M. Primavera 2 nd KLOE Physics Workshop, 10 th -12 th june 2002 Otranto (LE) 1 Perspectives on charged K physics in KLOE 2 nd KLOE Physics Workshop, 10

M. Primavera2nd KLOE Physics Workshop, 10th-12th june 2002 Otranto (LE)

1

Perspectives on charged K physics in KLOE

2nd KLOE Physics Workshop, 10th-12th june 2002 Otranto (LE)

M. Primavera for the Charged K Group:

P. Branchini, V. Casavola, E. De Lucia, P. De Simone, E. Gorini, V. Kulikov, M. Martemianov, L. Passalacqua,

V. Patera, M. Primavera, G. Saracino, B. Sciascia, A. Ventura


2

Some Initial Remarks

Nothing concerning systematics

Just a “statistical exercise” based on preliminary results of all the analysis performed up to now extrapolating it to 500 pb-1 where KLOE can give significative impr.s in the present “K± scenario?”

No description about details of the analysis

Not all analysis at the same stage! Some numbers could change if new inputs


3

Ke3 and K3 decays, Vus

“Shopping list”

K masses and lifetimes

BR’s : K , K 0, K 3, Kl4

Conclusions

Cross Section (see Maxim’s talk)

Dalitz plots of K 0 0 , K + -


4

K± Mass

World Data (in MeV)• 493.677 0.016 (fit) (PDG2001)

• 493.677 0.013 (average)

CPT measurement :

€

(MK + − M

K − )

World data (in MeV)• -0.032 0.090 (Ford,’72,1.5M)

Limited by the knowledge of m + - m - ( 70keV)

DataMC

=493.6 MeV/c2

=0.9 MeV/c2

=494.2 MeV/c2

=1.2 MeV/c2

Invariant mass of selected secondary particles triplets

K +-

Stat.:M ~ 2keV….but we are limited by DC calib.(p/p~10-4)

We can do better by using


5

K± Life Time

World Data (in ns)• 12.385 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

CPT measurement : averageKKτττ /)( −+ −

World data (%)

0.11 0.09 (Average) (PDG2001)

0.090 0.078 (best meas., ‘69)


6

Normalized K time distribution

# Data / (t)

(ns)=12.400.08(stat)+(?)(sys)

500 pb-1 stat 0.015 ns

t (ns)

17.5 pb–1

(end 2000)


7

Branching ratios

Two body decays in K+K- stream

Main BR for K+K- decays

± 63.51%

±0 21.16%

±+− 5.59%

e±0 4.82%

±0 3.18%

±00 1.73%

K+

K

+

1

2

For 500 pb-1 we have (rec.) approx. 300*106 K+K


8

Ratio o/

Zeller

Auerbach

Weissenberg

(ITEP) Usher(CERN)

KLOEPDG 2001

World data

0.3334 0.0028 (fit)

0.3316 0.0032 (Average) (PDG)

• 0.3329 0.0047 (USHER - 1992) (45k)

• 0.3355 0.0057 (WEISSENBERG - 1976)

• 0.305 0.018 (ZELLER - 1969)

• 0.3277 0.0065 (AERBACH - 1967)

0.3306 0.0012 (stat.)+(?)(sys.) (KLOE preliminary, 11.2pb-1)


9

Ratio o/Exp. ratio (o/)

2 ndf = 0.532 for 16 points

R/R ≈ 1% (world average) 0.5‰ (500 pb-1 only stat!)

+ – , e±0± 0, 0 0

o

CMSmomentum spectrum for +K decay


10

Branching ratio o

Preliminary estimation for total statistics: 2.6 pb–1

(end 2000)

Exp. BR(o)

20.560.26(stat.)+(?)(sys)

World Data, PDG2001 (10 -2 )

• 21.17 0.14 (fit)

• 21.18 0.28 (best exp.,16k)

KLOE can measure absolute BR’s

BR/BR ≈ 1.3% (best meas.) 1‰ (500 pb-1 only stat!)


11

Branching ratio

Exp. BR()

Preliminary estimation for total statistics: 2.6 pb–1

(end 2000)

World Data, PDG2001 (10 -2 )

• 63.51 0.18 (fit)

• 63.24 0.44 (best exp.,62k)

61.260.50(stat.)+(?)(sys)

BR/BR ≈ 0.7% (best meas.) 0.6‰ (500 pb-1 only stat!)


