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Anomalous Σ + emission following K - capture in nuclei

Anomalous Σ + emission following K - capture in nuclei. Kristian Piscicchia- Frascati/Rome. Sławomir Wycech - Warsaw, NCNR. Unnoticed discoveries. M. Agnello … FINUDA Collaboration The A(K - stop , π± Σ ∓ )A′

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Anomalous Σ + emission following K - capture in nuclei

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  1. Anomalous Σ+ emission followingK- capture in nuclei Kristian Piscicchia- Frascati/Rome Sławomir Wycech - Warsaw, NCNR

  2. Unnoticed discoveries M. Agnello … FINUDA Collaboration The A(K -stop, π± Σ∓ )A′ reactions on p-shell nuclei Phys.Lett. B704 (2011)474 D.F.Keane –Thesis Dublin – 1981 Staronski, s.w. J.Phys G .13(1987)1361

  3. ΣHyperon momenta from K- 6LiFINUDA Low momentum peak only with Σ+

  4. Expectation π • K A ΣA’ quasi bound large object decays with „zero” momentum,propagates large distance

  5. OPTION - Gamov states Nuclear +Coulomb potential States in continuum – decaying conditions α - decay Σ+ born inside a nucleus

  6. Gamov states of Σ+ In light nuclei : exist if Σ+ is almost bound the peak profile ~ Fourier transform of wave function

  7. Densities Carbon Nucleus, accessible atomic state 2p Gamov state10^(-19) sec 5 10 fm

  8. Σ+Gamov States in 11B K- 12 C  π- (Σ+ 11B ) AMADEUS - pending Coulomb barrier ~2.3 MeV „well localised” states E G ( 0 - 0.2 ) MeV

  9. Σ+ ,11B density in Gamov states E =.11 MeV , no absorption E =.13 MeV , absorption W o =4 MeV absorption + barrier pulls hyperon in

  10. Gamov states - Fourier transforms11B - no absorption E=.01MeV E=.11MeV

  11. Gamov states - Fourier transforms11B – with absorption W=4MeV , Γ~3MeV E=.056MeV E=.134MeV

  12. Shape of the low momentum peak P(p) = p <|Φ(q)Gamov|2 1/ [ EΣ +ER – EGamov ] 2 > = phase space <*Fourier transf *propagator> phase sp average High momenta cut by Φ(q) and propagator

  13. Expected low Σ+momenta peaks in AMADEUS K- Carbonno absorption ……………......Wo= 4 MeV

  14. Momenta in (Σ5He)no absorption ……….. Wo= 4 MeV

  15. Calculations of FINUDA peaks

  16. Extraction of nuclear parameters The existence of the peak determines potential well : if V= Vo ρ(r) 12Carbon (11B) Vo ~ -19±0.4 MeV 6Lithium (5He) Vo ~ -26±0.5 MeV Shape of the peak determines Σ-->Λ decay

  17. ALTERNATIVEΛN ΣN (virtual state) Offers Σ+ , Σ- asymmetry , but a very broad peak at low PΣ

  18. Conclusions Low energy Σ+ peak = Gamov state The position of maximum and shape fix Σ+ optical potential as quasi-bound state would do (how uniquely ?) New spectroscopy possible Comparison of the two peaks will give much more information.

  19. Thank you

  20. Anomaly of emission ratio Σ+π- / Σ- π +nuclear emulsion – D. Keane,D.Davis, Staronski J.Phys G .13(1987)1361

  21. Weak absorption / or final state + momentum resolution uncertainty

  22. Best fit to FINUDA

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