Two pion production in protonnucleon and proton nuclear

Two pion production in proton-nucleon and proton nuclear collisions T. Skorodko, Physikalisches Institut, Univ. Tuebingen for WASA collaboration, Jalta 2006 • Motivation • Proton-proton data at Tp < 1 Ge. V • Proton-proton data at Tp > 1 Gev • Proton-deutron data • Conclusion and outlook

Available data from WASA pp → ppp+ppp → ppp 0 p 0 pp → pnp+p 0 pp → nnp+p+ pp → dp+p 0 pd → 3 Hep+ppn → dp 0 p 0 pd → 3 Hep 0 p 0

WASA 4 p detector

Experimental and theoretical situation

Proton-proton data at Tp < 1 Ge. V

Roper excitation p+p- p 0 p 0 Roper parameters optimized for p+p- I=0, 1 Roper parameters optimized for p 0 p 0 I=0 N* Dp N(pp)l=I=0 Ns s ~ |a + b k 1 k 2|2

Dynamic s formation

Dynamic s formation Total cross section PROMICE/WASA CELSIUS-WASA

Proton-proton data at Tp > 1 Ge. V

Tp > 1 Ge. V: pp→ppp+p- (DD)0+-3+

0 p 0 pp→pp p Tp > 1 Ge. V: 1000 Me. V 1100 Me. V 1200 Me. V

Measurement of p-p→p 0 p 0 n from threshold to pp=750 Me. V/c Crystal Ball Phys. Rev. C 69, 045202(2004)

pp → nnp+p+ Bose-Einstein Correlations ? nnp+p+ pp → (ppp 0 p 0) D+ (p 0) D+ p+ ü two identical bosons in final state ü D+D+ intermediate state p+ (p 0)

pp → nnp+p+ Tp =1100 Me. V p r e l i m i (DD)0+ n a r y no Bose-Einstein correlations

Proton-deutron data at Tp > 1 Ge. V

pd 3 He pp at Tp=893 Me. V M. Bashkanov et. al, Phys. Lett. B 637 (2006) 223 -228 Mpp p +p - p 0 p 0

ABC effect on 3 He and d ΔΔ FSI ΔΔ

Conclusions and Outlook pp → pppp Tp < 1 Ge. V: ▪ Roper excitation ▪ dynamic s formation * Tp ≥ 1 Ge. V: ▪ dominant ▪ p 0 p 0: unexpected enhancement in Mpp – not BEC, since no enhancement in p+p+ channel ! – connection to ABC effect? pd → 3 Hepp and pn → dp 0 p 0 – ? ? * ABC effect may be explained by DD FSI