12

K±±+– (τ±) and K±±00 (τ’±) decays

Extremely interesting decays from direct CP point of view,by measuring

€

Aτ (τ ')

= τ (τ ' )Γ (K +) −τ (τ ' )Γ (K−)

τ (τ ' )Γ (K +) +τ (τ ' )Γ (K−)

World Data, PDG2001• (0.7 1.2) 10 -3 (Aτ world average)

• (0 6 ) 10 -3 (At’ world average)

… unfortunately theory provides O(10-8) and KLOE could have sensitivities down to ~ 10-5 with statistics comparable to CP to 10-4 in neutral kaons! with 500 pb-1 and present ττ’) we cannot do better than PDG on Aτ’, Aτ


13

K±±+– branching ratio

World Data ( 10 -2 )• 5.59 0.05 (fit), 5.52 0.10 (average) (PDG2001)

• 5.34 0.21 (PANDOULAS - 1970)

• 5.71 0.15 (DEMARCO - 1965)

• 6.0 0.4 (YOUNG - 1965)

• 5.54 0.12 (CALLAHAN - 1964, 2332 ev.)

• 5.1 0.2 (SHAKLEE - 1964)

• 5.7 0.3 (ROE - 1961)

€

K ± → π ±π +π − yield

≈ 300 pb−1

⇒ 150000 (500 pb−1)

⇒ ΔBR /BR ≈ 0.2%

(only stat.)

(2% best meas.)

€

K3π~ 0.5%

Without tagging!


14

K±±+– decay

DataMC

DataMC

Momentum of selected secondary particles

Invariant mass of selected secondary particles triplets

85MeV/c

85MeV/c=493.6 MeV/c2

=0.9 MeV/c2

=494.2 MeV/c2

=1.2 MeV/c2


15

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)

K±±00 branching ratio

Best measur. has 3.5% error,And it’s based on only 1307 events


16K±±00 measuring branching ratio and Dalitz plot parameters

K±±00 branching ratio Preliminary on 6.33 pb-1(December 2001)

€

K ± → π ±π 0π 0 yield ≈115 pb−1

⇒ ≈ 6 ×104 (500 pb−1)

⇒ ΔBR /BR ≈ 0.5% (only stat.)


17

Kl4 Decays

Good place to study hadronic physics and to test PT but low BR (~10 -5) :K+ +-e+e 3.910-5

K+ +-+ 1.410-5

K+ 00e+e 2.110-5

KL0 0ee 5.210-5

Form factors can be extracted from the decay rate as partial wave expansions containing the elastic scattering phase shifts (I

l)

K+e4 studied at CERN SPS (1977) by using 30000 rec. ev.

KLOE needs at least 10stat. to be significative, but

€

Ke4± yield ≈ 0.3 pb−1 ⇒ 150 (500 pb−1)


18Study on K±00e±e

Highest statistics in: (00e±e)/(0e±e) = (4.2±1.0)10–4 (BOLOTOV 86, 25 evts)

K±e±00 e studies World Data ( 10 -5 )• 2.1 0.4 (fit)

•2.54 0.89 (average) (Barmin 88,10 ev.)

1515 selected Ke4 events over 102600 MC generated

MC1.48% ~0.9 Ke4/pb–1 are expected on data

Only 2 Ke4 found in 6.33 pb–1 ~150 ev in 500pb–1

me

m

Data

m

me

MC rec


19

Vus from Kl3 decays

While theory provides the knowledge of form factors at q2=0:+ measured in Ke3 and K3, 0 only in K3 (suppressed in Ke3 by the

factor (me/MK)2 )

Assuming a linear expansion of the evolution of form factors f+

Kand f0K

( )

