KLOE @ FlaviaNet Orsay07

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Gruppo I KLOE 17 Dicembre 2007
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The KLOE experiment at DA?NE

• DAFNE _at_ Frascati Laboratories
• ee- collider with 2 separate rings
• ?s Mf 1019.4 MeV
• Luminosity up to 1.51032 cm-2s-1
• 2 interaction regions
• 1. KLOE 2700 pb-1
• 2. DEAR (kaonic atoms) 100 pb-1
  FINUDA (hypernuclei) 1100 pb-1

KLOE STATUS ? March 2006 end of KLOE data
taking 2500 pb-1 on-peak ? 8 109 f decays
200 pb-1 off-peak (energy scan1 GeV run) ? Dafne
test in progress
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KLOE physics program
Kaon physics CP and CPT violation, CKM
unitarity, rare decays, ChPT tests Hadron
physics lowest mass pseudoscalar, scalar and
vector mesons Hadronic cross-section below 1
GeV hadronic corrections to g-2

• List of the ? decays branching ratios and number
  of events on tape
• B.R. Nev KLOE (2.5 fb-1)
• ????KK- 0.49 3.7 ? 109
• ?K0K0 ??KSKL 0.33 2.5 ? 109
• ???????????? ?0.15 ?1.1 ? 109
• ??? 1.3 ? 10-2 9.7 ? 107
• ???? 1.2 ? 10-3 9.0 ? 106
• ??? 6.2 ? 10-5 4.6 ? 105
• Initial State Radiation ee- ?????????????????????
  ??????????

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The KLOE detector
A large drift chamber A hermetic calorimeter
A solenoidal superconducting coil
Drift Chamber (He-IsoBut. 2m 3m)
E.M. Calorimeter (lead-scintillating fibres)
Magnetic field (SuperConducting
Coil) 0.52 T (solenoid)
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Kaon decay
Naples Ambrosino, Massarotti, Meola, Saracino
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Forthcoming papers
waiting for referee comments
1) KLm3 ff submitted to JHEP
2) KLe3g decay submitted to PLB
?
3) K lifetime
paper written, under the review of the
collaboration

4) BR(KS ? gg)
?
5) BR(Ke3), BR(Km3)
paper in writing
6) Vus with KLOE data
whole data sample
? precise measurements
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Preliminary results
?
1) BR(K ? pp0)

2) Upper limit on BR(KS ? ee- )

?
3) Measurement of G(Ke2)/G(Km2)

4) KSKL interferometry
whole data sample
? precise measurements
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Vus from KLOE Kl3 data

KLe3 0.21547(72) 0.34
KLm3 0.21661(93) 0.43
KSe3 0.21522(145) 0.68
Ke3 0.21465(137) 0.64
K?m3 0.21302(155) 0.73
err
summer conf.
?Vus? f(0)
KLOE Avg 0.21556(59) c2/ndf 6.1/4 (19)
World Avg 0.21664(48)
0.2 with final lifetime

• Vus 0.2243(13)
• 1-Vud2-Vus2 154(79)?10-5

f(0)0.961(5)
RBC/UKQCD, 07 prel.
Vud 0.97372(26)
PRL96 032002,2006
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Vus f(0) whats missing on the experimental
side
world average _at_EPS07
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KL lifetime (and branching ratios)
Lifetime measurement from a sample of 8.5?106
KL?p0p0p0 events uniform reconstruction
efficiency over 0.4tL.
KLOE, PLB 626 (2005)
tL 50.92(30) ns
Absolute BRs KL decays tagged by KS?pp-
13?106
tagged, events
KLOE, PLB 632 (2006)
BR(0)(Ke3) 0.4049(21)
BR(0)(Km3) 0.2726(16)
present achievements
BR(0)(3p0) 0.2018(24)
BR(0)(pp-p0) 0.1276(15)
at tL(0) 51.54 ns
Improve to s 0.3 with ?5 avail. statistics
(work in progress)
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BR(KS? pen)
BRs from KLOE tagged KS beam, 1.2?108 events
(20 of full data sample)
KLOE PLB 632 (2006)
BR(KS ? pen)/BR(KS ? pp-) 10.19(13) ? 10-4
KLOE EPJC 48 (2006)
BR(KS ? pp-) /BR(KS ? p0p0) 2.2459(54)
Averaged with KLOE 02
These two measurements completely determine main
KS BRs
BR(KS ? pen) 7.046(91) ? 10-4
present achievements
AS (1.5 ? 9.6stat ? 2.9syst) ? 10-3
With 2.2 fb-1 we will measure BR stat
error will be 0.5
goal need to improve
on the present syst. (0.7) ? 6?10-3 AS
dominated by stat
? 4?10-3
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Km3 form factor slopes

• Standard method fit t-spectrum, t (pK-pp)2
• Difficult p/m separation at low energy
• Fit En spectrum (loss of sensitivity)

