1. Recent Results from KLOE experiment at DAFNE e+e- collider
Marco Incagli - INFN Pisa
Apr 2004

2. Marco Incagli - INFN Pisa
Greek mythology
Daphne ® DAFNE
(Greek dafnis, English laurel, Italian alloro)
daughter of the river god Peneios and Gaea (goddess of the earth)
flew the courting of Apoll and was metamorphosed into laurel by her mother; later on the name of this plant was attributed to Apoll
not to be confused with Daphnis
son of Hermes (Mercurius) and a Sicilian nymph
later a common name of herdsmen
Chloe ® KLOE
the greening, is a surname of Demeter (Ceres),
later on a common name of sheperdness
Daphnis and Chloe
couple of lovers in the hononymous novel of Logos (~300 BC)
made famous by Ravel symphonic poem
Marco Incagli - INFN Pisa

3. Marco Incagli - INFN Pisa
DAFNE
DEAR
DAFNE : e+ e - high luminosity collider (Ldesign= 5x1032cm-2s-1) set at the F peak:
s = MF = 1.02 GeV
s(F)  3.3 mb
a f-factory is mostly a kaon factory
kaons are produced back to back in the CoM with |p|~110 MeV
e+e- in two separate rings with crossing angle 25mrad at IP (small F momentum pF13MeV)
Decay
BR(%)
f  K+ K-
49.1
f  KS KL
33.8
f  r p / p+p-p0
15.6
f  h g
1.26
Marco Incagli - INFN Pisa

4. Characteristics of a F factory
Tagging: observation of KS,L signals presence of KL,S (same is true for K)
precision measurement of absolute BR’s
pL,S = 110 MeV lS = 0.6 cm Ks decays near interaction point
bL,S = lL = 3.4 m Large detector to keep reasonable acceptance for KLdecays (~0.5 lL)
The KK pairs in the final state have the same F quantum
numbers i.e. are produced in a pure JPC = 1– – state F
KS (K+)
KL (K-)
purity 10-10
Interferometry measurements of KSKL system
Marco Incagli - INFN Pisa

5. Marco Incagli - INFN Pisa
DAFNE performances
 L(pb-1)
DAFNE
Parameters
Design
2002
(KLOE)
N bunches
51+51
Lifetime (mins)
120 40
Bunch current(mA) 20
Lbunch (cm-2s-1)
4.4 · 1030
1.5 · 1030
Lpeak (cm-2s-1)
5.3 · 1032
0.8 · 1032
Standard analysis sample:
450 pb-1 from
Beam trajectory length ~ 98 m
Beam crossing frequency MHz
Bunch spacing : 2.7 ns
Bunch I.P.:
sx sy sz
2mm 20 mm 3 cm
Lpeak = 2 · 1032 cm-2s-1
L int / day = 10 pb-1
L int / year = 2 fb-1
(2109KSKL)
2004 goal
Marco Incagli - INFN Pisa

6. Physics reach vs Integrated luminosity
Interferometry
e/e to O(10-4) via double ratio
rare KS,L decays, CPT tests
5 fb-1
KS semileptonic asymmetry,
KS  3p0, KL  2p, KL gg,
K  mn,pp,ppp,pen,ppen,
s(e+e-  hadrons) to 1%
Today
500 pb-1
2001
50 pb-1
2000
KS physics
BR(KS  p+p-)/BR(KS  p0p0)
BR(KS pen)
f radiative decays
f  f0g, a0g
f  hg, hg
5 pb-1
1999
Marco Incagli - INFN Pisa

7. KLOE detector d=4m Lead, Scint.Fibers ECAL Helium, all stereo wires
Drift Chamber
Marco Incagli - INFN Pisa

8. Electromagnetic calorimeter
Pb - Sc.Fibres - Matrix
<r> = 5 g/cm3 ; <X0> = 1.6 cm
sampl. frac.~15% (m.i.p.)
Measured performances :
sE /E = 5.7% /E(GeV)
s t= 54 ps /E (GeV)  50 ps
1.2 mm
Lead
1.35 mm
1.0 mm
52.5 cm
15X0
450 cm
Efficient Detection of Photons  20 MeV
98% Hermetic Coverage
Discriminate KL p0p0 vs KL p0p0 p0
Excellent timing to reconstruct KL p0 p0 decay vertex with a precision < 1 cm
Serve as a 1st level Trigger
Marco Incagli - INFN Pisa

