1. PIONS in DIS
Bogdan Povh
Max-Planck-Institut fuer Kernphysik

2. Pion signature in experiment: Gottfried Sum rule Polarized structure function Forward neutrons in DIS

3. DIS on Proton and Deuteron
Gottfried sum rule
Spin structure function

4. Pion signature NMC detector at CERN
Deep inelastic scattering of muons off protons and deuterons

5. Pion signature
Gottfried sum rule
for flavour symmetric sea

6. Pion signature

7. SU(2) chiral model Eichten, Hinchliffe, Quigg Phys.Rev.D 45 1992
Baumgaertner, Pirner, Koenigsmann, P. ZP A
Pirner Prog. Part. Nucl. Phys

8. Pion signature
SU(2) chiral model:pion is a short cut for the quark-antiquark pair of the constituent quark
From GSR

9. Spin Structure function
“Theoretical predictions using SU(3)
Flavor model”:(Cabibbo, Nucl.Phys.B69,1974)
F+D=g_A, F-D=-0.34 and the experiment disagree:1/3 of the prediction
New value: quark carries 1/3 of the
spin of the constituent quark

10. SU(2) chiral model
from g_A

11. Pion signature
SU(2) chiral model

13. Forward Neutron Calorimeters at H1 and ZEUS at DESY

14. FNC – design specifications
The size and weight of FNC is defined by the space available in HERA tunnel
position– 105m from the interaction point, size ~ 70 x 70 x 200cm3 , weight <10t
geometrical acceptance is limited by beam-line elements <0.8mrad
should work in high radiation environment
A.Bunyatyan “Physics with FNC”

15. Pion signature
H1 detector at HERA collider

16. A.Bunyatyan “Physics with FNC”

17. Neutron and photon energy spectrum measured in H1
-cluster in Preshower = photon,
-cluster in main calorimeter and/or
Preshower = neutron
A.Bunyatyan “Physics with FNC”

18. Different pion fluxes used in analysis (different form factors)

19. Pion signature
Estimation of the probability of the p→n+p+ in DIS
from the neutron rate in DIS extrapolating to the full
energy range (for 2 different pion fluxes}
(Bunyatyan, Povh, EPJ A27,2006),
Absorption (D’Alesio&Pirner EPJ A7 2000)

20. Only one U quark contribute

21. The spin-flavor function symmetric

22. Conclusions

23. In the first order the nucleon is composed of three quarks and one
quark-antiquark pair.
One quarter of the quark-antiquark pair
shows up as a pion of the nucleon

24. Conclusions
The constituent quarks are a superposition of the
massive quarks and pions

25. Spontaneous breaking of the chiral symmetry and fossil pions

26. Microscopic view of the chiral symmetry breaking
Conclusions
Microscopic view of the chiral symmetry breaking d u
The interaction that is responsible for giving the mass to
quarks binds quark-antiquark to a pion

27. Chiral symmetry breaking
Peak of valence quarks

28. Chiral symmetry breaking

29. Chiral symmetry breaking

30. Chiral symmetry breaking
Nambu-Jona-Lasinio Model

31. Chiral symmetry breaking

32. Nambu-Jona-Lasinio Model in Cartoons
Chiral symmetry breaking
Nambu-Jona-Lasinio Model in Cartoons