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Charged Kaon experiment at CERN SPS - NA48/2

ICHEP, 2004. Charged Kaon experiment at CERN SPS - NA48/2. The goals Experiment configuration Asymmetry ( A g ) analysis ( status and prospects ) Rare decays. V.Kekelidze (JINR, Dubna) for the Collaboration NA48/2:

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Charged Kaon experiment at CERN SPS - NA48/2

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  1. ICHEP, 2004 Charged Kaon experiment at CERN SPS - NA48/2 • The goals • Experiment configuration • Asymmetry (Ag) analysis (status and prospects) • Rare decays V.Kekelidze (JINR, Dubna) for the Collaboration NA48/2: Cambridge, CERN, Chicago, Dubna, Edinburgh, Ferrara, Firenze, Mainz, Northwestern, Perugia, Pisa, Saclay, Siegen, Torino, Wien V.Kekelidze, JINR

  2. Physics motivation High precision study of charged Kaon decays as the probes for: • Qualitative tests of the SM & search for new physics  direct CP violation • high accuracy tests of low energy QCD (PT)  rare decays • tests of other models  high precision measurement of K±decay parameters V.Kekelidze, JINR

  3. Rare decays: to testPT & search for ACP Ke4 - scat. length ( ) < 1102 ( > 106events) • K   , K  0 DE K  e+e,K  + , Ke2, K l  l+l, K  0 , K  0l+l, … etc. The Goals of NA48/2 • Direct CP violation in K±  ±+ , K±  ±00 M(u)1 + gu, u= (2mK/m2) (mK/3 –E*-odd) (Ag) < 210 – 4(limited bystatistics) g + -g - Ag = ———— g+ +g- • Semileptonic decays: Ke3, K3 contribution to the measurement of |Vus| search for fT, fS V.Kekelidze, JINR

  4. |Ag| experiments by 2002 10-2 1.0E-02 NA48/2 10-3 1.0E-03 new physics SUSY 10-4 1.0E-04 SM 10-5 1.0E-05 10-6 1.0E-06 Ag: theory & experimental limits E.Shabalin-98 G.D’Ambrosio,G.Isidori, G.Martinelli-99 E.Shabalin-01,-04 I.Scimemi-04 G.D’Ambrosio-97 L.Maiani,N.Paver-95 V.Kekelidze, JINR

  5. The simultaneousK+and K-beams NA48 Set-Up B+ magnet 54 60 66 PK spectra, 603GeV/c DFDF Quadrupole 2nd Quadruplet ACHROMAT vacuum tank He tank + spectrometer 10 cm FRONT-END ACHROMAT 200 250 m 1cm beams coincide within <1mm 114m decay volume 50 100 NA48/2 experiment configuration TAX 17 TAX 18 FDFD K+ K+ focusing beams K- K- not to scale V.Kekelidze, JINR

  6. The simultaneousK+and K-beams NA48 Set-Up B+ magnet DFDF Quadrupole 2nd Quadruplet ACHROMAT vacuum tank He tank + spectrometer 10 cm FRONT-END ACHROMAT 200 250 m 1cm 50 100 NA48/2 experiment configuration alternate thebeam lines(weekly) TAX 17 TAX 18 FDFD K+ K+ focusing beams K- K- not to scale V.Kekelidze, JINR

  7. The simultaneousK+and K-beams NA48 Set-Up B+ magnet DFDF Quadrupole 2nd Quadruplet ACHROMAT vacuum tank He tank + spectrometer 10 cm FRONT-END ACHROMAT 200 250 m 1cm 50 100 NA48/2 experiment configuration alternate thebeam lines(weekly) TAX 17 TAX 18 FDFD K- K- focusing beams K+ K+ not to scale V.Kekelidze, JINR

  8. The simultaneousK+and K-beams NA48 Set-Up B- magnet DFDF Quadrupole 2nd Quadruplet ACHROMAT vacuum tank He tank + spectrometer 10 cm FRONT-END ACHROMAT 200 250 m 1cm 50 100 NA48/2 experiment configuration alternate magnet polarity daily (’03) 3-4h (’04) TAX 17 TAX 18 FDFD K+ K+ focusing beams K- K- not to scale V.Kekelidze, JINR

  9. The simultaneousK+and K-beams NA48 Set-Up B+ magnet DFDF Quadrupole 2nd Quadruplet ACHROMAT vacuum tank He tank + spectrometer 10 cm FRONT-END ACHROMAT 200 250 m 1cm 50 100 NA48/2 experiment configuration alternate magnet polarity daily (’03) 3-4h (’04) TAX 17 TAX 18 FDFD K+ K+ focusing beams K- K- not to scale V.Kekelidze, JINR

  10. Top view of the setup Z axis (beam direction) Saleve Jura • ASJ = (AS+AJ)/2g =Ag2gphysics asymmetries (to mask the results ASJ ,AS&AJ are presented with OFFSETS !) X axis • A± = (A++A)/2 = (AS-AJ)/2 asymmetry induced by the experimental setup ( many of the effects observed in A±cancel in ASJ) Ag measurement (acceptance cancellation) Physical asymmetries: • AS→ slope of ratio U(K+ B+) / U(K- B-) • AJ→ slope of ratio U(K+ B-) / U(K- B+) Apparatus-induced asymmetries: • A+→ slope of ratio U(K+ B+) / U(K+ B-) • A→ slope of ratio U(K- B+) / U(K- B-) V.Kekelidze, JINR

