The Final State Interaction in the pp  + (np) and pp  + (Λp) Reactions R. Siudak Institut für Strahlen- und Kernphysik der Universität Bonn, Bonn, Germany Institute of Nuclear Physics, Cracow, Poland Motivation Experimental technique Results and FSI analysis

FSI parameters of the np system very well known Motivation pp  + np

FSI parameters of the np system very well known ratio spin-singlet spin-triplet = ? Motivation

spin-singlet spin-triplet = ? pp  + np

FSI parameters of the np system very well known ratio spin-singlet spin-triplet = ? Motivation Detailed comparison of the and pp  + nppp  + d

pp  + np FSI parameters of the np system very well known ratio spin-singlet spin-triplet = ? pp→K + Λp FSI parameters of the Λp system can be deduced Search for strange (S=-1) dibaryons Motivation Detailed comparison of the and pp  + nppp  + d

Data from Nucl. Phys. A 567(1994) 819 F. Hinterberger and A. Sibirtsev, Eur. J. Phys. A 21 (2004) 313 pp→K + Λp FSI parameters of the Λp system can be deduced

pp→K + Λp

A. Gasparyan, J. Haidenbauer, C. Hanhart and. J. Speth Phys. Rev. C 69 (2004) Spin average scattering length of -1.5 fm

pp  + np FSI parameters of the np system very well known ratio spin-singlet spin-triplet = ? pp→K + Λp FSI parameters of the Λp system can be deduced Search for strange (S=-1) dibaryons Motivation Detailed comparison of the and pp  + nppp  + d

pp  + np FSI parameters of the np system very well known ratio spin-singlet spin-triplet = ? pp→K + Λp FSI parameters of the Λp system can be deduced Search for strange (S=-1) dibaryons Unique combination of the COSY cooled proton beam and the spectrograph Big Karl can deliver high resolution data for pp  + X and pp→K + X Motivation Detailed comparison of the and pp  + nppp  + d

Cooler Synchrotron COSY w Juelich - up to 3.6 GeV/c - e and stochastic cooling, - luminosity achieved: L = cm -2 s -1 - p and d beams - (cooled) beam quality:  = 0.4  mm mrad (  = 0.5 mm ) ~0.1% halo at  = 2.5 mm  p/p = 5  p vector polarised - d vector and tensor polarised

σ mm =97 KeV the deuteron peak

A. Betsch et al. pp  + X

I. Jour. Mod. Phys. A 20 (2005)291 spin triplet, isospin singlet a= fm r 0 = fm spin singlet, isospin triplet a= fm r 0 = 2.51 fm

Detailed comparison of the pp    np and pp   + d

pp→  + np

pp  + X pp  + pn 1 GeV A. Boduard et al. pd  p X spin-triplet ….... spin-singlet

D –state effects for pp  + np ? D –state effects for pp  + d Detailed comparison of the pp    np and pp   + d

D –state effects for pp  + np ? D –state effects for pp  + d Detailed comparison of the pp    np and pp   + d

R GEM unpublished T p (GeV) GEM Pleydon et al. R GEM unpublished

pp →K + Λ p p z (MeV/c) P y (MeV/c) P beam =2735 MeV/c p BK = 1070 MeV/c

p(p,X)

Θ = 0 deg  MM=350 keV

Summary - High resolution data for the pp  + X and pp  K + X reactions were measured Unique combination of the COSY cooled proton beam and the spectrograph Big Karl provides excellent resolution in np and Λp excitation energy - The reaction pp  + np is dominated by the spin-triplet contribution to the (np) FSI - Upper limit of possible singlet contribution was deduced - Hypothesis of the importance of the D-state in the np system Data analysis for the pp→K + X reaction in progress