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Experiments NA48/1 & NA48/2

Experiments NA48/1 & NA48/2. Status Report ( SPSC-2005-031 ). V.Kekelidze for. Collaboration:. CERN, Cambridge, Chicago, Dubna, E dinburgh, Ferrara, Firenze, Mainz, Northwestern, Perugia, Pisa, Saclay, Siegen, Torino, Vienna. Content. Introduction Rare decays in the experiment NA48/1

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Experiments NA48/1 & NA48/2

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  1. Status Report, SPSC Experiments NA48/1 & NA48/2 Status Report(SPSC-2005-031) V.Kekelidze for Collaboration: CERN, Cambridge,Chicago, Dubna, Edinburgh, Ferrara, Firenze, Mainz, Northwestern, Perugia, Pisa, Saclay, Siegen, Torino, Vienna

  2. Status Report, SPSC Content • Introduction • Rare decays in the experiment NA48/1 • Search for direct CP-violation in the NA48/2 • Test of PT: precise measurement of the - scattering length • Rare decay of charged kaons • Leptonic & semileptonic decays • Summary & request

  3. Status Report, SPSC Physics motivation for the experiments High Precision Study of Kaon & Hyperon Decays • Search for new physics & tests of the SM • High accuracy tests of low energy QCD (PT) • Quantitative tests of various model predictions • NA48/1 2000 Phase I (no spectrometer): KS & KLdecays 2002 Phase II (high intensity run):KS & Hyperon decays KS in fiducial volume: ~ 3.5 1010 • NA48/2 simultaneous K+ and K-beams2003 – 2004 K in fiducial volume: > 2. 1011

  4. Status Report, SPSC Rare decays in the experiment NA48/1

  5. Status Report, SPSC Measurement of Br(KSe) Br = (6.8  0.2stat  02sys)10-4 PDG value : (6.9  0.4)10-4 is improved in precision ~13’000 analysis finished paper preparation is in progress

  6. BR= (0+e-e)= (2.510.03stat 0.09syst)10-4 Status Report, SPSC 0+e+e decays BR= (2.57  0.12stat +0.10–0.09syst)10-4 in good agreement with our measurement:

  7. Status Report, SPSC 0+- decays BR= (2.2  0.3stat 0.2 syst)10-6 most precise measurement paper in preparation KTEV: 102 decays 32  3.0 background (4.7+0.2-1.4stat0.8sys)10-6

  8. Br(KS + - 0) submitted to PRL Status Report, SPSC R= N(0)/ N(0) R= (9.31  0.05stat 0.04 syst)10-2 new (preliminary)

  9. Status Report, SPSC Search for direct CP-violation in NA48/2

  10. Status Report, SPSC Goal • Direct CP violation in K±   ±  ±, K±  ±00 M(u)1 + gu,u = f( ) g = g+ - g- = 2Ag<g> (Ag ) < 210 – 4 (limited by statistics) g + - g - Ag = ———— g+ + g- Requirements to experiment: • high statistics (~ few109 decays) • stability in time • set –up symmetry

  11. Status Report, SPSC Measurements & predictions Experimental precisions by 2005: [Ag~10-3] Ford et al. (1970) 10-2 SM estimates vary within an order of magnitude (few 10-6…8x10-5). Models beyond SM predict substantial enhancement partially within the reach of NA48/2. HyperCP prelim. (2000) |Ag| TNF prelim. (2002) “neutral” mode Theory 10-3 NA48/2 proposal “neutral” 10-4 “charged” Asymmetry in decay widths expected to be smaller than in Dalitz-plot slopes (SM: ~10-7…10-6). 10-5 New physics 10-6 SM SUSY

  12. Status Report, SPSC NA48/2 method • Two simultaneous K+ and K– beams, superimposed in space, with narrow momentum spectra; • Detect asymmetry exclusively considering slopes of ratios of normalized U distributions; • Equalize K+ and K– acceptances by frequently alternating polarities of relevant magnets.

