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KLOE Elba Meeting 23-25/05/2001. Charged Kaons Analysis. http://www.fisica.unile.it/~ventura. Ratio K ±  ±  0 / K ±  ±  K ± Life Time K ±  0 e ±  Branching Ratio K ±  ±  0  0 Branching Ratio K ±  ±  +  – Branching Ratio. Introductory notes.

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charged kaons analysis

KLOE Elba Meeting 23-25/05/2001

Charged Kaons Analysis

http://www.fisica.unile.it/~ventura

Ratio K±±0/K±±

K± Life Time

K±0e± Branching Ratio

K±±00 Branching Ratio

K±±+– Branching Ratio

introductory notes
Introductory notes
  • Experimental Data collected can ensure
  • small statistical errors on measurements.
  • There are some MC–Data mismatches
  • and several technicalities which need to
  • be taken into account in order to improve
  • measurements and understand systematics.
ratio k 0 k
Ratio K±±0/K±±

M. Martemianov , V. Kulikov

  • World Data
  • 0.3331  0.0028 (fit), 0.3316  0.0032 (average) (PDG)
  • 0.339  0.007  0.007 (CMD-2 preliminary, 2000)
  • 0.3329  0.0047 (USHER - 1992)
  • 0.3355  0.0057 (WEISSENBERG - 1976)
  • 0.305  0.018 (ZELLER - 1969)
  • 0.3277  0.0065 (AUERBACH - 1967)
cuts on momentum distribution of secondary particles
Cuts on momentum distribution of secondary particles

-peak :

225 MeV/c < PCM < 245 MeV/c

-peak :

195 MeV/c < PCM < 215 MeV/c

 + – , e±0

± 0,  0 0

K

K0

Corrections for K

main problem for k tracks
Main problem for K± tracks

Kaon track

splitting (15 %)

  • RED - momentum distribution of secondary particles from KINE bank, if presents vertex from DVFS bank, MC data
  • PINK - momentum distribution of secondary particles from DVFS bank, MC data
corrections for wrong vertex selection
Corrections for wrong vertex selection

| PK - Psec | < 40 MeV

0.14 < | – |K - sec| | < 3.0

o and branching ratios
oand Branching Ratios

(preliminary estimation)

  • 0
  • Exp. ratio = 0.19160.0006
  • MC ratio = 0.19720.0024
  • Exp. data corrected by MC =
  • = 0.20560.0026 (stat.) + (?) (sys.)
  • 
  • Exp. ratio = 0.55870.0011
  • MC ratio = 0.57880.0047
  • Exp. data corrected by MC =
  • = 0.61300.0050 (stat.) + (?) (sys.)
  • 0/
  • = 0.33060.0012(stat.) + (?) (sys.)
other tasks
Other tasks
  • Estimation of trigger efficiency
  • Background / track reconstruction dependency
  • Investigations of systematic errors
k life time
K± Life Time

A. Ventura , E. Gorini , M. Primavera

  • World Data (in ns)
  • 12.386  0.024 (fit), 12.385  0.025 (average) (PDG)
  • 12.451  0.030 (KOPTEV - 1995) K at rest
  • 12.368  0.041 (KOPTEV - 1995) K at rest
  • 12.380  0.016 (OTT - 1971) K at rest
  • 12.272  0.036 (LOBKOWICZ - 1969) K in flight
  • 12.443  0.038 (FITCH - 1965) K at rest
advantages and problems in k measurement
Advantages and problems in K±measurement
  • Large K± statistics
  • Good momentum and spatial resolution
  • Wide fit region (~30 ns)
  • Systematics independent from trigger, event classification, timing (?)
  • Few information at r < 25 cm
  • Energy losses
  • Fake 2-tracks vertices
k track requirements and cuts
K track requirements and cuts
  • K+K– events selection and
  • K± tracks identification with KPMFILT filter
  • CALO + Cosmic Veto trigger
  • K decay vertex at rV>25 cm (2tracks)
  • Kaon track “refit” in K mass hypothesis
  • fake vertices rejection (  angle + |p| cuts)
  •  vertex at rV<5 cm
  • | pK – 127 | < 13 MeV/c ( frame)
k path length
K path length

