Salvatore Fiore University of Rome La Sapienza & INFN Roma1 for the KLOE collaboration
LNF Spring School “Bruno Touscheck”,
Frascati, 15-19 May 2006
CP/CPTCP/CPT tests at KLOE tests at KLOE
2
Neutral kaons at a -factory
• e+e b S = m = 1019.4 MeV• BR( K0K0) ~ 34%• ~106 neutral kaon pairs per pb-1 produced in an antisymmetric quantum state with JPC = 1
pKpKpKpK
2
N
pKpKpKpK2
1i
SLLS
0000
KLKS 106 /pb-1 ; p* = 110 MeV/cS = 6 mm KS decays near interaction point
L = 3.4 m Large detector to keep reasonable
acceptance for KLdecays (~0.3 L)
K+K- 1.5 106 /pb-1 p* = 127 MeV/c ±= 95 cm
3
Neutral kaons at a -factory: tagging
pK = 110 MeV/c S = 6 mm L = 3.5 m
The detection of a kaon at large (small) times tags a KS (KL)
KL,S
KS,L
t1
t2
t=t1- t2 f2
f1
possibility to select a pure KS beam (unique at a -factory, not possible at fixed targetnot possible at fixed target experiments)
The decay at rest provides monochromatic and pure beam of kaons
Tagging: observation of KS,L signals presence of KL,S
- precision measurement of absolute BR’s
4
DANE: the Frascati -factory
W = m
(1019.4 MeV)Ldesign
5 1032 cm-2 s-1
Data taking finished last March• Lpeak= 1.3 × 1032 cms
• Ltot 2.5 fb-1
2001 170 pb-1
2002 280 pb-1
2004 734 pb-1
2005 1256 pb-1
5
Be beam pipe (spherical, 10 cm , 0.5 mm thick) + instrumented permanent magnet quadrupoles (32 PMT’s)
• 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 PMT’s 98% solid angle coverage • Superconducting coil (B = 0.52 T)
The KLOE design was driven by the measurement of direct CP through the double ratio: R = (KL +) (KS 00) / (KS +)(KL00)
KLOE experiment
6
KLOE detector specifications
E/E5.7% /E(GeV)
t 54 ps /E(GeV) 50 psvtx() ~ 1.5 cm ( from KL )
p/p0.4 % (tracks with > 45°)
xhit150 m (xy), 2 mm (z)
xvertex ~1 mm
(M) ~1 MeV
7
KS tagged by KL interaction in EmCEfficiency ~ 30% (largely geometrical)KS angular resolution: ~ 1° (0.3 in )
KS momentum resolution: ~ 2 MeV
KKLL “crash”“crash”
= 0.22 (TOF)= 0.22 (TOF)
KKSS ee
KL tagged by KS vertex at IPEfficiency ~ 70% (mainly geometrical)KL angular resolution: ~ 1°KL momentum resolution: ~ 2 MeV
KKSS
KKLL 2 2
KS and KL tagging
8
BR KL CP Violation
CP violating decayRelated to K
using KL beam tagged by KS →
328 pb-1 ’01+’02 data
Selection• KL vertex reconstructed in DC• PID using decays kinematics• Fit with MC spectra including radiative processes Normalization using KL events in the same data set
(MeV) )( 22missmiss pE
KKNK LSLSLS ,,,
9
Preliminary resultBR(KL )= (1.963 0.012 0.017) 10-3
• in agreement with KTeV [PRD70 (2004),092006]
BR=(1.975 0.012)
• confirm the discrepancy (4 standard deviations) with PDG04 BR=(2.090 0.025)
PDG2004KTeVKLOE preliminary
BR
(KL
)
10-3
Using BR(KS ) and L
from KLOE and S from PDG04 | = (2.216 0.013) 10-3
|| PDG04 = (2.280 0.013)10-3
BR KL CP Violation (II)
1.5 with respect to prediction from Unitarity Triangle
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Measurements of KKS S K KLL observables observables can be used for these tests: KS
00KS
KS
kl3
S
L B(K
Ll3) ReRe yi( ImIm x)
S
L B(K
Ll3)(A
S+A
L)/4i( ImIm
x)S
L
KL
S
L
KL
CPT test: the Bell-Steinberger relation
f
SLS
MSW fKAfKAii *)()(1
)Im()Re()tan(1
Exact relation: phase convention independent, no approx, in the CPT limit
)()()(1 * fKBfAfA SffSL
S
4.43)(2
arctanLS
SLSW
mm MLS ,
Looking at Im(Looking at Im())0 as CPTV signal0 as CPTV signal )(1)(
2)(
)(2
)(
2
1 Oi
mm
imm
LSSL
KKKK oooo
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KSK
S
KS
KL
KLl
KS
KL
KS
SW= (0.759±0.001)
CPT test: inputs to the Bell-Steinberger relation
S 0.08958 ± 0.00006 ns
L= 50.84 ± 0.23ns
AL
AS
KL
KL
=0.757 ± 0.012= 0.763 ± 0.014Im x
+ = (0.8 ± 0.7) 10-2
Im xfrom a combined fit of KLOE + CPLEAR data
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We get the following results (error contours) on each term of the sum We get the following results (error contours) on each term of the sum
KS
00KS
KS
S
L B(K
Ll3)
AS+A
L)/4iIm x
S
L
KL
S
L
KL
10-4
Im
Re
CPT test: accuracy on i
13
Re Im CPLEAR: Re Im
CPT test: B-S KLOE result
KLOE preliminary:Re
Im
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