Hadronic results from KLOE

Hadronic results from KLOEHadronic results from KLOEE. Santovetti (INFN – Roma II)

for the KLOE Collaboration

European Physical SocietyInternational Europhysics Conference

on High Energy PhysicsEPS (July 17th-23rd 2003) in Aachen, Germany

E. Santovetti

DANE: the Frascati factory

HEP2003 Aachen, 17-23 July 2003

electron positron collider at the mass energy (ECM= 1020 MeV)

separate rings to minimize beam-beam interaction

two interaction points (KLOE – DEAR/FINUDA)

Machine parameters Design 2002

Total length (m) 98

Max. bunches 120 51

Bunch spacing (ns) 2.7 5.4

Lifetime (min) 120 40

Bunch current (mA) 40 20

L single bunch (cm-2 s-1) 4.4 1030 1.5 1030

L peak (cm-2 s-1) 5.3 1032 0.75 1032

per year (109) 15 0.9

E. Santovetti HEP2003 Aachen, 17-23 July 2003

KLOE data taking history

Yearpb-1/day

average peak

2000 25 pb-1 0.1 0.4 First published results

2001 170 pb-1 0.7 1.8Luminosity improved but high background

Further analyses published

2002 280 pb-1 2.0 4.5Higher luminosity and background reduced

Analysis in progress

An upgrade of the machine has been done. An increase in luminosity ( > x2 )is expected in the next data taking.

in 2002 31 2 17.8 10peakL cm s

Ldt

E. Santovetti

Kaon physics at DANE

HEP2003 Aachen, 17-23 July 2003

• The kaons are produced in pairs (K+ K- and KS KL ) with opposite momentum.

• The detection of a kaon on one side can be used to tag the other kaon in the opposite side

• Measure of absolute branching ratios

• Interferometry studies on KS KL system

e- e+

KL

KS

p (MeV/c) l (cm)

K+ K- 127 95

KS 110 0.6

KL 110 343

all KS decay close to the IPreasonable acceptance for KL

( ) 3e e b F decay % #/pb-1

K+ K- 49.2 1.5x106

KS KL 33.7 106

15.5 5x105

1.3 4x104


The KLOE detector

Electromagnetic calorimeter lead/scintillating fibers structure 15 X0 thickness 4880 PMT's

Drift chamber (4m Ø x 3.3m) 90% He – 10% IsoB mixture (X0 ~ 500m) 12582/52140 sense/total wires stereo geometry for z measurement

Quadrupole calorimeter lead/sc. tiles calorimeter surrounding the permanent quadrupoles (32 PMT's)

Superconducting coil (5m Ø) B = 0.52 T


Detector performancescalorimeter

Drift chamber

/ 5.7% / ( )E E E GeV

54 / ( ) 50t ps E GeV ps

High efficiency for low energy photons

, 150x y m 2z mm

/ 0.4% ( 45 )p p


KLOE physics program

1999

2000

2 pb–1

20 pb–1

200 pb–1

2 fb–1

2002

KS , KS 3, KS KL 2, KL Vus from K± and KL decays K± branching ratios (e+e– –) to 1%

radiative decays f0 , a0 scalar ’, pseudoscalar KS decays BR(KS –)/BR(KS ) BR(KS e) first published results

500 pb-1 now on tape

Discrete symmetries Re() via double ratio (CP direct) KLKS Semileptonic asymmetry (CPT) KLKS interferometry


mass and width

line shape has been fitted for the main decays

W(MeV)

- -

2 20

2 2 2 2( )

( - )e e X e e X

ms

s m m

+ corrections (phase space + contributions from )

K+K– 49.2%KLKS 33.7% 15.5% 1.3%

parameters:mass, total width, peak cross sections

K+K–

KSKL

In the case of a fit with several points has been used to find the correct line shape form (interference between direct, and )

With a combined fit, we measure the width: 4.19±0.04 MeV (preliminary)

(Mass is calibrated with the CMD-2 value)


Neutral kaon mass KLOE can study masses of particles with high accuracy thanks to excellent drift chamber momentum resolution

Neutral kaon mass can be measured using KS

22 2

2

4

0.05

K K

K K K K

K K K K

WM P

M P P P

M M P P

W (MeV)

(e

+e

-

KSK

L) (

b)

KSKL

KS

Energy scale from CMD-2 mass value

MKs=497.583±0.005stat±0.020syst MeV*PDG: 497.648±0.022 MeV

*KLOE Note 181 (http://www.lnf.infn.it/kloe/)

2001Energy scan

KS is tagged by identification of KL in the calorimeter (KL crash): a neutral cluster in a fixed time window

• efficiency ~ 30% ( largely geometrical)• angular resolution on tagged KS ~ 1°• momentum resolution ~ 2 MeV


KS/KL tagging

KL is tagged by identification of the KS - decay: a vertex near the interaction point with the kaon inv. mass

• efficiency ~ 70%• angular resolution on tagged KL ~ 1°• momentum resolution ~ 2 MeV

