nuclear captures of antiprotons

1. nuclear captures of antiprotons in the context of PUMA proposal S. Wycech, NCBJ , Warsaw

2. Content 1) Difficulties in understanding of antiprotonic atoms radiochemical studies of p absorption in nuclei pionic measurements • Some properties of optical N-Nbar, Nbar-nucleus potentials 3)Baryonia -their significance for PUMA Conclusion : good N-Nbar potential is useful tounderstand future PUMA results

3. testing nuclear densities via antiprotonic atomic shifts and pbar captures in flight capture lower level ρ upper level cold capture

4. one needs to input something Absorption rate Γto measure For nuclear physics studies Input : ψ = state of capture Rn/p = pbar-n capture / pbar -p capture Ps = final state interaction of pions output neutron haloes ρn To test subtreshold Interaction pbar - N nucleons atoms : ρ,ψ known , P=1 measure level shifts, widths in low overlap states output Im t , Re t

5. Uncertainties / puzzles in LEAR data atomic and inflight captures cold capture „Secret deal” A.T. Presents success of Munich-Warsaw group S.W. Presents dark side

6. Rn/p capture ratios in nuclei R.Bizzari , F.Balestra, W.Bugg XX century carbon 0.63 Energy dependent ? Density dependent ? N-Nbar potential needed reliable subthreshold scattering amplitudes

7. (Pbar N) center of mass energy below threshold in atomic states -40 -20 0 MeV • P • D T E=-Binding -Recoil He 4

8. Puzzles

9. Atomic anomaly

10. Radiochemical measurements of residual nuclei after p-bar absorption PS203 neutrondensity /proton density 20 measurements ↓ ↓ ↓ Lower level , Upper level , cold capture 96 Zr 1.61(6) 1.91(6) 2.6(3) 116 Cd 2.60(35) 3.33(37) 5.6(5) 124Sn 3.09(7) 3.43(25) 5.4(7) ANOMALIES ( 4 cases) ======================================== 106 Cd 1.65(80) 5.13(80) 0.5(1) proton halo not acceptable by nuclear models Large differences of neutron and proton separation energies

11. Neutron halo looks like proton halo neutron proton Interaction strength binding energies comparable different bindings simulate proton halo -15 -5 MeV

12. Extraction of spin averaged N-pbaramplitudes f p interactions with valence nucleons f( - EB – ERECOIL ) - 33 -15 -7 - 0 MeV 4He 3He 2H H Quasi free amplitudes in upper levels ( very low atomic nuclear overlap )

13. Level shifts in upper levels Small overlap Γ, ε < 100 eV ε-iΓ/2 = 2π/μ ʃdr φψ(r )[ a0(E) + 3a1(E) ∂∂ } φψ(r) φ nucleon wave functions ψ atomic wave function Energy dependent amplitudes : Spin averaged S,P waves Higher order terms ~5%

14. Baryonium in 33P1 state Paris potentials 1999 and 2009 -15 MeV -5 MeV Test in light antiprotonic atoms

15. 2P level shifts

17. Proper position of 33P1 bound state Paris potentials 1999 and 2009 -15 MeV -5 MeV removes cold capture and upper level anomalies

18. Problems are understood we have a good handle of subthreshold amplitudealso spin structure Paris N-Nbar potential requires refinment to generate precisely both 1S0 and 33P1 quasibound states

19. XX century pionisation experiments Bubble chambers M.Wade,V.G.Lind , W.M. Bugg C, N, Pb targets

20. Pion multiplicities freemeasured in nuclear capture n = 2 3 4 5 6 7

21. Charge pion multiplicities a phenomenological description M.Wada, S.W.

22. aborption and charge exchange reactions primordial p n measured channel charges • Q: -3 -2 -1 0 1 2 3

23. Phenomenological pion absorption and charge exchange parameters π+ absorption probability ~0.2 π- absorption probability ~0.3 π- πo rate ~0.1 π+  πo rate ~0.1 Indicates f.s. absorption on a correlated NN pair

24. An analysis of nuclear capture,extraction of neutron haloes cold capture = weak excitations of final nuclei two numbers measured ( N-1 ) /( Z-1) ratio  halo cold capture / total capture ~10 %  initial state PUMA = charge pion distribution up to 6 numbers measured , tremendous advantage

25. Relation of „dark angle” and number of emitted pions N+-  Ω  Rcapture

26. N+-  Ω  Rcapture

27. Rcapture = c + 1:35(10) fm Cugnon Width of the capture layer (R-0.5 , R+0.5 ) fm

28. W.Bugg s.w.

29. The full analysis • Phenomenological description of primordial and measured pion multiplicity distributions • Extraction of pion absorption and charge exchange parameters • Extraction of capture region • Neutron halo extraction • ------------------- quantum refinement • Understanding of parameters , check against atomic cascade • Errors of neutron halo measurements

30. Thank you

31. appendix

33. Potential in 11S Paris Paris,Bonn, Paris,K-W, D-R, B-P potentials To discern – go under threshold

35. BES: X(1869) X(2170)

36. Below threshold X(1835) is an interference of „extended „ bound statePARIS POTENTIAL INTERPTETATION

37. 1S amplitude below threshold broad state , strong Γ(E) dependence oooooooooo ATOMIC REGION

38. Guidelines : Paris N-Nbar potential model 2009: 4000 dataM. Lacombe, B. Loiseau, S.W. …C79(09)054001 Model dependence is sizeable

39. ATOMIC HINTS

40. 11S summary Paris potential approach ● X(1835) and X(1876) Interpreted as the same effect of quasi –bound state ● generated by conventional meson exchange forces ● X(2170) shape resonance generated by conventional meson exchange forces + assumption that system expands slightly during radiation