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
1
KPM Selection
Done
Selection Efficiency
KPM retracking
DST production
Charged Kaon
Reconstruction
In progress
In progress
To be done
Since November
the group is
working at the new
KPM reconstruction
B.Sciascia on behalf of the “Charged Kaon Group”
KLOE General Meeting - LNF 28 Mar 2002
2
KPM event selection (EvCl)
 OLD
1- f vertex + two kaons
2- two kaons
3- one kaon
 TOPOLOGICAL
 TAG
B.Sciascia on behalf of the “Charged Kaon Group”
KLOE General Meeting - LNF 28 Mar 2002
3
TAG efficiency
TRIG   FilFo   Acc  Trk   Sele
 TRIG  90%
 FilFo  99%
B.Sciascia on behalf of the “Charged Kaon Group”
KLOE General Meeting - LNF 28 Mar 2002
4
Tagging efficiency
 Tagging decays (K, K0) selected
using only Drift Chamber information.

   
TAG
TAG
0
 
can be estimated from Data
using the redundant calorimetric
information (N=0)
TAG

 From MC:  
 33.9%
TAG
   27.4%
TAG
 From Data:
B.Sciascia on behalf of the “Charged Kaon Group”
KLOE General Meeting - LNF 28 Mar 2002
5
KPM reconstruction AFTER EvCl
 KMERGE: Merge broken tracks K  and   /; 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
6
Kaon
candidates
from EvCl
algorithms
KMERGE
Cuts for track candidates for merging
(separately kaons and secondary particles)
On the transverse plane:
a) “Distance between the two tracks”
Creating new DPRS bank
(KPMJOIN subroutine)
b) Scalar product
c) Transverse momentum.
Extrapolation of the two tracks to a
common point, and new cut on the
scalar product.
Update hits bank (DHRE2)
Retracking
B.Sciascia on behalf of the “Charged Kaon Group”
KLOE General Meeting - LNF 28 Mar 2002
7
KMERGE
Kaon track
Merged event
Kaon track
Kaon track
Old event
Kaon track
B.Sciascia on behalf of the “Charged Kaon Group”
KLOE General Meeting - LNF 28 Mar 2002
8
KMERGE
B.Sciascia on behalf of the “Charged Kaon Group”
KLOE General Meeting - LNF 28 Mar 2002
9
ATFMOD/par=2
After KMERGE:
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
10
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
11
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
12
T0 global:tagged events K,0
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 0 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
13
T0 global (tag): resolution
DATA-MC
2001 data
t+-t- (ns)
t+-t- (ns)
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
14
T0 global: non tagged events
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.
(ns)
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
15
K±±00 : Dalitz plot parameters
si = ( pK – pi )2
s0 = isi/3
i = 1,2,3

X = (s1 – s2)/m2
Y = (s3 – s0)/m2
F(X,Y;g,h,k) = 1+gY+hY2+kX2
MC : 160000 events
fK+K– ; K±±00, K all ~5 pb-1
(DBV-12, MBCKADD+ACCELE on)
Data : 1.37 pb-1 (December 2001)
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
B.Sciascia on behalf of the “Charged Kaon Group”
KLOE General Meeting - LNF 28 Mar 2002
16
Performances of the kinematical fit
Clusters
energy
resolutions

(MC)
m

m
s
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
17
Dalitz plots : parameters extraction
 2 = bins[(Fexp – Ftheo)/sFexp]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
B.Sciascia on behalf of the “Charged Kaon Group”
KLOE General Meeting - LNF 28 Mar 2002
18
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
19
TAG
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
K 0
K 0
K 00
B.Sciascia on behalf of the “Charged Kaon Group”
KLOE General Meeting - LNF 28 Mar 2002
23