CPCPT tests at KLOE Salvatore Fiore University of

CP/CPT tests at KLOE Salvatore Fiore University of Rome La Sapienza & INFN Roma 1 for the KLOE collaboration LNF Spring School “Bruno Touscheck”, Frascati, 15 -19 May 2006

Neutral kaons at a f-factory • e+e f sf~3 mb S = mf = 1019. 4 Me. V • BR(f K 0 K 0) ~ 34% • ~106 neutral kaon pairs per pb-1 produced in an antisymmetric quantum state with JPC = 1 K +K - K LK S 1. 5 106 /pb-1 p* = 127 Me. V/c l±= 95 cm 106 /pb-1 ; p* = 110 Me. V/c l. S = 6 mm KS decays near interaction point l. L = 3. 4 m Large detector to keep reasonable acceptance for KLdecays (~0. 3 l. L) 2

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 BR’s p. K = 110 Me. V/c l. S = 6 mm l. L = 3. 5 m f 1 t 1 KS, L f Dt=t 1 - t 2 KL, S f 2 The detection of a kaon at large (small) times tags a KS (KL) possibility to select a pure KS beam (unique at a ffactory, not possible at fixed target experiments) 3

DAFNE: the Frascati f-factory W = m. F (1019. 4 Me. V) Ldesign 5 1032 cm-2 s-1 2001 170 pb-1 2002 280 pb-1 2004 734 pb-1 2005 1256 pb-1 Data taking finished last March • Lpeak= 1. 3 × 1032 cm 2 s 1 • Ltot 2. 5 fb-1 4

KLOE experiment The KLOE design was driven by the measurement of direct CP through the double ratio: R = G(KL p+p ) G(KS p 0 p 0) / G(KS p+p ) G(KL p 0 p 0) 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% C 4 H 10 12582 stereo sense wires almost squared cells Electromagnetic calorimeter lead/scintillating fibers (1 mm ), 15 X 0 4880 PMT’s 98% solid angle coverage • Superconducting coil (B = 0. 52 T) 5

KLOE detector specifications sp/p = 0. 4 % (tracks with q > 45°) sxhit = 150 mm (xy), 2 mm (z) sxvertex ~1 mm s(Mpp) ~1 Me. V s. E/E = 5. 7% / E(Ge. V) st = 54 ps / E(Ge. V) 50 ps svtx(gg) ~ 1. 5 cm (p 0 from KL p+p p 0) 6

KS and KL tagging KL “crash” b= 0. 22 (TOF) K S p +p K S p -e +n KS tagged by KL interaction in Em. C Efficiency ~ 30% (largely geometrical) KS angular resolution: ~ 1° (0. 3 in f) KS momentum resolution: ~ 2 Me. V KL 2 p 0 KL tagged by KS p+p- vertex at IP Efficiency ~ 70% (mainly geometrical) KL angular resolution: ~ 1° KL momentum resolution: ~ 2 Me. V 7

BR KL p+ p : CP Violation CP violating decay Related to K using KL beam tagged by KS → p+p 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 pmn events in the same data set 8

Preliminary result BR(KL p+p )= (1. 963 0. 012 0. 017) 10 -3 • in agreement with KTe. V [PRD 70 (2004), 092006] BR=(1. 975 0. 012) 10 3 • confirm the discrepancy (4 standard deviations) with PDG 04 BR=(2. 090 0. 025) 10 3 BR(KL p+p ) 10 -3 BR KL p+ p : CP Violation (II) PDG 2004 KTe. V KLOE preliminary Using BR(KS pp) and t. L from KLOE and t. S from PDG 04 | | = (2. 216 0. 013) 10 -3 | | PDG 04 = (2. 280 0. 013) 10 -3 1. 5 s with respect to prediction from Unitarity Triangle 9

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 p+p ) a 00= h 00 B(KS p 0 p 0) a+ g= h+ B(KS p+p g) akl 3 = 2 t. S/t. L B(KLl 3) [Re Re y i( Im d + Im x+)] = 2 t. S/t. L B(KLl 3)[(AS+AL)/4 i( Im d + Im x+)] a+ 0= t. S/t. L h+ 0* B(KL p+p p 0) a 000= t. S/t. L h 000* B(KL p 0 p 0 p 0) 10

CPT test: inputs to the Bell-Steinberger relation B(KS p+p )/B(KS p 0 p 0)=2. 2549 0. 0059 B(KS p+p g)<9 10 5 t. S= 0. 08958 ± 0. 00006 ns B(KL p+p g)=(29 1) 10 6 t. L= 50. 84 ± 0. 23 ns B(KL pln)=0. 6705 0. 0022 3 + 0 7 A =(3. 32 0. 06) 10 B(KS p p p )=(3. 2 1. 2) 10 L 3 + 0 A =(1. 5 10. 0) 10 B(KL p p p )=0. 1263 0. 0012 S B(KL p+p )=(1. 963 0. 021 ) 10 3 B(KS p 0 p 0 p 0)<1. 2 10 7 B(KL p 0 p 0)=(8. 65 0. 10) 10 4 f. SW = (0. 759± 0. 001) + =0. 757 ± 0. 012 000 + g f f , f =[0, 2 p] f 00 = 0. 763 ± 0. 014 Im x+ = (0. 8 ± 0. 7) 10 -2 Im x+ from a combined fit of KLOE + CPLEAR data 11

CPT test: accuracy on ai We get the following results (error contours) on each term of the sum 10 -4 a+ = h+ B(KS p+p ) a 00= h 00 B(KS p 0 p 0) a+ g= h+ B(KS p+p g) 2 t. S/t. L B(KLl 3) [ (AS+AL)/4 i Im x+] Im Re a+ 0= t. S/t. L h+ 0*B(KL p+p p 0) a 000= t. S/t. L h 000*B(KL p 0 p 0 p 0) 12

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 13