9. Marco Incagli - INFN Pisa
Drift Chamber
High and uniform track reconstruction efficiency
Determine the KL,S vertex with an accuracy  1mm
Good momentum resolution (dpt/pt0.4% )
Transparent to low energy g (down to 20 MeV) and KL,S regeneration
~52000 stereo wires
cell structure:
3:1 field:sense ratio
3 × 3 cm2 in the 46 outer layers
2 × 2 cm2 in the 12 inner layers
[90% He, 10% iC4H10 ( X0=900m )
mechanical structure in C-Fibre
(<0.1 X0)]
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10. Quadrupole Calorimeter (QCAL)
45 cm
0.5 mm Al-Be 9°
permanent magnet quadrupoles
10 cm
Spherical
Beam Pipe
QCal
Acceptance increased thanks
to Quadrupole Instrumentation:
Lead-Scintillator Tile Sampling Calorimeter
QCAL
Marco Incagli - INFN Pisa

11. A first glance at interference
KSKL  p+p-p+p-:
KLOE preliminary
340 pb-1 ’01 + ’02 data
Fit with PDG values for GS, GL
c2/d.o.f. = 43.7/47
Dm = (5.64  0.37)×109  s-1
PDG ’02: (5.301  0.016)×109  s-1
First observation of quantum interference in relative decay- time distribution of KS, KL
No simultaneous decays
to same final state ;
antisymmetric initial state
Peak position sensitive to Dm
Coherent KL regeneration on beam pipe
|t1 - t2|/t(KS)
Marco Incagli - INFN Pisa

12. Marco Incagli - INFN Pisa
KAON physics at KLOE
This talk
(KS KL interference in progress)
KSp0en Phys. Lett. B537(2002)21, update
KSp0p0p0 preliminary results
Other topics
Kpp0p0 hep-ex/
KSp+p-(g)/p0p0 Phys. Lett. B538(2002)21
KS mass KLOE note 181 (
KLgg/p0p0p0 Phys. Lett. B566(2003)61
KL semileptonic decays in progress
K semileptonic decays in progress
Kp0en in progress
Kpp0/mn in progress
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13. KL on ECAL as a tag of KS “beam”
KS tagged by KL interaction in EmC
Efficiency ~ 30% (largely geometrical)
KS angular resolution: ~ 1° (0.3 in f)
KS momentum resolution: ~ 1 MeV
b* = velocity of KL in rest frame of f
Nominal b*
0.218
KL “crash”
= 0.22 (TOF)
KS  p-e+n
To get the particle TOF, the global event t0 must be fixed
Tag efficiency is slightly dependent on the KS decay due to the different global t0 estimation
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14. KS  p+p- as a tag of KL “beam”
sM ~ 1 MeV/c2
KS  p+p-
KL tagged by KS  p+p- vertex at IP
Efficiency ~ 70% (mainly geometrical)
KL angular resolution: ~ 1°
KL momentum resolution: ~ 1 MeV
KL  2p0
Marco Incagli - INFN Pisa

