Hadronic results from KLOE E. Santovetti (INFN – Roma II) for the KLOE Collaboration European Physical Society International Europhysics Conference on High Energy Physics EPS (July 17th-23rd 2003) in Aachen, Germany

E. Santovetti DA  NE: the Frascati  factory HEP2003 Aachen, July 2003  electron positron collider at the  mass energy (E CM = 1020 MeV)  separate rings to minimize beam-beam interaction  two interaction points (KLOE – DEAR/FINUDA) Machine parametersDesign2002 Total length (m)98 Max. bunches12051 Bunch spacing (ns) Lifetime (min)12040 Bunch current (mA)4020 L single bunch (cm -2 s -1 ) L peak (cm -2 s -1 )  per year (10 9 ) 150.9

E. SantovettiHEP2003 Aachen, July 2003 KLOE data taking history Year pb -1 /day averagepeak pb First published results pb Luminosity improved but high background Further analyses published pb Higher luminosity and background reduced Analysis in progress An upgrade of the machine has been done. An increase in luminosity ( > x2 ) is expected in the next data taking. in 2002

E. Santovetti Kaon physics at DA  NE HEP2003 Aachen, July 2003 The kaons are produced in pairs (K + K - and K S K L ) with opposite momentum. The detection of a kaon on one side can be used to tag the other kaon in the opposite side Measure of absolute branching ratios Interferometry studies on K S K L system  e-e- e+e+ KLKL KSKS p (MeV/c)l (cm) K + K KSKS KLKL all K S decay close to the IP reasonable acceptance for K L F decay%#/pb -1 K + K x10 6 K S K L       15.55x10 5  1.34x10 4

E. SantovettiHEP2003 Aachen, July 2003 The KLOE detector Electromagnetic calorimeter  lead/scintillating fibers structure  15 X 0 thickness  4880 PMT's Drift chamber (4m Ø x 3.3m)  90% He – 10% IsoB mixture (X 0 ~ 500m)  12582/52140 sense/total wires  stereo geometry for z measurement Quadrupole calorimeter  lead/sc. tiles calorimeter surrounding the permanent quadrupoles (32 PMT's) Superconducting coil (5m Ø)  B = 0.52 T

E. SantovettiHEP2003 Aachen, July 2003 Detector performances calorimeter Drift chamber High efficiency for low energy photons

E. SantovettiHEP2003 Aachen, July 2003 KLOE physics program pb –1 20 pb –1 200 pb –1 2 fb –  K S  , K S  3 , K S    K L  2 , K L    V us from K ± and K L decays  K ± branching ratios   (e + e –     – ) to 1%   radiative decays   f 0 , a 0  scalar    ’ ,  pseudoscalar  K S decays BR(K S     – )/BR(K S      ) BR(K S   e ) first published results 500 pb -1 now on tape Discrete symmetries  Re(  ) via double ratio (CP direct)  K L K S Semileptonic asymmetry (CPT)  K L K S interferometry

E. SantovettiHEP2003 Aachen, July 2003  mass and width  line shape has been fitted for the main  decays W(MeV) + corrections (phase space + contributions from  ) K + K – 49.2% K L K S 33.7%  15.5%  1.3%  parameters: mass, total width, peak cross sections K+K–K+K– KSKLKSKL   In the case of  a fit with several points has been used to find the correct line shape form (interference between direct,  and  ) With a combined fit, we measure the  width:    4.19±0.04 MeV (preliminary) (Mass is calibrated with the CMD-2 value)

E. SantovettiHEP2003 Aachen, July 2003 Neutral kaon mass KLOE can study masses of particles with high accuracy thanks to excellent drift chamber momentum resolution Neutral kaon mass can be measured using K S      W (MeV)  (e + e -   K S K L ) (  b) KSKLKSKSKLKS Energy scale from CMD-2  mass value M Ks = ±0.005 stat ±0.020 syst MeV* PDG: ±0.022 MeV * KLOE Note 181 ( Energy scan

K S is tagged by identification of K L in the calorimeter (K L crash): a neutral cluster in a fixed time window efficiency ~ 30% ( largely geometrical) angular resolution on tagged K S ~ 1° momentum resolution ~ 2 MeV E. SantovettiHEP2003 Aachen, July 2003 K S /K L tagging K L is tagged by identification of the K S     - decay: a vertex near the interaction point with the kaon inv. mass efficiency ~ 70% angular resolution on tagged K L ~ 1° momentum resolution ~ 2 MeV

 (K S       )/  (K S      ) Can be used to extract     phase shifts and K   amplitudes Provides information on isospin symmetry breaking from EM terms Chiral pert. theory First part of the double ratio From the K   decays (K S, K + ), in the exact isospin symmetry hypothesis, we have: E. Santovetti HEP2003 Aachen, July 2003 considering the EM correction: K   decays measure     To extract    , we need a theoretical input  EM. Important to know the effective E  cutoff in      decay

