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Status report on WW to l n l n

Graham W. Wilson. Some history Some physics ?. Status report on WW to l n l n. LL-code based acoplanar di-lepton selection developed starting at LEP1.5 (Terry) WW-code based acoplanar di-lepton selection developed starting at LEP161 (Graham). Used for all WW XS and BR results so far.

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Status report on WW to l n l n

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  1. Graham W. Wilson Some history Some physics ? Status report on WW to lnln

  2. LL-code based acoplanar di-lepton selection developed starting at LEP1.5 (Terry) WW-code based acoplanar di-lepton selection developed starting at LEP161 (Graham). Used for all WW XS and BR results so far. Manchester students: Kay Roscoe (BRs), David Futyan, Tom Marchant (searches). 1999/2000 Achim Stahl implemented Tau Platform lepton ID. Early 2001. Commissioned TP lepton id (G), and event mixing (T). Major “recent publications”. PR321 “189 GeV WW XS and BR”, June 2000. Used WW-code based lnln selection from March 2000. Performance e=82%, p=98% PR385 “Final LEP2 acoplanar di-leptons”, July 2003. Performance, e=88%, p>97% History

  3. What’s different between PR321 and PR385 selections ? • 12 person years of hard work aimed at improving the efficiency, robustness against background (remember the “stau excess”), lepton classification, AND dealing with the major experimental systematic (occupancy) in a correct way.

  4. What happened • March 2000. WW-based selection in WW code. • Spring 2000. WW-based selection starts using LL variables for instrumental background rejection. • August 2000. LL-based selection improved dramatically • (documented thoroughly in TN). • Jan. 2001. TP lepton ID incorporated into production ntuple job • Spring 2001. Random event (BXRSA) mixing implemented for MC. • Summer 2001. WW-based changes fed back into private version of WW code. • Summer 2001. Tom Marchant starts acoplanar di-lepton ntuple production. • 2002-2005 Entropy … • 2005. Some work. Graham goes to CERN, January 2005, realizing that for all this work to reach publication, probably have to be able to reproduce the analysis.

  5. What was wrong. • Code used in ww, tpuser, and probably ll libraries no longer exists. • Several of these were removed for good when Tom surrendered his afs account. Others disappeared with the shift disks. • This sounds really bad, but the reality is that as I was working in a manner intended to update WW, I had most of the edits in hand. There are a few days of work associated with integrating the code in the WW/LL/TP/ROPE framework that are the main source of concern/discrepancy. • In addition, some of the external input files, like TP reference histograms, and random ntuples are not necessarily the same. • I have very little diagnostic information at all in terms of eg. 2001 production job logs, output ntuples, normalization information. • All, I really have is candidate ntuples which include event mixing. • But not for KANDY samples generated more recently.

  6. Where have I gotten to ? • I have recuperated the WW-based part of the selection. • I always had in hand the LL-based part. • There are still some lingering doubts about the integrity of the co-habitation. • (some of the LL coding practices associated with REAL<->INT really rile me …) • I have not bothered too much with trying to recuperate the TP functionality

  7. Data Tests Dadlist of 1239 selected acoplanar dilepton events from PR385 processed with new code. • Perfect agreement in numbers of events in each selection category with that of PR385. Period 120 FYZ1 events. Observe 1.6% difference in number of events making ntuple. Currently gearing up to process all the data.

  8. Yesterday: preparing production data jobs • Implemented: • Identical beam energy selection to Eric/Mark • Comparison of status cuts • Addition of 4f weights from XTRA block • Job level REPORTING of event selection stats. • Estimate, a few days needed for jobs to run (mostly just 1nh)

  9. Plan • Once data selection is completely reproducible, or potential bugs are understood, will turn attention to signal MC. • (I am concerned that the PR385 results may not have required LOWM for MC …) • For signal MC, event selection without event mixing should be straightforward. • With event mixing, may not be too difficult. • Can use particular samples like kwllll where I have event mixing to estimate potential systematic errors if I was not able to get event mixing to work. • TP lepton ID would be nice, but I think it’s probably a bridge too far. • I would really appreciate the opportunity of using the semester break to get this sorted out. (no teaching till late January).

  10. How data events get selected (1239 from PR385) • Bins • 1: GSEL • 2: TSEL • 3. GSEL+TSEL • 4. TSEL_S • 5. TSEL_D (not WW)

  11. Classification as di-leptons (1091 WW candidates) • Bins • 0. unclassified • 1. ee • 2. mu mu • 3. tau tau • 4. e mu • 5. e tau • 6 mu tau

  12. 4f MC As you’d expect these distributions are not so far off. (this plot uses PR385 ntuples)

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