15. KS pen decays – Physics issues
Can be studied in e+e- machines only!
Sensitivity to CP violation in K0-K0 mixing:
AS = 2Re e (CPT symmetry assumed) - never measured before _
G(KS,L  p-e+n) - G(KS,L  p+e-n)
G(KS,L  p-e+n) + G(KS,L  p+e-n) _
AS,L =
If CPT holds, AS=AL
ASAL signals CPT in mixing, with possible contribution from DSDQ
DS=DQ rule can be probed through the measurement of:
SM predictions: GammaS = GammaL, As = AL = 2Re epsilon
Can extract |Vus| via measurement of BR(KS  pen) - in progress
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16. KS pen decays – Analysis outline
Main background from KS pp(g)
Kinematic rejection: Mpp < 490 MeV
TOF identification: compare p-e expected flight times, reject pp,pm bkg
Data
MC pen
e-p+ 5 5 4 4 3 3
dt(p-e+) (ns) 2 2
e+p-
Pipi rejection: Invariant mass, Signal TOF selection, Kinematic closure. 1 1 -1 -1 -1 1 2 3 4 5 -1 1 2 3 4 5
dt(e-p+) (ns)
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17. KS pen decays – Analysis outline
6000
Kinematic closure: use KL to obtain KS momentum PK and test for presence of neutrino:
Emiss = MK2 + PK2 – Ep – Ee
Pmiss = |PK – Pp – Pe |
Determine number of signal counts by fitting data to a linear combination of MC spectra for signal and background
 Data
— MC sig + bkg
5000
4000
3000
2000
Pipi rejection: Invariant mass, Signal TOF selection, Kinematic closure.
1000
-60
-40
-20 20 40 60 80
Emiss–cPmiss(MeV)
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18. KS pen decays – Analysis outline
400
1200
1600
2000
800
Signal spectrum clearly sensitive to the presence of a photon in the final state
 Data
— MC sig + bkg
Include radiative effects through an IR-finite treatment in MC (no energy cutoff)
Normalize signal counts to KS pp(g) counts in the same data set
Use BR(KSpp(g)) from previous KLOE measurement
Pipi rejection: Invariant mass, Signal TOF selection, Kinematic closure.
Emiss–cPmiss(MeV) 10
-10
-20 20 30
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19. KS pen decays – Preliminary results
Correct for charge-dependent efficiencies, mostly extracted from data (data control sample of KL  pen) e  20% given the tag
BR(KS  p-e+n) = (3.54  0.05stat  0.05syst) 10-4
BR(KS  p+e-n) = (3.54  0.05stat  0.04syst) 10-4
KLOE preliminary
Evaluation of the systematics near completion
AS = (-2  9stat  6syst) 10-3
BR(KS  pen) = (7.09  0.07stat  0.08syst) 10-4
Published results:
BR(KS  pen) = (6.91  0.34stat  0.15syst) 10-4, KLOE ’02
AL = (3.322   0.047) 10-3 [KTeV 2002]
AL = (3.317   0.072) 10-3 [NA ]
Branching ratio, Rex, As
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20. Marco Incagli - INFN Pisa
Check of DS=DQ rule
The quantity Rex+ can be different from zero only if the DS=DQ rule is violated
The Standard Model predicts a value Rex+ ~10-6
Using 2001 data only:
Rex+ =(2.25.3stat3.5syst)10-3
In agreement with the validity of the rule DS=DQ and with the published CPLEAR result
Marco Incagli - INFN Pisa

