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Recent results from KLOE at DA  NE

Recent results from KLOE at DA  NE. Barbara Sciascia INFN Laboratori Nazionali di Frascati representing the KLOE Collaboration. IFAE 2004 – Torino. KLOE: physics at a f - factory. Kaon physics CP: double ratio/interferometry CPT tests: semileptonic K S , K L charge asymmetries

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Recent results from KLOE at DA  NE

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  1. Recent results from KLOE at DANE Barbara Sciascia INFN Laboratori Nazionali di Frascati representing the KLOE Collaboration IFAE 2004 – Torino

  2. KLOE: physics at a f - factory • Kaon physics • CP: double ratio/interferometry • CPT tests: semileptonic KS,KLchargeasymmetries • Vus : kaon form factors from semileptonic KS,L ,K decays • Rare KS,L decays: KS3p0, p+p-p0 , KL gg • Non Kaon Physics • radiative f decays (scalars,pseudoscalars + photon) • rp final states • rare h decays • hadronic cross section: see D.Leone talk

  3. Integrated luminosity (pb-1) Days of running KLOE data taking 2000: 25 pb-1 80•106f decays First published results 2002 2001 2001: 176 pb-1 550 •106f decays 2002: 296 pb-1 920 •106f decays Analysis in progress 2000 Goal for 2004-5: L > 1 fb-1 • New interaction region • Injection efficiency improved • Wiggler magnets modified

  4. The KLOE detector • Al-Be beam pipe • (spherical, 10 cm , 0.5 mm thick) • Instrumented permanent magnet quadrupoles(32 PMT’s) • Drift chamber •  Gas mixture: 90% He + 10% C4H10 •  4 m   3.75 m, CF frame •  12582 stereo–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)

  5. Detector performance sp/p = 0.4 % (tracks with q > 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p+p-p0)

  6. Kaon properties KS, K+ f KL, K- Production: KSKL (K+K-) produced in pure JPC = 1-- state: Observation of KS,L signals presence of KL,S Allows precision measurement of absolute BR’s Allows interference measurements of KSKL system Properties: lS = 6 mm: KS decays near interaction point lL = 3.4 m: Appreciable acceptance for KL(~0.5lL) NSL ~106 /pb-1; p* = 110 MeV/c l= 0.9 m: 60% acceptance for kaon tracking N+- ~ 1.5106/pb-1; p* = 127 MeV/c

  7. Tagging of KS and KL “beams” • KL“crash” • = 0.22 (TOF) KS p+p- KS p-e+n KL 2p0 KL tagged by KS  p+p- vertex at IP Efficiency ~ 70% (mainly geometrical) KL angular resolution: ~ 1° KL momentum resolution: ~ 1 MeV KS tagged by KL interaction in EmC Efficiency ~ 30% (largely geometrical) KS angular resolution: ~ 1° (0.3 in f) KS momentum resolution: ~ 1 MeV

  8. KSp0p0p0 – Test of CP and CPT • Observation of KS  3p0 signals CP violation in mixing and/or in decay: • SM prediction: GS = GL|e|2, giving BR(KS  3p0) = 1.9 10-9 • Present published results: BR(KS  3p0) < 1.4 10-5 (90% CL) • Uncertainty on KS  3p0 amplitude limits precision of CPT test: from unitarity: (1 + i tanfSW)Re e - Sf A*(KSf) A(KLf)/GS = (-i + tanfSW) Im d (eS,L = e  d) • A limit on BR(KS  3p0) at 10-7 level translates into a 2.5-fold improvement on the accuracy of Im d (510-5  210-5), i.e. • d(MK0 - MK0) _  5 10-19 MK _ ( GK0 = GK0 assumed )

  9. Search for KSp0p0p0 -- KS  3p 0 (MC) -- MC BKG  Data c2Fit KS’s tagged by Kcrash identification (1.5 • 108 events) 6 photons (neutral clusters, TOF consistent with b = 1)  No charged tracks from IP  Kinematic fit: • Impose KS mass and energy-momentum conservation, • b = 1 for each g • Estimate Eg, rg, tg, s, p Rejection power of c2fit not sufficient to eliminate main background due toKS p0p0 + 2 fake g’s

  10. Search for KSp0p0p0 – 2p0 vs 3p0 To reject background compare 3pvs 2p hypotheses : Data MC KS 3p0 c22p 80 c23p- pairing of 6g clusters with best p0 mass estimates c22p– best pairing of 4g’s out of 6: p0 masses, E(KS), P(KS), c.m. angle between p0’s 60 40 Definition of the signal box obtained from analysis of 6-pb-1-equivalentMCsubsample 20 c23p 0 10 20 30 0 40

