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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