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Stato dell’analisi e della presa dati di KLOE

Stato dell’analisi e della presa dati di KLOE. G. Venanzoni LNF-Frascati For the KLOE Collaboration. Outline . Current physics results Current data taking The ultimate goal: physics with 2.5 fb -1 Beyond the 2.5 fb -1 : off-peak physics Conclusions. . . . . .

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Stato dell’analisi e della presa dati di KLOE

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  1. Stato dell’analisi e della presa dati di KLOE G. Venanzoni LNF-Frascati For the KLOE Collaboration

  2. Outline • Current physics results • Current data taking • The ultimate goal: physics with 2.5 fb-1 • Beyond the 2.5 fb-1: off-peak physics • Conclusions

  3.     Current Kaon Physics results

  4. FISICA DEL KL • Misura dei BR’s dei principali canali di decadimento • Misura della vita media del KL • Misura dei fattori di forma semileptonici • Vus e test di unitarietà della CKM

  5. Major KL decays: absolute BRs • DATA SAMPLE: 2001+2002 data sample: 400 pb-1 statistics, 50 x 106 tagged KL - 3/4 of 2001-2002 data has been used for efficiency evaluation - 1/4 for BR measurement corresponding to 13106 tagged KL BR(KL e() ) = 0.4049  0.0010stat 0.0031syst~ 8105 events BR(KL () ) = 0.2726  0.0008stat 0.0022syst~ 5105 events BR(KL 3) = 0.2018  0.0004stat 0.0026syst~ 7105 events BR(KL () ) = 0.1276  0.0006stat 0.0016syst~ 2105 events • Absolute BRs results obtained with tKL= (51.54 ± 0.44) ns in the acceptance evaluation

  6. KL BR’s comparison KL e KL  KLOE NA48 KTeV PDG04 KLOE KTeV PDG04 KLOE NA48 KTeV PDG04 KL π+π-0 KL  30 KLOE KTeV PDG04

  7. Major KL decays: absolute BRs We measure SBR(KL all) = 1.0104  0.0076 Including rare decays from PDG (0.36%) KL)= (50.72  0.14  0.36) ns Imposing S BR(KL all) =1  BR(KL e() ) = 0.4007  0.0006  0.0014(tag-trk) BR(KL () ) = 0.2698  0.0006  0.0014(tag-trk) BR(KL 3) = 0.1997  0.0005  0.0019(tag- -counting) BR(KL () ) = 0.1263  0.0005  0.0011(tag-trk) ~0.5% accuracy !

  8. + data KL lifetime from KL30 L = (50.87 ± 0.16stat± 0.26syst ) ns (KLOE direct) L = (51.54±0.44) ns (Vosburgh et al.) Events/0.3 ns KLOE average: τL = (50.81± 0.23) ns KLOE direct t*= LK/c (ns) KLOE indirect  14 x 106 events Fit region = 6 -26 ns (40%tL) Vosburgh et al, PRD 6 (1972), 1834 To be submitted to PLB

  9. Semileptonic Form Factors • Semileptonic FF describe the t- distribution of the decays • Phase space integral depends on such a parametrization • Koe-3, Koe+3, Kom-3, Kom+3 Dalitz plot analyses • Tagging : clusters from KS decay associated to triggering sectors of the • calorimeter • Selection : 2 opposite-charge tracks with vertex : 35<Rt<120, | Z |<120 • Comparison between different mass hypotheses to identify Klong charged decays : • - p+p-po, p+p- • - semileptonic decays Statistical Precision - 330 pb-1 Study of systematics in progress Results expected for EPS conference

