1. B. Povh, MPIK Heidelberg Th. Walcher, Uni Mainz
The Nucleon Spin in DIS
B. Povh, MPIK Heidelberg
Th. Walcher, Uni Mainz

2. Conflict
Constituent Quark Model
DIS
ΔΣ≈0.6
ΔΣ=0.33±…

3. In the Constituent Quark Model ΔΣ follows from gA gA = 5/3 1.27
Only 80% of the Constituent Quark is active in the np+e-+ consequently ΔΣ=0.6

4. DIS
for ΔxB intervals
It would be correct if the nucleon had only 3 valence quarks and not any pairs.
ΔΣ=0.33±… in EMC, SMC, NMC, Hermes, Slac

5. Intrinsic quark sea Gottfried Sum Rule DIS with the forward neutron
DIS with the forward proton

7. DIS with forward neutron
Both violation of Gottfried Sum Rule and forward neutron in DIS. Pion probability in the nucleon is 25%.

8. DIS with forward proton

9. DIS with forward proton

10. Conclusion
The polarization ΔΣ≈0.6 of the quark model and the polarization ΔΣ=0.33 requires the average number of quarks and antiquarks in the nucleon to be about 4.5.
This number is a lower limit!