Analysis of W' → WZ Production Limits and Exclusions

1. Search for W’WZ  evjjPreblessing David Toback & Chris Battle Texas A&M Henry Frisch University of Chicago

2. History and Status • This is an analysis which was blessed twice prior to 1996 (1: preliminary and 2: all-but-systematics) • Systematics were finished and shown at Exotics meeting. People were happy with them as well. • Godparent committee formed; reviewed most of the analysis • Agreement on schedule: write paper then bless the text and systematics together • Unfortunately, we started something new. Never formally blessed or finished paper • We’ve picked it up again and want to publish/bless it ASAP. Get back to Run II!

3. Outline Summary of: • Theory and Signature • Cuts and Data reduction • What signal would look like; Acceptance • Backgrounds; What signal would look like on top of backgrounds • Comparison of Data and Backgrounds • Fitting and Systematics • Limits • Conclusions

4. Feynman Diagram

5. Branching Ratio for W’WZ • Reference Model • W’ is the same as the SM W only heavier • Large width large branching ratio • Extended Gauge Model • Mixing angle between W and W’

6. Event Selection & Summary • 1 electron • Missing ET • 2 Jets • 110 pb-1 of data from Run 1A and 1B

7. Overview of Analysis • Constrain PTn using W mass • Reconstruct dijet and W+dijet masses • Look for bumps in dijet vs. W+dijet mass plane using a fit Reconstruction procedure does a good job of reproducing W’

8. Acceptance vs. W’ Mass • Good Acceptance for W’ • Reference Model • Large width at large mass • Lots of low mass events • Lower acceptance

9. Summary of Backgrounds Estimated from data PYTHIA and cross sectionnormalization Combination of VECBOS and PYTHIA VECBOS fit shape. Large k factor uncertainty. Take normalization from fit to data outside signal region

10. What would a signal look like? Dijet and W+dijet mass spectrums with and without 400 GeV reference model W’

11. Looking at the Data • Data looks like real W’s • W+jets normalized to data and non-W+jets • Good fit to data

12. Dijet Mass Distributions • No evidence of Z produced in association with W • W+jets normalized to data and non-W+jets

13. W+dijet Mass Distributions • No evidence of W’ or other new particle production • W+jets normalized to the data and non-W+jets

14. W+dijet in 3 Mass Regions • Data outside Z mass region is well modeled telling us that the data inside the Z mass region is well modeled. • No evidence for WZ production. ( Figure 1 in PRL)

15. Turning the Crank • Searching the data for W’ • Look for excess in dijet vs. W+dijet mass plane • Fit the data to signal, W+jets and non-W+jets • Allow W+jets and signal to float • Normalization mostly comes from outside signal region • Same technique as Dijet Mass bump search (R. Harris) • No evidence for signal (as seen in previous plots and in the fit results) • Get 95% C.L. cross section upper limit from the fit • Incorporate systematic errors

16. Systematic Errors • Use same methods as dijet mass bump search • Vary signal by 1 sigma and refit • Add uncertainty into limit • Absolute energy scale dominates the error • Shifts signal into region with lots more background

17. Errors Cont.:Extended Gauge Model • Narrower width = less systematic uncertainty • Absolute energy scale again dominates the error

18. 95% C.L. Limits: Reference Model • We exclude the reference model of W’ from 200 to 480 GeV. • Taken in conjunction with exclusions from the W’ev limits, we exclude the entire model * Plot for preblessing

19. 95% C.L. Limits: Ext. Gauge Model • 95% C.L. upper limits on cross section vs. W’ mass for the extended gauge model • No mass limits for very small angles • Cross section limits applicable for any new particle production with narrow width XWZ * Plot for preblessing

20. Cross Section vs. Mixing Angle 95% C.L. upper limits on cross section vs. W – W’ mixing angle * Plot for preblessing

21. Cross Section vs. W’ Width • 95% C.L. upper limits on the cross section vs. W’ width • These limits are good for any new particle production with XWZ , narrow or wide width * Plot for preblessing, PRL figure 2

22. Limits on Mixing Angle vs. W’ Mass • 95% C.L. exclusion region for mixing angle vs. W’ mass * Plot for preblessing, PRL Figure 3

23. Conclusions • No evidence forW’ WZin the enjjdecay channel • First limits on W’ WZ • Reference model completely excluded • Large exclusions in an extended gauge model • Web page at -http://hepr8.physics.tamu.edu/hep/wpprl.html • All plots, documentation, and PRL draft • CDFNote 3094 on web page and will be re-posted to CDFNotes • PRL draft with GPS and available on web page • Hope to bless in two weeks