Transcript Slajd 1

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
ȠN: N (1535)
above threshold
KN: Λ(1405),Σ(1385)
below threshold
ƞN
;
external quark state 
N (1535)
K matrix ~1/(E-Eo)
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 ( 3He ,ƞ)
Saclay,Uppsala,Juelich
Signal of (4He ,ƞ)
N. Willis
Many quasi-bound nuclear ƞ
states predicted
No convincing experimental evidence ?
Signal of (4He ,ƞ)
in a decay process
DD  (4He ƞ ) 
3He
π- p
Wasa –COSY 11 Phys Rev 87
Pawel Moskal
No clear signal > 30 nb
Cross section DD 
3He
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
(4He ƞ) formation σ
~4 nb at the peak
within experimental limits
W.Krzemien, SW
π- p
problems
1) Interference is difficult to calculate
2) The 3He π- p decay mode may be
overestimated
multinucleon non-mesic decays ?
Non-mesic ƞNN decay modes
pn  pnƞ
pp  ppƞ , pn  dƞ
 weak absorptive optical
Wnn(0) = 1 MeV , Inn=0
4 MeV ,Inn=1
Fairly small in nuclei, noticeable in 4He
KLEO/AMADEUS RESULT
preliminary : courtesy Oton Vazquez-Doce, details Laura Fabbietti
K- He  p Σ 0 , X
2.15
Kp p  Σ p
2.35
GeV
calculable
Multinucleon captures dominate
M(p Σ 0 )
KNNN capture mode
step 1
step 2
(K- p  Σπ ) ; ƞN  π N
π NN  NN
Δ region
known input
P wave needed
Captures broadening nuclear
states of ƞ mesons
pn  pnƞ
pp  ppƞ , pn  dƞ
 weak absorptive optical
Wnn(0) = 1,4 MeV ( Inn=0,1)
Ƞ
K-matrix for Nƞ,
optical potential for π NN
 Wnnn(0)≈ 10 MeV
in Helium
π
Ƞ
This broadening applies to ƞ’
π N  ƞ’ N
π NN  NN
~ 100 μ bn , slow ƞ’
S,P resonances in π N
1650, 1720 M eV
Absorption may be sizeable in He,
C = 3α
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