Dijets at low Bjorken-x, Tom Danielson, U. Wisconsin Wisconsin Group Meeting, 5 August 2004

Tom DanielsonUniversity of Wisconsin

An Investigation of the low Bjorken-x breakdown of DGLAP

Inclusive Dijets in Low Bjorken-Inclusive Dijets in Low Bjorken-xxInclusive Dijets in Low Bjorken-Inclusive Dijets in Low Bjorken-xx

Dijets at low Bjorken-x, Tom Danielson, U. Wisconsin Wisconsin Group Meeting, 5 August 2004

Main Issue: Low Main Issue: Low xx DGLAP DGLAP BreakdownBreakdown

Main Issue: Low Main Issue: Low xx DGLAP DGLAP BreakdownBreakdown

Gluon ladder

DGLAP: Ladder “kt – ordered” kt1 > kt2 > kt3 > …

1

2

BFKL: Scheme based on log(1/x)

Well-suited to low-x events (forward jets) No kt-ordering of ladder

Dijets at low Bjorken-x, Tom Danielson, U. Wisconsin Wisconsin Group Meeting, 5 August 2004

Ground Work: Selecting EventsGround Work: Selecting EventsGround Work: Selecting EventsGround Work: Selecting Events

Issue 1: Detector vs. Generator level kinematics for MC

Ariadne with Q2min = 10 GeV2

True level x, Q2 plotted against xda and Q2da

calculated from zufos

True level y plotted against yjb calculated from zufos

Cuts applied progressively

Dijets at low Bjorken-x, Tom Danielson, U. Wisconsin Wisconsin Group Meeting, 5 August 2004

Initial DistributionsInitial DistributionsInitial DistributionsInitial Distributions

Almost no cuts jet finding on-line: needed cut to avoid electron being mistaken for jets.

-1 < <3 No jet Et cut – very few events lost

Dijets at low Bjorken-x, Tom Danielson, U. Wisconsin Wisconsin Group Meeting, 5 August 2004

Cut 1: 25 < QCut 1: 25 < Q22dada < 150 GeV < 150 GeV22Cut 1: 25 < QCut 1: 25 < Q22dada < 150 GeV < 150 GeV22

Dijets at low Bjorken-x, Tom Danielson, U. Wisconsin Wisconsin Group Meeting, 5 August 2004

Next cut: 10Next cut: 10-2-2 < < xx < 10 < 10-4-4Next cut: 10Next cut: 10-2-2 < < xx < 10 < 10-4-4

Dijets at low Bjorken-x, Tom Danielson, U. Wisconsin Wisconsin Group Meeting, 5 August 2004

Next Cut: .04 < yNext Cut: .04 < yjb jb <.7<.7Next Cut: .04 < yNext Cut: .04 < yjb jb <.7<.7

Dijets at low Bjorken-x, Tom Danielson, U. Wisconsin Wisconsin Group Meeting, 5 August 2004

Next cut: 35 < E – pNext cut: 35 < E – pz z < 65< 65Next cut: 35 < E – pNext cut: 35 < E – pz z < 65< 65

Dijets at low Bjorken-x, Tom Danielson, U. Wisconsin Wisconsin Group Meeting, 5 August 2004

Next cut: |zNext cut: |zvtxvtx| < 50 cm| < 50 cmNext cut: |zNext cut: |zvtxvtx| < 50 cm| < 50 cm

Dijets at low Bjorken-x, Tom Danielson, U. Wisconsin Wisconsin Group Meeting, 5 August 2004

Next cut: DIS03Next cut: DIS03Next cut: DIS03Next cut: DIS03

Electron energy cut Ee > 10 cuts no events

Dijets at low Bjorken-x, Tom Danielson, U. Wisconsin Wisconsin Group Meeting, 5 August 2004

Final Cut: Asymmetric EFinal Cut: Asymmetric ETT Cut on Cut on JetsJets

Final Cut: Asymmetric EFinal Cut: Asymmetric ETT Cut on Cut on JetsJets

Electron box cut eliminates no events.ET,1 > 7 GeV, ET,2 > 6 GeV

Dijets at low Bjorken-x, Tom Danielson, U. Wisconsin Wisconsin Group Meeting, 5 August 2004

Future PlansFuture PlansFuture PlansFuture Plans

• Immediate future:• Evaluate effectiveness of cuts

• Data/MC control plots

• After control plots:distributions

• Order jets in , plot distributions of trailing jet • Cross sections

• Possible measurements of between 2 leading ET jets