Ricardo Goncalo SFEW Review Meeting 5 June 2001 1

Neutral Current 1999/00 e+p

5th June 2001

Chris Cormack

Matthias Moritz

Henning Schnurbusch

Ricardo Gonçalo

Since DIS01:

•xF3 and helicity plot from Matthias

My analysis:

•Data sample and event selection

•Control plots

•Results

Ricardo Goncalo SFEW Review Meeting 5 June 2001 2

Since DIS01:

Matthias’ results:

xF3 from 1998/99 and 1999/00 with systematics (same systematic error treatment in both data sets)

Ricardo Goncalo SFEW Review Meeting 5 June 2001 3

Matthias:

Helicity plot in NC

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~

322

32 xFFyxFF

Y pepeNC

Draft NC 99/00 paper for Budapest:http://www-zeus.desy.de/~schnurbu/ZEUS/talks_ps/budapest.ps

Please read and send comments

Ricardo Goncalo SFEW Review Meeting 5 June 2001 4

Reconstruction:

• Electron finder: SINISTRA, FINDIS option 5.

• Hadronic final state: CorAndCut.

•Kinematic variables: Double Angle.

•Electron track angle taken if within CTD acceptance.

Corrections:

• Data: noise suppression and RCALCorr (in orange).

•Data/MC: dead material and non-uniformity corrections.

•MC: Vertex reweighting (1999/00) and electron energy smearing (width=0.2; cutoff=4.0).

My Analysis

Summary:• Statistical errors only.

• No background subtraction or RapGap Monte Carlo yet.

• Used Orange release 2000a.2.

• Measured F2 using 1999/00 e+p data: compared to 1996/97 measurement.

• Measured xF3 using 1998/00 data.

Ricardo Goncalo SFEW Review Meeting 5 June 2001 5

NC 99/00 e+p data/MCMy analysis - DATA:•Run range 33125 up to 37165 only•Integrated Lumi 57.6 pb-1

•DST bit 12•Runs excluded by EVTAKE

Monte Carlo: funnel num98t3.1• 2 pb-1 with Q2 > 25 GeV2

• 4 pb-1 with Q2 > 40 GeV2

• 64 pb-1 with Q2 > 100 GeV2

• 95 pb-1 with Q2 > 400 GeV2

• 253 pb-1 with Q2 > 1250 GeV2

• 407 pb-1 with Q2 > 2500 GeV2

• 1.6 fb-1 with Q2 > 5000 GeV2

• 8.6 fb-1 with Q2 > 10 000 GeV2

• 77 fb-1 with Q2 > 20 000 GeV2

• 220 fb-1 with Q2 > 30 000 GeV2

• 1104 fb-1 with Q2 > 40 000 GeV2

• 5661 fb-1 with Q2 > 50 000 GeV2

Djangoh; CTEQ5D; Ariadne

Henning & Matthias:

•Data: 56.7 pb-1 for Q2<800 GeV2 63.0 pb-1 for Q2>800 GeV2

•Run range: 33125-37715

•Runs excluded by EVTAKE and PRESTAKE for Q2<800 GeV2

(uncalibrated presampler)

•Monte Carlo: Photoproduction and RapGap Monte Carlo included

•Slightly different binning

•A lot of systematic errors done

Still to compare to my analysis in detail

Ricardo Goncalo SFEW Review Meeting 5 June 2001 6

Selection cutsGeneral:• Sinistra probability > 0.9• Ee > 10 GeV2

• -50 cm < Zvtx < 50 cm• Electron DCA < 10 cm• Energy in cone not from electron < 5 GeV2

• pT/ET < 4 GeV• Simple elastic QED Compton rejection Cuts for e < 17º

• 44. < E-pZ < 65 GeV

• pT,e > 30. GeV

Cuts for 17º < e < 163º

• pTRK,e > 5. GeV

Cuts for e > 17º

• 38. < E-pZ < 65 GeV

Kinematics:• Q2 > 185 GeV2 (lower bound of first bin)• yel < 0.95

Henning & Matthias:

•Require electron with track if within CTD acceptance

•Extra cut on Rcal electron radius > 175 cm

Ricardo Goncalo SFEW Review Meeting 5 June 2001 7

Reduced cross section:

LNC

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LNC

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FY

yxF

Y

YF

FY

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YF

2

32

2

32

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Unfolding & etc:

Cross-check of the reduced cross section:

LFY

yF

2

2 22

Measurement

of xF3:32 xFYY

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And F2EM:

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Ricardo Goncalo SFEW Review Meeting 5 June 2001 8

Control plots

Ricardo Goncalo SFEW Review Meeting 5 June 2001 9

Reasonable agreement between Monte Carlo and data but must add PhP and Rapgap soon

Control plots

Ricardo Goncalo SFEW Review Meeting 5 June 2001 10

Unfolding:

Results: single differential cross section

Theory

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NC

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Ricardo Goncalo SFEW Review Meeting 5 June 2001 11

Purity and efficiency

Ricardo Goncalo SFEW Review Meeting 5 June 2001 12

Results: double differential reduced cross section

Ricardo Goncalo SFEW Review Meeting 5 June 2001 13

Results: double differential reduced cross sections as a

function of Q2

Bins to be excluded

Ricardo Goncalo SFEW Review Meeting 5 June 2001 14

Results: double differential reduced cross section

Ricardo Goncalo SFEW Review Meeting 5 June 2001 15

Results: xF3

from 1998/99+1999/0

0

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Ricardo Goncalo SFEW Review Meeting 5 June 2001 16

Unfolding:

Results: F2em from 99/00 data

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2 L

Ricardo Goncalo SFEW Review Meeting 5 June 2001 17

Results: F2em from 99/00 data

Ricardo Goncalo SFEW Review Meeting 5 June 2001 18

Systematic error status

alignment complete/to be checked?

Energy scale almost done/smearing?

CAL non-uniformity done

backsplash/ZUFO vs. CCut done

chimney/Supercrack/RCAL radius done

e-finder efficiency done

track matching efficiency done

RapGap bug fixed done

PhP normalisation & check to do

pilot bunches done

vertex distribution done

Compton study done

comparison e-finder/reconstruction done

trigger efficiency almost done

higher order EW terms under investigation

hadronisation started

Systematics studies for 98/99: much in common with 99/00