(KS)/(KS)• Can be used to extract phase shifts and K amplitudes

• Provides information on isospin symmetry breaking from EM terms Chiral pert.

theory

• First part of the double ratio

0 2

0 2

2

0 2

00 0 2

0 2

2 1

3 3

1 2

3 3

3

4

i i

i i

i

A A e A e

A A e A e

A A e

From the K decays (KS, K+), in the exact isospin symmetry hypothesis, we have:

E. Santovetti

considering the EM correction:

( )i ii ii i i

EMi i i i

Ae A A e

K decays measure

To extract , we need a theoreticalinput EM.Important to know the effective E cutoff in decay

(KS)/(KS)


KS

at least 3 neutral clusters in time Ecl> 20 MeV, |cos| < 0.9 to reduce machine Bkg Efficiency ~ 90%

KS

2 tracks from IP extrapolated to the EmC (120 MeV <pTRK < 300 MeV) Efficiency ~ 60%

The measurement is fully inclusive in the radiated photon energy (no cut in the invariant mass)Efficiency is corrected for the radiated photon in the final state by folding the MC distribution (linear interpolation) with the photon spectrum theoretically predicted 0.3% effect

MC

MC

(KS)/(KS)


KLOE ‘02

KLOE '02 2.236 0.003 0.015

17 pb-1 2000 data

PDG ’02 2.197 0.026 World average

KLOE (KS)/(KS) 47.8±2.8

47.7±1.5**PDG '02

(KS)/(KS)56.7±8.0

*

Physics Letters B538 (2002)

*Cirigliano et al. (2000)

**G. Colangelo et al. (2001)

( )SK MC ( )SK ev MCCut on time of flight:

, 1 2( ) ( )

( ) ( )

, ,

t ab t a t b

t i i i

d m m

m t L m c

a b e

The mass hypothesis m=me and m=m on both tracks allows to discriminate a large part of background


KSe+, e-

Together with the KLe can be used to strictly test CPT and the S=Q

Provides information about Vus

• Difficoult to isolate Kse respect to the more abundant (x1000) Ks best measurement CMD-2: BR(Kse) = (7.2 ± 1.4) x 10-4 (75 events)


KSe+, e-Use of variable Emiss-cpmiss

For e decays this is the neutrino mass, while for the decays a value larger than zero is expected.

A fit of the data to the sum of the signal and background spectra simulated by MonteCarlo allows to extract the number of events.

KLOE preliminary (170 pb-1 '01 data)

BR(e+) 3.46 ± 0.09stat ± 0.06syst

BR(e-) 3.33 ± 0.08stat ± 0.05syst

BR(e) 6.81 ± 0.12stat ± 0.10syst

6 7 8 ×10-4

CMD-2 ’99

PDG eval. from KL

KLOE ’02* (17 pb-1 2000 data)

KLOE ’03 preliminary

*Physics Letters B535 (2002)


K0e, CPT and S=Q0

0 * *

0

0 * *

| |

| |

| |

| |

W

W

W

W

e H K a b

e H K a b

e H K c d

e H K c d

KLOE preliminaryAS = (19 ± 17stat ± 6syst) x 10-3

First measurment of AS !

,

( ) ( )

( ) ( )S L

e eA

e e

AS = AL if CPT conserved

AL

PDG '02 (3.33 ± 0.14) x 10-3

KTeV '02(3.322 ± 0.058 ± 0.047) x

10-3

Re(x) (x 10-3)

KLOE preliminary

3.3 ± 5.2 ± 3.5

CPLEAR '98-1.8 ± 4.1 ±

4.5

CPT: b = d = 0

SQ transitions are forbidden at lowest order in the SM

1Re

2

e eS Le e

S L

x

0*

0

( )

( )

A K lx c a

A K l

S=Q: c = d = Re(x) = 0

Re( / )S LA A b a


(KL)/(KL)• Provide information about the absortive contribution (Aabs) to the KL decay

(long-distance term) – Prediction on Ks• Very sensitive to the calorimeter performance in reconstructing the neutral vertex

• very clean signals: low background (KL)KL

• inclusive measure: at least four neutral clusters in time with E > 20 MeV• Efficiency > 99%

• Background ~ 0.4% (KL)

KL• Close kynematics: cuts on - E*

tot, Collinearity, Invariant mass

• Efficiency ~ 80%• Background negligible(KL)/(KL) (x10-3)

KLOE '03* 2.793 ± 0.022stat ± 0.024syst

NA48 '02 2.81 ± 0.01stat ± 0.02syst

PDG '02 2.82 ± 0.08 *Physics Letters B? (2003)

invariant mass plot after the cut on collinearity and total energy

362 pb-1 of data analysed('01+'02 data)

Preliminary1/10 of 362 pb-1

L (ns)

51.7 ± 0.4PDG '02

51.5 ± 0.4KLOE

KL


KL charged (very preliminary)

