On nuclear states of ƞ ( and K - ) S. Wycech NCBJ Warsaw 1) Introduction 2) Non-mesic decay modes

Why do we study these bound states ? 1)Conservatism of the human mind 2) A new binding mechanism

Eta mesic   K mesic nuclei Similar binding mechanism : an external state a resonance N: N (1535) KN: Λ(1405),Σ(1385) above threshold below threshold

ƞ N ; N (1535) external quark state  K matrix ~1/(E-E o ) threshold effect, weak subthreshold absorption

Essential problem : continuation from physical region to resonant region is parameter unstable Σ (1385) Λ(1405) KN ( experiments ) indirect look under threshold Experiments : Σπ- final state spectra bound K-meson -K atoms, nuclear capture Models : effective ( chiral ) approach, K matrix + dispersion relations

Few nucleon systems

Signal from (d, ƞ ) Uppsala

Signal from ( 3 He, ƞ ) Saclay,Uppsala,Juelich

Signal of ( 4 He, ƞ ) N. Willis

Many quasi-bound nuclear ƞ states predicted No convincing experimental evidence ?

Signal of ( 4 He, ƞ ) in a decay process DD  ( 4 He ƞ )  3 He π- p Wasa –COSY 11 Phys Rev 87 Pawel Moskal

No clear signal > 30 nb

Cross section DD  3 He π- p CRUDE Estimate BS wave function Φ ~ exp -1/2(p ƞ R) 2 On shell ƞ formation I amplitude I experiment Off shell extension of ƞ formation operator ~ Φ Decay operator expressed by width ( 4 He ƞ ) formation σ ~4 nb at the peak within experimental limits W.Krzemien, SW

problems 1)Interference is difficult to calculate 2)The 3 He π- p decay mode may be overestimated multinucleon non-mesic decays ?

Non-mesic ƞ NN decay modes pn  pn ƞ pp  pp ƞ, pn  d ƞ  weak absorptive optical Wnn(0) = 1 MeV, Inn=0 4 MeV,Inn=1 Fairly small in nuclei, noticeable in 4 He

KLEO/AMADEUS RESULT preliminary : courtesy Oton Vazquez-Doce, details Laura Fabbietti K - He  p Σ 0, X GeV M(p Σ 0 ) Kp p  Σ p calculable Multinucleon captures dominate

KNNN capture mode step 1 (K - p  Σ π ) ; ƞ N  π N step 2 π NN  NN Δ region known input P wave needed

Captures broadening nuclear states of ƞ mesons pn  pn ƞ pp  pp ƞ, pn  d ƞ  weak absorptive optical Wnn(0) = 1,4 MeV ( Inn=0,1) K-matrix for N ƞ, optical potential for π NN  W nnn (0)≈ 10 MeV in Helium π

This broadening applies to ƞ ’ π N  ƞ ’ N ~ 100 μ bn, slow ƞ ’ π NN  NN S,P resonances in π N 1650, 1720 M eV Absorption may be sizeable in He, C = 3 α

Summary Three nucleon non-mesic processes In K-NNN ƞ -NNN In dense nuclei α, C= 3 α Induce addtional some 10 MeV level broadnings Good quantification required