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

pp +np FSI parameters of the np system very well known

•

ratiospin-singlet

spin-triplet= ?

Motivation

•

spin-singletspin-triplet = ?

pp +np

pp +np FSI parameters of the np system very well known

•

ratiospin-singlet

spin-triplet= ?

Motivation

Detailed comparison of the andpp +np pp +d

• •

pp +np FSI parameters of the np system very well known

•

ratiospin-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 andpp +np pp +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

pp→K+Λp

A. Gasparyan, J. Haidenbauer, C. Hanhart and. J. Speth Phys. Rev. C 69 (2004) 034006

Spin average scattering length of -1.5 fm

pp +np FSI parameters of the np system very well known

•

ratiospin-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 andpp +np pp +d

• •

• •

pp +np FSI parameters of the np system very well known

•

ratiospin-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 andpp +np pp +d

• •

• •

Cooler Synchrotron COSY w Juelich

- up to 3.6 GeV/c

- e and stochastic cooling,

- luminosity achieved: L = 1032 cm-2s-1

- p and d beams - (cooled) beam quality: = 0.4 mm mrad ( = 0.5 mm ) ~0.1% halo at = 2.5 mm p/p = 510-5

- p vector polarised

- d vector and tensor polarised

0

100

200

300

400

c ou n

ts

1875.3 1875.4 1875.5 1875.6 1875.7 1875.8 1875.9 1876.0

missing mass (MeV/c2)

data292.2 * EXP(-((MM - 1875.63) / (2^(1/2)*0.0976))^2)

σmm=97 KeV

the deuteron peak

102

103

104

c ou n

ts

-10 0 10 20 30 40

Q (MeV)

Uppsala 30 degreeGEM 0 degree

A. Betsch et al.

pp +X

I. Jour. Mod. Phys. A 20 (2005)291

spin triplet, isospin singlet

a= +5.396 fm

r0= 1.726 fm

spin singlet, isospin triplet

a= -23.678 fm

r0= 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

Tp (GeV)

GEM

Pleydon et al.

R

GEM unpublished

pp→K+Λp

pz(MeV/c)

Py

(MeV/c)

Pbeam =2735 MeV/c pBK = 1070 MeV/c

Pbeam =2735 MeV/c pBK = 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