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

2. 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

3. 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

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

5. 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

6. 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

7. 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

8. 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

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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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 : 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

17. 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

18. 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

19. 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

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

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

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

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