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Study of few-body problems at WASA

Wasa-at-Cosy. Study of few-body problems at WASA. Content. General overview  decays dd   0 -mesic helium The ABC effect d . See talk A. Winnemoeller Friday 18:40. The ABC effect. ABC effect. Experimentally low-mass enhancement in M 

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Study of few-body problems at WASA

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  1. Wasa-at-Cosy Study of few-body problems at WASA

  2. Content • General overview •  decays • dd  0 • -mesic helium • The ABC effect • d • 

  3. See talk A. Winnemoeller Friday 18:40

  4. The ABC effect

  5. ABC effect • Experimentally • low-mass enhancement in M • observed in many fusion reactions • accompanied with ΔΔ excitations • Theoretically • originates from t-channel ΔΔ excitation • expected double-hump structure in M (not supported by experimental observations)

  6. pn d00

  7. 2D x-section

  8. t - channel  Total x-section pp d+0 pn d+- pn d00 (+0)=(I=1) (+-)=0.5(I=1)+2(I=0) (00)=(I=0)=0.2(I=1)

  9. Total x-section  mass d threshold

  10. Total x-section  mass d threshold

  11. Δ π d π Δ Δ π p d n π Δ Qualitative description p n +

  12. Total xsection slices: qualitative description

  13. Total xsection slices: qualitative description

  14. Total xsection slices: qualitative description

  15. Total xsection slices: qualitative description

  16. Total xsection slices: qualitative description

  17. Total xsection slices: qualitative description

  18. Total xsection slices: qualitative description

  19. Total xsection slices: qualitative description

  20. Total xsection slices: qualitative description

  21. Total xsection slices: qualitative description

  22. Total xsection slices: qualitative description

  23. Total xsection slices: qualitative description

  24. Total xsection slices: qualitative description

  25. Total xsection slices: qualitative description

  26. Total xsection slices: qualitative description

  27. Total xsection slices: qualitative description

  28. Total xsection slices: qualitative description

  29. Total xsection slices: qualitative description

  30. Total xsection slices: qualitative description

  31. Total xsection slices: qualitative description

  32. Dalitz plot (peak region)

  33. pn  d00 and pp  d+0 (p-spectator) (n-spectator)

  34. +0 invariant mass Tp  1GeV pp  2He p0p0 pp  d p+p0

  35. ABC in 3He

  36. pd3Heππ, Tp=0.89 GeV (I=0,1) (I=0) M.Bashkanov et. al, Phys. Lett. B637 (2006) 223-228

  37. dd  4He p0p0 : Invariant Mass p0p0 1.117 GeV 1.05 GeV 0.9 GeV See talk A. Pricking Tuesday 17:30

  38. Conclusion • ABC effect due to narrow s -channel resonance with • More data next year • -decays • dd  0 • dd  () 3He+N+

  39.  * *  Thank you

  40. Outlook • Finish data analysis • Perform Partial Wave Analysis (JPC) • Do we need polarization? • Analysis of • Measure • Measure pn elastic scattering

  41. 1010=35282710 Multiplet Y()=2 I()=0  * *  Kim Maltman, Nucl. Phys. A501 (1989) 843

  42. Tp = 1.0 GeV : 70 kEvents(80%) Tp = 1.1 GeV : Tp = 1.2 GeV : 26 kEvents(15%) Tp = 1.3 GeV : Tp = 1.4 GeV : 47 kEvents(25%) Data analyzed so far

  43. Angular distribution (in the peak)

  44. Dalitz plot

  45. Additional corrections and cross-checks

  46. Angular distribution (in the peak)

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