21. KS p0p0p0 – test of CP and CPT
Observation of KS  3p0 signals CP violation in mixing and/or in decay:
SM prediction: GS = GL|h|2, giving BR(KS  3p0) = 1.910-9
Present published limit: BR(KS  3p0) < 1.410-5
Uncertainty on KS  3p0 amplitude limits precision of CPT test:
from unitarity
Sf A*(KSf) A(KLf)/GS = (1 + i tanfSW)Re e+ (i - tanfSW) Im d
(eS,L = e  d)
SM prediction
Dominating contribution in real part of Bell-Steinberger relation, allow estimate of M11-M22 (ReDelta)
A limit on BR(KS  3p0) at 10-7 level translates into an improvement on the accuracy of Im d, i.e.
d(MK0 - MK0) d(MK0 - MK0) _ _
 210-18 
 810-19
(MK/MPlanck = 410-20) MK MK
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22. Search for KS p0p0p0 – 2p0 vs 3p0
Data
MC KS  3p0
c22p
Compare 3p vs 2p hypotheses: 80
c23p - pairing of 6g clusters with better p0 mass estimates
c22p - best pairing of 4g’s out of 6: p0 mass, p(KS), CoM angle between p0’s 60 40
Signal selection: 6 prompt clusters, test of energy-momentum conservation, test of 2pi vs 3 pi hypotheses
normalize to Ks->pi0pi0
Definition of the signal box obtained from analysis of 6-pb-1-equivalent MC subsample 20
c23p 10 20 30 40
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23. Search for KS p0p0p0 - sidebands
c22p
 Data
 MC KS  2p0
 BR(KS  3p0) = 10-5
Data
MC KS  3p0 80
300 60 40 20
200
c23p 10 20 30 40
KS  3p0 decay switched on during MC production of 450 pb-1 equivalent data, with BR equal to the present upper limit
Signal selection: 6 prompt clusters, test of energy-momentum conservation, test of 2pi vs 3 pi hypotheses
normalize to Ks->pi0pi0
100
c23p 20 40 60
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24. Search for KS p0p0p0 - sidebands
c22p
 Data
 MC KS  2p0
 BR(KS  3p0) = 10-5
Data
MC KS  3p0 80 60
750 40 20
c23p
500 10 20 30 40
Signal selection: 6 prompt clusters, test of energy-momentum conservation, test of 2pi vs 3 pi hypotheses
normalize to Ks->pi0pi0
250
c23p 10 20 30 40 50
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25. Search for KS p0p0p0 – signal region
200
c22p
 Data
 MC KS  2p0
 BR(KS  3p0) = 10-5
Data
MC KS  3p0 80 60
150 40 20
100
c23p 10 20 30 40
Signal selection: 6 prompt clusters, test of energy-momentum conservation, test of 2pi vs 3 pi hypotheses
normalize to Ks->pi0pi0 50
c23p 10 20 30 40 50
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26. KS p0p0p0 – Preliminary results
Nsel(data) = 4 events selected as signal, with efficiency e3p = 23%
Nsel(bkg) = 31.3 0.2 bkg events expected from MC, to estimate the BR upper limit use Nsel(bkg) = 1.6
Can state: N3p < 5.83 with a 90% CL
N2p / e2p
BR(KS  p0p0p0) =
BR(KS  p0p0) < 2.110-7,
N3p / e3p
Normalize signal counts to KS  p0p0 count in the same data set:
Signal selection: 6 prompt clusters, test of energy-momentum conservation, test of 2pi vs 3 pi hypotheses
normalize to Ks->pi0pi0
A(KS  p0p0p0)
A(KL  p0p0p0)
Which translates into a limit on |h000| = < 2.410-2
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27. Summary & Outlook – Kaon physics
Present status - KS:
Sensitivity to BR’s at the 10-7 level (preliminary limit for KS  3p0)
Measurement of Ke3 mode at the % level, <10-2 accuracy on AS
Expect 2 fb-1 of integrated luminosity in 2004, would allow:
AS with a total accuracy of , first test of SM prediction AS = 2 Re e
Sensitivity to KS  3p0 at 10-8 level
A measurement of BR(KS  p+p-p0) with 20% relative uncertainty
First direct measurement
Test of the cPt prediction, BR(KS  p+p-p0) = (2.4  0.7) 10-7
2fb-1 will allow:
As to 1%, Sensitivity to BR(3pi0) at 10-8 level
BR(Ks gg) at xx%, BR(Ks pi+pi-pi0) at 20%
BR(Ks ppg)
In progress:
Measurement of BR’s for semileptonic KL and K decays
Huge statistics: uncertainty will be limited by systematics
Measurement of Vus with d|Vus|2 0.1% accuracy
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28. Non-KAON physics at KLOE
This talk
s(hadronic) hep-ex/ , update
Other topics
frp, p+p-p0 Phys. Lett. B561(2003)55
ff0g, a0g Phys. Lett. B536(2002)209, B537(2002)21
fh’g, hg Phys. Lett. B541(2002)45
hggg hep-ex/ , submitted to PLB
h p+p-p0, p0p0p0 in progress
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29. Marco Incagli - INFN Pisa
Hadronic cross section - am
Motivation: Determination of Hadronic Vacuum Polarization = High Precision Test of the Standard Model:
Anomalous magnetic moment of the muon am = (gm-2)/2
Running fine structure constant at Z0-mass aQED (MZ)
Updated measurement from averaging results for m+ and m-:
am = (  6) 10-10
am(QED),
 0.3
Standard Model
prediction
am(weak),
15.4  0.2
am(hadr),
700
Hadronic Vacuum Polarization
2nd largest contrib., cannot be calculated in pQCD
Error of hadronic contribution is dominating total error !
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30. Hadronic cross section - am
