Paolo Branchini* on behalf of the KLOE collaboration

*Università and INFN ROMA III.

5th International Conference on Hyperons, Charm and Beauty hadrons.

Results from KLOE

Talk outlook:

DANE & KLOE

Ks properties.

Results on decays.

DEAR

DANE : the Frascati - factory

DANE parameters: now design

• number of bunches : 45 120

• Bunch spacing : 5.4 2.7 ns

• Bunch current : 20 40 mA

• Single bunch luminosity : 1030 4·1030 cm2 s1

•Daily delivered luminosity : 3pb1

DANE performance

Present day performance: peak averageL(cm2 s1) 5·1031 3.5·1031

day L dt (pb1) 3 1.8

Data taken from april 1999 to december 2001~ at peak + 1 energy scan

Analysis status:

2000 data ~completed (25 pb-1 7.5 x 107 )

Results in publication

2001 data in progress (190 pb-1 5.7 x 108 )

The KLOE detector

Lead/scintillating fiber

4880 PMTs

98% coverage of solid angle

4 m diameter × 3.3 m length

90% helium, 10% isobutane

12582/52140 sense/total wires

All-stereo geometry

E/E = 5.7% /Sqrt(E(GeV))

t = 54 ps /Sqrt(E(GeV)) 50 ps

p/p = 0.4 %

= 150 m

z = 2 mm

KLOE detector performance

m = 497.7 MeV/c2

m = 1 MeV/c2

m = 497.7 MeV/c2

m = 1 MeV/c2

KKSS ++--

• s from the of KL interacting in the EmC• s from Bhabha electrons momenta measurement

00

At current luminosity Dane energy at 0.01% within 1 minute of data taking using KL , Bhabha and KS energy

1999

2000

2 pb-1

20 pb-1

200 pb-1

2 fb-1

KL form factors, rare KS decays, KL KL , K ± decays(ee to < 1 % (stat)

’ to via double ratioSemileptonic asymmetry (CPT test)KLKS Interferometry

KS physicsBR(KS BR(KS )BR(KS e)

radiative decays f0, a0 ’

2001

First results

On tape

KLOE physics program

K0 mass from KSKL, KS Method: KSKL , KS

M2K=W2/4 - P2

K

W from e+e invariant mass spectrum; absolute calibration from - scan (normalizing to CMD-2 Mvalue) PK from KS

Result: single event kaon mass resolution ~ 430 keV MK = 497.574 ± 0.005stat ± 0.020syst MeV

W (MeV)

(e+

e

KSK

L )(

b)

CMD-2 NA48 KLOE

1015 1020 1025 1030

497.9

497.7

497.5

0.10

0.05

0.00

-0.05

-0.10

1.0

0.8

0.6

0.4

0.2

0.0

(b

)

KLOE NOTE 181

tagging of a pure KS beam (unique opportunity of a -factory).KL interaction in the calorimeter (ToF signature)

s measurement KS “tagging”

Measurement of KS decays

Analysis of about 20 pb-1 data concentrated on: semileptonic KS decay(KS / (KS

Results on Ks physics

(KS +- ()) / (KS 00) Motivations: First part of double ratio Notice: experiments measure double ratio at 0.1% and the single ratio at 1% KLOE aims to measure each single ratio (KL and KS) at 0.1% Extractions of Isospin Amplitudes and Phases A0 A2 and 0-2 consistent treatment of

soft in KS +- () [Cirigliano, Donoghue, Golowich 2000] Selection procedure: 1. KS tagging 2. KS +-() two tracks from I.P +

acceptance cuts: fully inclusive measurement: no request on in calorimeter

(E*) from MC folded to theoretical spectrum

3.KS 00

neutral prompt cluster (E>20 MeV and (T-R/c) < 5t ) at least 3 neutral prompt clusters (0 e+e- included)