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K? BR and lifetime measurements
Absolute BR(K?e3 ) and BR(K?m3 ), tagging with K?
? m?n and K? ? p?p0 8 measurements in total,
each with 105
BR(K?e3) 4.965(52)
at t?(0) 12 .385 ns, with dBR/BR -0.5dt? /t?
KLOE final ArXiv 0707.2532
BR(K?m3) 3.233(39)
K? lifetime using two different methods
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K lifetime experimental picture
Discrepancy between in-flight and at-rest
measurements Discrepancy among different
stoppers in at-rest measurements Confirmation
is needed
tPDG (12.385 0.024) ns
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Method 2 proper time fit
t? 12.391(49)(25) ns
t? 12.367(44)(65) ns
gt2l?
t? from the K decay length, using tagged
vertices in DC
t? from the K decay time, using g from K? ? p
?p0 decays
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Measurement of the BR(K?pp0)
PDG fit 06 BR(K?pp0) (20,92 0.12)
DBR/BR 0.6 CHIANG 72 BR(K?pp0) (21,18
0.28) DBR/BR 1.3 this decay enters in the
normalization of BR(K?l3) by NA48, ISTRA, E865
Npp(fit) 8183471912 Ntag 12113686

• Tag with K??m?n decays.
• Determine the momentum of the charged decay
  particle in the kaon rest frame assuming mp p.
• Selection efficiency measured on data.
• Count K?pp0 events fitting p distribution
  with three contributions mn and pp0 peaks from
  data control samples, 3-body decays from MC.

ev/bin
p(MeV)
BR(K ? pp0(g) (20.658 0.065stat
0.090syst) -1.3 respect to PDG 06
srel 0.5
KLOE preliminary ArXiv 0707.4631
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Impact of the new BR(K?pp0)
Impact of the KLOE preliminary measurement wrt
PDG06 fit value on the BR(Kl3) -
measurements normalized to Kp2 decays -
comparison with absolute BR(Kl3) measurements
from KLOE
BR(Km3)
BR(Ke3)
5.2
3.4
5.1
3.3
5.0

• using PDG06 BR(Kp2)
• using KLOE BR(Kp2)

• using PDG06 BR(Kp2)
• using KLOE BR(Kp2)

3.2
4.9
KLOE NA48/2
KLOE NA48/2 ISTRA
3.1
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Need to close K? BRs
_at_ KAON07

• Not possible to fit only new K? data (unlike KL)
• Only Kl3, Kl3/pp0, Kpp0p0 and Km2 measured
  recently
• - Kl3 and pp0 highly correlated in fit
• - New measurement of pp0 is crucial

Fit rests heavily on Chiang (no radiative
corrections, 6 BR constrained by SBR1,
correlations not available). BR(p?pp-) needed
to remove Chiang
BR(K? ? p0e?n)
BR(K? ? p0m?n)
PDG 04
PDG 04
PDG 06
PDG 06
Kaon07
Kaon07
BR(K? ? m?n)
BR(K? ? p?p0)
PDG 04
PDG 04
KLOE in progress
PDG 06
PDG 06
Kaon07
Kaon07
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BR(K??p?pp-)

• PDG fit 06 DBR/BR 0.5 CHIANG 72
  DBR/BR 3.6
• Signal require two tracks making a vertex along
  the K path beforeDC
• Look for the signal in the missing mass
  spectrum (?mp2).

Expect sstat 0.1 (work in progress)
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Lepton universality from Ke2?Km2
SM no hadronic uncertainties (no fK) ? 0.4?10-3
In MSSM, LFV can give up to deviations
Masiero, Paradisi, Petronzio
NP dominated by contribution of e??
?e ????
?(K?e?e)?(K?e??)
RK?
?(K????)
with effective coupling
mK4
m?2
RK ? RKSM 1 ?R312 tan6?
mH4
me2
1 effect (?R31 5x10-4, tan?????? mH500GeV)
not unnatural
Present accuracy on RK _at_ 6 need for precise
(lt1) measurements
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LFV in Ke2 decay
KLOE preliminary result _at_ KAON07 (8k evts, 2.7
uncertainty)
RK 2.55(7)10-5
ArXiv 0707.4623
ArXiv 0707.4623
Will push error to 1 final result will be
compared with P326/NA62 measurement (more than
100k events already acquired)
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K??e?vep0p0

• Considering kaon decays with two p0
• K? X p0 p0 ?X gg gg
• We look for two vertex asking
• clusters on time
• (t - r/c)g1 (t r/c)g2
• p0 invariant mass
• agreement between kaon flight
• time and clusters time
• Charged vertex in FV

Ee,xe,te
e
xK
pK
lK
Kmn tag
tm
t0
pK
p0
Eg,tg,xg
p0
Eg,tg,xg
Eg,tg,xg
Eg,tg,xg
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K00e4 BR Kinematic fits
????3 hypotesis
???e4 hypotesis

• 4-momentum conservation
• p0 invariant mass
• clusters on time

• missing 4-momentum
• having zero mass
• p0 invariant mass
• clusters on time

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Radiative decay
Naples Ambrosino, Capussela, Di Donato, Perfetto
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Results on pseudoscalar mesons
waiting for referee comments
?