  10. l+ = 0.0226  0.0114 from KTeV + ISTRA l+ = 0.0023  0.0004 l0 = 0.0154  0.0008 Vus from Kl3 decays and L |Vus| from neutral Kl3 partial decay widths |Vus f+Kp(0) |2 G(K0  pln(g))  I(lt) (1 + DI(lt,a)) (1 + dEM) Prescription from hep-ph/0411097 (F. Mescia @ICHEP04): 1) Quadratic parametrization of the form factor : x 2 better than PDG ! 2) KL lifetime from KLOE (average of the two measurements) : tKL= (50.81  0.23) ns (contribution to Vus ~ 0.1%) 3) BRs from KLOE (setting the sum =1): 4) Form factor BR(KL e) = 0.4007  0.0006  0.0014 BR(KL ) = 0.2698  0.0006  0.0014 f+K(0) from Leutwyler-Roos: 0.961(8)

  11. Vus from Kl3 decays and L |Vus|  f+Kπ(0) KLOE results: |Vus|f+K(0) (KSe3) = 0.2169 0.0017 |Vus|f+K(0) (KLe3) = 0.2164 0.0007 |Vus|f+K(0)(KLm3) = 0.2174 0.0009 From Unitarity: (1-|Vud|2)1/2f+K(0) = 0.2177 0.0028

  12. With charged Kaons With neutral Kaons The grand summary on Vus with 0.5 fb-1

  13. FISICA DEL Ks • BR del KSpen (Vus,asimmetria di carica, test DS=DQ) • BR del KSp0p0p0 • BR del KSp+p-p0

  14. 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) KS semileptonic decay 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 Test of the DS = DQ rule,G(KS  pen)/G(KL  pen) = 1 + 4 Re(x) Can extract |Vus| via measurement of BR(KS  pen)

  15. e 11531 181 EMISS – cPMISS(MeV) e 11805  177 KS  e  410pb-1 of 2001/02 data • KS tagged by KL interaction in EMC • KS p+p-background (x103)suppressed by • vertex, 2-track mass • e/p ID by TOF • e+) = (24.10.1 0.2)% • e-) = (23.60.1  0.2)% • Radiative decays included in MC • Fit data to MC spectra of signal (missing E - cP ~ 0) + background • Normalize to PDG BR(KS p+p-) to get BR(KS pen) BR(KSe) = (7.09  0.07stat 0.08syst)  10-4 AS = (-2  9stat  5syst) 10-3 AL = (3.322  0.058  0.047) 10-3 [KTeV 2002] AL = (3.317  0.070  0.072) 10-3 [NA48 2003]

  16.  2002 Data KS m+p-n +ppg+ pp  2002 Data KS m-p+n +ppg+ pp 4686 4654 Cuts on P*(p) + dpos + rvtx Cuts on P*(p) + dpos + rvtx 40 -20 0 20 40 40 -20 0 20 40 DE(pm)(MeV) DE(pm)(MeV) BR(KS  pn) • Same motivations of KSe3, but more difficult • Lower BR: expect 4 x 10-4 • Background events from KS pp, p  mn: same PIDs of the signal • Troublesome charge identification for the signal • Anyway, never done before. Here it is:

  17. 1 f (1 + i tan SW) [Re i Im ] A*(KS f ) A(KL f ) S Compare to mK/mPlanck = 4 1020 Im  < ~ 2  105 < ~ 8 1019 KS 30 test of CP and CPT Observation of KS 30 signals CP violation in mixing and/or decay: If CPT conserved: S000= L000|000|2BR(KS 30) ~ 2 109 Best results: BR < 1.4 105 90% CL SND ’99 BR < 7.4  107 90% CL NA48 ’04 Uncertainty on KS 30 amplitude currently limits precision on Im  From unitarity (Bell-Steinberger relation): Best results: Im  = (2.4  5.0)  105 CPLEAR ’99 Im  = (1.2  3.0)  105 NA48 ’03 preliminary describes CPV  describes CPTV