Dispersion integral relates amhad(vac-pol) to s(e+e-  hadrons)
Im[ ]  | hadrons |2
amhad =
pp (s<0.5GeV)
pp (except r)
pp (r region)
w + ppp f
rest (<1.8GeV)
rest (1.8-5 GeV)
pQCD (>5GeV)
s-1
d2(amhad)
Process e+e-  s < 1 GeV contributes as much as 66% to amhad
Say: disagreement at 2-sigma level
For am calculation, Pipi transition is the dominating contribution (60%)
CHECK tau data: what kind of extraction, what is really extracted
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31. am – SM prediction vs experiment
So far, estimates of amhad from:
measuring s(e+e-  p+p-) vs s at an e+e- collider, varying the beam energy (CMD2, 0.9% rel. uncertainty)
using the spectral function from t  pp0nt (LEP, CESR data)
CMD2
L= nb-1
 events in  meson region
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32. am – SM prediction vs experiment
So far, estimates of amhad from:
measuring s(e+e-  p+p-) vs s at an e+e- collider, varying the beam energy (CMD2, 0.9% rel. uncertainty)
using the spectral function from t  pp0nt (LEP, CESR data)
hadrons   W  e+ e–
CVC: I =1 & V
W: I =1 & V,A
: I =0,1 & V
However, amth(e+e-) – amth(t)  (20±10)10-10
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33. Muon-Anomaly: Theory vs. Experiment
Comparison Experimental Value with Theory - Prediction
New cross section data have recently
lowered theory error:
a) CMD-2 (Novosibirsk/VEPP-2M) p+ p-
channel with 0.6% precision < 1 GeV
b) t-Data from ALEPH /OPAL/CLEO
Theoretical values taken from
M. Davier, S. Eidelman, A. Höcker,
Z. Zhang
hep-ex/
THEORY
’20/‘03
e+ e- - Data: 2.7 s - Deviation
t – Data: s - Deviation
Experiment BNL-E821
Values for m+(2002) and m-(2004)
in agreement with each other.
Precision: 0.5ppm
Experiment
’20/‘04
am ∙ 10-10
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34. Hadronic cross section - aW(MZ)
The same diagram (vacuum polarization) also affects the value of aW(MZ)
In this case there is not the 1/s enhancement, so the relevant part of thespectrum is in the region 1<s<5 GeV not probed by KLOE
Rhad=s(had)/s0(mm)
contribution
to da(MZ)
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35. Marco Incagli - INFN Pisa
Radiative Return
Standard method for cross section measurement is the energy scan, i.e. the
systematic variation of the c.m.s.-energy of the accelerator
DAFNE is a f - factory and therefore designed for a fixed c.m.s.-energy:
s = mf = MeV; a variation of the energy is not foreseen in near future
Complementary approach:
Take events with Initial State Radiation (ISR)
“Radiative Return” to r-resonance:
e+ e- r + g  p+ p- + g r0
Cross section as a function of the
2-Pion invariant mass s’=Mpp
MC- Generator PHOKHARA = NLO
J. Kühn, H. Czyż, G. Rodrigo
Radiator-Function H(s)
ISR
H(s) s’
ds(e+ e- p + p- g )
dMpp
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36. s(e+e-  p+p-) from ppg events
Measure s(e+e-  p+p-g) at fixed s Exploit ISR to extract s(e+e-  p+p-) for s´ from 2mp  s
Have to watch out for hard FSR:
Rate <ISR due to r resonance
FSR causes events with Mg* = s to be assigned to lower s´ values
Measure sigma p+p-g at fixed beam energy and exploit ISR to measure s(p*p-) exploring energy range 2mpi,sqrt(s):
L measurement at one fixed value of sqrt(s)
Have to: 1) take out hard FSR, same order of signal; 2) Include ISR+FSR; 3) Correct vacuum polarization, not to double count..
FSR correction
Have to properly include radiative corrections,
VP correction
Must remove vacuum polarization,
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37. Measurement of sppg – Analysis scheme
Two high-q tracks from a vertex close to IP
Compute photon momentum, without explicit g detection: pg = pe++ pe- - pp+- pp-
Select signal with a small-q photon, to enhance ISR: dsISR/dW  1/sin2q
relative contribution of hard FSR below the % level over entire Mpp spectrum
Analysis outline:
Select signal with low theta photon, high theta pions, to enhance ISR
No events with Mpp< 600 MeV
Reduce background
Residual background from p+p-p0, e+e-g, m+m-g
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38. Background I - m+m-g, p+p-p0
Kinematical selection based on trackmass (Mtrk) variable:
For ppg events Mtrk~mp
For ppgg events Mtrk>mp  the cut may reject events with multiphoton emission
Estimate and subtract residual background by fitting data to a linear combination of signal and bkg MC distributions
rp preselection
already applied
MTRK (MeV)
p+ p- p0
p+p-p0
p+p-gg tail
signal
region
p+ p- g mp mm
m+m-g
m+ m- g
mr2
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39. Marco Incagli - INFN Pisa
Background II - e+e-g
To reduce Bhabha contamination, a -e separation is performed using a particle ID estimator based on:
e e 
before cutting on
particle ID estimator
TOF of charged clusters in EMC
Shape and energy deposition of the cluster
  