Very preliminary78 pb-1 ’02 data

*Errors are statistical only!(including MC statistics)

Systematic errors also ~1-2% but not yet fully evaluated

Pmiss - Emiss in or hyp. (MeV)

e

KLOE* PDG ‘02

KL 0.1320.002 0.12570.0019

KL 0.2710.002 0.27170.0025

KLe 0.3840.002 0.38780.0027

KL (2.020.19)·10-3

(2.0810.026)·10-

3


K± (') • Direct CP violation in the charge asimmetry (from theory 10-6 ÷ 10-

4)

• Dalitz plot parameters (CP)

• Extract isospin amplitudes and phase shifts for K decay (PT)(') best value (PDG '02) has ~2% error and concerns only K+

0 0

– K–

K++ 0

Selection/0 – tagging and self-triggering 2-tracks vtx in DC volume p* < 135 MeV/c 4 clusters ontime @ vtx (t<4) Etot < 450 MeVBackground: main K± decays, Ke4’

Efficiencies evaluated from data by using control samples(ex. cl from K±)


K± (')

BR(K±±00) (%)

KLOE '03* 1.781±0.013stat±0.016syst

PDG '02 1.73±0.04

187 pb-1 event counting (~80000 ev.)250 pb-1 efficiency estimate

si=( PK–Pi )2

s0=isi/3 ;

X=(s1–s2)/m2

Y=(s3–s0)/m2

KLOE* (6.3 pb-1) PDG '02

g 0.586±0.010 ±0.012 0.652±0.031

h 0.030±0.010 ±0.013 0.057±0.018

k0.0055±0.0026

±0.00180.0197±0.005

4

*KLOE Note 187

Preliminary Dalitz plot analysis:F(X,Y) = 1+gY+hY2+kX2

Charge asimmetry analysis in progress


Vus determination

For Ke3 modes:

0

0

20

1

2

1

BR

BR

2

1

f

f

V

V

us

us

exp th

|Vus| = 0.2196 ± 0.0019exp ± 0.0018th

Introduced in 1963, known to 1.5%

Experimental inputs to Vus from PDG 02

Mode BR(%) 103 103

K+e3 4.87 ± 0.06

28.5 ± 2.1

K0e3

38.79 ± 0.27

29.1 ± 1.8

K+3 3.27 ± 0.06 3.3 ± 1.0 4 ± 9

K03

27.18 ± 0.25

3.3 ± 0.5 27 ± 6

L = (5.17 ± 0.04) · 10-8 sS = (8.9598 ± 0.0007) · 10-11 s + = (1.2384 ± 0.0024) · 10-8 s

KLOE preliminary BR’s confirm previous values for K0

e3, K03

KLOE will have BR(Ke3) soon

KLOE will measure all BR’s to < 1% and can also significantly improve , , L

preliminary

E865


Dane produces 5·105 0 events/pb-1 ,allowing a detailed study of the decay dominated by the intermediate state: mass measurement (CPT)

Selection 2 charged tracks with vtx at I.P. |Mmiss– M° | < 20 MeV (0 mass) 2 photons (cos * < –0.98) (collinearity) 2 = (Etot- M )2/E

2 + (M-M°)2/M2 < 8

Efficiency ~ 30% - Negligible background

A : 3 terms : M+, M–, M0 and (Gounaris Sakurai shape)A : standard Breit WignerAdir: constant ad ei

d : |ad|2 = |Adir|2 / |A|2

Fit of the Dalitz plot considering a direct decay together with (dominant) and intermediate staes:

0

0

22 2

( , )

dir

p pA X Y A

A A A A

aaaaaaaaaaaaaaaaaaaaaaaaaaaa


2×106 events analyzed (16 pb–1 – 2000 data)

X=(E+– E–)/3Y=(E°– M°)

KLOE* (6.3 pb-1) PDG '02

M (MeV) 775.8 0.5 0.3 771.1 0.9

(MeV) 143.9 1.3 1.1 149.2 0.7

m0-m± (MeV) 0.4 0.7 0.6 0.4 ±0.8

m+-m- (MeV) 1.5 0.8 0.7

ad 0.78 0.09 0.13

a(7.1 0.6 0.8)×10–3

Relative decay intensities from integration of |A|2 over Dalitz plot

I = 0.937

Idir = 0.0085

I = 0.0002 I + Idir + I 1 (+6%)

Interference between and direct decays

*Physics Letters B561 (2003)

Very different valuesdepending on the used techniques:e+e-, decay, hadronproduction


Conclusions and outlook

DANE luminosity has been continuously improving. KLOE expects to collect at least 1 fb-1 in 2003/2004

Analysis of 2000-2001 data brought to several published results on neutral kaons and decays

Work in progress with 2001/2002 data:

- K , KL semileptonic decays (Vus)

– Rare kaons decays: KS , KS 3, KS e+e, KS

– decays (about 2×107 produced in 500 pb-1)

Documents

Hadronic results from KLOE