  18. BR(KS0) BR(KS) ≤ 1.2 x 10-7 @90% CL. Best limit Rarest decay studied by KLOE so far Data sample: 0.5 fb-1 2001-2002 run • 37.8 x 106 (KL-crash tag + KS) Require 6 prompt photons: large background ~40K events Kinematic fit, 20, 30 estimators (z2, z3) After all analysis cuts (3 = 24.4%) • 2 candidate events found • Expected backgr. = 3.13 ± 0.82 ± 0.37 Published in PLB619 61 (2005) MC background (not scaled) data

  19. Search for KS+0 started • Motivation • Present status • BR(CPC)~ 3x10-7, BR(CPV)~1.2x10-9 • Direct measurement of CPC part possible with ultimate 2fb-1 • Measurement tests untested prediction of cPT • Data sample: 740 pb-1 • 373pb-1 (2001/2 data) + 367 (2004 data !) • Assuming BR=3x10-7, ~230 signal events produced

  20. KS p+p-p0: Background rejection • c2 from kinematic fit: • MC background • MC signal (L× ~100) From MC, 24060 events expected after preselection (of which ~16 signal) • Reject background with kinematic fit • Constraints (8): • Global 4-momentum conservation • g’s from p0 have b = 1 • M(gg) = m(p0) • M(p+p-gg) = m(KS) • Require c2 < 30: • Cut efficiency = 48.5% • Overall signal efficiency = 3.3% • > 99% of background rejected • Preliminary results with 740 pb-1: • Signal efficiency: ~ 1.5%, 6 candidates • Background (sidebands): ~ 3.5 events • Statistical error: ~ 100%, systematics in progress

  21. FISICA DEL K± • BR K±mn(g) and Vus • BR K±l3 • Misura della vita media del K±

  22. Tagging of charged kaons • Tag performed selecting • K±±, ±0 decays (85% of K±) • by measuring the charged particle • momentum in the K rest frame (P*) • Trigger required on the tag side.

  23. Particle momentum in K rest frame   e P()*(MeV) Measurement of BR(K++()) Combining the experimental value of (K())/(()) with fK/f from lattice calculations we can extract the ratio |Vus|/|Vud| (Marciano hep-ph/0406324) Selection • Tag from K-- (self-triggering) • 2002 data 175 pb-1 (2/3 is used as • efficiency sample) • Background events identified by • the presence of a neutral pion.

  24. BR(K+m+n(g)) = 0.6366  0.0009stat. 0.0015syst. The result

  25. Vus from K++() Following the method from Marciano hep-ph/0406324 : fK /f=1.210±0.014 (MILC Coll. hep-lat/0407028) Vud=0.9740±0.0005 (superallowed -decays) Vus=0.2223±0.0025 KLOE preliminary new unpublished Vud value will shrink the error band

  26. m- K- g K++0 tag K+ e+ g Semileptonic decays of K± • Absolute BR measurement. • Tagging with K±,  • Kl3 selection: • K± vertex in DC • Rejection of K2, K2 background • p0 in time • Spectrum of charged daughter mass from TOF m2=p2 [(cT/L)2-1] • Ratio of data and MC efficiency is used to correct MC acceptance. Result will be announced at EPS

  27. Measurement of K± lifetime the Particle Data Group values are questionable tK = (12.385  0.025) ns we have two different methods to measure the charged kaon lifetime : (1) by K decay length and (2) by K decay time

  28. t (p0 vtx) – t (DC vtx) st 400 ps c2 = 1.6 ns ns Measurement of K± lifetime: fit of the proper time slope the proper time slope is fitted with an exponential function convoluted with the appropriate DCvtx resolution functions bin by bin (500 ps) DCvxt resolution obtained smearing the MC DCvtx resolution  comparing (t (p0vtx) – t (DC vtx)) in DATA and MC

