1. 1

2. Àngels Ramos Recent Progress in Many-Body Theories 14 Barcelona, July 16-20, 2007

3. 3 Strangeness nuclear physics is a field that emerged after the discover of the strange particles ( ,K -,K + ) in 1947. It has experienced an steady progress in major laboratories across the world CERN (Europe) Brookhaven (USA) KEK (Japan) Jlab (USA) FiNUDA@DAPHNE (Italy) MAMIc@Mainz (Germany) J-PARC (Japan) HypHI@FAIR PANDA@FAIR Past (1970-2005) Present Future 2008 2012? (in lates 50’s  emulsions, from 70’s  colliders)

4. 4 This field studies nuclear phenomena involving one or more strange particles (containing the s quark or antiquark) This talk will focuss on: HYPERNUCLEI KAON PHYSICS NEUTRON STARS (briefly)

5. 5 The hypernuclear chart as of 1989 And almost 20 years later: basically the same hypernuclei … but measured with better statistics and energy resolution  excited hypernuclear states are now available! HYPERNUCLEI

6. 6

7. 7 (K -,  - ) (  +,K + ) ( ,K + )  A AA PRODUCTION OF HYPERNUCLEI (collider era) Strangeness exchange: CERN, BNL, KEK, DAPHNE Associated production: BNL, KEK Electroproduction: JLab

8. 8 n    Fixing the indicent beam energy and the detection angle, the energy of the emitted meson (K + ) is directly related to the  binding energy H. Hotchi et al., PRC64 (2001) 044302

9. 9 UcUc RNRN See e.g. D.J. Millener, C.B. Dover and A. Gal, Phys. Rev. C38 (1988) 2700

10. 10 6 MeV ~6 MeV  neutron spin orbit: 6 MeV  neutron PLUS  hyperon spin orbit: ~ 6 MeV W. Brückner et at, Phys. Lett. 55B(1975)107 Spin-orbit potential for the  hyperon is very weak! Spin-orbit potential

11. 11 Isospin  = 0 Isospin  = 1 Th. A. Rijken, Y. Yamamoto, V.G.J. Stoks, PRC59 (1999) 21 B. Hozelkamp, K. Holinde, J. Speth, NPA500 (1989) 485 M.M. Nagels, Th.A. Rijken, J.J. de Swart, PRC40 (1989) 2226 Juelich A,B Nijmegen NSC89 Nijmegen NSC97 Fitted to: 4300 data on NN scattering 35 data on YN scattering + SU(3) YN interaction (bare) J. Haidenbauer, U.G. Meissner, PRC72 (2005) 044005 Th. A. Rijken, Y. Yamamoto, V.G.J. Stoks, PRC73 (2006) 044008 H. Polinder, J. Haidenbauer, U.G. Meissner, NPA779 (2006) 244Juelich (EFT) Nijmegen ESC04

12. 12 Total cross sections for YN scattering

13. 13 Effective YN interaction (G-matrix: microscopical approach) B1B1 B5B5 B3B3 B2B2 B6B6 B4B4 B1B1 B3B3 B4B4 B2B2 G B1B1 B3B3 B4B4 B2B2 V =+ BiBi BiBi BjBj Coupled channel problem! S=-1:  N,  N S=-2: ,  N,  I. Vidaña, A. Polls, A. Ramos and M. Hjorth-Jensen, Nucl. Phys. A644 (1998) 201 I. Vidaña, A. Polls, A. Ramos and H.-J. Schulze, Phys. Rev. C64 (2001) 044301 Medium effects: Pauli blocking Baryon dressing YN models explain the depth of the  nucleus potential the spin-dependence varies considerably in the different YN models  apreciable differences in the spectra of hypernuclei!