  11. NA48/2 runs 2003 run:~ 50 days (~ 1 month stable conditions) 2004 run: ~ 60 days ~ 200 TB of data recorded V.Kekelidze, JINR

  12. Statistics ~ 1 month of data taking in 2003 at stable conditions have been analyzed V.Kekelidze, JINR

  13. Time-dependence of alignment MSaleve–MJura, keV/c2 Max. DCH4 shift of 70 m Day-sample Spectrometer calibration • P = P0∙(1+β)∙(1+qbP0) P0 – measured momentum; P – corrected momentum; q – track charge; b – magnetic field sign. • Time-dependent corrections: • β– for magnetic field integral • – for spectrometer misalignment V.Kekelidze, JINR

  14. K Events even pion in beam pipe |V| odd pion in beam pipe K+ Events U Dalitz plot for K  + - & M(3) SS1-3 data: > 1120 million events selected M3π, GeV/c2 M3π, GeV/c2 V.Kekelidze, JINR

  15. AS+offset AJ+offset A+ A- Asymmetry vs. PK(1 month ’03 data,preliminary) K±p±p+p- c2/ndf 6/11 ASJ + offset = 0 ± 0,117.10-3 (AS+AJ)/2 + offset Statistical error of Ag: 2,7.10-4 Statistical error of A : 2,7.10-4 PK, GeV/c PK, GeV/c c2/ndf 6,7/11 A = (0,131 ± 0,117).10-3 (A++A-)/2 V.Kekelidze, JINR

  16. AS+offset AJ+offset A+ A- Asymmetry vs. time (1 month ’03 data,preliminary) K±p±p+p- c2/ndf 13,5/12 (AS+AJ)/2 + offset Day-sample pair Day-sample pair c2/ndf 5,6/12 (A++A-)/2 Day-sample pair Day-sample pair V.Kekelidze, JINR

  17. Results on Ag one month of NA48/2 data taking in 2003: • K± +  ±Agc= ( .. 2.7)∙10-4 • K±00 ± (36M events) Ag0 = ( 5.0)∙10-4 uncertainties dominated by the statistical errors! • Other experiment data onAgc • BNL (1970): (- 7.0 ± 5.3)∙10-3 • FNAL, HyperCP –2000 (preliminary)(2.2±1.5±3.7)∙10-3 • Serpukhov data onAg0 • I.V.Ajinenko et al., PLB567(2003)159.: (5.1 ± 2.8 )∙10-3 • G.A.Akopdzhanov, hep-ex/0406008 prelim.:(0.2 ± 1.9 )∙10-3 V.Kekelidze, JINR

  18. Rare Decays of Charged Kaons 1 month of running in 2003 V.Kekelidze, JINR

  19. K±π+π-e±ν (Ke4) decays • Physics interest: • Low energy ππscattering predicted by the Chiral Perturbation Theory first principles. • Predicted by the PTa00=0.220±0.005 related to the qq QCD condensate [Colangelo, Gasser, Leutwyler, hep-ph/0103088] • ππscattering length a00can be determined from form-factors of Ke4decays. • Previous measurements: • Geneva-Saclay (1977): 30,000 events • Brookhaven E865 (2001): 400,000 events a00= 0.216±0.013stat 2 experiments, errors > theoretical uncertainties. V.Kekelidze, JINR

  20. Ke4 hypothesis K- mass 0.3 0.4 m(), GeV/c2 0 0.1 0.2 m(e), GeV/c2 Background K±+-e±ν (Ke4) (1 month ’03 data,preliminary) Cabibbo-Maksymowicz variables [backgr. in red] 2003 data: expected > 500k events (background ~ 0.6 %) V.Kekelidze, JINR

  21. Measurement of a0-a2 pion scattering length from K  (3) decays • A threshold effect in M(00) has been observed • for the first time by NA48/2 thanks to • high resolution in energy • high statistics collected • The rescattering of +  -  0 0 • in the decay K  + -   0 0  • allows to study of a0-a2 • in a very accurate way N. Cabibbo arXiv: hep-ph 0405001 V.Kekelidze, JINR

  22. K±  ±+- > 1000ev. (PDG: ~ 800) K±±e+e- & K±±+- (1 month ’03 data,preliminary) K±  ± e+e- > 2600ev. Form-factor M(± e+e-), GeV/c2 • low background (1-2%) • expected data sample in 2003-2004 • comparable to the World best sample V.Kekelidze, JINR

  23. K- K- K±  π±   decays (1 month ’03 data,preliminary) ~ 100 x world statistics • Physics interest: • O(p2) PT amplitude vanishes; • O(p4) amplitude is computed (up to an unknown parameter); • Fit of M distribution to check O(p6) PTexpansion. first NA48/2 data V.Kekelidze, JINR

  24. Summary • NA48/2 has completed the data taking • ~4 B ofK±  ± +-decays are recorded, which allow to achieve the statistical precision of (Ag) < 210-4 • World largest multipurpose sample of charged kaon decays is accumulated to study various K±rare decays V.Kekelidze, JINR

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