%2.0

sec100024.02386.1 8

=Δ

⋅±=

+

+

−+

τ

τ

τK

%8.0

sec1004.015.5 8

=Δ

⋅±= −

L

L

KL

τ

τ

τ

400 k

3 M

)0(+fVus

€

fx (0)

obtained by the measurement of

( ) ( ) Kll KBRK τ33 =Γ

€

fxKπ q2

( ) = fxKπ 0( ) ⋅ 1+

λ xKπ

mπ2

q2 ⎛

⎝ ⎜

⎞

⎠ ⎟


20

Experimental status of K+e3 and K+

3 decays

€

BRKe 3

+ = 4.85 ± 0.09( )%

ΔBR

BR=1.8%

€

+Ke 3

+

= 0.0278 ± 0.0019

Δλ

λ= 6.8%

3516, ‘72

( )%06.008.086.4 syststat ±±

syststat 002.00015.00293.0 ±±

€

0.0278 ± 0.0017stat ± 0.0015syst (KEK-E246)

(ISTRA+)

≥100 k, 2001 41 k, 2001-2002

€

+Kμ 3

+

= 0.031± 0.008 Δλ

λ= 25%

€

0Kμ 3

+

= 0.006 ± 0.007 Δλ

λ= 24%

syststat 002.0004.00321.0 ±±

( )%14.007.033.3 syststat ±± 2345,’72

syststat 002.0004.00209.0 ±±

statstat 004.0005.0022.0 ±±

(ISTRA+)

112 k

€

BRKμ 3

+ = 3.18 ± 0.08( )% ΔBR

BR= 2.5%


21

€

Vus

Vus

= 0.59% ± 0.37% ± 0.86%

Vus with K+e3 decays

( )( )0

005.05.0

3

3

+

+

+

+

+

+ Δ±

Δ±⎟⎟⎠

⎞⎜⎜⎝

⎛ Δ±

Δ=

Δ

f

f

BR

BR

V

V

e

e

K

K

us

us

λ

λ

τ

τ

( ) 0084.09874.00 ±=+fContributions to the total error

0.22%(from the most recent measur.of


22

K+

e3 yield in KLOE

€

NKe 3

± ≈ 2000 pb−1

⇒ 106 (500 pb−1)

⇒ ΔV /V ≈ 0.3%

20 pb-1

Preliminary

(stat. only)


23

CP ASYMM. (g+- g-) / (g++ g-) Theory provides Ag,Ag

0 ~10-6 up to 10-4 (more effordable than Aτ(τ’))

K±±00 measuring branching ratio and Dalitz plot parameters

si = ( PK – Pi )2 i = 1,2,3

s0 = isi/3 = (mK2 + m

2 + 2m°2)/3 X = (s1 – s2)/m

2

Y = (s3 – s0)/m2

F(X,Y;g,h,k) = 1+gY+hY2+kX2

Dalitz plots parameters in τ(τ’) decays

Ag measured (-7±5) 10-3 with ~ 106 ev.(KLOE is out), Ag

0 never measured

1 year of data taking @NA48’ (~ 109 τ decays and ~ 108 τ’) Ag,Ag

0 ~ 10-4


24

QUADRATIC COEFFICIENT k 0.0197±0.0045±0.0029 (BATUSOV 98)

ASYMMETRY (g+- g-) / (g++ g-)NEVER MEASURED

6.33 pb-1

~15500 K°°

(MC normalized)

KLOE 6.33 pb–

1 PDG

g 0.607±0.026 0.652±0.031

h 0.026±0.027 0.057±0.018

k0.0080±0.0037

0.0197±0.0054

VERY

PRELIMINARY


25

Conclusions

We can improve life times, absolute BR’s and Vus knowledge, keeping well under control systematics

We cannot do much more on charged K masses

CP viol. in partial decay rates (Aτ(τ’) is out

We can measure Ag0 (but should be done before

NA48 !)