14. 14 New info from precise  -ray (coincidence) experiments ! BNL E930, Tamura speakperson H. Akikawa et al, PRL88 (2002) 082501 The new generation of experiments performed in the last 5 years have disclosed many interesting aspects of hypernuclear structure  crucial information for constraining the YN interaction! Nijmegen NSC97f  spin-orbit splitting in 9  Be: 150-200 keV E.Hiyama et al., PRL85 (2000) 270 Nijmegen ESC03  spin-orbit splittings in 9  Be: ~ 80 keV

15. 15 Sigma-hypernuclei Narrow  states in spite of  N   N conversion? R. Bertini et al, Phys.Lett 83B (1979) 306 S. Bart et al, Phys. Rev. Lett 83 (1999) 5238 Not confirmed with better statistics!

16. 16 (K -,  - ) (  +,K + ) ( ,K + )  A AA WEAK HYPERNUCLEAR DECAY Weak decay of hypernuclei allows to obtain new and complementary information on the properties of hypernuclei and the weak YN interaction Hypernuclear structure

17. 17  N  N N N  MESONIC NON-MESONIC  n :  n   n n  p :  p   n p   :       p k N ~100 MeV/c < k F   :       n Pauli blocked! k N ~400 MeV/c  2 :  N N  n N N  N N ~~~ N N N k N ~340 MeV/c  T =  M +  NM =   +   +  n +  p +  2 WEAK HYPERNUCLEAR DECAY

18. 18 free  :   free = 3.8 10 9 s -1 Hypernuclear width:  T ~   free Observed decay rates BNL, 91 KEK, 95, 98 Jülich, 93, 97, 98   free /   free =1.78 ~ 2   I=1/2 !   free :      p   free :      n

19. 19 The emerging nucleons are very energetic and this process is not sensitive to nuclear structure details Q ~ m  - m N ~ 175 MeV  Ideal process to characterize the baryon-baryon weak interaction!  S=1  S=0 NON-MESONIC DECAY:  N  N N In particular, for processes having  S=1 (  N  NN), the PC amplitude is not masked by the strong interaction like in the case  S=0 (NN  NN) Both PC and PV weak amplitudes can be studied from hypernuclear weak decay Only the PV amplitudes are accessible W.M. Alberico and G. Garbarino, Phys. Reports 369 (2002) 1 E. Oset and A. Ramos, Prog. Part. Nucl. Phys. 41 (1998) 191

20. 20 Non-mesonic processes:  n :  n  n n  p :  p  n p weak interacction:  meson exchange: ,K, ,K*  quark models strong interaction between initial  N and final NN pair  Decay width  1 =  n +  p well reproduced by all models but…  not the ratio  n /  p !  OPE mechanism dominated by tensor transitions 3S1  3D13S1  3D1  N  NN Antisymmetry requires isospin I=0 nn pairs are in isospin I=1   n :  n  nn supressed in OPE!

21. 21 00.511.52 n/pn/p BNL, 91 KEK, 95 KEK, 02 BNL, 91 Theoretical models A. Parreño, A. Ramos and C. Bennhold, PRC 56 (1997) 339 D. Jido, E. Oset and J. E. Palomar, NPA 694 (2001) 525 K. Itonaga, T. Ueda and T. Motoba, PRC65 (2002) 034617 K. Sasaki, T. Inoue and M. Oka, NPA 669 (2000) 331... A challenge in hypernuclear weak decay for many years!

22. A realistic analysis of  n  p must consider: 1. The influence of the 2-nucleon induced decay (  2 ) N n =  p + 2  n + 2  2 N p =  p +  2 p p  n nn  n nn  p np 2. The final state interaction (FSI) of the primary nucleons A. Ramos, M.J. Vicente-Vacas and E. Oset, PRC55 (1997) 735-743; Erratum: ibid. C66 (2002) 039903 A. Ramos, E. Oset and L.L. Salcedo, PRC50 (1994) 2314 The primary nucleons produced in the weak decay continuously change energy, direction, charge and new secondary nucleons are emitted. Theoretical improvements

23. 23 Measuring distributions of NN pairs in coincidence permits a better determination of the ratio  n /  p. The more exclusive measurement of final states: Reduces contamination from the process  2 :  NN  NNN Eliminates some FSI effects Angular correlations  12 Energy correlations: T 1 +T 2 T1T1 T2T2 Experimental improvement: NN coincidences