after cutting on
particle ID estimator
The event is selected if at least one of the charged tracks is identified to be a pion.
p+ p-p0 mp
m+ m- g
Mtrack
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40. Marco Incagli - INFN Pisa
Luminosity
L = NBhabhas / seffMC
Experimental precision:
Theory precision (radiative corrections):
Large Angle Bhabha Events > 55º
Excellent agreement Data – MC
Background-”free” ( 0.5% p+p- )
Experimental uncertainty 0.3%
BABAYAGA event generator (Pavia group)
systematic comparison among other generators
(Berends, KKMC, VEPP-2M), max. D=0.7%
Theoretical uncertainty 0.5% (BABAYAGA)
Polar Angle [°]
Acoll. [°]
Momentum [MeV]
Cut
55°<Q<125°
p>400MeV
Acoll.<9° MC
Data
Bhabhas
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41. (e+e-  p+p-g) (nb/GeV2)
Analysis s( e+e-  p+p-g) ds
Efficiencies:
- Trigger & Cosmic veto
Tracking, Vertex
p- e- separation
Reconstruction filter
Trackmass-cut
Unfolding resolution
Acceptance —
(e+e-  p+p-g) (nb/GeV2)
dMpp2
Errors:
L = 141pb-1
1.5M events
1.0%
Background:
e+ e- e+ e- g
e+ e-  m+ m- g
f  p+ p- po
0.5%
obtained from
PHOKHARA
H(Mpp2)
Luminosity:
Bhabhas at large angles
> 55°, seff = 430 nb,
0.3%exp
0.5%theo
Mpp2 (GeV2)
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42. Marco Incagli - INFN Pisa
Extraction s( e+e-  p+p-)
Radiator-Function (ISR):
s( e+e-  p+p-)
ISR-Process calculated at NLO-level
Generator PHOKHARA (Kühn et.al)
Comparison with KKMC (Jadach et.al.)
Precision: 0.5%
Radiative Corrections:
i) Bare Cross Section
divide by Vacuum Polarization
ii) FSR - Corrections
Cross section spp must be incl. for FSR
Vacuum Polarization
Cross Section
Marco Incagli - INFN Pisa