  13. The simultaneousK+andK-beams NA48 Set-Up B+ magnet 54 60 66 PK spectra, 603GeV/c BM z focusing beams DFDF Quadrupole Quadruplet vacuum tank He tank + spectrometer 10 cm FRONT-END ACHROMAT 200 250 m 1cm beams coincide within <1mm 114m decay volume 50 100 Status Report, SPSC NA48/2 experiment configuration TAX 17 TAX 18 FDFD K+ ~71011 ppp K+ K- 2nd ACHROMAT K- not to scale

  14. Status Report, SPSC NA48/2 runs 2003run:~ 50 days (~ 1 month stable conditions) 2004run: ~ 60 days ~ 200 TB of data recorded

  15. Status Report, SPSC Statistics data taken in 2004: calibrated, reprocessed & filtered analysis started

  16. Status Report, SPSC Super-samples 2003 Statistics selected for Ag measurement, events x106

  17. Status Report, SPSC Selected statistics 2003 M=1.7 MeV/c2 Data-taking 2003: 1.61x109 events selected Events |V| even pion in beam pipe  K+ : 1.03x109 events odd pion in beam pipe  K: 0.58x109 events U

  18. Beam profile @DCH1 (a small fraction of data) Y, cm 0.8 0.4 0 -0.4 -0.8 -0.8 -0.4 0.8 0.4 0 X, cm Status Report, SPSC Beam movement in time DCH1 (upstream magnet) K K+ Y, cm X, cm Typical scales: • beam movement in time ~2mm • beam width ~5mm X, cm

  19. N(A+B+K+) RUS= N(A+B-K-) N(A+B-K+) RUJ= N(A+B+K-) N(A-B+K+) RDS= N(A-B-K-) N(A-B-K+) RDJ= N(A-B+K-) Status Report, SPSC Acceptance cancellation within a supersample Detector left-right asymmetry cancels in 4 ratios of K+over Ku-spectra: R(u)=RUS  RUJ RDS RDJ=N(1+4gu) • same deviation direction by spectrometer magnet in numerator and denominator; • data from 2 different time periods used at this stage. Y X Achromats: K+Up B+ Jura Z B Saleve Achromats: K+ Down Indexes of R’s correspond to • beamline polarity (U/D); • direction of kaon deviation in spectrometer magnet field (S/J)

  20. Status Report, SPSC Example of fits: supersample 1 AUS=(2.4±4.6)x10-4 2=37.5/38 AUJ=(-0.2±4.6)x10-4 2=50.5/38 U U ADS=(8.2±4.4)x10-4 2=35.6/38 ADJ=(-1.0±4.4)x10-4 2=34.8/38 U U R(u)/N =(2.3±2.2)x10-4 2=38.1/38 U

  21. set-up asymmetry: left / right up / down Status Report, SPSC Time-stability (vs super-sample) x10-4 20 (D-U)/2 (S-J)/2 15 10 5 0 -5 Monte-Carlo describes effects of permanent magnetic fields and differences of beamline properties -10 -15 -20

  22. Status Report, SPSC Stability vs kinematic variables g x10-4 g x10-4 80 40 60 30 40 20 20 10 0 0 -20 -10 -40 -20 -60 -30 -80 -40

  23. Status Report, SPSC Result & systematics Combined result: Δx104 (3 independent analyses) L2 trigger systematics included

  24. Status Report, SPSC Preliminary result: 2003 data Slope difference: Δg= (-0.2±1.0stat.±0.9stat.(trig.)±0.9syst.)10-4 = (-0.2±1.7)10-4 Charge asymmetry: Ag= (0.5±2.4stat.±2.1stat.(trig.)±2.1syst.) 10-4 = (0.5±3.8)10-4 • systematic errors are conservative for preliminary result • better control of systematics in 2004 due to: - more frequent polarity alternation - better L2 performance

