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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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Wasa-at-Cosy Study of few-body problems at WASA
Content • General overview • decays • dd 0 • -mesic helium • The ABC effect • d •
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)
t - channel Total x-section pp d+0 pn d+- pn d00 (+0)=(I=1) (+-)=0.5(I=1)+2(I=0) (00)=(I=0)=0.2(I=1)
Total x-section mass d threshold
Total x-section mass d threshold
Δ π d π Δ Δ π p d n π Δ Qualitative description p n +
pn d00 and pp d+0 (p-spectator) (n-spectator)
+0 invariant mass Tp 1GeV pp 2He p0p0 pp d p+p0
pd3Heππ, Tp=0.89 GeV (I=0,1) (I=0) M.Bashkanov et. al, Phys. Lett. B637 (2006) 223-228
dd 4He p0p0 : Invariant Mass p0p0 1.117 GeV 1.05 GeV 0.9 GeV See talk A. Pricking Tuesday 17:30
Conclusion • ABC effect due to narrow s -channel resonance with • More data next year • -decays • dd 0 • dd () 3He+N+
* * Thank you
Outlook • Finish data analysis • Perform Partial Wave Analysis (JPC) • Do we need polarization? • Analysis of • Measure • Measure pn elastic scattering
1010=35282710 Multiplet Y()=2 I()=0 * * Kim Maltman, Nucl. Phys. A501 (1989) 843
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