Results from KLOELNF Scientific Committee 23/05/2002

C.BiniUniversita’ “La Sapienza” and INFN Roma

(1) First published papers (2) Analyses in progress

(3) 2001/2002 data physics perspectives

KLOE physics papers [4+1] (based on data taken in 2000: ~20 pb-1):

(1) Measurement of the branching fraction for the decay KS e Phys.Lett. B 535 37 (2002)(2) Study of the decay with the KLOE detector Phys.Lett. B 536 209 (2002)(3) Study of the decay with the KLOE detector Phys.Lett.B 537 21 (2002)(4) Measurement of (KS))/(KS) hep-ex/0204024 , accepted by Phys.Lett.B(5) Measurement of ’ / KLOE Note 179to be submitted to Phys.Lett.

B

KLOE detector papers:

(6) The KLOE electromagnetic calorimeter Nucl.Instr. and Meth. A482 364 (2002) (7) The QCAL tile calorimeter of KLOE Nucl.Instr. and Meth. A483 649 (2002) (8) The KLOE drift chamber accepted by Nucl.Instr. and Meth. A (9) The KLOE trigger system submitted to Nucl.Instr. and Meth. A

Results on KS physics [papers (1) and (4)]: 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 2000 data concentrated on: semileptonic KS decay(KS + / (KS 00) Other analyses in progress on larger statistics.

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

KS Semileptonic decays

Paper dedicated to the memory of L. Paoluzi

Selection uses: 2 tracks invariant mass difference of ToF between e and

ToF selection illustrated for MC eventsNotice: sign of the charge is determined Semileptonic asymmetry accessible

MC: the signal

MC: the background

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

(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 E

cut )

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

Results on radiative decays: [papers (2), (3) and (5)]

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:

’ / [paper (5)] [paper (2)] [paper (3)]

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

Motivations: f0, a0, not easily interpreted as qq states; other interpretations suggested: qqqq states (lower mass) [Jaffe 1977];

KK molecule (m(f0,a0)~2m(K)) [Weinstein, Isgur 1990];

f0 , a0 BR, mass spectra sensitive to f0,a0 nature [Achasov, Ivanchenko 1989]:

f0,a0

Kaon loop final state

radiative

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

Overlap = structure dependent function

k = f0 momentum

Kaon loop approach:

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

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

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)

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) ’

Results:

N(a) = 50210 220 N(b) = 120 12stat ±5bck

Invariant mass spectrumof ’

BR( ’) R = = (4.70 0.47stat 0.31syst) x 10-3

BR( )

P = ( 41.8 1.7)o [ P = (-12.9 1.7)o ]

Using the PDG value for BR( ) BR(’ ) [PDG : (6.7 ) 10-5 ]

BR(’ ) = (6.10 0.61stat 0.43syst) x 10-5

+ preliminary result using +-7; +-(00) 000 (+-0) BR (’ ) = (7.0 0.6 1.0) 10-5 (not included in paper (5))

to get R, effect of non resonant e+e-( : 5% correction (opposite sign interference of with and’)

5.1

4.1

BR (’ ) helps in assessing the ’ gluon content: combined analysis.

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

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

Result

BR

(

’

) x

10-5

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

11.007.0

22 95.0 YX

2000 data

CMD-2 SND KLOE

10

8

6

4

2

0

Analyses in progress (aim to publish by end of 2002): Published results x 10 statistics + improve systematic. In particular: -BR(KS e ) measurement down to 2% + first look at charge asymmetry -(KS))/(KS) measurement down to 0.1% (work on systematic) -high statistics a0 spectrum

KL / KL 30 (**) Hadronic cross-section (e+e- -) vs s 2m < s < m Measurement of the K0 mass from KSKL, KS KLOE Note 181

Dynamics of the decay parameters Upper limit on (test of C invariance in EM decays) KLOE Note 180

( KL KL )

Motivations: Long distance contribution to the rare KL decay Predictions on KS Test of Chiral Perturbation Theory

BR(KL ) = (5.86 ±0.15) x 10-4 [NA31 BR(KL ) /BR KL )] KLOE improvement to 1% measurement

Normalization to BR KL )1.3% uncertainty (not 2.2%)

KL well measured in all the fiducial volume:

Measurement of KL

Drift Chamber volume

Event Selection: KL tagging (by KS Neutral Vertex from 2 E > 100 MeV

8540 ± 120 events (after background subtraction) from 150 pb-1 analyzed Efficiency checks in progress (data vs Montecarlo)

Distribution of M(): data (red) MC signal (black) MC bckg (blue)

Hadronic cross-section (e+e- -) vs s 2m < s < m

Measured by Radiative Returncomplementary approach to the standard energy scan

Key points: knowledge of ISR function background (mostly FSR) EVA MontecarloSelect -events. Tracks from I.R. 40o < TRACK < 140o + Part.ID using calorimeter. 1) large angle 55o < < 125o (blue) a in the calorimeter required 2) small angle < 15o or > 165o (red) no requiredSample 1) = higher background (FSR + ); all M spectrum Sample 2) = higher , less background but kinematically limited (acceptance loss)

M2

ddM2

photon

pions

Comparison of data (22.6 pb-1) with Montecarlo (EVA + detector response): [visible cross-section, no unfolding applied]1) Large angle sample (45000 events) - 2) Small angle sample (265000 events)

55o < < 125o

• MC

• data

d(

e e

)/

dM

2(n

b/G

eV

2)

• MC

• data

< 15o or > 165o

d(

e e

)/

dM

2(n

b/G

eV

2)

(DATA-MC)/MC (%)(DATA-MC)/MC (%)

Outlook:

• KLOE 2001 data (175 pb-1) are enough to measure the hadronic cross-section ee with a statistical uncertainty of ~ 0.15% for small angle sample and ~ 0.3% for large angle sample.

• The new NLO generator from Kühn et al. (PHOKARA,), improves the theoretical description of ISR.

The uncertainty from unaccounted higher order ISR is estimated to be around 0.5% (hep-ph/0112184)

• Expected improvement in the knowledge of the radiator function and in the luminosity measurement.

Results are expected before the end of the year!

Measurement of the 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)

2001/2002 data physics perspectives:

KS decays: with measurement of spectrum limits on

KL decays: /

l±sinC

decays: [6 x106 in 2001 tag from E = 363 MeV photon] (improve C-test) (photon spectrum) (Dalitz plot slopes) (branching ratio)[significant checks of Chiral Perturbation Theory]

K decays: mutual tagging [6 x 105 tags / pb-1 large statistics] but: sensitive to machine background difficult analysis (requiring specific tools)

List of items: l±sinC (check with sinC from KL) … all K BR can be improved fK

Dalitz plot parameters radiative decays final state +

Tagging: K+ + tags K

momentum distributionof the daughter particlein the K rest frame:

peak

peak

Conclusion

First 4+1 papers using a ~20 pb-1 sample: previous results are improved.

We have learned how to extract physics results from our data: Machine parameters monitor and control (example)

Calibration Efficiency from data Corrections to Montecarlo

We warmly acknowledge the DANE team for their efforts in providing us good data.