Inclusive Jet Cross-Sections in Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Neutral Current DIS Events Using the

Breit FrameBreit FrameAnalysis Status

Jeff StandageYork University

Thomas SchoernerHamburg University

Marcos Jiminez

Claudia Glasman

Juan TerronUniversidad Autonoma de Madrid

Contents

• Cross-section & NLO:Data ratio comparisons

• Differences between two analyses – so far

QCD Meeting, 10th March 2005 Jeff Standage, York University

Q2

JT/OG

(DESY 02-112)

96-97

JS/TSS

98-00

MJ/CG/JT

99p-00

QCD Meeting, 24th March 2005 Jeff Standage, York University

JS/TSS

98-00

MJ/CG/JT

99p-00

ET(jet)

QCD Meeting, 10th March 2005 Jeff Standage, York University

JT/OG

(DESY 02-112)

96-97

JS/TSS

98-00

MJ/CG/JT

99p-00

η (jet)

QCD Meeting, 10th March 2005 Jeff Standage, York University

JT/OG

(DESY 02-112)

96-97

Differences Between JS/TS and MJ/CG/JT Analyses

• Analysis codeOrange/phantom 2004a(.1,.2) Private EAZE job

Orange variables for cuts Release 2004a.1 (pro)

Zufos/cells for offline jet finding

• Noise Suppression (noise02s.fpp)

ecut(1) = 0.08 ecut(1) = 0.10

ecut(2) = 0.14 ecut(2) = 0.15

imbacut = 0.7 imbacut = 0.9

• CAL corrections (escale03.fpp)

Individual RCAL cell corrections No RCAL cell by cell corrections

Global corrections - Global corrections -

FCAL HAC: 0.941 FCAL HAC: 0.95

FCAL EMC: 1.024 FCAL EMC: 1.04BCAL HAC: 1.0962 BCAL HAC: 1.08BCAL EMC: 1.05315 BCAL EMC: 1.04RCAL HAC: 1.022 RCAL HAC: 1.025RCAL EMC: 1.022 RCAL EMC: 1.025

JS/TS MJ/CG/JT

QCD Meeting, 10th March 2005 Jeff Standage, York University

Differences Between JS/TS and MJ/CG/JT Analyses

• VertexCell position corrected for Cell position corrected for z-vertex only.

X,Y,Z vertices

• Lepton beam energyOrange: Ee = 27.56 GeV Ee = 27.5 GeV

Offline: Ee = 27.52 GeV

• Isolation (cone) cutA cut is put on the electron candidate such that the total energy not associated with the candidate in a radius of R is eta-phi space is less than 10%. This removes

photoproduction events and events where a jet remnant is falsely identified as the positron.

R = 0.8 R = 0.7

• Sinistra electronElectron corrected for dead material. Uncorrected Sinistra candidate

is used.Orange variable: Siecorr(3,1) Corresponds to SiCalEne(1)

• Event variablesOrange variables being used, All values calculated directly from cells

e.g. SiQ2da(1), SiCeHMom(4,1) information.

Evidence of further orange corrections/differences.

JS/TS MJ/CG/JT

QCD Meeting, 10th March 2005 Jeff Standage, York University

Summary

• Analysis differences lead to ~10% difference in events selected

Claudia had 992 events that I have rejected or have no jets.

I have 825 such events that Claudia doesn’t.• Analysis differences lead to complete discrepancy in number of jets in each event.• Have over-ridden orange routines to implement her analysis criteria.

Of those 992 events are still losing 20:

(i) 1 event: Q2 difference (2 cells have different energy).

(ii) 2 events: cosGammaHad.

(iii) 11 events: isolated cone cut (after moving to 0.7).

(iv) 6 events have no jets (still to look into jet finding).

not using orange jets!

QCD Meeting, 10th March 2005 Jeff Standage, York University

Further Progress• Have over-ridden orange routines to implement her analysis criteria.

Of those 992 events are still losing 20:

(i) 1 event: Q2 difference (2 cells have different energy).

(ii) 2 events: cosGammaHad.

(iii) 11 events: isolated cone cut (after moving to 0.7).

(iv) 6 events have no jets (still to look into jet finding).

not using orange jets!