  29. Kaon physics results with 0.5 fb-1 (2001-02) • KLOE has performed a preliminary measurement of • Major KL BRs with 0.5% accuracy • KL lifetime with 0.6% accuracy • BR(KS  pen with 1% accuracy • BR(K+ n with 0.2% accuracy NEW • All BRs are inclusive of the radiation • Final papers are under review by the collaboration • KLOE has set the best upper limit on BR(KS3p0) • A large number of K± semileptonic decays has been selected and allows a BR measurement with accuracy < 1%. • KLOE is now measuring: • K± lifetime • Kl3 form factors • BR(KS p+p-p0) • Coming soon: G(KSpp(g))/G(KSp0p0) with few ‰ accuracy. Mature analysis

  30.   Current results on  radiative decays

  31. f0 contribution to e+e  p+ p g final state Forward-backward pion asymmetry Asymmetry Data EVA (ISR+FSR) EVA (ISR+FSR) + f0 (K-loop model) Mpp [MeV] Mpp [MeV] With the insertion of the f0(980) the MC now has the same shape of data

  32. BR(hp0gg). Tests O(p6) cPT GAMS (1984) Crystal Ball (2004) KLOE signal + background after fit reproduces well the data NDATA = 735 Nbkg = 667  36 Nsig = 68  23 N(3p0) = 2,288,882 KLOE Preliminary BR(h  p0gg) = ( 8.4 ± 2.7stat±1.4syst ) x 10-5

  33. |Fp(s)|2 KLOE vs. CMD-2 45 Relative Difference e+evs. t 40 s(e+e- p+p-) CMD-2 KLOE = t – Data (ALEPH, OPAL, CLEO) pa2 35 20% b3|Fp(s)|2  3s Pion Form- factor 30 10% 25 0% 20 15 -10% 10 - 20% 1.3% Error 5 0.9% Error 0 0.2 0.4 0.6 0.8 1.0 s (GeV2) s (GeV2) 0.4 0.5 0.6 0.7 0.8 0.9 s (GeV2) A. Höcker @ ICHEP04 e+e- and t – data incompatible! Isospin breaking effects?! Fair agreement, but relatively large deviations: reasons unknown. The Pion form factor, extracted froms(e+e p+p g) PUBLISHED

  34. New Information: • New KLOE Measurement • Phys. Lett. B606 (2005) 12 • New 4th order QED calculation • (Kinoshita, Nio) • Phys.Rev.D70 (2004) 113001 • New ‘Light-by-light’ calculation • (Melnikov, Vainshtein) • Phys.Rev.D70 (2004) 113006 A. Höcker @ ICHEP04: hep-ph/0410081 DEHZ’03 [e+e- based] DEHZ’03 [t based] contains CMD-2 and KLOE Theory: DEHZ’04 [e+e-] • –Data not considered unsufficient understanding of isospin breaking corrections! Experiment E821 • Theory (SM) - Experiment amexp - amtheo = ( 25.2 ± 9.2 ) ·10-10 2.7 “standard deviations” am-11 659 000 ∙ 10-10 am- 11 659 000 x 10-10 140 150 160 170 180 190 200 210 am- 11 659 000 ∙ 10-10 Our data used in am calculations

  35. And new e+e- data enter the game… hep-ex/0506076 (30 Giugno 2005) 2 A session at EPS devoted to s hadronic SND data just released CMD-2 new data will be published soon…

  36. Stato della presa dati

  37. INTEGRATED LUMINOSITY Plot by P. Franzini 2001 2002 2004 2005 Ad oggi abbiamo ~1.7 fb-1 di dati raccolti su nastro

  38. MONTH LUMINOSITY Plot by P. Franzini L’incremento in luminosita’ e’ stato accompagnato da una riduzione dei fondi macchina

  39. DAILY LUMINOSITY Plot by P. Franzini L/day 10.5 pb-1 7 pb-1 3.5 pb-1 2004 2005

  40. Reconstruction in 2004-05 • Runs 28700 (9 May 04) to 37457 (30 Jun 05) • 1190 pb-1 of data on disk OK for reconstruction • 1176 pb-1 of data with full calibrations • 1107 pb-1 of data fully reconstructed • (94% eff) The reconstruction follows closely the data acquisition (each reconstruction job lasts 2h as maximum ) Data quality continuously monitored “online”!

