1. Mikhail Bashkanov Encounters with Di-Baryons from the ABC-effect to a Resonance in the Proton-Neutron System Wasa-at-COSY

2. Content 2

3. Double-pionic fusion 3 np np  

4. The ABC-effect 4 np np  

5. History of the ABC effect Low mass enhancement in M  Alexander Abashian, Norman E. Booth Kenneth M. Crowe, Phys. Rev. Lett. 5, 258 (1960) M.Bashkanov et. al, Phys. Lett. B637 (2006) 223-228 P. Adlarson et. al, Phys. Rev. C86 (2012) 032201 P. Adlarson et. al, Phys. Rev. Lett. 106 (2011) 242302

6. Two-pion production 6 N*    “”“”   T p < 1.5 GeV

7. Isospin Decomposition T. Skorodko et al., PLB 679 (2009) 30 N * (1440)   (1600) 7

8. Expectations in total cross section 8

9. 9 “ABC resonance”  70 MeV Total cross section pn  d  0  0 P. Adlarson et. al Phys. Rev. Lett. 106:242302, 2011  NN*(1440)

10. 10 Angular distribution in the peak J=1 J=3

11. Quantum numbers of the structure Antisymmetrization: J p =1 + or 3 + : if L ΔΔ =0 pn  d*  ∆∆  d  0  0 pn  d  0  0 pn  d  0  0 I=0,1I=0I=0,2 I=0 1+1+1+1+ 3+3+3+3+ 1 + excluded by  (  ). 3 + assigned 11

12. 12 t-channel  “ABC effect” M  for different energies

13. 13 Status of Theoretical Description pn  R    d     Δ Δ d π π p n I(J p ) = 0(3 + )

14. Isospin relations 14 I=0 I=1

15. 15 Total cross section pN  d  P. Adlarson et. al Phys. Lett. B721 (2013) 229

16. 16 M  in pN  d 

17. 17 M  in pN  d 

18. 18 M  in pN  d 

19. Isospin violation 19 +-+- 0000

20. 20

21. 21 pn  pp  -  0 ABC “expected”  Conventional process Conventional process +ABC P. Adlarson et al., arXiv: 1306.5130v1

22. 22

23. 23 3 + Resonance in np np L=2 n L=4

24. 24 Total pn cross-section SAID Devlin et al, PRD8, 136 (73) LisowskI et al, PRL49, 255(82)

25. 25 Expectations p n n p SAID SAID with resonance

26. 26 Expectation p n n p SAID

27. 27 Reality p n n p SAID

28. 28 pn Vector Analysing Power SAID

29. Conclusion 29

31. Multiplet 10  10=35  28  27  10   *  *  Y(  )=2 I(  )=0 Kim Maltman, Nucl. Phys. A501 (1989) 843

32. Mirror dibaryon 32   I(J p ) = 0(3 + ) d* u u u d d d I(J p ) = 3(0 + )   u u u u u u

33. Mirror Multiplet 10  10=35  28  27  10   *  *  *+  *  *  *+   *  *+  *  **   ++ ----

34. Beam polarization 0 Polarization 2 Polarization 1

35. 35 Total cross section pp  d  +  0 Shimizu et al. F. Kren et al.

36. 36 Total cross section pn  d  0  0

37. 37 Total cross section pn  d  +  -

38. 38 Total cross section pn  d  +  -

39. Kinematics 39 Proton spectator proton neutron dp  np + p sp

40. 40 Status of the ABC Resonance decay channel branching status ------------------------------------------------------------------------ d      15 % observed d     25 % observed pp     7 % observed np     (12 %, predicted * ) data analysis WASA np     (31 %, predicted * ) data analysis HADES np (10 %, predicted) data analysis WASA * Fäldt & Wilkin, PLB 701 (2011) 619 * Fäldt & Wilkin, PLB 701 (2011) 619 Albaladejo & Oset, arXiv:1304.7698 [nucl-theor] Albaladejo & Oset, arXiv:1304.7698 [nucl-theor]