1. Observation of Σ + trapping in Gamov states
Sławomir Wycech - Warsaw
Kristian Piscicchia – Rome
For AMADEUS

2. Σ Hyperon momenta from K- 6Li FINUDA
Low momentum peak only with Σ+

3. AMADEUS

4. AMADEUS

6. Expectation π
K A
Σ A’
quasi bound large object decays with „zero” momentum,propagates large distance

7. OPTION - Gamov states Nuclear +Coulomb potential
Decaying States in the continuum –
Outgoing wave conditions

8. Gamov states of Σ + In light nuclei - exist if Σ + is almost bound
Solutions for real potential Vculomb + Vnucl

9. Densities in Gamov states
top C mid B bottom He

10. Capture in C Gamov states in B
E [MeV] Rms [fm] Γ [keV]
Limits Σ potential well depth to +/- 0.4 MeV
Trapping time ~ 10^4 Λ(1405) lifetime

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

12. Technical description of Gamov
states

15. Advantages of Gamov states
Semi - eqivalence to hypernuclei
Studies of Kn amplitudes

17. Hyperon momentum spectra
Magnitude of Gamov peak depends on T(Kn ->Σπ) at a fixed energy

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 gives
more information.

19. Advantages of Gamov peaks
Peak maximum, width
-> fixes Σ + nuclear well depth to 0.4 MeV
Peak strength
-> fixes |T(K- p -> Σ+ π- )|
at given energy |T(~1410)| relative to
an average <|T|> in ( ) MeV region

20. Thank you