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

Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame. Analysis Status Jeff Standage, York Thomas Schoerner, Hamburg. Selection of DIS Events Selection of Jets Jet Reconstruction & Selection Cross-section plots (Requests for prel.) Systematic checks.

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

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  1. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Analysis Status Jeff Standage, York Thomas Schoerner, Hamburg • Selection of DIS Events • Selection of Jets • Jet Reconstruction & Selection • Cross-section plots (Requests for prel.) • Systematic checks 29th July 2004Jeff Standage, York University

  2. EVENT SELECTION 1 • Standard DIS Event Selection for ZEUS: • Trigger bit b12 and DIS03. • Chain: (FLT 40,41,43,44,46) and (GSLT6_6) and TLT4 • Q2 > 125 GeV2 • -0.7 < cosγh < 0.5 • yel < 0.95 Ee’ > 10 GeV • 38 < E – pz < 65 (GeV) • |zvtx| < 50 cm • Radius cut 36 cm. 29th July 2004Jeff Standage, York University

  3. EVENT SELECTION 2 • PT/(ET1/2) < 2.5 GeV1/2 • where PT is the missing transverse momentum and ET is the total transverse energy both measured in the CAL. • Total energy not associated with positron inside cone of radius 0.8 units in - plane around positron direction is less than 10%. • Total fraction of positron energy inside cone around positron direction of radius 0.3 should be greater than 90(98)% for positron angles satisfying 30 < e < 140 (e < 30). 29th July 2004Jeff Standage, York University

  4. ZEUS 98-2000 ARIADNE Control Plots Q2DA YJB Yele cosγh Ee(corr) E-pz zvtx θe

  5. Jet Selection and Reconstruction • Jets reconstructed from ZUFOs/hadrons boosted into the Breit Frame • KT Cluster algorithm used in inclusive mode (3212). • Jets selected using criteria: • Breit Frame: • ETB > 8 GeV • -2.0 < ηB < 1.8 • Lab Frame: • ETL > 2.5 GeV • -1.0 < ηL < 2.0 • Events with a jet “close” to the scattered lepton are rejected. • Events with 1+ jets of ETB>5 GeV located in very backward direction (ηL < -2) are also rejected.

  6. ZEUS 98 - 2000 ARIADNE Jet Control Plots Breit η ET Lab

  7. Q2 ET(jet) η(jet) Jet Control Plots Acceptance: QED radiative: Hadron-Parton corrections:

  8. ZEUS 98 – 00 (JS) ZEUS 96 – 97 (OG) Cross-sections: η(jet) Q2 ET(jet) Better agreement with previous analysis. 29th July 2004Jeff Standage, York University

  9. Preliminary Plots REQUEST FOR PRELIMINARY 29th July 2004Jeff Standage, York University

  10. Systematics: • Jet Energy Scale 1(3)% for ET<(>)10GeV: (~4%). • Positron Energy Scale 1%: (~1%). • Use of Djangoh for acceptance corrections: (~7%). • Use of EM electron finder instead of Sinistra: (~1%). • Cut ETL(jet) > 4.0 GeV instead of 2.5 GeV: (negligible). • CutsL > -3.0, -1.5 instead of -2.0: (~1%). 29th July 2004Jeff Standage, York University

  11. Ongoing and Future Plans • Thomas redoing jet energy corrections/cross-sections, to get back agreement. • Further systematics to do. • More NLO work, now have samples with different PDFs, need to add in theoretical errors. • Using these calculations, calculate αs. 29th July 2004Jeff Standage, York University

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