Developments with the Cone Algorithm in Run II John Krane Iowa State University MC Workshop Oct , Fermilab Part I: Data vs MC, interpreted as physics Part II: Data vs MC, interpreted as a tuning problem

2 John Krane -- DØ Lost Jets and Search Cones CDF: Matthais Toennesmann DØ: John Krane Cones can iteratate away from “small” Energy clusters There is a reason I’m showing the CDF image

3 John Krane -- DØ Best Description of Procedure Use a small cone to find jets and iterate locations Expand cone size to full 0.7 and save Find midpoints Iterate 0.7 size midpoint jets Wanted to check CDF’s solution and provide feedback

4 John Krane -- DØ Results on selected sample (45 evts) Seed tracking on a sample of 45 suspicious events Distance of nearest found jet from original seed Symmetric in y- , so just use R... Abs y drift Abs  drift Each point was a seed

5 John Krane -- DØ Drift distance for 0.7 cones, p T >15 GeV If a seed is too close (R/2) to existing jet, ignore it Standard cones can drift very long distances! Search cone R/2 limits drift to R

6 John Krane -- DØ R=0.5 Cones Same comments apply...

7 John Krane -- DØ R=0.3 cones Again...

8 John Krane -- DØ Normalize drift distances by R R=0.5 cones, scaled distance

9 John Krane -- DØ x-axes have suppressed zero

10 John Krane -- DØ CPU Requirements

11 John Krane -- DØ Conclusions for Search Cones Cones can drift quite far from the seed, even for reasonably high-p T Jets >15 GeV This doesn’t mean a jet is “lost” every time this happens (I have yet to find a lost jet in DØ data) Search cones can limit drift as much as we like R/2 works well (almost perfectly)  R

12 John Krane -- DØ Suggestions for Future Work Run full Reco tests for CPU time and consistency Consult CDF and try to converge on a parameter – Informally, Joey Huston thinks R/2 works well – Would like permission to show this talk externally

13 John Krane -- DØ Inclusive Jet and Dijet Mass

14 John Krane -- DØ Integrated Luminosity for Moriond

15 John Krane -- DØ Current Jet Triggers

16 John Krane -- DØ Future Jet Triggers

17 John Krane -- DØ