1. Dijets at low Bjorken-x, Tom Danielson, U. WisconsinWisconsin Group Meeting, 5 August 2004 Tom Danielson University of Wisconsin An Investigation of the low Bjorken-x breakdown of DGLAP Inclusive Dijets in Low Bjorken-x

2. Dijets at low Bjorken-x, Tom Danielson, U. WisconsinWisconsin Group Meeting, 5 August 2004 Main Issue: Low x DGLAP Breakdown Gluon ladder  DGLAP: Ladder “k t – ordered”  k t1 > k t2 > k t3 > … 1 2  BFKL: Scheme based on log(1/x)  Well-suited to low-x events (forward jets)  No k t -ordering of ladder

3. Dijets at low Bjorken-x, Tom Danielson, U. WisconsinWisconsin Group Meeting, 5 August 2004 Ground Work: Selecting Events  Issue 1: Detector vs. Generator level kinematics for MC  Ariadne with Q 2 min = 10 GeV 2  True level x, Q 2 plotted against x da and Q 2 da calculated from zufos  True level y plotted against y jb calculated from zufos  Cuts applied progressively

4. Dijets at low Bjorken-x, Tom Danielson, U. WisconsinWisconsin Group Meeting, 5 August 2004 Initial Distributions  Almost no cuts  jet finding on-line: needed  cut to avoid electron being mistaken for jets.  -1 <  <  3  No jet E t cut – very few events lost

5. Dijets at low Bjorken-x, Tom Danielson, U. WisconsinWisconsin Group Meeting, 5 August 2004 Cut 1: 25 < Q 2 da < 150 GeV 2

6. Dijets at low Bjorken-x, Tom Danielson, U. WisconsinWisconsin Group Meeting, 5 August 2004 Next cut: 10 -2 < x < 10 -4

7. Dijets at low Bjorken-x, Tom Danielson, U. WisconsinWisconsin Group Meeting, 5 August 2004 Next Cut:.04 < y jb <.7

8. Dijets at low Bjorken-x, Tom Danielson, U. WisconsinWisconsin Group Meeting, 5 August 2004 Next cut: 35 < E – p z < 65

9. Dijets at low Bjorken-x, Tom Danielson, U. WisconsinWisconsin Group Meeting, 5 August 2004 Next cut: |z vtx | < 50 cm

10. Dijets at low Bjorken-x, Tom Danielson, U. WisconsinWisconsin Group Meeting, 5 August 2004 Next cut: DIS03 Electron energy cut E e > 10 cuts no events

11. Dijets at low Bjorken-x, Tom Danielson, U. WisconsinWisconsin Group Meeting, 5 August 2004 Final Cut: Asymmetric E T Cut on Jets Electron box cut eliminates no events. E T,1 > 7 GeV, E T,2 > 6 GeV

12. Dijets at low Bjorken-x, Tom Danielson, U. WisconsinWisconsin Group Meeting, 5 August 2004 Future 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 E T jets