24. Single proton spectra

25. Neutron spectrum

26. Angular correlation between n and p pairs

27. Kinetic energy correlations between np pairs

28. B.H. Kang et al., Phys. Rev. lett. 96 (2006) 062301

29. Without FSI and ignoring  2 : With FSI: N nn, N np : number of nucleon-nucleon per weak decay (after FSI) G. Garbarino, A. Parreño and A. Ramos, PRL 91, 112501 (2003) The  n /  p problem has been solved!  n  n n  p  n p

30. 30  + n  K +  New challenge in hypernuclear decay: Asymmetry 12 C   y: polarization axis KK p n 0.5 0 -0.5 E278 E462 E508 aa K. Sasaki, T. Inoue, M.Oka, Nucl. Phys. A707 (2002) 477 A. Parreño and A. Ramos, Phys. Rev. C65 (2002) 015204 W. Alberico, G. Garbarino, A. Parreño and A. Ramos, Phys. Rev. Lett. 94 (2005) 082501 (FSI)

31. An EFT study has revealed the dominance of an scalar (J=0) and isoscalar (I=0) contact term which is crucial to reproduce the small value of the asymmetry parameter a  This term can be interpreted as coming from the exchange of the broad  meson (J=0,I=0). M  ~ 450 MeV A. Parreño, C. Bennhold and B.R. Holstein, Phys. Rev. C70 (2004) 051601(R) D. Jido, E. Oset, J.E. Palomar, Nucl. Pys. A694 (2001) 525 Recent improvements: From a fundamental point of view, the  meson is dynamically generated from correlated two-pion exchange

32. OME OME+2  C. Chumillas, G. Garbarino, A. Parreño, A. Ramos,, e-Print: arXiv:0705.0231 [nucl-th]

33. 33 (ANTI)KAONS IN THE MEDIUM The K - feels attraction in the medium  Kaon condensation in neutron stars? D.B. Kaplan and A.E. Nelson, Phys. Lett. B175 (1986) 57 G. E. Brown and H. A. Bethe, Astrophys. Jour. 423 (1994) 659   ee 2 200 (MeV) KK 31 400 Kaons are bosons  a condensate of (anti)kaons would appear

34. Best fits to kaonic atoms seem to prefer U K ~ - 200 MeV at  0 K-K- A E. Friedman, A. Gal, and C.J. Batty, NPA 579 (1994) 518 Phenomenology:

35. 35 In the S=-1 strangeness sector   (1405) resonance 27 MeV below K - p thresold  Coupled-channel Bethe-Salpeter equation = + T ij = V ij + V il G l T lj MjMj BjBj BiBi V ij = MiMi  KK KN 125513311435 166317411814 (MeV) 1) 2) Microscopic theory: Implement Unitarity Take an elementary KN interaction (e.g. from Chiral Lagrangian)

36. 36 Since the pioneering work of Kaiser, Siegel and Weise [Nucl. Phys. A594 (1995) 325] many other chiral coupled channel models have been developed. E. Oset and A. Ramos, Nucl. Phys. A635 (1998) 99 J.A. Oller and U.G. Meissner, Phys. Lett. B500 (2001) 263 M.F.M. Lutz, E.E. Kolomeitsev, Nucl. Phys. A700 (2002) 193 C.Garcia-Recio et al., Phys. Rev. D (2003) 07009 M.F.M. Lutz, E.E. Kolomeitsev, Nucl. Phys. A700 (2002) 193 more channels, next-to-leading order, Born terms beyond WT (s-channel, u-channel), Fits including new data … B.Borasoy, R. Nissler, and W. Weise, Phys. Rev. Lett. 94, 213401 (2005); Eur. Phys. J. A25, 79 (2005) J.A. Oller, J. Prades, and M. Verbeni, Phys. Rev. Lett. 95, 172502 (2005) J. A.Oller, Eur.Phys.J.A28, 63 (2006) B. Borasoy, U. G. Meissner and R. Nissler, Phys.Rev.C74, 055201,2006.

