KLOE General Meeting - LNF March,28 2002 Charged Kaon Group Status Report KLOE General Meeting - LNF March,28 2002 B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

Charged Kaon Reconstruction KPM Selection Done Selection Efficiency In progress KPM retracking In progress Since November the group is working at the new KPM reconstruction DST production To be done B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

KPM event selection (EvCl) OLD 3- one kaon 1- f vertex + two kaons 2- two kaons TOPOLOGICAL TAG B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

TAG efficiency Monte Carlo B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

Tagging efficiency Tagging decays (K, K0) selected using only Drift Chamber information. can be estimated from Data using the redundant calorimetric information (N=0) Differences are present in all of the selection cut efficiencies. From MC: From Data: B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

KPM reconstruction AFTER EvCl KMERGE: Merge broken tracks K  and p  /m; write the ECLO bank T0_find/par=2: T0_global for KPM events ATFMOD/par=2: re-fit ALL of the tracks taking care of the KPM ToF 1- re-fit KPM identified by ECLMOD, evaluating ToF inside the DC inner cylinder AND the total KPM ToF 2- re-fit ALL of the other tracks, ADDING the KPM ToF shift (…if possible) VTXFIN/par=2 B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

Cuts for track candidates for merging Update hits bank (DHRE2) KMERGE Kaon candidates from EvCl algorithms Cuts for track candidates for merging (separately kaons and secondary particles) Creating new DPRS bank (KPMJOIN subroutine) On the transverse plane: a) “Distance between the two tracks” b) Scalar product c) Transverse momentum. Extrapolation of the two tracks to a common point, and new cut on the scalar product. Track merging procedure Update hits bank (DHRE2) Retracking B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

KMERGE Merged event Old event Kaon track Kaon track Kaon track B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

KMERGE B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

ATFMOD/par=2 After KMERGE: Kaons corrected for:  kaon ToF before DC ToF(KPM) “extrapolated” av: 4.3 ns rms: 0.7 ns ToF(KPM) “decay” av: 17.5 ns rms: 7.8 ns Kaons corrected for:  kaon ToF before DC  dE/dx on pipe + DC inner wall Decay products corrected for:  kaon ToF B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

ATFMOD/par=2 “official” Datarec: 33.3% KPM broken tracks 41.9% secondary broken tracks Datarec {KMERGE+retracking}: 13.0% KPM broken tracks 27.1% secondary broken tracks T0_GLOBAL correction not applied yet B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

T0 global for KPM (T0_FIND) The “standard” t0 global can badly fail in charged K events. Two different specific procedures has been developed to fix the problem: ns The algorithms used to find the t0 global are different for the events selected by different EVCL selection algorithms: - ToF based algorithm, for events where a charged K decay has been detected (TAG events) - Cumulative hit distribution based algorithm, for the other streamed events B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

T0 global:tagged events Kmn,pp0 Applied to events with K decay products with ECAL cluster associated. From K decay vertex position, cluster times, track length and momentum of K and charged daughter is possible to trace back the T0 global. With pp0 decays is possible to check neutral vs charged decay time With double tagged events is possible to extract T0 resolution from data ( t+ vs t-) B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

T0 global (tag): resolution t+-t- (ns) DATA-MC t+-t- (ns) 2001 data The T0 global algorithm has high efficiency ~ 96% and good resolution st0 ~ .7 ns that can be monitored from data with double tagged events. B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

T0 global: non tagged events (ns) T0 derived from the cumulative time distribution of the DCH hits. Only hits associated to track with nhits>15 and p>50 MeV to avoid machine bck. The resolution can be obtained from data, applying the method to tagged events. Resolution is poor: st0 ~ 7-8 ns (better than the standard T0) (ns) B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

K±±00 : Dalitz plot parameters si = ( pK – pi )2 i = 1,2,3 s0 = isi/3  X = (s1 – s2)/m2 Y = (s3 – s0)/m2 F(X,Y;g,h,k) = 1+gY+hY2+kX2 mj1j2  m° j = 1,2 E°1+ E°2  EK – E p°1+ p°2  pK – p  m°1 °2   mK si  mK2 + m2 + 2m°2 MC : 160000 events K+K– ; K±±00, K all ~5 pb-1 (DBV-12, MBCKADD+ACCELE on) Data : 1.37 pb-1 (December 2001) B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

Performances of the kinematical fit Clusters energy resolutions (MC)  m m  Before fit After fit m° 17.8 MeV 1.27 MeV mK 32 MeV 1.05 MeV Ev 11.2 MeV 0.27 MeV pvxi ~16 MeV ~0.15MeV s0 ~4500 MeV2 22 MeV2 B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

Dalitz plots : parameters extraction  2 = bins[(Fexp – Ftheo)/Fexp]2 minimized with g,h,k free A0(g,h,k) = F(X,Y;g,h,k)dxdy normalization is applied Efficiencies estimated from Monte Carlo First look at the procedure results KLOE 1.37 pb–1 PDG g 0.679±0.046 0.652±0.031 h 0.086±0.080 0.057±0.018 k 0.0196±0.0126 0.0195±0.0054 All the present KLoE statistics should reduce the PDG errors by factors 37 and allow to study asimmetries g, h, k. B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

Conclusions and Outlook New selection ready and working within reprocessing Selection efficiency estimation from Data under way New KPM retracking in good shape, to be finalized within April 15th Ready to start DST production before end of April First look at BR’s with 2001 Data using DST as soon as possible… B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

TAG B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

TAG B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

TAG B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002

TAG K pp0 K mnp0 K pp0p0 B.Sciascia on behalf of the “Charged Kaon Group” KLOE General Meeting - LNF 28 Mar 2002