K - 4 He  3 He, π-, Λ and some consequences S. Wycech – NCBJ – Warsaw

Motivation K - n  Λ π - In Helium : the easiest reaction but not understood

THE MOTIVATION Bunnell..Phys Rev D2(1970) 1/3 not explained

Origin of high momenta 1)short range correlation in initial n- 3He wave (zero in e.m. form factor) 2) High momenta of K meson 3) P wave interaction

Pion energy, with Σ atomic S-wave preferred No high energy excess

Two basic modes

The aim known KN  Σ(1385) Extract KN  Λ π S- wave some 40 MeV below threshold (binding + recoil )

Recoupling parameter M K /(M K +M n )  Σ(1385) s p p s

The result from total momentum spectra KLOE- stopped and in-flight

Conclusions, questions 1)The precision of this determination ? 2)If true, sizable effect of P-wave 3)If true, sizable effects of P-wave in (KPP), (KNNN)….. ? 4) Decay modes via P wave interactions

CORRECTIONS, UNCERTAINTIES Σ  Λ Conversion Final state interactions Helium wave function, K wave function

Σ  Λ conversion Removed from data but Λ  Λ a problem

Pion momentum, Λ Separation of events done by experiment by ( P Λ, P π ) plane

KLOE –Kristian Piscicchia direct inelastic

The separation is precise K.P.

Final State Interactions separable, range (from Hiyama) E B 0 + Hypernucleus f( 3 He – Λ) E B Im f fm Re f 5– MeV Q CM

Region strongly affected by 3He-Λ hypernucleus

Conclusions, questions 1)sizable effects of P-wave in K capture ! 2)Sizable effects of P waves in (KPP), (KNNN)….. ? 3) Decay modes via P wave interactions ?

With strongly bound KPP ( MeV) Σ(1385) is attractive but weak With weakly bound KPP ( MeV) Σ(1385) is repulsive and strong Proper 3 body x 3 channel calc. needed

Suggestion It is worth-while to study K - p p  Λ π 0 p decays ( Λ π 0 p ) correlation /invariant mass in K capture