Result (from 17 pb-1): Nev (KS +- ) = 1.098 x 106

Nev (KS 00 ) = 0.788 x 106

R = 2.239 ± 0.003stat ± 0.015syst

stat. uncertainty at 0.14% level contributions to “systematic”:tagging eff. Ratio 0.55% photon counting 0.20%tracking 0.26%Trigger 0.23%--------------------------------------Total syst. uncertainty 0.68%

PDG 2001 average is

2.197 ± 0.026 ( without clear indication of Ecut )

Notice: efficiencies by data controlsamples (statistically limited)Goal = reach 0.1% systematic uncertainty[< 2 x 10-4 on Re(’/)].Physics letters B 538 pag 21.

Analysis of KS e decays

/e identification using time-of-flightCuts on Dt(, e), (e, ), (), e.g.:

Dt(,e) =[t1-t2] – [T1()exp – T2(e)exp]

0.8t 9 ns

= 1t 7 nse

dedicated to the memory of L. Paoluzi

Motivation: If (CPT ok) .AND. (S=Q at work): (KS e ) = (KL e ) BR(KS e ) = BR(KL e ) x (L/S) = ( 6.704 ± 0.071 ) x 10-4

(using all PDG information). Only one measurement 75 events (CMD-2 1999): = ( 7.2 ± 1.4 ) x 10-4

Preselection on Me and KS momentum

Acceptance and selection efficiency from MC

2000

BR(KS e ) = (6.91 ± 0.34stat ± 0.15syst) x 10-4

After ToF cuts assignment of electron and pion Emiss –Pmiss distribution a clear signal peaked at 0

BR

(KS

e

)

Result from 17 pb-1

Physics Letter B 535 pag 37 may 2002

Results on radiative decays:

Rad. Decay BR (PDG) 1.26% 1.3 x10-3 ’ ~10-4

~10-4 ~10-4

P (0+)

S (0++) S /

Analysis of 2000 data on:

’ /

Pseudoscalar + ’According to quark model: assuming: no other contents (e.g. gluon))

0 = (uu-dd)/2 = cosP (uu+dd)/2 + sinPss ’ = -sinP (uu+dd)/2 + cosPss

assuming: = ss state (V=0) (F slowly varying function; model dependent)

( ’) K’

R = = cotg2P ( )3 x F(P, V)

( ) K

Decay chains used: (same topology 2T + 3 photons / final states different kinematics) (a) (b) ’

• 3 “prompt” with E > 7 MeV and >

21o .and. 2 tracks vertex in IP

• Preliminary kinematic fit: conservation of total E, p and = 1 for each

• Simple kinematic cuts to eliminate background:

with extra

KSKLwith lost

• negligible background but N(a)N(b)/100

Used decay chains:

a’

b

the topology is the

same: 2 tracks 3

radiative decays:’Motivations:

Measurement of BR(’)/BR( ) gives an accurate determination of pseudoscalar mixing angle.

The BR(’) allows to estimate the gluon content of ’.

Selection:

BR( ’)/BR( ) = (5.3 0.5stat 0.3syst) ·10-3

using PDG value for BR() we obtain:

BR(’) = (6.0.6stat 0.5syst) ·10-5

7151

7.15.1

714

0.40..P

P

.θ

radiative decays:’

KLOE 2000 data

(flavor basis)(octet-singlet basis)

’ = X ’ (uu+dd)/2 + Y ’ ss + Z ’ gluonium

Assume Z ’ =0 evaluate X ’ from other channels evaluate Y ’ from ’

Result

comparison of KLOE results on BR (’ ) with previous results (from VEPP-2M)

11.007.0

22 95.0 YX

Gluonium:

BR

(’

) x

10-5

2000 data

CMD-2 SND KLOE

10

8

6

4

2

0

Los Alamos Archive HEPX 0206010

Precise measurements of BR(f) and BR(a) may distinguish between

various models for f0 and a0 mesons : qqqq state, KK molecule, ordinary qq meson.

f0 , a0 sensitive to f0,a0 nature [Achasov, Ivanchenko 1989]: phenomenological

framework (kaon loop model) coupling constants

g(KK) from (K+K-) g(f0KK) g(a0KK) f0, a0 model g(f0) g(a0) M() M() spectra

f0,a0

Kaon loop final state

radiative

For the f0 analysis usedfa5 final state.