  25. Status Report, SPSC Asymmetry inK±  ±00 preliminary result based on SS0-SS3 (~ 48 M decays) specific features: • one charged track (±) to measure asymmetry • Lkr used for00identification • different acceptance (u) & largeg0= 0.652 ± 0.033

  26. Status Report, SPSC reconstruction algorithm K  00  + 4  LKr pairs of’s should have a common vertex compatible with kaon decay E1E2  (d12)2 m

  27. Status Report, SPSC Reconstructed decaysK±  ±00 preliminary result based on SS0-SS3 (~ 48 M decays) K- K+ ~31M ~17M

  28. Status Report, SPSC Data analyzed: SS-0,-12,-3 g0 = (2.2  2.2 stat)10-4 R(u), 10-4 SS0 u R(u), 10-4 SS12 u R(u), 10-4 SS3 u

  29. set-up asymmetry: left / right up / down MC exper. Status Report, SPSC Stability check & comparison with MC 10-4 AS-AJ g0 AU-AD

  30. Status Report, SPSC Stability checks of obtained g0 10-4 g0 PK Vz 10-4 g0 |V| day sample

  31. Status Report, SPSC Result (preliminary): three analyses obtain very close results A0gmajor systematics in 10-4 units: alignment (< 0.1) acceptance & beam geometry (< 0.1) momentum scale (< 0.1) u-calculation & fit (< 0.4) accidentals (< 1.0) L1 trigger (< 1.5), L2 trigger (< 0.4), fit region (0.0025), LKr nonlinearity corrections (< 0.4) A0g= (1.7  1.7stat  1.2trig  1.0syst  0.2extern)10-4

  32. Status Report, SPSC Test of PT : precise measurement of the - scattering length

  33. m p+ = 0.220 ± 0.005 m p+ = - 0.0444 ± 0.0010 ( - ) m p+= - 0.265±0.004 mp+ • Experimental measurements • mesoatom lifetime (DIRAC)  • form-factors in Ke4decays for the first time: Geneva-Saclay (1977): 30,000 events best measurement: BNL E865 (2001): 400,000 events precision limited by statistics | - |2 = 0.216 ± 0.013stat ±0.002syst±0.002theor  ~ 6 % Status Report, SPSC p-pscattering length • Theory calculation • predicted by PT first principles (Weinberg 1966) • G.Colangelo, J.Gasser, H.Leutwyler, NP B603(2001)125  1.5% • Statistics ofNA48/2: > 1,000,000Ke4events

  34. A threshold effect in M(00) has been observed (cusp structure) for the first time in NA48/2 thanks to • high resolution in energy • high statistics collected indication to the re-scattering of +  -  0 0 in the decay K  + -   0 0  is related to ( - ) ( - ) Status Report, SPSC New way ! measurement of from K  (3) • simple model:N. Cabibbo, P.L.B 93(2004)121801 • two loops approximation:N.Cabibbo, G.Isidori, JHEP03(2005)021 • (I symmetry is foreseen) • introduce I-breaking parametere= (m+2 - mo2)/m+2 =0.065 • M.Knecht, R.Urech, N.P. B519(1998)329; • G. Colangelo,J.Gasser,B.Kubis,A.Rusetsky:Kaon Mini-workshop (CERN-05)

  35. 4m2()= 0.0779(GeV/c2)2 M2(00), (GeV/c2)2 Status Report, SPSC First Observation of the + - -thresholdin K  M0 0 decays ~23M decays M2(00), (GeV/c2)2

  36. Status Report, SPSC Fit quality  = data - MC • Simple Cabibbo model: axm+=(a0 -a2)m+/3 2/D.F. = 420.1 / 148 • Cabibbo, Isidori: two loop approximation; I- breaking (1 parameter)(a0 -a2)m+, a2m+,g0,h+,N 2/D.F = 154.8 / 146 • …..+pionium (1.61  0.66)10-5 2/D.F.=149.1 / 145 consistent with Z.Silagadze calc: 0.810-5 • excludepionium region2/D.F.=145.5 / 139