  11. Search for KSp0p0p0 - sidebands c22p Data MC KS 3p0  Data  MC KS 2p0  BR(KS 3p0) = 10-5 80 300 60 40 20 200 c23p 0 0 10 20 30 40 KS  3p0 decay switched on during MC production of 450 pb-1 equivalent data, with BR equal to the present upper limit 100 c23p 0 20 40 0 60

  12. Search for KSp0p0p0 - sidebands c22p Data MC KS 3p0  Data  MC KS 2p0  BR(KS 3p0) = 10-5 80 60 40 750 20 c23p 0 500 0 10 20 30 40 Absolute BKG normalization better than 10% in all control boxes 250 c23p 0 10 20 30 40 0 50

  13. Search for KSp0p0p0 – signal region c22p 200  Data  MC KS 2p0  BR(KS 3p0) = 10-5 Data MC KS 3p0 80 60 150 40 20 100 c23p 0 0 10 20 30 40 50 c23p 0 10 20 30 40 0 50

  14. KSp0p0p0 – Preliminary results Normalize signal counts to KS  p0p0 count in the same data set: N3p / e3p BR(KS  p0p0p0) = BR(KS  p0p0) < 2.1 10-7, N2p / e2p A(KS  p0p0p0) A(KL  p0p0p0) Nsel(data) = 4 events selected as signal, with efficiency e3p= 23% Nsel(bkg) = 31.3 0.2 bkg events expected from MC, use Nsel(bkg) = 1.6 Can state: N3p < 5.83 with a 90% CL Which translates into a limit on |h000| = < 2.4 10-2

  15. KSpen decays – Physics issues AS,L = _ Sensitivity to CP violation in K0-K0 mixing: AS = 2Re e (CPT symmetry assumed) _ G(KS,L  p-e+n) - G(KS,L  p+e-n) _ G(KS,L  p-e+n) + G(KS,L  p+e-n) Sensitivity to CPT violating effects through charge asymmetry: If CPT holds, AS=AL ASAL signals CPT violation in mixing and/or decay with DSDQ AS never measured before Can extract |Vus| via measurement of BR(KS  pen)

  16. KSpen decay – Analysis outline MC pen Data e-p+ 5 5 ddt, pe(ns) 4 4 3 3 2 2 e+p- 1 1 0 0 ddt,ep(ns) -1 -1 1 2 3 4 5 0 1 2 3 4 5 -1 -1 0 Kcrash tag + 2 tracks from IP with Mpp < 490 MeV (reject KS pp(g)) TOF identification: compare p-e expected flight times, reject pp,pm bkg dd t, pe = dt(mp) -dt(me)(dt(m) = tcluster-t.o.f.)

  17. KSpen decay – Events counting Emiss = MK2 + PK2 – Ep – Ee Pmiss = |PK – Pp – Pe | Kinematic closure: use KL to obtain KS momentum PK and test for presence of neutrino: 6000  Data — MCsig + bkg 5000 4000 Determine number of signal counts by fitting data to a linear combination of MC spectra for signal and background 3000 2000 1000 0 -60 -40 -20 0 20 40 60 80 Emiss–cPmiss (MeV)

  18. KSpen decay – Events counting 2000 1600 1200 800 400 0 -20 -10 0 10 20 30 Signal spectrum sensitive to the presence of a photon in the final state  Data — MCsig + bkg Include radiative effects through an IR-finite treatment in MC (no energy cutoff) Normalize signal counts to KS pp(g) counts in the same data set (use PDG03 for BR(KSpp(g)), dominated by KLOE measurement ) Emiss–cPmiss (MeV)

  19. KSpen decay – BR and AS Selection efficiency (given the tag) is evaluated by charge, using data control sample of KL  pendecaying close to IP: e (p-e+) = (24.1±0.1± 0.2)% ; e (p+e-) = (23.6±0.1 ± 0.2)% BR(KS  p-e+n) = (3.54 0.05stat0.05syst) 10-4 BR(KS  p+e-n) = (3.540.05stat 0.04syst) 10-4 preliminary evaluation of the systematics near completion BR(KS  pen) = (7.09  0.07stat  0.08syst) 10-4 (Published result: (6.91  0.34stat  0.15syst) 10-4, Phys.Lett.B535:37-42,2002 ) ASe = (-2  9stat  6syst) 10-3(never measured before) (AL = (3.322  0.058  0.047) 10-3 , KTeV 2002 ) future: 2004-5 run: 2 fb-1s(ASe) ~ 310-3 CPT test:20 fb-1 needed to reach s(RedK)= ¼ s(ASe) = 310-4