V

A  DVFS*

B  DHIT*

C  DTFS

D  DVFS

xy view

D

L

C

O :  vertex

P : DC walls crossing

F : track first hit

L : track last hit

V : K± decay vertex

A

B

F

O

P

time of flight distributions on mc
Time of flight distributionson MC
  • Times converted
  • in K rest frame

MCpro:

Geanfi

MCrec:

DataRec

MC pro

MC rec

t (ns)

efficiency e t of k selection on mc
Efficiencye(t) of K± selection on MC

t (ns)

12 ns  28+45 cm

Fiducial region=[12,40] ns

40 ns  28+210 cm

normalized k time distribution
Normalized K time distribution

# Data / e(t)

17.5 pb–1

(end 2000)

  • (ns)=12.40±0.08

(stat)+(?)(sys)

t (ns)

supposing de=0stat  0.030 ns

facing systematics and beyond
Facing systematics and beyond
  • Momentum
  • Spatial
  •  dependency on K decay channel to be tested

}

resolutions and offsets vst

  • CPT measurement ? :
k 0 e branching ratio
K±0e± Branching Ratio

B. Sciascia

  • World Data ( 10 -2 )
  • 4.82  0.06 (fit), 4.85  0.09 (average) (PDG)
  • 4.86  0.10 (CHIANG - 1972)
  • 4.7  0.3 (SHAKLEE - 1964)
  • 5.0  0.5 (ROE - 1961)
k 0 tagging
K±±0tagging
  • K+K– events selection and
  • K± tracks identification with KPMFILT filter
  • K decay vertex(2tracks)
  • |psec – 205| < 10 MeV/cat decay vertex(K frame)
  • at least 2 neutral clusters in EMC
  • back to back neutral clusters (0 frame)
  • (* selection)
  • recovering of splitted clusters

}±

}

0

k 0 tagging1
K±±0tagging

Momentum of secondaries

(K frame in m hypothesis)

0 mass

in K0 tag

=132Mev/c2

=5Mev/c2

=205Mev/c

=2Mev/c

k selection
K±±selection

Momentum of secondaries

(K frame in m hypothesis)

( pmissc – Emiss ) vspsec

=235Mev/c

=3Mev/c

  • |pmissc – Emiss|< 10 MeV

Efficiency of K selection ~30% (from MC)

k 0 selection
K±±0selection

Momentum of secondaries

(K frame in m hypothesis)

0 mass

for K0 signal

=205Mev/c

=3Mev/c

=133Mev/c2

=18Mev/c2

  • |psec – 205| < 10 MeV/c
  • at least 2 neutral clusters ( from tag)
  • * selection
  • recovering of splitted clusters

Efficiency of K0 selection ~20% (from MC)

k 0 l selection
K±0l±selection

0 mass

for K0l signal

  • No K nor K0
  • selection
  • K decay track (lepton)
  • at least 2 neutral clusters
  • ( from tag)
  • (Tcl1 – L1/c) – (Tcl2 – L2/c) minimum
  • recovering of
  • splitted clusters

=131Mev/c2

=20Mev/c2

k 0 e and k 0
K±0e±and K±0±

ml2obtained imposing 0 = T

me

m

ml2 < 6000 MeV2Ke3

ml2 > 6000 MeV2K3

ml2

Efficiency of Kl3 selection ~ 4–8 % (from MC)

k 0 0 branching ratio
K±±00 Branching Ratio

C. Lecci , E. Gorini , M. Primavera

  • World Data ( 10 -2 )
  • 1.73  0.04 (fit), 1.77  0.07 (average) (PDG)
  • 1.84  0.06 (CHIANG - 1972)
  • 1.53  0.11 (PANDOULAS - 1970)
  • 1.8  0.2 (SHAKLEE - 1964)
  • 1.7  0.2 (ROE - 1961)
preliminary cuts
Preliminary cuts
  • K+K– events selection and
  • K± tracks identification with KPMFILT filter
  • CALO + Cosmic Veto trigger
  • at least 4 neutral clustersin EMC
  • K decay vertex atrV>40 cm (2tracks)
  • fake K±K± , ±± vertices rejection (angle cut)