Measurement of the ? mass Dynamics of ?
???0?0?0decays Dynamics of ? ??? ?-?0decays
paper written, under the review of the
collaboration
whole data sample
? precise measurements
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Precision measurement of the ??mass
Motivated by the discrepancy between the two best
measurements NA48 (2002) M(?) 547.843
0.030 0.041 MeV GEM (2005) M(?) 547.311
0.028 0.032 MeV (? gt10 ?, PDG average gives a
scale factor of 5.8 !) Recently a new measurement
has been published by CLEO CLEO (2007) M(?)
547.785 0.017 0.057 MeV
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Precision measurement of the ??mass

• KLOE method analysis of fully neutral 3? events
• ??????? with ??????
• ???????? with ???????
• 3 clusters in the calorimeter only.
• Kinematic fit with 4 constraints gt energies by
  cluster positions
• Discrimination between ? and ?? very easy from
  Dalitz plot.
• Absolute energy scale from the ee- center of
  mass energy ?s
• (kinematic fit input) - calibrated comparing M(?)
  obtained by the
• energy scan to the PDG value (dominated by CMD-2)
  

KLOE final result M(?) 547.873 0.007
0.031 MeV
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Dynamics of the ????3? decay
????'???3? decay ? isospin violation in strong
interactions mu ? md ? ms A test of low energy
effective theories of QCD
KLOE has studied with high statistics the
dynamics of both channels (a) ?? ? ???????Dalitz
plot analysis 1.34 ?106 events (b) ?? ?
???????slope analysis 0.65 ?106 events
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Dynamics of the ????3? decay
(a) ?? ? ??????? Dalitz plot - large
statistics - negligible background - use X and
Y variables
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Fit results of the ?? ? ???????Dalitz plot
Including systematic errors a-1.090 ? 0.005
0.008 -0.019 b 0.124 ? 0.006 ? 0.010 d 0.057 ?
0.006 0.007 -0.016 f 0.14 ? 0.01 ? 0.02
Comments 0. the odd terms (c and e) in X are
compatible with 0 (no asymmetries) 1. the
quadratic term in X (d) is unambiguosly different
from 0 2. the cubic term in Y (f) is needed to
get an acceptable fit 3. the ba2/2 (current
algebra rule) is largely violated.
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Fit results of the ?? ? ???????slope
The slope is evaluated by comparing the z
distribution of the data with a Montecarlo
simulation with ?0 (pure phase space) ? High
sensitivity to the M(?) value (Dalitz plot
contour)
MC with M(?)547.3
MC with M(?)547.822
New (preliminary) result ? -0.027 ? 0.004
0.004 -0.006 ? in agreement with Crystal Ball
(?-0.031?0.004)
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? gluonic content
R.Escribano, J.Nadal (JHEP 0705,006,2007)
reanalyze all V? P? and P? V? decays updating
wavefunction overlaps parameters and neglecting
the Y1 constraint ? no evidence of gluonium
content
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Conclusions
Kaon and hadronic physics allows for precision
SM tests (and beyond)
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Spares
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KL lifetime update with 2 fb-1

• Same technique used for the measurement on
  2001/2002 data (KL?p0p0p0).
• Factor 5 in statistics at least a factor 2
  better wrt the published stat. error (0.17 ns)
• Syst. error dominant (0.25 ns). Aim to at least
  a factor 2 better.
• Bkg less than 1, in FV.

• Data
• KL?3p0
• KL nucl.int.
• KLm3
• KLe3
• KL?2p0
• KL regen.
• KL?pp-p0

1) Improve quality of the neutral vertex
algorithm (better agreement wrt MC). 2) Improve
clustering algorithm 3) Study of background at
the edge of FV (mainly KL?pp-p0 and KL nuclear
interaction) allow to extend the fit range (at
least 27 ns instead of 24.8 ns)
Proper time (ns)
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Searching for Ke2 _at_ KLOE (I)
BR(Ke2)2x10-5, expect 4x104 events in KLOE data
sample (2.3 fb-1)
perfom direct search for Ke2 without tag ? gain
4 of statistic search for a vertex inside the
Fiducial Volume (40ltrxylt150) cm cuts on track
quality for K and secondary tracks, cuts on vtx
quality
B/S(-3000.ltM2leplt3000.) 10.
kaon momentum is measured with 1 resolution
close kinematics ?we get Mlep
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Searching for Ke2 _at_ KLOE (II)
PID exploits the granularity of KLOE EmC shower
profile along the particle path variables used
E2RMS Si1..N(E(i)-ltEgt)2/N, E/P, cluster
shape
B/S(-3000.ltM2leplt3000.) 2.
signal efficiency 0.647(6) background
rejection 300
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Ke2 signal event counting
Ke2 event counts likelihood fit of Mlep vs
ERMS input MC shapes for Ke2(g) and background
fit parameters of Ke2 and background, get
8090160 observed evts
correct for ratio of Ke2 and Km2 trigger and vtx
efficiencies, and for PID Ke2 efficiency