Group A meeting Update on signal selection Valerio Vagelli

All-electron analysis

Group A meeting

Update on signal selection

Valerio Vagelli

Status at Jan2014 GM

Binning● Redefinition of binning

– Same binning up to 100 GeV (3 sigma)

– 5 sigma binning up to 220 GeV

– Bins ad-hoc above

● Results in a more smooth spectrum in [100-200] GeV

Double_t AMSBinning[58] = { 0.50, 0.72, 0.98, 1.29, 1.65, 2.05, 2.51, 3.01, 3.57, 4.19, 4.87, 5.60, 6.40, 7.26, 8.20, 9.20, 10.28, 11.44, 12.68, 14.01, 15.43, 16.95, 18.57, 20.30, 22.14, 24.10, 26.18, 28.40, 30.76, 33.26, 35.93, 38.76, 41.76, 44.96, 48.35, 51.94, 55.76, 59.81, 64.11, 68.67, 73.51, 78.64 ,84.08, 89.86, 95.98, 102.47,113.95, 126.57, 140.47, 155.76, 172.59, 191.10, 220.00, 260.00, 350.00, 500.00, 700.00, 1000.00 };

Energy Corrections● EcalShower::GetCorrectedEnergy(2,2) instead of EnergyE

– Templates and efficiencies calculated in the same energy definition

– We need to re-evaluate the systematic due to energy migration

– The very last bin [700-1000] GeV is now more in line with the others ( probably less contamination? )

Statistics added● Added ISS.B620/pass4 5 months of new data

– Preselection routine run. Files available in CASTOR/CNAF● We tried to use the really same selection as before, some

differences may come from bug-fixes to the patch / different DB

Statistics added● Added ISS.B620/pass4 5 months of new data

DOE Review

TOF scans

● Seems there is a slightly higher amount of events/time in the last preselected events

Difference in trigger efficiency at low energies

More evident in the ECAL triggers

BDT v6● BDT v6

– trained in CorrEne bins

– More training statistic

– “Same” cuts to define training sample as in the main analysis

BDT v6

*with a “temporary” choiche of templates

Errors comparison

● Zhili○ Us

● Zhili○ Us

● Zhili○ Us

*BDTv6 analysis

Roofit Error

Toy: check how the RooFit error changes with different fits scenario.

GENERATE AND FIT WITH SAME TEMPLATES → TEMPLATES ARE 100% CORRECT1) One Gaussian + One Gaussian with tail (Cball,n=1,alpha=4), б=1, different separations, S/N=0.2

GENERATE AND FIT WITH DIFFERENT TEMPLATES → 1 TEMPLATE IS NOT CORRECT2) Generate two gaussians, б=1, different separations, S/N=0.2 Fit with a wrong gaussian (gaussian with tail (Cball, n=1.5, alpha=8) ) Simulates electron tails in proton templates

3) Generate two gaussians, б=1, different separations, S/N=0.2 Fit with a gaussian with less shoulder (splitted gaussian, бleft=0.85, бright=0.85) Simulates a bias induced by ECAL selection on the shoulder on the opposite side from the signal in the proton template

Roofit Error

μ=±5 μ=±2

μ=±1 μ=±0.5

1) One Gaussian + One Gaussian with tail (Cball), б=1, different separations, S/N=0.2

Fiterror/sqrt(fitted)

Roofit Error2) Generate two gaussians, б=1, different separations, S/N=0.2 Fit with a wrong gaussian (gaussian with tail (Cball, n=1.5, alpha=8) ) Simulates electron tails in proton templates

μ=±5 μ=±2

μ=±1 μ=±0.5

Roofit Error3) Generate two gaussians, б=1, different separations, S/N=0.2 Fit with a gaussian with less shoulder (splitted gaussian, бleft=0.85, бright=0.85) Simulates a bias induced by ECAL selection on the shoulder on the opposite side from the signal in the proton template

μ=±5 μ=±2

μ=±1 μ=±0.5

Selection Systematics● Mainly given by the ambiguity to determine the shape of

the proton templates from data– R>0 protons, R<0 protons, AllR protons

– No cut on BDT, BDT<0

– Strenght of E/P cut

● All these cuts bias the shape is some direction

Selection Systematics● Different template definition gives different efficiency curves

R<0, no BDT cut→ too much electrons in tail

● The most visible effect is the rigidity sign, but also the BDT cut and E/P have an effect

*BDTv6 analysis

Selection Systematics● Effect on the final result

Template used for the signal extraction

Tem

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Fixed BDT cut (noBDT in this case)Fixed R cut (R>0 in this case)Change the strenght of the E/P cut induces a trend



Tem

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Fixed R cut (R>0 in this case)For a given E/P cut, applying or not a BDT cut on the proton template gives a different result

No BDT cut

BDT<0



Tem

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Adding also negative protons, again changes the result

No BDT cut

BDT<0

R>0 No cut on R



Tem

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The same is true for fixed signal extraction and changing the template used to evaluate the efficiency



Tem

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We can think to add also the templates with R<0.This has some sense only when fitting efficiencies (because we fit the negative sample)Also, we cannot use these templates without a cut on BDT, otherwise the signal contamination in the electron tail fakes the normalization, which is critical for the efficiency evaluation.Therefore, the only meaningful addition is the highlighted one.

But: it is correct to add these to the final result? The systematic also will increase by a lot!

Same square

Asbefore

R<0R<0

R<0

Selection Systematics● A reasonable choice of templates

– Signal extraction:

● R>0 + allR, noBDTcut, EoP [0.5-0.7]

● R>0 + allR, BDT<0, EoP [0.7-0.9]

– Efficiency evaluation


● R>0 + allR, BDT<0, EoP [0.7-0.9]

● R<0, BDT<0, EoP [0.7-0.9] AllR

NoBDTcutEoP [0.5-0.7]

AllRBDT<0

EoP [0.7-0.9]

AllRBDT<0

EoP [0.7-0.9]

AllRNoBDTcut

EoP [0.5-0.7]AllR

BDT<0EoP [0.7-0.9]

R>0NoBDTcut

EoP [0.5-0.7] R>0BDT<0

EoP [0.7-0.9]

*BDTv6 analysis

Selection Systematics● A reasonable choice of templates

– Signal extraction:


● R>0 + allR, BDT<0, EoP [0.7-0.9]

– Efficiency evaluation


● R>0 + allR, BDT<0, EoP [0.7-0.9]

● R<0, BDT<0, EoP [0.7-0.9] AllR

NoBDTcutEoP [0.5-0.7]

AllRBDT<0

EoP [0.7-0.9]

AllRBDT<0

EoP [0.7-0.9]

AllRNoBDTcut

EoP [0.5-0.7]AllR

BDT<0EoP [0.7-0.9]

R>0NoBDTcut

EoP [0.5-0.7] R>0BDT<0

EoP [0.7-0.9]

*BDTv5 analysis

(Old) ECAL Simple Cuts efficiency● Cut on the energy deposit in the first 3 superlayers (normalized on data)

– F1SL in [9%-91%] efficiency



● Cut efficiency estimated from MC

Is this a real trend? Need more MC

(new) Simple Cuts

Mainly transformationsNeed to gaussianize variablesMore stable than box-cox transf.

Documents

Group A meeting Update on signal selection Valerio Vagelli