26

%86.0%22.0%59.0 ±±=

us

us

VV

Vus with K+e3 decays (new)


27

Present statistics

Experimental Data

Selection: 1099682 K± , 1075 K±3

MC stream1 K3p

Generated K±all 980k 800k

Generated K±±+– 54.8k 422k

Selection: 299880 K± , 352 K±3

3.16 pb-1 (July 2000, DBV4)


28

Selected Kaons on MC

€

K3π≡

N(K ± → π ±π +π −)selected

N(K ± → π ±π +π −)generated

= (0.635 ± 0.012)%

)%05.050.30()(

)(±=

→→

≡ ±

±

generated

selected

allKNallKN

K


29

±±+– Branching Ratio

=→

→= ±

−+±±

3

K

K

selectedallK

selectedKBR

(stat.) )%17.071.4( ±=

* Background contamination negligible (<0.3% from MC)

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

(preliminary estimation)

*

**


30

Statistics analized

3.16 pb-1 (July 2000, DBV4)Experimental Data

Selection: 1099682 K± , 869 K±±00

MC stream1 K3p0

Generated K±all 980k 560k

Generated K±±00 16.9k 285k

Selection: 299880 K± , 347 K±±00


31

Selected Kaons on MC

€

K ≡N(K ± → all)selected

N(K ± → all)generated

= (30.50 ± 0.05)%

)%025.0826.1()(

)(00

00

3±=

→→

≡ ±±

±±

generated

selected

KNKN

K


32

±±00 Branching Ratio

=→

→= ±

±±

3 )(

)( 00

K

K

data

data

allKN

KNBR

(stat.) )%03.032.1( ±=

* Background contamination subtracted (~0.3% in MC preliminary)** 0.34% subtraction KPMFILT selecting nonK+K– events (MC)

(very preliminary estimation)

*

**


33

Filter algorithm (I)Preliminary requirements

Cosmic Veto (DC+EMC) Trigger

Any of the 5 EvCl algorithms

a 2-tracks vertex in the DC involving a K± track

Distance between the two tracks’ first/last hit < 50 cm

Angle at vertex between the two tracks > 2°



34

Filter algorithm (II)Further requirements

4 “ontime” non-associated clusters coming from the charged vertex: |ti–tj–(Li–Lj)/c|<3t(Ei,Ej) i,j=1,..,4

Considered the best possible quartet of clusters: 80 MeV < m12,m34 < 190 MeV ( 3m cut )

Charged product track momentum: |pdau| < 135 MeV in K± frame


all contamination ~0.4% (MC)


35

Tagging strategies

1) K±±0

2) K±±


Daughter momentum: 199 MeV < |pdau| < 211 MeV in K frame Missing mass at K vertex: 90 MeV < mm < 180 MeV 2 ontime non-associated clusters: 120 MeV < m < 150 MeV



Daughter momentum: 226 MeV < |pdau| < 245 MeV in K frame Missing mass at K vertex: |mm|< 5 MeV


36

BR measurement method

BR(K±00) = 1Ntag

[Nobs ]tag

[ ]tag

±00

±00 tag = 0,

[ ]tag does not depend on FILFO , EvCl , tag

independence from trig to be tested

±00


= K(pK) vtx(pK,p) 4clu(E) 2

pairing(E)

WORK IN

PROGRESS


37

Efficiencies (Data and MC )


K vs # of non-associated clusters

(non-tag, E > 20 MeV)All tag events sample

vtx (p)

00 events subsample

clu (E)

0 events subsample

WORK IN

PROGRESS


38

Ratio o/

Ratio tagging

• peak window 225 MeV/c < PCM < 245 MeV/c

• peak window 195 MeV/c < PCM < 215 MeV/c

• Decay vertex with Rxy > 40 cm

• For good trigger efficiency : one kaon track has a decay o

• Cut for secondary vertex and secondary momentum 20 MeV/c <Psec < 400 MeV/c

• Cut for kaon momentum at decay

point 80 MeV/c < PK < 120 MeV/c

CMSmomentum spectrum for +K decay

+ – , e±0± 0, 0 0

o


39

Branching ratio of o,

Branching ratio cuts

• Number of K all caluclated as number of decays

in secondary monentum window from 20 to

400 MeV/c• Decay vertex with Rxy > 40 cm

• peak window and peak window

• Using only drift chamber information

MCKKN

MCallKN

dataallKN

dataKKN

BR),0(

)(

)(

),0(

υ

υ±→±±→±

→±

→±

±→±±→±

=

υ ±→±±→ KKPDG

,0

Documents

M. Primavera 2 nd KLOE Physics Workshop, 10 th -12 th june 2002 Otranto (LE) 1 Perspectives on charged K physics in KLOE 2 nd KLOE Physics Workshop, 10