37. 37 K in a nuclear medium: The presence of the  (1405) resonance makes the in-medium KN interaction to be very sensitive to the particular details of the many-body treatment.  we’d better do a good job! (SELF-CONSISTENCY) Pauli blocking free (repulsive) medium (attractive) Self-consistent kaon dressing pion and kaon dressing K K K K K K    Weise, Koch Ramos,Oset Lutz

38. 38 and kaonic atom data are also well described! S. Hirenzaki et al., PRC61 (2000) 055205 A. Baca, C. García-Recio, J. Nieves, NPA 673 (2000) 335 Microscopic models  moderate attraction for the K-nucleus potential! A. Ramos and E. Oset, NPA 671 (2000) 481 Kaonic atom data are not sensitive to the K-nucleus potential at  0  only the nuclear surface (up to  ~  0 /4) is explored!

39. 39 Deeply bound kaonic nuclear states? In spite of te relatively shallow potentials (U K = -70 to -50 MeV) predicted by various self-consistent many-body approaches: there has been high expectations about the existence of deeply bound kaonic states triggered by the work of Akaishi and Yamazaki Y.Akaishi, T.Yamazaki, Phys.Rev.C65,044005 (2002) Simple local KN-  potential: +simplified many-body treatment (self-consistency ignored) Subsequent few body calculations (variational): Y.Akaishi, A. Dote, T.Yamazaki,Phys.Lett.B613, 140 (2005)  nucleus shrinked enourmously (  (0)~10  0 !) and B K = 169 MeV in ppn-K - (T=0) B K = 194 MeV in pnn-K - (T=1) A. Ramos, E. Oset, Nucl. Phys. A671, 481 (2000) L. Tolós, A. Ramos, E. Oset, Phys. Rev. C (2006) J. Schaffner-Bielich, V.Koch, M. Effenberber, Nucl. Phys. A669, 153 (2000) A.Cieply, E.Friedman, A.Gal, J.Mares, Nucl. Phys. A696, 173 (2001)

40. 40 The KEK proton missing mass experiment: T. Suzuki et al., Phys. Lett. B597, 263 (2004) S 0 is a tribaryon with S = -1 and T = 1 If interpreted as a pnn-K - bound system…  B K = 197 MeV formation rate: 1% per absorbed K - But withdrawn in a recent reanalysis of data (Iwasaki, HYP06) arXiv:0706.0297[nucl-ex]

41. 41 Conventional view: K - absorption by two nucleons leaving the other nucleons as spectators E. Oset, H. Toki, Phys. Rev. C74, 015207 (2006) do not absorbe energy nor momentum from the probe some Fermi motion broadening is possible,  it would explain the ~60 MeV/c peak spreading

42. 42 The FINUDA proton missing mass experiment: M. Agnello et al, Nucl. Phys. A775, 35 (2006) This view is consistent with the observation by the FINUDA collaboration of a peak in the proton missing mass spectrum at ~ 500 MeV/c (from K - absorbed in 6 Li) A study of the angular correlations (p and  - are emitted back-to-back) allow them to conclude that the reaction: in 6 Li is the most favorable one to explain their signal 6 Li 4 He

43. 43 Another FINUDA experiment: measuring the (  p) invariant mass M. Agnello et al. Phys. Rev. Lett. 94, 212303 (2005) But here both emitted particles are detected! (not just the proton)  the invariant mass of the  p pair is measured, M  p The same elementary reaction takes place: K - p p   p (select p  > 300 MeV/c to eliminate K - N   A peak for the transition to the g.s. of the daugther nucleus should be observed at: Nuclei:

44. 44 Transition to the g.s. of daughter nucleus Interpreted by the FINUDA experiment as a (K - pp) bound state M. Agnello et al. Phys. Rev. Lett. 94, 212303 (2005) Another view (conventional): Final State Interactions (FSI) of the primary  and p (produced after K- absorption) in their way out of the daughter nucleus!

