1. DIS off Pions Bogdan Povh
Max-Planck-Institut fuer Kernphysik, Heidelberg

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. Pion signature
Toy model

8. Forward Neutron Calorimeters at H1 and ZEUS at DESY

9. 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”

10. Pion signature
H1 detector at HERA collider

11. A.Bunyatyan “Physics with FNC”

12. The H1-FNC energy response
CERN test-beam
Ebeam= GeV
A.Bunyatyan “Physics with FNC”

13. 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”

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

15. Rapgap-MC after tuning
Data
Acceptance determined by MC
A.Bunyatyan “Physics with FNC”

16. “Measurement of leading proton and neutron production in DIS at HERA”
H1 Publications:
“Measurement of leading proton and neutron production in DIS at HERA”
DESY
“Measurement of dijet cross sections in ep interactions with a leading
neutron “,
DESY
ZEUS Publications:
“Study of the pion trajectory in the photoproduction of leading neutrons
at HERA” DESY
“Photoproduction of D* mesons associated with a leading neutron”” DESY
“Leading neutron production in ep collisions at HERA” DESY
“Measurement of dijet cross sections for events with a leading neutron in
photoproduction at HERA”
DESY
“Observation of events with an energetic forward neutron in DIS at HERA” DESY
A.Bunyatyan “Physics with FNC”

17. F2p from ZEUS

18. F2LN(3) (z=0.7) Gp Xp
Data show sensitivity to the parameterizations of the pion structure function (constrained for x (=b)>0.1 from the fixed target experiments).
A.Bunyatyan “Physics with FNC”

19. e.g. rgp < rjj < rD* ≤ rDIS
Comparison of LN production rate for different processes (ZEUS)
e.g. rgp < rjj < rD* ≤ rDIS
Absorption - ratio depends on the transverse size of
virtual photon
A.Bunyatyan “Physics with FNC”

20. 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 three different pion fluxes}

21. SU(2) chiral model

22. Conclusions

23. Conclusions

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

25. Conclusions
Gluonic structure of the nucleon-
resolution on the order of 0.3 fm