 (K S       )/  (K S      ) E. SantovettiHEP2003 Aachen, July 2003 K S      at least 3 neutral clusters in time E cl > 20 MeV, |cos  | < 0.9 to reduce machine Bkg Efficiency ~ 90% K S      2 tracks from IP extrapolated to the EmC (120 MeV <p TRK < 300 MeV) Efficiency ~ 60% The measurement is fully inclusive in the radiated photon energy (no cut in the      invariant mass) Efficiency is corrected for the radiated photon in the final state by folding the MC distribution (linear interpolation) with the photon spectrum theoretically predicted 0.3% effect MC  MC 

 (K S       )/  (K S      ) E. SantovettiHEP2003 Aachen, July 2003 KLOE ‘02 KLOE '   pb data PDG ’  0.026World average         KLOE  (K S       )/  (K S      ) 47.8± ±1.5** PDG '02  (K S       )/  (K S      ) 56.7±8.0* Physics Letters B538 (2002) *Cirigliano et al. (2000) **G. Colangelo et al. (2001)

Cut on time of flight: The mass hypothesis m=m e and m=m  on both tracks allows to discriminate a large part of background E. SantovettiHEP2003 Aachen, July 2003 K S    e +,   e - Together with the K L   e  can be used to strictly test CPT and the  S=  Q Provides information about V us Difficoult to isolate K s   e respect to the more abundant (x1000) K s   best measurement CMD-2: BR(K s   e ) = (7.2 ± 1.4) x (75 events)

E. SantovettiHEP2003 Aachen, July 2003 K S    e +,   e - Use of variable E miss -cp miss For  e decays this is the neutrino mass, while for the     decays a value larger than zero is expected. A fit of the data to the sum of the signal and background spectra simulated by MonteCarlo allows to extract the number of events. KLOE preliminary (170 pb -1 '01 data) BR(   e + )3.46 ± 0.09 stat ± 0.06 syst BR(   e - )3.33 ± 0.08 stat ± 0.05 syst BR(  e )6.81 ± 0.12 stat ± 0.10 syst ×10 -4 CMD-2 ’99 PDG eval. from K L KLOE ’02* (17 pb data) KLOE ’03 preliminary * Physics Letters B535 (2002)

E. SantovettiHEP2003 Aachen, July 2003 K 0   e, CPT and  S=  Q KLOE preliminary A S = (19 ± 17 stat ± 6 syst ) x First measurment of A S ! A S = A L if CPT conserved ALAL PDG '02(3.33 ± 0.14) x KTeV '02(3.322 ± ± 0.047) x Re(x) (x ) KLOE preliminary3.3 ± 5.2 ± 3.5 CPLEAR ' ± 4.1 ± 4.5 CPT:  b = d = 0  S   Q transitions are forbidden at lowest order in the SM  S=  Q: c = d = Re(x) = 0

E. SantovettiHEP2003 Aachen, July 2003  (K L   )/  (K L        ) Provide information about the absortive contribution (A abs ) to the K L   decay (long-distance term) – Prediction on K s   Very sensitive to the calorimeter performance in reconstructing the neutral vertex very clean signals: low background (K L      ) K L        inclusive measure: at least four neutral clusters in time with E  > 20 MeV Efficiency > 99% Background ~ 0.4% (K L      ) K L   Close kynematics: cuts on - E * tot, Collinearity, Invariant mass Efficiency ~ 80% Background negligible  (K L   )/  (K L        ) (x10 -3 ) KLOE '03 * ± stat ± syst NA48 ' ± 0.01 stat ± 0.02 syst PDG ' ± 0.08 * Physics Letters B? (2003)  invariant mass plot after the cut on collinearity and total energy 362 pb -1 of data analysed ('01+'02 data) Preliminary 1/10 of 362 pb -1  L (ns) 51.7 ± 0.4PDG ' ± 0.4KLOE KLKL

E. SantovettiHEP2003 Aachen, July 2003 K L  charged (very preliminary) Very preliminary 78 pb -1 ’02 data *Errors are statistical only! (including MC statistics) Systematic errors also ~1-2% but not yet fully evaluated P miss - E miss in  or  hyp. (MeV)  e    KLOE*PDG ‘02 KLKL   K L     K L   e   KLKL (2.02  0.19)·10 -3 (2.081  0.026)·10 -3

