Charged kaons analysis
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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

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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


Wrong secondary vertex association

Wrong secondary vertex association

Correct Vertex


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)


K time distributions mc data comparison

K time distributionsMC – Datacomparison

Data

MC

# MC

# Data

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


Efficiencies after k 0 tagging

Efficiencies after K±±0 tagging


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


Selected kaons on mc

Selected Kaons on MC


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


Selected kaons on mc1

Selected Kaons on MC


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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