45. 45 Monte Carlo simulation of K - absorption by pp and pn pairs in nuclei Primary  and N emitted according to phase space: The K - is absorbed by two nucleons with momenta randomly chosen within the local Fermi sea: The  or N scatter within the nucleus, loosing energy and producing new (slow) nucleons Finally, the invariant  p mass is reconstructed from the final events V.K. Magas, E. Oset, A. Ramos, H. Toki, Phys.Rev. C74, 025206 (2006)

46. 46 A peak is generated when the primary  and p, undergo quasi- elastic collisions with the nucleus, exciting it to the continuum. (it is the analogue of the quasi-elastic peak observed in nuclear inclusive reactions using a variety of different probes: (e,e’), (p,p’), (  ’),…)

47. 47 N.V. Shevchenko, A. Gal, J. Mares, Phys.Rev.Lett.98,08230 1(2007) (Fadeev) A. Doté, W. Weise, nucl-th/071050 (Variational) All the experimental claims for the existence of very deeply bound kaonic nuclear states can be explained in terms of conventional nuclear physics processes. This is further substantiated by NEW theoretical developments:  realistic few body calculations of the K-pp system: Crucial ingredient: realistic NN SRC (which prevent from reaching densities  o !) B K ~ 50-70 MeV  ~ 100 MeV

48. 48 STRANGENESS IN NEUTRON STARS Central density ~  c = (4 – 8)  0 (  0 = 0.17 fm -3 = 2.8 10 14 g/cm 3 ) Mass ~ 1.4 to 2.2 M sun Radius ~ 10 km Strangeness confined form deconfined form hyperons:  -,  kaons: K - strange quark matter u d s

49. 49 The central density of a neutron star is high  c = (4 – 8)  0 (  0 = 0.17 fm -3 = 2.8 10 14 g/cm 3 ) The nucleon chemical potential increases very rapidly with density  Above a threshold density,  T = (2– 3)  0, hyperons are created in the stellar interior! HYPERONS IN NEUTRON STARS  HYPERONIC MATTER First proposed in 1960: V.A. Ambartsumyan, G.S. Saakyan, Sov. Astron. AJ. 4 (1960) 187 The core of a neutron star is a fluid of neutron rich matter in equilibrium with respect to the weak interactions (  -stable nuclear matter) Why is it likely to have hyperons?

50. 50  -stable hadronic matter  Equilibrium with respect to weak interaction processes:  Charge neutrality:

51. 51 The Equation-of-State (EoS) of hyperonic matter The presence of hyperons produces a softening in the EoS! The composition of a neutron star depends on the hyperon properties in the medium (i.e. on the YN and YY interactions)

52. 52 Profile of a neutron star with hyperons Neutron stars are “giant hypernuclei” under the influence of gravity and strong interactions I. Vidaña, A. Polls, A. Ramos, L. Engvik and M. Hjorth-Jensen, Phys. Rev. C62 (2000) 035801

53. 53 Influence of hyperons: lower maximum massessmaller radiushigher central densities  need extra pressure at high density Three-body forces: YNN, YYN, YYY ?? H. J. Schulze, A. Polls, A. Ramos, I. Vidaña, PRC 73, 058801 (2006) Other degrees of freedom: quarks ?? Observational limit ~ 1.44 M 3 (but PSR0751+1807 (2005): 2.1 M 3 )

54. 54 STRANGENESS NUCLEAR PHYSICS is a fascinating field that adds a new dimension (strangeness) into conventional nuclear physics and opens the door to investigate new phenomena associated to the enlarged flavour SU(3) world Interdisciplinary field ! hypernuclear structure:  properties of the YN, YY interactions  the  penetrates inside the nucleus hypernuclear decay: ASTROPHYSICS (neutron star interior) mesonic mode non-mesonic mode  weak non-leptonic baryon-baryon interaction NUCLEAR PHYSICS PARTICLE PHYSICS