The adecay chain was analyzed both in the 5 final state (and in the very clean 2tracks + 5 final state ( )

Scalar Meson + [f0(980) I=0, a0(980) I=1]

• 5 “prompt” with E > 7 MeV

• | cos| < 0.93 (to avoid background from I.P.)

• 5Ei > 700 MeV to reject KLKS neutrals

• kinematic fit (4-mom. + |t-r/c| )

Radiative decays: f f0 , a0 5 final state

Photon pairing in the hypothesis

1. 002. 03. 000 (M(0)=M())4. 3 (rejecting events and with E =363 MeV)

kinematic fit with mass constraint

• for (2) and 0 mass• for (1) and (3) two 0

1 • 0• 00000

|M

(1) -

M

(2) |

(MeV

)

M (MeV/c2)

e+e 0

00

final state

Background sources

5 final states

final state

Result (from 17 pb-1): Nev = 2438 61

BR()=(1.09 0.03stat 0.05syst)x10-4

CMD-2 (0.92 0.08 0.06)x10-4

SND (1.14 0.10 0.12)x10-4

Fit to the M spectrum (kaon loop): contributions from f0 + “strong” negative interference negligible contribution Fit results:

M(f0) = 973 1 MeV g2(f0KK)/4 = 2.79 0.12 GeV2

g(f0) /g(f0KK) = 0.50 0.01

g() = 0.060 0.008

BR( f0) = (1.49 0.07)x10-4

Physics Letter B537 pag 21 june 2002

Measured in 2 final states: (Sample 1) (5) (Sample 2) (2t + 5) Results (from 17 pb-1): (Sample1) Nev = 916 Nbck = 309 20

BR() = (8.5 0.5stat 0.6syst)x10-5

(Sample2) Nev = 197 Nbck = 4 4

BR() = (8.0 0.6stat 0.5syst)x10-5 CMD-2 (9.0 2.4 1.0) x 10-5

SND (8.8 1.4 0.9) x 10-5

Combined fit to the M spectra: dominated by a0 negligible

Fit results: M(a0) = 984.8 MeV (PDG) g2(a0KK)/4 = 0.40 0.04 GeV2

g(a0) /g(a0KK) = 1.35 0.09

BR( a0) = (7.4 0.7)x10-

5

Physics letter B536 pag 209 june 2002

Summary: KLOE Results on Scalars vs. models.

KLOE qqqq qq(1) qq(2) g2

f0KK/(4) 2.790.12 “super-allowed” “OZI-allowed” “OZI-forbidden”(GeV2) (~2 GeV2)g2

a0KK/(4) 0.400.04 “super-allowed” “OZI-forbidden” “OZI-forbidden”(GeV2) (~2 GeV2)gf0 /gf0KK 0.500.01 0.3—0.5 0.5 2ga0/ga0KK 1.350.09 0.9 1.5 1.5

2)ddu(ua ; 2)ddu(uf (2)

2)ddu(ua ; ssf (1)

00

00

• f0 parameters compatible with 4q model • a0 parameters not well described by the 4q model (2001 data more accurate study of a0)

Conclusions:

We have a very good detector and we are fully exploiting itsmain characteristic in the analysis we are doing. We still need an improvement in DAluminosity.

KLOE side:

DANE side:

Therefore: Stay tuned!!!!

A dramatic improvement in delivered luminosity has been reached since 1999.We believe the latest forseen upgrades will allow DAto reach the ambitious goal of 5*1032 cm-2s-1