K charged status report

1. K charged status report • DST production status • New analysis items: • fK+K- cross section/ f line shape • BR measurement strategy • enhanced 2 body decay tag • BR systematic vs cosmic veto KLOE general meeting 19-20 December 2002 Tor Vergata

2. K charged DST production • K charged DST production code has been finalized • Production started on a limited number of runs (~ 4.5 pb-1) • Energy scan runs are used as bench mark: DST produced directly from raw data ( not from streamed ) to avoid bias on the K+K- cross section analysis • Production now stopped due to the TAPE shortage KLOE general meeting 19-20 December 2002 Tor Vergata

3. Analysis items: Some items are brand new and the correlated job sharing/items assignment is not yet frozen; furthermore a lot of items overlap each other. A tentative and approximate job sharing list can be: • fK+K- cross section : P.Branchini,B.Sciascia,L.Passalacqua • K±pp0p0 : E.Gorini, M.Primavera, A.Ventura • BR(K±mn)/BR(K±pp0): M.Martemianov, R.Versaci, V.Patera • Ke3, Km3 : E.De Lucia, P.De Simone, L.Passalacqua, B.Sciascia • DST :production/check : all together KLOE general meeting 19-20 December 2002 Tor Vergata

4. Analysis : f line shape fit fK+K- cross section points obtained counting events with single vs double K pp0 decay Both line shape and cross section value at peak must be checked using the new DST with retracking MeV Fit by M.Antonelli KLOE general meeting 19-20 December 2002 Tor Vergata

5. Analysis: BR measurement strategy • Based on the tag mechanism: given an identified 2 body K± decay on one emisphere (handle) then we look at K ± decay on the other side (signal) • The tag decay must have triggered by itself the events so to cancel out etrigger from eID of the signal • To achieve emisphere separation only EMC trigger must be considered • Also the m cluster of the Kmn decay can trigger firing two adjacent trigger sectors with good efficiency (30%) • Two auto triggering tag types with different topologies allow good systematic checks KLOE general meeting 19-20 December 2002 Tor Vergata

6. m Kmn auto trigger The high energy m cluster can stretch between two adjacent sector. The muon inpinges on the ECAL surface with an angle, going through 2 sectors all m trg m m energy (MeV) all m qm trg m qm KLOE general meeting 19-20 December 2002 Tor Vergata

7. Tag statistic The request to have a clean “handle” (  clean 2 body decay auto triggering ) to study the K decay on the other side reduce our analysis sample. We evaluated our yeld on a 4.85 pb-1 sample, considering “signal” any K decay in FV with any charged track attached: 70 MeV < PK < 130 MeV 20 cm > |zip| 10 cm > Rip 40 cm < Rvertex < 150 cm KLOE general meeting 19-20 December 2002 Tor Vergata

8. mn tag vs pp0 tag: signal shape The signal shape seems to be independent from the tag used as “handle” Red = Kmn Blue = Kpp0 KLOE general meeting 19-20 December 2002 Tor Vergata

9. % % BR vs Cosmic veto Double pp0 tag events The cosmic veto could bias the BR measure expecially in case of muon tag. We used the double tag events to measure the effect. The two ecosmic from N2/N0 and N1/N0 are equal if there is no depletion of N2 events by cosmic veto. T3 filter seems to recover the cosmic vetoed events double mn tag events Cosmic sectors fired KLOE general meeting 19-20 December 2002 Tor Vergata

10. Conclusions and outlook • Needed to restart DST production as soon as possible • Cross section measure can be used as bench mark for systematics and correlation of retracking vs old reconstruction • Some analysis is already in advanced stage ( see A.Ventura talk) • Group effort on analysis is increasing KLOE general meeting 19-20 December 2002 Tor Vergata