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Multi-quark Components in Baryons Bing-song Zou Institute of High Energy Physics, Beijing

Multi-quark Components in Baryons Bing-song Zou Institute of High Energy Physics, Beijing B.S.Zou and D.O.Riska, “The ` ss component of the proton and the strangeness magnetic moment”, hep-ph/0502225 B.C.Liu and B.S.Zou, “Mass and K L coupling of N*(1535)”, nucl-th/0503069.

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Multi-quark Components in Baryons Bing-song Zou Institute of High Energy Physics, Beijing

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  1. Multi-quark Components in Baryons Bing-song Zou Institute of High Energy Physics, Beijing B.S.Zou and D.O.Riska, “The`ss component of the proton and the strangeness magnetic moment”, hep-ph/0502225 B.C.Liu and B.S.Zou, “Mass and KL coupling of N*(1535)”, nucl-th/0503069

  2. 1. Classical picture of the nucleon

  3. 2. Flavor asymmetry of light quarks in the nucleon sea Deep Inelastic Scattering (DIS) + Drell-Yan (DY) process `d –`u ~ 0.12 Meson cloud model: | p > ~ | uud > + e | n ( udd ) p+ (`du ) > + …

  4. DIS Gottfried Sum Rule :assuming `d =`u

  5. 3. The`ss component of the proton and the strangeness magnetic moment ms neutrino DIS sizable charm production , Meson cloud model: | p > ~ | uud > + e | n ( udd ) p+ (`du ) > + e’ | L (uds) K+ (`su ) > + …

  6. Parity violating electron scattering ms Strong experiment evidence forms> 0 HAPPEX/CEBAF, SAMPLE/MIT-Bates, A4/MAMI Meson cloud models ms< 0 p  L (uds) K+ (`su )

  7. B.S.Zou and D.O.Riska, “The`ss component of the proton and the strangeness magnetic moment”, hep-ph/0502225 considers general (uuds`s) orbital-flavor-spin configurations For proton, spin-parity is ½+ . One quark or antiquark needs to be in p-state

  8. [4]x [31] x All possible (uuds`s) configurations Flavor-spin hyperfine interaction :

  9. Wave functions for [4]x and [31]x configurations : J.-Q. Chen, Group Representation Theory for Physicists, World Scientific, Singapore (1989)

  10. Calculation of the strangeness magnetic momentms : ms= < p | ms | p > Results : (uuds) ground states  ms< 0 except for S(4q)=2 (uuds) [31]x states  ms> 0 except for J(4q)=0 Diquark`s[ud][us]pentaquark models  ms> 0 Triquark-diquark {`ssu}[ud] model  ms< 0

  11. Conclusion on `ss configuration : Strong experiment evidence for ms > 0 suggests that the`ss configuration in the proton be such that the`s is in the ground state and the (uuds) system has total angular momentum 1 . Not the conventional KL configuration. This suggests that the (qqqq`q) components in baryons may be mainly in colored quark cluster configurations rather than in ``meson cloud'' configurations.

  12. 4. New information on N*(1535) BES Collaboration, Phys. Lett. B510 (2001) 75

  13. N*(1535) in J/y p K-`L + c.c. Nx Nx Events/10MeV (Arbitrary normalization) PS, eff. corrected Nx BES, Int. J. Mod. Phys. A20 (2005)

  14. B.C.Liu and B.S.Zou, nucl-th/0503069 From relative branching ratios of J/y p`N*  p (K-`L) / p (`ph) gN*KL /gN*ph /gN*pp ~ 1.3 : 1 : 0.6 Smaller N*(1535) BW mass

  15. Mass of N*(1535) (1) (2) (3)

  16. A.Zhang, Y. Liu, P. Huang, W. Deng, X.Chen, S.L. Zhu, hep-ph/0403210 : 1/2- and 1/2+ octet N* pentaquarks have similar masses in Jaffe-Wilczek diquark model N*(1535) ~ uud (L=1) + e[ud][us]`s + … N*(1440) ~ uud (n=2) + x (2/3[ud][ud]`d +1/3 [ud][us]`s ) + … Larger [ud][us]`s component in N*(1535) makes it coupling stronger to strangeness and heavier !

  17. 5. Concluding remarks Multiquark components in baryons Pentaquark vs Meson Cloud Which is the correct picture ? Re-examination of many previous studied processes is necessary ! P ~ uud (n=2) + e (2/3[ud][ud]`d +1/3 [ud][us]`s ) + …  `d –`u ~ 0.12 >15% in the nucleon, ?% in N* and D*

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