E. SantovettiHEP2003 Aachen, July 2003 K ±        (  ') Direct CP violation in the charge asimmetry (from theory ÷ ) Dalitz plot parameters (CP) Extract isospin amplitudes and phase shifts for K   decay (  PT) (  ') best value (PDG '02) has ~2% error and concerns only K + 00 00 –– K–K– K+K+ ++ 00       Selection   /  0 – tagging and self-triggering  2-tracks vtx in DC volume  p * < 135 MeV/c   4 clusters vtx (  t<4  )  E tot < 450 MeV Background: main K ± decays, K e4 ’ Efficiencies evaluated from data by using control samples (ex.  cl from K ±      )

E. SantovettiHEP2003 Aachen, July 2003 K ±        (  ') BR(K ±  ±  0  0 ) (%) KLOE '03*1.781±0.013 stat ±0.016 syst PDG '021.73± pb -1 event counting (~80000 ev.) 250 pb -1 efficiency estimate s i =( P K –P i ) 2 s 0 =  i s i / 3 ; X =(s 1 –s 2 ) / m  2 Y =(s 3 –s 0 ) / m  2 KLOE* (6.3 pb -1 )PDG '02 g0.586±0.010 ± ±0.031 h0.030±0.010 ± ±0.018 k0.0055± ± ± * KLOE Note 187 Preliminary Dalitz plot analysis: F(X,Y) = 1+gY+hY 2 +kX 2 Charge asimmetry analysis in progress

E. SantovettiHEP2003 Aachen, July 2003 V us determination For K e3 modes: expth |V us | = ± exp ± th Introduced in 1963, known to 1.5% Experimental inputs to V us from PDG 02 ModeBR(%)10 3  10 3  K+e3K+e ± ± 2.1 K0e3K0e ± ± 1.8 K+3K+ ± ± 1.04 ± 9 K03K0 ± ± ± 6  L = (5.17 ± 0.04) · s  S = ( ± ) · s  + = ( ± ) · s KLOE preliminary BR’s confirm previous values for K 0 e3, K 0  3 KLOE will have BR(K  e3 ) soon KLOE will measure all BR’s to < 1% and can also significantly improve , ,  L preliminary E865

E. SantovettiHEP2003 Aachen, July 2003         Da  ne produces 5·10 5      0 events/pb -1,allowing a detailed study of the decay dominated by the  intermediate state:  mass measurement (CPT) Selection  2 charged tracks with vtx at I.P.  |M miss – M  ° | < 20 MeV (  0 mass)  2 photons (cos  *  < –0.98) (collinearity)   2 = (E tot - M  ) 2 /  E 2 + (M  -M  ° ) 2 /  M 2 < 8 Efficiency ~ 30% - Negligible background A  : 3 terms : M  +, M  –, M  0 and   (Gounaris Sakurai shape) A  : standard Breit Wigner A dir : constant  a d e i  d : |a d | 2 =  |A dir | 2 /  |A  | 2 Fit of the Dalitz plot considering a direct decay together with  (dominant) and  intermediate staes :

E. SantovettiHEP2003 Aachen, July 2003         2×10 6 events analyzed (16 pb –1 – 2000 data) X=(E  + – E  – ) /  3 Y=(E  ° – M  ° ) KLOE* (6.3 pb -1 )PDG '02 M  (MeV)775.8  0.5   0.9   (MeV)143.9  1.3   0.7 m 0 -m ± (MeV)0.4  0.7  ±0.8 m + -m - (MeV)1.5  0.8  0.7 adad 0.78  0.09  0.13 aa (7.1  0.6  0.8)×10 –3 Relative decay intensities from integration of |A| 2 over Dalitz plot I  = I dir = I  = I  + I dir + I   1 (+6%) Interference between  and direct decays * Physics Letters B561 (2003) Very different values depending on the used techniques: e + e -,  decay, hadronproduction

E. SantovettiHEP2003 Aachen, July 2003    The    decay is a C-violating decay with a branching ratio theoretically predicted extremely low ( < )  production chain: 44 E  = 363 MeV Background: 44 55 33 Analysis strategy: N* prompt-clusters = 4 E min > 50 MeV |cos(  )| < Kinematical fit Constraint: 1) energy momentum conservation 2) t = r/c (photons)  2 min To reject background channels with  0 we cut on m  of any pair of photons. The background shape and normalization is estimated from the data B.R.(    ) C.L. 95% KLOE '03 (preliminary)< 1.4·10 -5 Crystall Ball< 5·10 -5 PDG '02< 5·10 -4

E. SantovettiHEP2003 Aachen, July 2003 Conclusions and outlook DA  NE luminosity has been continuously improving. KLOE expects to collect at least 1 fb -1 in 2003/2004 Analysis of data brought to several published results on neutral kaons and  decays Work in progress with 2001/2002 data: - K , K L semileptonic decays (V us ) – Rare kaons decays: K S      , K S  3  , K S      e + e , K S   –  decays (about 2×10 7  produced in 500 pb -1 )