  20. Unitarity test of CKM matrix – Vus d|Vus| dG dlt df+K0p-(0) = 0.5  0.05  lt |Vus| f+K0p-(0) Most precise test of unitarity possible at present comes from 1st row: |Vud|2 + |Vus|2 + |Vub|2~ |Vud|2 + |Vus|2  1 – D Can test if D = 0 at few 10-3 :PDG02 D = 0.0042 ±0.0019 from super-allowed 0+ 0+ Fermi transitions, n b-decays: 2|Vud|dVud = 0.0015 from semileptonic kaon decays (PDG 2002 fit): 2|Vus|dVus = 0.0011 To extract |Vus| from K0e3 decays, have to include EM effects: |Vus f+K0p-(0) |2 G(K0  pen(g))  I(lt) (1 + DI(lt,a)) (1 + dEM) Fractional contributions to the uncertainty: G 0.5%   0.3% 1%

  21. KSpen decay – Vus f+Kp(0) • Compare our Ks measurement • of Vus f+Kp(0) with: • PDG02 fit results for G(K+ p0 l+n) and G(KL p-l+n) • (radiation effects not known) • G(K+ p0e+n) from E865 experiment (uses PDG fits) • CKMwg prescription is used to extract Vus f+Kp(0) from the partial decay width E865 KLOE Our preliminary result agrees better with latest K+ data, while showing a appreciable deviation from old K0e3

  22. KSpen decay – Vus determination Unitarity and Vud E865 KLOE PDG02, CKMwg use: from Leutwyler, Roos Z.Phys. C 25 1984, cPT toO(p4), confirmed by a lattice calculation (hep-ph 0403217) A recent determination of f+(0) (Cirigliano et al. hep-ph 0401173 ) differs by +2%; the same authors suggest to use experimental ratio G(K0e3)/G(K+e3) to improve the theoretical estimate of f+Kp

  23. KL decays – Present knowledge G(KL  pmn) Rm/e = = 0.702  0.011[Argonne HBC 1980] G(KL  pen) Knowledge of 4 main KL BR’s at present dominated by 3 measurements: G(KL  p0p0p0) G(KL  p0p0p0) and , with 2% relative uncertainty [NA31] G(KL  pen) G(KL  p+p-p0) 3-s discrepancy (4%)between measurement and expectation for Rm/e: Rm/e = 0.671  0.002, direct measurement for K+, from KEK-E246 2001 Rm/e calculable from the slopes l+ and l0 of vector and scalar form factors: 0.670  0.002, if l0 = 0.0183  0.0013, from ISTRA+ 2003 0.668  0.006, if l0 = 0.017  0.004, from one-loop cPt

  24. KL decays – Status and objectives Have to precisely measure absolute branching ratios, with rel. accuracy < 1% KL beam tagged by identification of KS p+p- 100 pb-1 ’01 data 103 Ev/MeV 125 KL decay vertex in a given fiducial volume in DC 100 KL  pmn Kinematic identification using reconstructed momenta 75 450pb-1  3•106 Ke3 events 50 KL  pen KL  p+p- In progress: * New detailed MC with radiation and p-m-KL response 25 KL  p+p-p0 * Selection efficiency as a function of KL vertex position and momenta of decay products -150 -100 -50 0 -50 100 150 Pmiss- Emiss (MeV) Lesser of (Pmiss- Emiss) in pm or mp hyp.

  25. Charged kaons – Tagging – 102 Ev/0.5MeV – Kinem. ID  Data — fit: 3000 + + 2000 1000 K+m+nmK–p–p0 180 200 220 240 p*p(MeV) Measurement of absolute BR’s: K+ beam tagged from K- p-p0, m-n • Two-body decays identified as peaks • in the momentum spectrum of secondary • tracks in the kaon rest frame: 6•105 tags/pb-1 mn pp0

  26. Charged kaons – K±l3 decays After tag a dedicated reconstruction of K tracks is performed, correcting for charged kaon dE/dx in the DC walls Kl3 selection: Ev/(14MeV)2 TOF ID 8000 p0en • 1-prong kaon decay vertex in a given fiducial volume in DC • Reject two-body decays by cutting on P*p • p0 search: 2 neutral clusters in EmC, with tof matching the K decay vertex • Obtain charged daughter mass spectrum from TOF measurement:  Data  MC fit p0mn 4000 tdecayK = tlept -Llept /(bleptc) = tg-Lg/c 0 0 20000 40000 Mlept2 (MeV2) 450pb-1  3•105 Ke3 events

  27. Outlook Present status - KS: Sensitivity to BR’s at the 10-7 level (preliminary UL for KS 3p0) Measurement of Ke3 mode at the % level, 10-2 accuracy on AS Expect 2 fb-1 of integrated luminosity in 2004-5, would allow: AS with a total accuracy of 4 10-3, first test of SM prediction AS = 2 Re e Sensitivity to KS  3p0 at 10-8 level A measurement of BR(KS  p+p-p0) with 20% relative uncertainty • First direct measurement • Test of the cPt prediction, BR(KS  p+p-p0) = (2.4  0.7) 10-7 In progress: • Measurement of BR’s for semileptonic KL and K+ decays • Huge statistics, uncertainty will be limited by systematics • Will clarify the situation concerning the experimental parameters for the determination of Vus

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