Hadronic results from KLOE

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European Physical Society International
Europhysics Conference on High Energy Physics EPS
(July 17th-23rd 2003) in Aachen, Germany
Hadronic results from KLOE
E. Santovetti (INFN Roma II) for the KLOE
Collaboration
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DAFNE the Frascati F factory

• electron positron collider at the f 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
f per year (109) 15 0.9
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
3
KLOE data taking history
Year pb-1/day pb-1/day
Year average peak
2000 25 pb-1 0.1 0.4 First published results
2001 170 pb-1 0.7 1.8 Luminosity improved but high background Further analyses published
2002 280 pb-1 2.0 4.5 Higher luminosity and background reduced Analysis in progress
in 2002
An upgrade of the machine has been done. An
increase in luminosity ( gt x2 ) is expected in
the next data taking.
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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Kaon physics at DAFNE

• 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

F decay /pb-1
K K- 49.2 1.5x106
KS KL 33.7 106
r p / p p- p0 15.5 5x105
h g 1.3 4x104
p (MeV/c) l (cm)
K K- 127 95
KS 110 0.6
KL 110 343
all KS decay close to the IP reasonable
acceptance for KL
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
5
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

E. Santovetti
HEP2003 Aachen, 17-23 July 2003
6
Detector performances
calorimeter
Drift chamber
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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KLOE physics program
1999
500 pb-1 now on tape
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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f mass and width
corrections (phase space contributions from
w r )
f line shape has been fitted for the main f decays
KK 49.2 KLKS 33.7 ?? 15.5 ??
1.3
f parameters mass, total width, peak cross
sections
With a combined fit, we measure the f width
Gf4.190.04 MeV (preliminary) (Mass is
calibrated with the CMD-2 value)
W(MeV)
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
9
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 KSgpp-
Energy scale from CMD-2 f mass value
fgKSKL KSgpp-
s(ee- g KSKL) (mb)
W (MeV)
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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KS/KL tagging
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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G(KSgpp-(g))/G(KSgp0p0)

• Can be used to extract d0-d2 phase shifts and
  Kgpp amplitudes
• Provides information on isospin symmetry
  breaking from EM terms Chiral pert. theory
• First part of the double ratio

E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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G(KSgpp-(g))/G(KSgp0p0)
KSgp0p0 at least 3 neutral clusters in time Eclgt
20 MeV, cosq lt 0.9 to reduce machine Bkg
Efficiency 90 KSgpp- 2 tracks from IP
extrapolated to the EmC (120 MeV ltpTRK lt 300 MeV)
Efficiency 60
The measurement is fully inclusive in the
radiated photon energy (no cut in the pp-
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
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
13
G(KSgpp-(g))/G(KSgp0p0)
KLOE '02 2.236 ? 0.003 ? 0.015 17 pb-1 2000 data
PDG 02 2.197 ? 0.026 World average
Physics Letters B538 (2002)
c0-c2 d0-d2
KLOE G(KSgpp-(g))/G(KSgp0p0) 47.82.8 47.71.5
PDG '02 G(KSgpp-(g))/G(KSgp0p0) 56.78.0 47.71.5
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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KSgp-en, pe-n
Together with the KLgpen, can be used to strictly
test CPT and the DSDQ Provides information
about Vus

• Difficoult to isolate Ksgpen respect to the more
  abundant (x1000) Ksgpp
• best measurement CMD-2 BR(Ksgpen) (7.2 1.4)
  x 10-4 (75 events)

E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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KSgp-en, pe-n
Use of variable Emiss-cpmiss
For pen decays this is the neutrino mass, while
for the pp- 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(p-en) 3.46 0.09stat 0.06syst
BR(pe-n) 3.33 0.08stat 0.05syst
BR(pen) 6.81 0.12stat 0.10syst
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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K0gpen, CPT and DSDQ
CPT b d 0
AS AL if CPT conserved
KLOE preliminary AS (19 17stat 6syst) x
10-3 First measurment of AS !
AL 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) Re(x) (x 10-3)
KLOE preliminary 3.3 5.2 3.5
CPLEAR '98 -1.8 4.1 4.5
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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G(KLggg)/G(KLgp0p0p0)

• Provide information about the absortive
  contribution (Aabs) to the KLgmm decay
  (long-distance term) Prediction on Ksggg

• Very sensitive to the calorimeter performance in
  reconstructing the neutral vertex
• very clean signals low background (KLgp0p0)

• KLgp0p0p0
• inclusive measure at least four neutral
  clusters in time with Eg gt 20 MeV
• Efficiency gt 99
• Background 0.4 (KLgp0p0)
• KLggg
• Close kynematics cuts on
• - Etot, Collinearity, Invariant mass
• Efficiency 80
• Background negligible