  37. ( - ) ( - ) m+ = 0.268  0.010stat  0.004syst  0.013ext m+= - 0.041  0.021stat  0.014syst Status Report, SPSC Results (paper in preparation): two analysis (different MC & criteria) obtain very close results m+major systematics: acceptance (0.001) trigger (0.001) fit region (0.0025) LKr resolution & nonlinearity (0.001) track- separation (0.002) taking into account uncertainty in theory ~ 5% (ext):

  38. & ( - ) Status Report, SPSC Results(continuation): m+= 0.220  0.006stat  0.004syst  0.003R  0.011theor m+= 0.264  0.006stat  0.004syst  0.003R  0.013theor taking into account uncertainty in R= A ++- / A+00 & theoretical constrains between experimental uncertainty < 3% - limited by statistics which will be increased using 2004 data by factor ~ 4

  39. expected precision in better than±0.010stat Status Report, SPSC K±+-e±ν (Ke4) selection: 2003 data SS1-3: ~ 350k (background ~0.5%) taking into account additional data (SS0 & 2004) it is expected in total: > 1000k decays background mproducts

  40. both K+ and K- decays are accumulated at similar experimental conditions this allows to tests CP, and CPT (for the fist time) and provide reliable cross checks for possible systematic ancertainties Status Report, SPSC Cabibbo-Maksymowicz variables  - line of flight in K rest frame ,ehave opposite sign for K+& K- (T.D. Lee and C.S.Wu –1966) d5K-(m,me,,e,)= d5K+(m,m e,,-e,+) background

  41. Status Report, SPSC Other Rare Decays of Charged Kaons SS1-3: ~1 month of running in 2003

  42. Status Report, SPSC Goals • Rare decays to testPT & search for ACP K   , K  0 DE K  e+e,K  + , Ke2 K l  l+l K  0 , K  0l+l, … etc.

  43. Status Report, SPSC K   0  PDG T: 55 – 90 MeV • Br=(2.750.15)10-4 DE contribution: • Br=(4.70.9)10-6 Interference term – possible source of CPV (order of magnitude • higher than others)

  44. Status Report, SPSC K±±e+e- & K±±+- Statistics > PDG K±  ± e+e-. M(± e+e-), GeV/c2 Z=(M(ee)/MK)2 Statistics comparable to the World best sample at low background (1-2%) Analyses are ongoing: form-factors study

  45. Status Report, SPSC Leptonics & Semileptonics of Charged Kaons Special minimum-bias runs in2003&2004

  46. Status Report, SPSC Goals • Leptonics & Semileptonic decays: Ke3, K3 BR’s  to improve precision of |Vus| & checkCKMunitarity, check -e universality form-factors  to search for fT, fS

  47. Status Report, SPSC Results (preliminary) • R(Ke3/K2) = 0.2505  0.0009stat  0.0012syst • R(K3/K2) = 0.1646  0.0006stat  0.0011syst • R(K3/Ke3) = 0.657  0.003stat  0.003syst • R(Ke2/K2)= 2.416  0.043stat  0.024syst2003 run • R(Ke2/K2)= 2.453  0.046stat  0.026syst2004 run PDG = 2.45  0.11 SM = 2.472  0.001

  48. Status Report, SPSC Summary & Request Special minimum-bias runs in2003&2004

  49. Status Report, SPSC • NA48/1 high precision results are obtained on • Ks decays and hyperon semileptonics, (analysis continues) • NA48/2 first results are obtained on • charged asymmetry in both • K±  ± +-and K±  ± 00decays • based on 2003 data • achieved precision is limited by statistics

  50. Status Report, SPSC NA48/2(cont.) • A “cusp” structure has been observed • for the first time • in K  0 0 decays • which allows to high precision measurement • of -scattering length • Large sample of both signs of K±e4decays • provides good opportunity for • high precision measurements of • -scattering length • & for the first time - various asymmetries

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