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Grigoriev Dmitry , BINP (on behalf of the CMD-2 and SND collaborations)

The recent results of the study of the hadronic production with the CMD-2 and SND detectors at the VEPP-2M collider. Grigoriev Dmitry , BINP (on behalf of the CMD-2 and SND collaborations). Outline. Introduction e + e -  kaons e + e -  pions Electromagnetic processes Conclusion.

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Grigoriev Dmitry , BINP (on behalf of the CMD-2 and SND collaborations)

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  1. The recent results of the study of the hadronic production with the CMD-2 and SND detectors at the VEPP-2M collider Grigoriev Dmitry, BINP (on behalf of the CMD-2 and SND collaborations)

  2. Outline • Introduction • e+e- kaons • e+e- pions • Electromagnetic processes • Conclusion

  3. VEPP-2M collider CMD-2 1992-2000 SND 1995-2000

  4. The Cryogenic Magnetic Detector (CMD-2) 1 - vacuum pipe, 2 - drift chamber, 3 - Z-chamber, 4 - main solenoid, 5 - compensating solenoid, 6 - endcap calorimeter, 7 - barrel calorimeter, 8 - range system, 9 - flux return yoke, 10 - storage ring lens.

  5. The Spherical Neutral Detector(SND) 1 - vacuum pipe, 2 - drift chambers, 3 - scintillation counter, 4 - light guides, 5 -PMTs, 6 - NaI(Tl) crystals, 7 - vacuum phototriodes, 8 - iron absorber, 9 - streamer tubes, 10 - 1cm iron plates, 11 - scintillation counters, 12 - storage ring lens, 13 - bending magnets.

  6. e+e-KLKS, KS+- (CMD-2) • 2E=1.0-1.04 GeV L=2 pb-1, N=2.7105 0(KLKS )=1413624 nb m=1413624 MeV/c2 =4.2800.0330.025 MeV systematic error in (e+e- KLKS ) 1.7% • 2E=1.05-1.38 GeV, L=5.8 pb-1, N=103 systematic error in (e+e- KLKS ) 5-10% solid curve is VDM with (770),(783),(1020) + X dash curve is VDM with (770),(783),(1020) only

  7. Systematic source Shift, keV Error, keV Beam energy measurement 13 ¸ 19 Energy calibration model dependency 3 Radiative corrections to initial state - (80 ¸ 630) 2 ¸ 12 Beam energy spread correction + 3 0.3 Radiative corrections to final state - 6 6 Nonlinearity shift 60 ¸ 140 6 ¸ 15 Correction for pion decay in flight + 4 3 Background 4 Z-chamber thermal expansion 3 Selection criteria 6 Fit bounds 8 Charged pion mass uncertainty 0.04 Neutral Kaon Mass Measurement at CMD-2 (preliminary) Resonant depolarization beam energy measurement Systematic due to initial state radiative corrections, beam energy measurement and nonlinearity shift are energy dependent

  8. e+e-K+K- Separation of kaons: CMD-2 - dE/dX in DC SND - the distribution of the energy deposition in the calorimeter Different detectors, different methods, but good agreement! systematic error in (e+e- K+K- ) 6% Cross section can not be described by (770),(783),(1020) only (solid curve)

  9. e+e-+-0 (SND) Nevents  1.5106 Fit: A() + A() + A() + A(’) + + A(’’) + A(e+e-0 )

  10. e+e-+-0 (SND) Results of fit best fit indication of ?

  11. e+e-0 ,0 (CMD-2) • limits on the cross sections of the direct processes s1/2, MeV , nb (90% CL) 00 (non-0)0 920-100 0.07 0.13 1934-1200 0.11 0.06 1200-1300 0.09 0.14 1300-1380 0.07 0.10 • limits on the radiative transition (1300-1380 MeV) final state meson , nb (90% CL) 00 f0(600) 0.19 f0(980) 0.05 f2(1270) 0.23 0 a0(980) 0.05 a2(1320) 0.70 fit with (770), ’(1450) don’t need ’’(1700) good agreement with SND data

  12. e+e-4 e+e-0 ,+-0 e+e-2+2- CMD-2 data in 4 channel is lower! After reanalysis CMD-2 data agrees with SND data will agree after reanalysis in +-20 also?

  13. e+e-0 0 Fit results Model g,Branching 1052/ndf GeV-1 00 00  with  16.41.4 19/28 no  18.91.1 27/28 other 17.0 0.4 0.6 7.22.5 experiments (e+e-0 ,0 (GAMS) at E>920 MeV) Model with  is better consistent with other experimental results red curve - fit with  blue curve - fit without 

  14. e+e-+-,  (SND) First data on the cross section below 1300 MeV! Nevents350 Systematic error  0.04 nb Good agreement with CMD-2 data (e+e-+-, +-0)

  15. e+e- (SND) black curve - fit with  red curve - fit without  Data Br() Br() PDG 2002 (8.71 0.4)% (7.9  2.0)*10-4 (4.5  0.5)*10-4 (charged) SND 2003 (9.34  0.15  0.31)% (5.15  1.16  0.73)*10-4 (30% of statistics) preliminary (9.18  0.10  0.30)% (4.41  0.82  0.60)*10-4 ( all statistics)

  16. e+e- e+e- (CMD-2) • Br( e+e- )= (8.7±0.9 ±0.5) 10-4 • Br( e+e- ) < 3 10-5 (90% C.L)

  17. Conclusion • VEPP-2M has been stopped at 2000 but new data still arrives • Large statistics and small systematic errors • Only left shoulders of the excited ,, are seen VEPP-2000 will give possibility to study them

  18. VEPP-2000 • round beams • Ec.m. up to 2 GeV • L up to 1032 cm-2s-1

  19. Neutral Kaon Mass Measurement at CMD-2 (method)

  20. e+e-+- 0 0 0 not 0 Total cross section

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