1. The role of pSIDIS data in QCD global fits
Rodolfo Sassot
Universidad de Buenos Aires
Primer pagina
DIS06, Tsukuba April 22, 2006

2. how SIDIS data help to constrain , and
lagrange multipliers to estimate uncertainties
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3. D. de Florian, G. Navarro and X. Jiang
In collaboration with
D. de Florian, G. Navarro and X. Jiang
based on Phys.Rev.D71, (2005),
hep-ph/ , and references therein.
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4. why do we use semi-inclusive data?
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5. why do we use semi-inclusive data?
polarized inclusive DIS (pDIS) data fail to constrain pPDFs.
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6. why do we use semi-inclusive data?
polarized inclusive DIS (pDIS) data fail to constrain pPDFs.
e.m. interactions can not discriminate quarks from antiquarks:
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7. why do we use semi-inclusive data?
polarized inclusive DIS (pDIS) data fail to constrain pPDFs.
e.m. interactions can not discriminate quarks from antiquarks:
valence vs. sea quarks
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8. why do we use semi-inclusive data?
polarized inclusive DIS (pDIS) data fail to constrain pPDFs.
e.m. interactions can not discriminate quarks from antiquarks:
valence vs. sea quarks
spin/flavour symmetry: model dependence to be tested
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9. why do we use semi-inclusive data?
polarized inclusive DIS (pDIS) data fail to constrain pPDFs.
e.m. interactions can not discriminate quarks from antiquarks:
valence vs. sea quarks
spin/flavour symmetry: model dependence to be tested
polarized semi-inclusive (SIDIS) data
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10. why do we use semi-inclusive data?
polarized inclusive DIS (pDIS) data fail to constrain pPDFs.
e.m. interactions can not discriminate quarks from antiquarks:
valence vs. sea quarks
spin/flavour symmetry: model dependence to be tested
polarized semi-inlcusive (SIDIS) data
CERN: p, d h±
DESY: p,d,He h±, π±, K±
CERN: …..
CLAS & JLAB: …..
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11. how do we deal with pSIDIS data?
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12. how do we deal with pSIDIS data?
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13. how do we deal with pSIDIS data?
W R. Mertig, W. L. van Neerven, Z.Phys.C (1996)
W. Vogelsang, Phys.Rev.D (1996)
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14. how do we deal with pSIDIS data?
W R. Mertig, W. L. van Neerven, Z.Phys.C (1996)
W. Vogelsang, Phys.Rev.D (1996)
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15. how do we deal with pSIDIS data?
W R. Mertig, W. L. van Neerven, Z.Phys.C (1996)
W. Vogelsang, Phys.Rev.D (1996)
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16. how do we deal with pSIDIS data?
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17. how do we deal with pSIDIS data?
D. de Florian et al. Nuc.Phys.B470 (1996) 195
M. Stratmann W.Vogelsang Phys.Rev.D64 (2001)
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18. how do we deal with pSIDIS data?
D. de Florian et al. Nuc.Phys.B470 (1996) 195
M. Stratmann W.Vogelsang Phys.Rev.D64 (2001)
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19. NLO combined analysis:
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20. NLO combined analysis:
pDIS can probe:
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21. NLO combined analysis:
pDIS can probe:
pSIDIS give access to:
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22. NLO combined analysis:
pDIS can probe:
pSIDIS give access to:
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23. NLO combined analysis:
pDIS can probe:
pSIDIS give access to:
positivity relative to MRST02:
A.D. Maritn et al. Eur.Phys.J.C28 (2002) 455
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24. does it work?
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25. does it work? consistency: pSIDIS data fix quarks without spoiling
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26. does it work? consistency: pSIDIS data fix quarks without spoiling
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27. does it work? consistency: pSIDIS data fix quarks without spoiling
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28. does it work? consistency: pSIDIS data fix quarks without spoiling
combined λ=1
478-20=458 d.o.f
313 pDIS
165 pSIDIS
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29. does it work? consistency: pSIDIS data fix quarks without spoiling
combined λ=1
478-20=458 d.o.f
313 pDIS
165 pSIDIS
pDIS λ=0
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30. does it work? consistency: pSIDIS data fix quarks without spoiling
478-20=458 d.o.f
313 pDIS
165 pSIDIS
combined
pDIS
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31. does it work? consistency: pSIDIS data fix quarks without spoiling
478-20=458 d.o.f
313 pDIS
165 pSIDIS
combined
pDIS
KRE: S. Kretzer Phys.Rev.D (2000)
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32. does it work? consistency: pSIDIS data fix quarks without spoiling
478-20=458 d.o.f
313 pDIS
165 pSIDIS
combined
pDIS
KRE: S. Kretzer Phys.Rev.D (2000)
KKP: B. A. Kniehl, G. Kramer, B. Potter,
Nucl.Phys.B (2000)

33. what do we get from pSIDIS data?
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34. what do we get from pSIDIS data?
do pSIDIS data actually constrain ?
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35. what do we get from pSIDIS data?
do pSIDIS data actually constrain ?
J. Pumplin et al. Phys.Rev.D (2002)
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36. what do we get from pSIDIS data?
do pSIDIS data actually constrain ?
