Salvatore Fiore

1
CP/CPT tests at KLOE

• Salvatore Fiore
• University of Rome La Sapienza INFN Roma1 for
  the KLOE collaboration
• LNF Spring School Bruno Touscheck,
• Frascati, 15-19 May 2006

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Neutral kaons at a f-factory

• ee? ? f sf3 mb ?S
  mf 1019.4 MeV
• BR(f ? K0K0) 34
• 106 neutral kaon pairs per pb-1 produced in an
  antisymmetric quantum state with JPC 1??

KLKS 106 /pb-1 p 110 MeV/c lS 6 mm
KS decays near interaction point lL 3.4 m
Large detector to keep reasonable acceptance for
KLdecays (0.3 lL)
KK- 1.5? 106 /pb-1 p 127 MeV/c
l 95 cm
3
Neutral kaons at a f-factory tagging
The f decay at rest provides monochromatic and
pure beam of kaons

• Tagging observation of KS,L signals ? presence
  of KL,S
• - precision measurement of
  absolute BRs

pK 110 MeV/c lS 6 mm lL 3.5 m
The detection of a kaon at large (small) times
tags a KS (KL)
possibility to select a pure KS beam (unique at a
f-factory, not possible at fixed target
experiments)
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DAFNE the Frascati f-factory
2001 170 pb-1 2002 280 pb-1
2004 734 pb-1 2005 1256 pb-1
W mF (1019.4 MeV) Ldesign 5 ? 1032 cm-2 s-1

• Data taking finished last March
• Lpeak 1.3 1032 cm-2s-1
• Ltot? 2.5 fb-1

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KLOE experiment
The KLOE design was driven by the measurement of
direct CP through the double ratio
R G(KL ?pp?) G(KS ?p0p0) /
G(KS ?pp?) G(KL?p0p0)

• Be beam pipe (spherical, 10 cm ?,
• 0.5 mm thick) instrumented permanent
• magnet quadrupoles (32 PMTs)
• Drift chamber (4 m ? ? 3.75 m, CF frame)
• ? Gas mixture 90 He 10 C4H10
• ? 12582 stereo sense wires
• ? almost squared cells
• Electromagnetic calorimeter
• ? lead/scintillating fibers (1 mm ?), 15 X0
• ? 4880 PMTs
• ? 98 solid angle coverage
• Superconducting coil (B 0.52 T)

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KLOE detector specifications
sp/p 0.4 (tracks with q gt 45) sxhit 150 mm
(xy), 2 mm (z) sxvertex 1 mm s(Mpp) 1 MeV
sE/E 5.7 /?E(GeV) st 54 ps /?E(GeV) ? 50
ps svtx(gg) 1.5 cm (p0 from KL ? pp-p0)
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KS and KL tagging
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BR KL ?p p- CP Violation
CP violating decay Related to eK

• using KL beam tagged by KS ? pp-
• 328 pb-1 0102 data
• Selection
• KL vertex reconstructed in DC
• PID using decays kinematics
• Fit with MC spectra including
• radiative processes
• Normalization using KL ? pmn events in the same
  data set

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BR KL ?p p- CP Violation (II)
Preliminary result BR(KL ? pp-) (1.963 ?0.012
?0.017) ?10-3
PDG2004 KTeV KLOE preliminary

• in agreement with KTeV
• PRD70 (2004),092006
• BR(1.975 ? 0.012) ?10-3
• confirm the discrepancy
• (4 standard deviations) with PDG04
• BR(2.090 ? 0.025) ?10-3

BR(KL ? pp-) ?10-3
Using BR(KS? pp) and tL from KLOE and tS from
PDG04 e (2.216 ? 0.013) ?10-3 e PDG04
(2.280 ?0.013)?10-3
1.5 s with respect to prediction from Unitarity
Triangle
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CPT test the Bell-Steinberger relation
Exact relation phase convention independent, no
approx, in the CPT limit
Looking at Im(D)?0 as CPTV signal
Measurements of KS KL observables can be used
for these tests
a- h- B(KS?pp-)
akl3 2tS/tL B(KLl3) Re ? - Re y??i( Im d Im
x) 2tS/tL B(KLl3)(ASAL)/4??i( Im d
Im x)
a00 h00 B(KS?p0p0)
a- g h- B(KS?pp-g)
a-0 tS/tL h- 0 B(KL?pp-p0)
a000 tS/tL h 000 B(KL?p0p0p0)
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CPT test inputs to the Bell-Steinberger relation
B(KS?pp-)/B(KS?p0p0)2.2549?0.0059 B(KS?pp-g)lt9
?10-5 B(KL?pp-g)(29?1) ?10-6 B(KL?pln)0.6705?0.
0022 B(KS?pp-p0)(3.2?1.2) ?10-7 B(KL?pp-p0)0.1
263?0.0012 B(KS?p0p0p0)lt1.2 ?10-7 fSW
(0.7590.001) f000 , f-0 , f-g0,2p
tS 0.08958 0.00006 ns tL 50.84
0.23ns AL(3.32?0.06) ?10-3 AS(1.5?10.0)
?10-3 B(KL?pp-)(1.963 ? 0.021 )
?10-3 B(KL?p0p0)(8.65 ?0.10) ?10-4 f- 0.757
0.012 f00 0.763 0.014 Im x (0.8 0.7)
?10-2
red KLOE measurements
Im x from a combined fit of KLOE CPLEAR data
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CPT test accuracy on ai
We get the following results (error contours) on
each term of the sum
10-4
2tS/tL B(KLl3) (ASAL)/4??i Im
x
a- h- B(KS?pp-)
Im
a-0 tS/tL h- 0B(KL?pp-p0)
a00 h00 B(KS?p0p0)
Re
a000 tS/tL h 000B(KL?p0p0p0)
a- g h- B(KS?pp-g)
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CPT test B-S KLOE result
Im ?
Re ?
KLOE preliminary
Re ? (160.2 ? 1.3) ?10-5? Im ? (1.2 ? 1.9) ?
10-5
CPLEAR Re ? (164.9 ? 2.5) 10-5? Im ? (2.4
? 5.0) 10-5