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
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
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
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
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
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)
m
all m
qm
trg m
qm
KLOE general meeting 19-20 December 2002 Tor Vergata
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
Tag
N/pb-1
Ntrig/pb-1
Nsignal/pb-1
Nsignal@
200pb-1
Kpp0
9.5x104
7.3x104
1.7x104
3.4x106
K mn
2.79x105
9.5x104
2.3x104
4.6x106
total
3.74x105
1.87x105
4.0x104
8.0x106
KLOE general meeting 19-20 December 2002 Tor Vergata
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
Double pp0
tag events
double mn
tag events
Cosmic sectors fired
BR vs Cosmic veto
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
%
%
KLOE general meeting 19-20 December 2002 Tor Vergata
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