G(KLggg)/G(KLgp0p0p0) (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)
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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KLg charged (very preliminary)
KLOE PDG 02
KLgpp-p0 0.132?0.002 0.1257?0.0019
KLgpmn 0.271?0.002 0.2717?0.0025
KLgpen 0.384?0.002 0.3878?0.0027
KLgpp- (2.02?0.19)10-3 (2.081?0.026)10-3
Errors are statistical only! (including MC
statistics) Systematic errors also 1-2 but not
yet fully evaluated
Very preliminary 78 pb-1 02 data
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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Kgp?p0p0 (t')

• Direct CP violation in the charge asimmetry
  (from theory 10-6 10-4)
• Dalitz plot parameters (CP)
• Extract isospin amplitudes and phase shifts for
  Kgppp decay (cPT)

(t') best value (PDG '02) has 2 error and
concerns only K

• Selection
• ?mn/pp0 tagging and self-triggering
• 2-tracks vtx in DC volume
• p lt 135 MeV/c
• ?4 clusters ontime _at_ vtx (Dtlt4s)
• Etot lt 450 MeV
• Background main K decays, Ke4

Efficiencies evaluated from data by using control
samples (ex. ecl from Kgp?p0)
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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Kgp?p0p0 (t')
BR(K???0?0) () BR(K???0?0) ()
KLOE '03 1.7810.013stat0.016syst
PDG '02 1.730.04
KLOE Note 187
Preliminary Dalitz plot analysis F(X,Y)
1gYhY2kX2
si( PKPi )2 s0?isi/3 X(s1s2)/m?2
Y(s3s0)/m?2
KLOE (6.3 pb-1) PDG '02
g 0.5860.010 0.012 0.6520.031
h 0.0300.010 0.013 0.0570.018
k 0.00550.0026 0.0018 0.01970.0054
Charge asimmetry analysis in progress
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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Vus determination
Introduced in 1963, known to 1.5
Vus 0.2196 0.0019exp 0.0018th
Experimental inputs to Vus from PDG 02 Experimental inputs to Vus from PDG 02 Experimental inputs to Vus from PDG 02 Experimental inputs to Vus from PDG 02
Mode BR() 103 l 103 l0
Ke3 4.87 0.06 28.5 2.1
K0e3 38.79 0.27 29.1 1.8
Km3 3.27 0.06 3.3 1.0 4 9
K0m3 27.18 0.25 3.3 0.5 27 6
tL (5.17 0.04) 10-8 s tS (8.9598
0.0007) 10-11 s t (1.2384 0.0024) 10-8
s
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
22
f grp,pp-p0
DaFne produces 5105 pp-p0 events/pb-1 ,allowing
a detailed study of the decay dominated by the rp
intermediate state r mass measurement (CPT)

• Selection
• 2 charged tracks with vtx at I.P.
• Mmiss Mp lt 20 MeV (p0 mass)
• 2 photons (cos qgg lt 0.98) (collinearity)
• c2 (Etot- Mf )2/sE2 (Mgg-Mp)2/sM2 lt 8
• Efficiency 30 - Negligible background

Fit of the Dalitz plot considering a direct decay
together with rp (dominant) and wp intermediate
staes
Arp 3 terms Mr, Mr, Mr0 and Gr (Gounaris
Sakurai shape) Awp standard Breit Wigner Adir
constant ? ad eifd ad2 ? Adir2 /
? Arp2
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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f grp,pp-p0
2106 events analyzed (16 pb1 2000 data)
Very different values depending on the used
techniques ee-, t decay, hadronproduction
KLOE (6.3 pb-1) PDG '02
Mr (MeV) 775.8 ? 0.5 ? 0.3 771.1 ? 0.9
Gr (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
aw (7.1 ? 0.6 ? 0.8)103
X(E? E?)/?3 Y(E? M?)
Physics Letters B561 (2003)
Relative decay intensities from integration of
A2 over Dalitz plot Irp 0.937 Idir
0.0085 Iwp 0.0002
Irp Idir Iwp ? 1 (6) Interference
between rp and direct decays
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
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hg3g
The hg3g decay is a C-violating decay with a
branching ratio theoretically predicted extremely
low ( lt 10-12)
? production chain
E? 363 MeV
Analysis strategy
4?
Kinematical fit Constraint 1) energy momentum
conservation 2) t r/c (photons)
Nprompt-clusters 4 Emin gt 50 MeV cos(?) lt
0.91

Background
4g

• To reject background channels with ?0 we cut on
  m?? of any pair of photons.
• The background shape and normalization is
  estimated from the data

3g
B.R.(hg3g) C.L. 95
KLOE '03 (preliminary) lt 1.410-5
Crystall Ball lt 510-5
PDG '02 lt 510-4
5g
E. Santovetti
HEP2003 Aachen, 17-23 July 2003
?2min
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Conclusions and outlook

• DA?NE 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 ? pp- g, KS ?
  3p0, KS ? pp- ee?, KS ? gg
• ? decays (about 2107 ? produced in 500
  pb-1)

E. Santovetti
HEP2003 Aachen, 17-23 July 2003