43. Marco Incagli - INFN Pisa
FSR Correction *
10%
FSR (nlo) /ISR 8% 6% 4%
Before trackmass cut 2%
The contribution of FSR is as large as 5% in low M2pp bins
The cut in the M2pp -Mtrk plane rejects ISR+FSR events
FSR contribution + cut efficiency are evaluated by MC 0%
-2%
After trackmass cut
-4%
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
M2pp
Marco Incagli - INFN Pisa

44. Charge asymmetry at large qg
To check FSR evaluation in MC, we measure the charge asymmetry (Aq) induced by ISR-FSR interference
The asymmetry is suppressed at small photon angles, so it has been evaluated in the angular region 50o<qg<150o
The preliminary difference data-MC is 10-20% which we completely assign to a lack of knowledge of FSR
FSR correction is ~2% , so the maximum effect on am is 0.4%
0.9 – 1. GeV2
data
D(Aq) ~ 15% MC
KLOE preliminary
0.8 – 0.9 GeV2
data
D(Aq) ~ 13% MC
Marco Incagli - INFN Pisa

45. Marco Incagli - INFN Pisa
Muon Anomaly
We have evaluated the dispersions integrals for the 2-Pion-Channel
in the energy range 0.35 <Mpp2<0.95 GeV2
ampp = (389.2  0.8stat  4.7syst  3.7theo) 10-10
Comparison with CMD-2 in energy range 0.37 <Mpp2<0.93 GeV2
KLOE
(376.5  0.8stat  5.4syst+theo) 10-10
CMD2
(378.6  2.7stat  2.3syst+theo) 10-10
Discrepancy of ca. 10% between e+e- - Data and t – Data (ALEPH)
for Mpp2 > 0.6 GeV2
KLOE – data confirms discrepancy with respect to t – data !
Explanation: m(r0)  m(r) ???
Marco Incagli - INFN Pisa

46. Marco Incagli - INFN Pisa
Muon Anomaly
|Fp|2
We have evaluated the dispersions integrals for the 2-Pion-Channel
in the energy range 0.35 <Mpp2<0.95 GeV2
— KLOE 40
ampp = (389.2  0.8stat  4.7syst  3.7theo) 10-10
 CMD2 30
Comparison with CMD-2 in energy range 0.37 <Mpp2<0.93 GeV2 20
KLOE*
(376.5  0.8stat  5.4syst+theo) 10-10
CMD2
(378.6  2.7stat  2.3syst+theo) 10-10 10
* Error on model dependence FSR and VP not included!
Discrepancy of ca. 10% between e+e- - Data and t – Data (ALEPH)
for Mpp2 > 0.6 GeV2
0.5
0.7
0.9
KLOE – data confirms discrepancy with respect to t – data !
Explanation: m(r0)  m(r) ???
Marco Incagli - INFN Pisa

47. Muon-Anomaly: Theory vs. Experiment
Comparison Experimental Value with Theory - Prediction
Preliminary
New cross section data have recently
lowered theory error:
a) CMD-2 (Novosibirsk/VEPP-2M) p+ p-
channel with 0.6% precision < 1 GeV
b) t-Data from ALEPH /OPAL/CLEO
Theoretical values taken from
M. Davier, S. Eidelman, A. Höcker,
Z. Zhang
hep-ex/
THEORY
’20/‘03
e+ e- - Data: 2.7 s - Deviation
t – Data: s - Deviation
Including KLOE result
Experiment BNL-E821
Values for m+(2002) and m-(2004)
in agreement with each other.
Precision: 0.5ppm
Experiment
’20/‘04
am ∙ 10-10
Marco Incagli - INFN Pisa

48. Marco Incagli - INFN Pisa
Summary on s(had)
We have proven the feasibility to use the Radiative Return to
perform a high-precision measurement of the hadronic cross
section at the f-factory DAFNE
Statistical Error is negligible
In the energy range Mpp2 > 0.6 GeV2 we do reproduce
the large deviation seen by t-data with respect to e+e-
Our evaluation of the hadronic contribution of the muon
anomaly confirms the deviation btw. Theory and Experiment
of about 3 sigma
A draft for a paper is under collaboration-wide review!
and in this sense data has still to be considered as PRELIMINARY
Marco Incagli - INFN Pisa

49. Marco Incagli - INFN Pisa
am – Prospects
4000
Measure s(pp) in the region close to threshold, Mpp < 600 MeV, responsible for 20% of amhad
This region currently excluded by angular selection
N(ppg) / MeV
3000
2002 data
ISR+FSR MC
2000
1000
Mpp (MeV)
N(ppg) / MeV
103
Pion FF vs Mpp, comparison wrt CMD2
Prospects for measurement of the region close to threshold, around xx% of the pipi contribution to am, poorly known
Normalize to mumugamma and check ISR,FSR calculated from scalar QED (Kuhn)
102
Mpp (MeV) 10
Mg* (MeV)
300
400
500
600
700
800
900
Marco Incagli - INFN Pisa

50. Marco Incagli - INFN Pisa
Summary and Outlook
KLOE experiment has already provided relevant results, in particular in KS physics and s(hadronic)
Continue analysis on s(hadronic) in order to cover the region close to threshold (contribution to am  20%)
Analysis on KS,L and K decays with current luminosity
New data taking just started
Expext to collect >2fb-1, with instant luminosity close to the design one, in order to study
KS- KL interference pattern
Re(e’/e) with double ratio method
KS,L rare decays …
Marco Incagli - INFN Pisa