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

11

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

12

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