QCD Meeting, 24th March 2005 Jeff Standage, York University

Reasons Q2 difference due to different cell assignment to some cells used in the event (e.g. cells 1162,1178 CG: FEMC, JS: FHAC):

CG uses phantom routine, ccwhat.fpp, to determine cell type. JS using orange which uses these lines of code:

fbr = 1 + Caltru_CellNr/16384 ! Determines forward/barrel/rear (1,2,3) eh = min(2,max(1, mod(Caltru_CellNr,16)/2 -4)) ! Determines EMC/HAC (1,2)

Further Progress (cont …)

QCD Meeting, 24th March 2005 Jeff Standage, York University

Reasons (cont …)•Isolated cone differences due to CG applying this cut only if scattered positron angle is between 20 and 140 degrees, while JS applied it throughout.

• Hadronic angle, cos differences are due to “extra cells” in my events.

• Events with no jets in have not yet been looked at. Suspect same cells difference as the cause.

• Have over-ridden orange routines to implement her analysis criteria.

Of those 992 events are still losing 20:

(i) 1 event: Q2 difference (2 cells have different energy).

(ii) 2 events: cosGammaHad.

(iii) 11 events: isolated cone cut (after moving to 0.7).

(iv) 6 events have no jets (still to look into jet finding).

not using orange jets!

QCD Meeting, 24th March 2005 Jeff Standage, York University

In Conclusion

• For 99p-00 data:

CG has 9227 DIS events with 1+ jet(s).

Using her methods, cuts, etc., I get 9222• Differences:

CG has 14 events I don’t (2 cos, 7 no jets, no run 37715).

I have 9 that CG doesn’t.

9 events have different jet data (ET, L/B).

Rest of the events are identical.

Differences due to slight difference in cells used in the events?

Future steps

• Nail down last few events cut differences (worth it?). • Currently comparing detector level MC.

• Repeat process for the hadron level in MC

(using JT/CG get_hadsys.fpp).• Compare acceptance corrections.• Jet energy corrections.• Cross-sections.• Decide which methods/corrections are the right ones (why)?

QCD Meeting, 24th March 2005 Jeff Standage, York University

So…• Nail down last few events cut differences (worth it?). - Not worth it. • Detector level MC. (no further changes). - CG has 20237 (1+ jet) events with 28679 jets. - JS has 20239 events with 29669 jets (no corrections).• Repeat process for the hadron level in MC. (scaling of massless hadrons). - CG has 32211 (1+ jet) events with 48526 jets. - JS has 32233 events with 48566 jets (no corrections). • Jet energy corrections. - Process of getting jet energy corrections is subjective.

- Using CG numbers, I get similar level of agreement to above.

- My jet energy corrections look similar by eye, but give different results.

- Jet energy scale corrections agree precisely (no further changes).• Compare acceptance corrections. - Highly dependent on energy jet energy corrections.• Cross-sections. - Small dependence on energy jet energy corrections.

QCD Meeting, 7th April 2005 Jeff Standage, York University

So…

• Compare acceptance corrections. - Highly dependent on energy jet energy corrections.

QCD Meeting, 7th April 2005 Jeff Standage, York University

Bjetd

d

CG JS (with CG jet corr.) JS (with own jet corr.)

6.02 6.03 6.03

53.4 53,4 53.4

156.8 156.3 156.4

171.8 171.3 171.4

110.9 111.3 112.4

Cross-sections. - Small dependence on energy jet energy corrections.

CG JS (with CG jet corr.) JS (with own jet corr.)

0.944 0.923 1.005

0.827 0.814 1.149

1.025 1.015 1.533

1.134 1.126 1.630

1.031 1.031 1.389

Acc

(jet)

QCD Meeting, 7th March 2005 Jeff Standage, York University

Summary• I have reproduced CG results using her methods.

• Details of differences between two analysis methods have been shown.

• Differences between CG/MJ/JT and JS/TSS analyses now found and have been shown.

• Many differences seem to have a minor but cumulative effect.

• Results are very sensitive to scattered electron four-momentum effect on the boost to/from Breit frame.

• Acceptance corrections very sensitive to the jet energy corrections used, although final cross-sections are not.

Future steps• Decide between discrepancies, sets of corrections, etc.• Extend to include electron data.• Incorporated QED, hadron-parton corrections.• Crunch numbers to get systematic errors.• Produce preliminary plots.