  41. 2004 L = 397pb-1 L = 294pb-1 Sep-04 May-04 Oct-04 Dec-04 2005 L = 248pb-1 L = 85pb-1 20-Apr-05 9-May-05 Feb-05 21-Apr-05 Stability of beam energy at O(100 KeV) s mostly between 1019.3 and 1019.6: OK. Better than 2001

  42. Feb-05 20-Apr-05 21-Apr-05 9-May-05 KS invariant mass stable within O(50 KeV)

  43. Prospettive con 2.5 fb-1

  44. K0Lpen 0.19%  0.22% 0.3% K0Lpmn 0.28%  0.22% 0.3% K0Spen 0.75%  0.04%  0.3% K0Spmn -  0.04%  0.3% K±pen 0.60%  0.10%  0.3% K± pmn 0.90%  0.10%  0.3% Further information from KLOE Vus from Kl3 decays and L - Contributions to the relative error on |Vus|f+K(0) Black = KLOE Blue = PDG

  45. K0Lpen 0.19%  0.22% 0.3% K0Lpmn 0.28%  0.22% 0.3% K0Spen 0.50% 0.04%  0.3% K0Spmn 0.90% 0.04%  0.3% K±pen 0.30% 0.10% 0.3% K± pmn 0.40%0.10% 0.3% Vus from Kl3 decays and L Contributions to the relative error on |Vus|f+K(0) Further information from KLOE

  46. 2.5 fb-1 prospects for rare KS decays • Good opportunity to measure interesting rare KS decays, down to BR ~ few x 10-8 • However, need to exploit to the maximum KLOE and DANE

  47. 2.5 fb-1 prospects for KS0 • Increased statistics: x 6.5 improvement • Luminosity  x 5 • Add tagging by KL vertex in DC  x 1.3 • Increased background rejection • Largest bkg source after all cuts is the splitting of e.m. clusters • Merging procedure removes bkg but leaves signal untouched • Candidates in data go from 2 to 0, in MC from 3.13 to 2 • Optimization of kinematic fit • Overall better understanding of the known background If we will be able to suppress the background to a ~negligible level UL can be improved up to a factor of 10 (down to few 10-8)

  48. 2.5 fb-1 prospects for KS+ 0 • Signal efficiency ~ 1.5% • Very, very preliminary results with 0.74 fb-1 • Candidates: 6events • Background ~3.5events (estimated from side bands in data) • Observed events consistent with expectations within the statistical error (~100%) • no systematic error, no error on background • Scaling the values of signal and background to 2 fb-1 we expect • ~16events, of which~9background • ~60%statistical accuracyon BR(KS+ 0) With further effort by KLOE to suppress background and 2.5 fb-1 by DANE, we can measure this BR with accuracy below 50% competitive with other measurements (and the only direct search!)

  49. 2.5 fb-1 prospects for BR KS  pln • Fractional accuracy <1% on the BR KS  pen • Sensitivity at the level of 3 10-3 on the charge asymmetry AS (dA2Re(e)) • The first direct measurement of BR KS  pmn, accuracy <2%: • Total uncertainty expected to be largely dominated by statistics • Measurement of charge asymmetry much more complicated than KSe3

  50. -radiative and -dalitz decays with 2.5 fb-1 • In addition to radiative, also Dalitz decays of the  can be studied: N(2fb-1) ~ 7x109 • M(dilepton) spectra give transition FF(q2). FF(q2) with BR can test VMD and Lattice theoretical models • Predicted BR( ) = 5.3-6.8 x 10-6 • Then, can also study Dalitz and double Dalitz decays of , ’ (eeee, BR ~ 6.5 x 10-5, never observed) • Reach the ultimate goal of understanding better the nature of ’, f0, a0 mesons (via Dalitz plot analysis)

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