Kinematical cuts

  • |p| < pmax at decay vertex (K frame)
  • 2 on-time clusters couples with inv. mass  [100,170] MeV/c2
  • Momentum-Energy conservation in decay vertex
  • |pT| < 50 MeV/c , |E| < 50 MeV
correct 2 vertex selection
Correct 2 vertex selection

Rejected for

high ±

momentum

k charged vertices mc r vs z distributions
K±-± Charged Vertices(MC r vs z distributions)

Wrong charge Vertex K±-

Correct Vertex K±-±

momentum distribution of secondary particles k frame
Momentum distribution of secondary particles (K frame)

Data

MC

Data

MC

4 clus, rv>40cm,

no FakeVtx + Kinematical cuts

4 clus, rv>40cm

k 0 0 physical topics
K±±00 physical topics

g1+g2fitperformed

=490.5 MeV/c2

=19 MeV/c2

1=131.5MeV/c2

1=18MeV/c2

1=130.5MeV/c2

1=16MeV/c2

=488.9 MeV/c2

=19 MeV/c2

Invariant mass of selected

clusters couples

Invariant mass of selected

secondary particles triplets

statistics analized
Statistics analized

Experimental Data

Selection: 1099682 K± , 869 K±±00

3.16 pb-1(July 2000, DBV4)

Selection: 299880 K±, 347 K±±00

0 0 branching ratio
±±00Branching Ratio

(very preliminary estimation)

*

**

*Background contamination subtracted (~0.3% in MCpreliminary)

**0.34% subtraction KPMFILT selecting nonK+K– events (MC)

present studies and future plans
Present studies and future plans
  • Understand the disagreement with PDG results
  • and look for systematics (background,trigger,EVCL,MC-Data,…)
  • Possible tagging with K±±
  • Dalitz plots’ parameters for K+,K– & asymmetries(?)
k branching ratio
K±±+– Branching Ratio

V. Casavola , E. Gorini , M. Primavera

  • World Data ( 10 -2 )
  • 5.59  0.05 (fit), 5.52  0.10 (average) (PDG)
  • 5.34  0.21 (PANDOULAS - 1970)
  • 5.71  0.15 (DEMARCO - 1965)
  • 6.0  0.4 (YOUNG - 1965)
  • 5.54  0.12 (CALLAHAN - 1964)
  • 5.1  0.2 (SHAKLEE - 1964)
  • 5.7  0.3 (ROE - 1961)
preliminary cuts1
Preliminary cuts
  • K+K– events selection and
  • K± tracks identification with KPMFILT filter
  • CALO + Cosmic Veto trigger
  • at least 4 tracks apart from identified Kaon track(s)
  • K decay vertex at rV>40 cm (4tracks)

Kinematical cuts

  • Charge conservation in decay vertex
  • Momentum-Energy conservation in decay vertex
  • |p| < 40 MeV/c , |E| < 30 MeV
wrong 4 vertex association
Wrong 4 vertex association

Fake 4 Vertex

(other K)

k physical topics
K±±+– physical topics

Data

MC

Data

MC

85MeV/c

85MeV/c

=493.6 MeV/c2

=0.9 MeV/c2

=494.2 MeV/c2

=1.2 MeV/c2

Momentum of selected

secondary particles

Invariant mass of selected

secondary particles triplets

present statistics
Present statistics

Experimental Data

Selection: 1099682 K± , 1075 K±3

3.16 pb-1(July 2000, DBV4)

Selection: 299880 K±, 352 K±3

branching ratio
±±+–Branching Ratio

(preliminary estimation)

*

**

*Background contamination negligible (<0.3% from MC)

**0.34% subtraction KPMFILT selecting nonK+K– events (MC)

present investigations and perspectives
Present investigations and perspectives
  • Comprehension of incompatibility with PDG results
  • and study of systematics (trigger efficiency,EVCL,MC-Data,…)
  • Optimization of fake vertices rejection
  • Possible tagging with K±±0
  • Dalitz plots’ parameters & asymmetries(?)
  • Background rejection in K±e4 , K±4 channels
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