J. Pumplin et al. Phys.Rev.D (2002)
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37. what do we get from pSIDIS data?
do pSIDIS data actually constrain ?
J. Pumplin et al. Phys.Rev.D (2002)
KRE: S. Kretzer Phys.Rev.D (2000)
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38. what do we get from pSIDIS data?
do pSIDIS data actually constrain ?
J. Pumplin et al. Phys.Rev.D (2002)
KRE: S. Kretzer Phys.Rev.D (2000)
KKP: B. A. Kniehl, G. Kramer, B. Potter, Nucl.Phys.B (2000)
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39. what do we get from pSIDIS data?
do pSIDIS data actually constrain ?
J. Pumplin et al. Phys.Rev.D (2002)
KRE: S. Kretzer Phys.Rev.D (2000)
KKP: B. A. Kniehl, G. Kramer, B. Potter, Nucl.Phys.B (2000)
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40. what do we get from pSIDIS data?
do pSIDIS data actually constrain ?
J. Pumplin et al. Phys.Rev.D (2002)
KRE: S. Kretzer Phys.Rev.D (2000)
KKP: B. A. Kniehl, G. Kramer, B. Potter, Nucl.Phys.B (2000)
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41. what do we get from pSIDIS data?
do pSIDIS data actually constrain ?
J. Pumplin et al. Phys.Rev.D (2002)
KRE: S. Kretzer Phys.Rev.D (2000)
KKP: B. A. Kniehl, G. Kramer, B. Potter, Nucl.Phys.B (2000)
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42. does it make sense?
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43. does it make sense?
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44. does it make sense?
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45. (not included in the fit)
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46. (not included in the fit) (not included in the fit)
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47. what can we expect from pSIDIS in the future?
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48. what can we expect from pSIDIS in the future?
COMPASS d h± (inminent)
CLAS p π± (inminent)
JLAB E p,d h±, π±, K± (2008)
E proton
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49. what can we expect from pSIDIS in the future?
COMPASS d h± (inminent)
CLAS p π± (inminent)
JLAB E p,d h±, π±, K± (2008)
E proton
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50. what can we expect from pSIDIS in the future?
COMPASS d h± (inminent)
CLAS p π± (inminent)
JLAB E p,d h±, π±, K± (2008)
E proton
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51. Conclusions:
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52. Conclusions:
pSIDIS opens a window to sea quarks and helps to constrain other densities
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53. Conclusions:
pSIDIS opens a window to sea quarks and helps to constrain other densities
overall picture combined NLO global fits:
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54. Conclusions:
pSIDIS opens a window to sea quarks and helps to constrain other densities
perfect consistency pDIS/pSIDIS
overall picture combined NLO global fits:
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55. Conclusions:
pSIDIS opens a window to sea quarks and helps to constrain other densities
perfect consistency pDIS/pSIDIS
improved constraints on pPDFs
overall picture combined NLO global fits:
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56. Conclusions:
pSIDIS opens a window to sea quarks and helps to constrain other densities
perfect consistency pDIS/pSIDIS
improved constraints on pPDFs
overall picture combined NLO global fits:
best fits favor SU(3) in the sea
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57. Conclusions:
pSIDIS opens a window to sea quarks and helps to constrain other densities
perfect consistency pDIS/pSIDIS
improved constraints on pPDFs
overall picture combined NLO global fits:
best fits favor SU(3) in the sea
agreement with preliminary data on
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58. Conclusions:
pSIDIS opens a window to sea quarks and helps to constrain other densities
perfect consistency pDIS/pSIDIS
improved constraints on pPDFs
overall picture combined NLO global fits:
best fits favour SU(3) in the sea
agreement with preliminary data on
next round: COMPASS, CLAS & E04-113
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59. Conclusions:
pSIDIS opens a window to sea quarks and helps to constrain other densities
perfect consistency pDIS/pSIDIS
improved constraints on pPDFs
overall picture combined NLO global fits:
best fits favor SU(3) in the sea
agreement with preliminary data on
improved direct constraints on
next round: COMPASS, CLAS & E04-113
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60. Conclusions:
pSIDIS opens a window to sea quarks and helps to constrain other densities
perfect consistency pDIS/pSIDIS
improved constraints on pPDFs
overall picture combined NLO global fits:
best fits favor SU(3) in the sea
agreement with preliminary data on
improved direct constraints on
next round: COMPASS, CLAS & E04-113
indirect constraints on
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61. Conclusions:
pSIDIS opens a window to sea quarks and helps to constrain other densities
perfect consistency pDIS/pSIDIS
improved constraints on pPDFs
overall picture combined NLO global fits:
best fits favor SU(3) in the sea
agreement with preliminary data on
improved direct constraints on
next round: COMPASS, CLAS & E04-113
indirect constraints on
flavour fragmentation
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63. NLO combined analysis: data
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66. Fragmentation functions input:
KRE: S. Kretzer Phys.Rev.D (2000)
KKP: B. A. Kniehl, G. Kramer, B. Potter, Nucl.Phys.B (2000)
flavor separation:
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