron/jet matches removed, jet matches removed, jet ηη<2.4<2.4

- truth- full

sim

Log scale→

Multiplicity greatly reduced

JETSJETSSanity plots: phiSanity plots: phi

Cuts: ΔR (e-jet) > 0.7 Jet η < 2.4

- truth- full

sim

JETSJETSSanity plots: etaSanity plots: eta

Shape before η

cut


- truth- full

sim

JETSJETSCuts:

ΔR (e-jet) > 0.7 Jet η < 2.4 ΔR(jet-

truth)<0.5

Matching jets with truth in (Matching jets with truth in (ηη,,φφ) space:) space:

22 )()( TTR

Log scale→If (ΔR<0.5) match is found

JETSJETSSanity plots: ETSanity plots: ET


- truth- full

sim

Jets not reconstru

cted < 10GeV

JETSJETSET resolution: (sim-truth)/truthET resolution: (sim-truth)/truth

Cuts: ΔR (e-jet) > 0.7 Jet η < 2.4 ΔR(jet-truth)<0.5

JETSJETSSanity plots: EnergySanity plots: Energy


- truth- full

sim

JETSJETSEnergy resolution: (sim-truth)/truthEnergy resolution: (sim-truth)/truth

Cuts: ΔR (e-jet) > 0.7 Jet η < 2.4 ΔR(jet-truth)<0.5

JETSJETSSanity plots: ETSanity plots: ET


- truth- full

sim

Strange: data is shifted down from truth.

22 pEmass

JET ISSUESJET ISSUES

Jets from electrons are easily identified and Jets from electrons are easily identified and removed by an exclusion cut in (removed by an exclusion cut in (ηη,,φφ) space.) space.

Not certain this is the best algorithm, but Not certain this is the best algorithm, but other available algorithms have more other available algorithms have more problems.problems.

Jet statistics low after removal of electrons, Jet statistics low after removal of electrons, therefore resolutions not well defined.therefore resolutions not well defined.

Meaning of jet “mass” not well understood, Meaning of jet “mass” not well understood, left-shift of simulation w.r.t. truth left-shift of simulation w.r.t. truth unexpected.unexpected.

MISSING ENERGYMISSING ENERGY

- truth: calculated from non-interacting particles

- full sim: corrected, inc. muons

Sanity plots: Missing ETSanity plots: Missing ET

Probably not properly

calibrated

Cuts: Ptele > 25GeV At least one

track matched IsEM=0 Electron η < 2.4 Jet η < 2.4 ΔR (e-jet) > 0.7 MET>25GeV

Cut on MET>25GeV

MISSING ENERGYMISSING ENERGYCuts:

Ptele > 25GeV At least one


Missing ET Resolution:Missing ET Resolution:

Asymmetry reflecting right-

shift of data w.r.t. truth

MISSING ENERGYMISSING ENERGY

- truth- full

sim



Missing ET Missing ET φφ distribution distribution::

W RECONSTRUCTIONW RECONSTRUCTION

- truth- full

sim



W transverse mass reconstructed from W transverse mass reconstructed from Missing ET and highest ET electron:Missing ET and highest ET electron:

)cos1(2 Tmiss

Te

TW ppm

Conclusions:Conclusions:

The W looks like TDR (right)! The W looks like TDR (right)! Electrons are well reconstructed.Electrons are well reconstructed. The e/p variable in the egamma container The e/p variable in the egamma container

should probably be fixed.should probably be fixed. Electrons with mis-identified charge not Electrons with mis-identified charge not

yet understood.yet understood. Missing energy doesn’t seem best Missing energy doesn’t seem best

corrected to match truth.corrected to match truth. Insufficient stats for decent jet resolution.Insufficient stats for decent jet resolution. Jet “mass” shift seems strange.Jet “mass” shift seems strange.

validation of dc3 fully simulated w→eν samples (nlo, reconstructed in 11.0.42) laura gilbert...

Documents

electrons cuts

selection cuts cuts

sim cuts

track matched isem

electrons truth

bitwise cuts

checking cuts

electron selection cuts