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VILLARS 2004 CERN SPS and PS Committee L. Nemenov 25 September 2004

VILLARS 2004 CERN SPS and PS Committee L. Nemenov 25 September 2004.

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VILLARS 2004 CERN SPS and PS Committee L. Nemenov 25 September 2004

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  1. VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 Creation of an intense source of ππ, πKand other exotic atoms at SPS proton beam and using them for accurate measurements of ππ, πKscattering length and other low energy parameters to check the precise low energy QCD predictions

  2. Theoretical motivation Standard Model Q>> Q<< VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 QFD QED QCD HIGH energy (small distance) LOW energy (large distance) perturbative QCD: LQCD (q,g) interaction  „weak“ (asympt. freedom): expansion in coupling Check only Lsym chiral sym. & break: Leff (GB: ,K,) interaction  „strong“ (confinement) - but: expansion in energy Check Lsym as well as Lbreak-sym q-condensate

  3. VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004  scattering ChPT predicts s-wave scattering lengths: Chiral expansion of the  mass: (1)

  4. Experimental Status VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 1) Rosselet et al. CERN, 1977 using Roy eq. 2a) Pislak et al. E865/BNL, 2001/03 2b) using Roy eq. & DIRAC after analysis of all collected data preliminary

  5. K scattering VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 I. ChPT predicts s-wave scattering lengths: V. Bernard, N. Kaiser, U. Meissner. –1991 A. Rossel. – 1999 J. Bijnens, P. Talaver. – April 2004 II. Roy-Steiner equations: III. AK lifetime: J. Schweizer. – 2004

  6. π+ π0 π0 π K+ π0 K0 π VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 1. A2πtime of life (*) A. Gall et al. PR(2001) DIRACADDENDUM 2. AK+π- and AK+π-time of life (**) J. Schweizer (2004) DIRAC ADDENDUM

  7. Energy Splitting between np - nsstates in ( + -  ) atom  E2 ≈  0.56 eV VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 For n = 2 (1979) A. Karimkhodzhaev and R. Faustov (1999) A. Gashi et al. (1983) G. Austen and J. de Swart (2000) D. Eiras and J. Soto (1986) G. Efimov et al. A. Rusetsky, priv. comm.

  8. Method of A2π Observation VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 (A2π) too small to be measured directly e.m. interation of A2π in the target A2π  π+π Q < 3MeV/c E+ E lab < 2.5 mrad “atomic pairs” Coulombfrom short-lived sources non- Coulombfrom long-lived sources “free pairs”

  9. VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 PBr=0.447±0.023stat +0.44stat =2.85 [fs] 0.38stat

  10. Metastable atoms +   1s = 2.9 × 10 15 s , 1s = 1.7 × 10 3 cm 2s = 2.3 × 10 14 s , 2s = 1.4 × 10 2 cm 2p = 1.17 × 10 11 s , 2p = 7 cm 3p  23 cm 4p  54 cm External beam is a metastable atom small angle  * A2 VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 For pA = 5.6 GeV/c and  = 20 p Probabilities of the A2π breakup (Br) and yields of the long-lived states for different targets provided the maximum yield of summed population of the long-lived states:Σ(l ≥1)

  11. VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 Yields of the long-lived states 2p (m = 0) as a function of the A2π lifetime for Beryllium targets (Z = 04). Target thicknesses are given in microns on the right side of the picture.

  12. ≡ relative distance between + and  mesons in A2 atom  z + ≡ laboratory magnetic field ≡ electric field in the CM system of an A2 atom A A2 , r B Lab F VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 External magnetic and electric fields Atoms in a beam are influenced by external magnetic field and the relativistic Lorentz factor

  13. The dependence of A2π life time in 2p-states eff from a strength of the electric field F where: VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 BLab = 4 Tesla

  14. Upgraded DIRAC setup VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 (Addendum to DIRAC/PS212 (CERN) (13/04/04): CERN-SPSC-2004-009 (SPSC-P-284 Add.4)) Schematic top view of the updated DIRAC spectrometer. Downstream of the magnet, in each spectrometer arm: drift chambers (DC), vertical and horizontal scintillation hodoscopes (VH, HH), gas Cherenkov counters (Ch), preshower detector (PSh) and, behind the iron absorber, muon detector (Mu). In the left arm:Aerogel Cherenkov counters. Upstream of the spectrometer magnet: microdrift chambers (MDC) , scintillating fiber detectors (SFD) , ionization hodoscopes (IH).

  15. VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 A2π and AπKproduction

  16. Inclusive cross-sections for π+, π - mesons generation VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004

  17. Inclusive cross-sections for K+,K - mesons generation VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004

  18. A2πmomentum distributions VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004

  19. A2πmomentum distributions VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004

  20. VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004

  21. 24 GeV/c L=5.7º (old) 450 GeV/c L=5.7º (old) VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 A2π momentum distributions — - redcurve A2π spectra in channel the aperture  - green curve A2π spectra registered by the set-up

  22. VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004

  23. 24 GeV/c L=5.7º (old) 450 GeV/c L=5.7º (old) 450 GeV/c L=5.7º (new) VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 AK+π- momentum distributions — - redcurve A2π spectra in the channel aperture  - green curve A2π spectra registered by the set-up

  24. 24 GeV/c L=5.7º (old) 450 GeV/c L=5.7º (old) 450 GeV/c L=5.7º (new) VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 Aπ+K momentum distributions — - redcurve A2π spectra in the channel aperture  - green curve A2π spectra registered by the set-up

  25. Conclusions VILLARS 2004 CERN SPS and PS Committee L. Nemenov25 September 2004 Present low energy QCD predictions forππand πKscattering lengths Expected results of DIRAC ADDENDUM at PS CERN DIRAC at SPS CERN

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