Summary
A model for the polarized proton, neutron and deuteron structure functions embodying various features expected from the theory is presented. Each structure function is constructed from its asymptoticx behaviours, consistent with theoretical expectations at largex and smallx, while theQ 2-dependence is obtained using the perturbative QCD evolution equations. By using QCD improvements on the first moments of various distributions, and including, from axial anomaly, a direct gluonic contribution tog 1, good agreement with data on polarized deep inelastic scattering is obtained. Assuming that this gluonic component can be absorbed in a redefined polarized quark density, we reproduce the unexpected results on the Ellis-Jaffe sum rule and on spin content of the nucleon with no need of an initially strange sea quark polarization.
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References
SLAC-YALECollaboration (G. Baum et al.),Phys. Rev. Lett.,51 (1983) 1135.
EMCCollaboration (J. Ashman et al.),Nucl. Phys. B,328 (1989) 1.
Ellis J. andJaffe R. L.,Phys. Rev. D,9 (1974) 1444;Phys. Rev. D,10 (1974) 1669.
Anselmino M., Efremov A. andLeader E.,The theory and phenomenology of polarized deep inelastic scattering, to be published inPhys. Rep.
SMCCollaboration (B. Adams et al.),Phys. Lett. B,329 (1994) 399;
SMCCollaboration (B. Adeva et al.),Phys. Lett. B,302 (1993) 533;Frois B.,The spin structure of the deuteron, talk at theXXI SLAC Summer Institute on Particle Physics, July-August 1993;
SMCCollaboration (B. Adeva et al.),Phys. Lett. B,320 (1994) 400.
SLAC-E142Collaboration (P. L. Anthony et al.),Phys. Rev. Lett.,71 (1994) 959;
SLAC-E142Collaboration (K. Abe et al.),Phys. Rev. Lett.,74 (1995) 346;
Breton V., Fonvieille H. andRoblin Y.,Spin structure functions at SLAC, E142–E143 experiments, talk atFew Body 94, Williamsburg, Va, USA;
SLAC-E143Collaboration (K. Abe et al.),Precision measurement of the deuteron spin structure functions g d1 , SLAC-PUB-95-6734.
Bjorken J. D.,Phys. Rev.,148 (1966) 1467;Phys. Rev. D,1 (1970) 1376.
Carlitz R. D., Collins J. C. andMueller A. H.,Phys. Lett. B,214 (1988) 229;Jaffe R. L. andManohar A.,Nucl. Phys. B,337 (1990) 509;Vogelsang W.,Z. Phys. C,50 (1991) 275;Ross G. C. andRoberts R. G.,The gluon contribution to polarized nucleon structure functions, RAL-90-062;Bass S. D. andThomas A. W.,J. Phys. G,19 (1993) 925;Patel B.,Nucl. Phys. B,428 (1994) 98.
Altarelli G. andStirling W. J.,Particle World,1 (1989) 40.
Gehrmann T. andStirling W. J.,Z. Phys. C,65 (1994) 461.
Bertini M., Giffon M. andJenkovszky L.,Proceedings of VI Rencontres de Blois «The Heart of the Matter», Château de Blois, France (1994), to be published;Bertini M. andGiffon M.,A two-component model for the Pomeron in deep inelastic scattering, to be published inInt. J. Phys.
López C. andYnduráin F. J.,Nucl. Phys. B,171 (1991) 231.
Martin A. D.,Structure function and small x physics, DTP/94/32;Martin A. D., Stirling W. J. andRoberts R. G.,Phys. Rev. D,50 (1994) 6734;
CTEQCollaboration (H. L. Lai et al.),Global QCD analysis and the CTEQ parton distributions, MUS-HEP-41024.
Kodaira J. et al., Nucl. Phys. B,159 (1979) 99;Kodaira J.,Nucl. Phys. B,165 (1980) 129;Larin S. A.,Phys. Lett. B,334 (1994) 192;Kataev A. L.,Phys. Rev. D,50 (1994) 5469.
Chiapetta P. andNardulli G.,Z. Phys.,51 (1991) 435.
Lacombe M. et al., Phys. Lett. B,101 (1981) 139.
Close F. E. andRoberts R. G.,Phys. Rev. Lett.,60 (1988) 1471;Brodsky S. J. andSchmidt I.,Phys. Lett. B,234 (1990) 144.
Gribov V. N. andLipatov L. N.,Sov. J. Nucl. Phys.,15 (1972) 438;Altarelli G. andParisi G.,Nucl. Phys. B,126 (1977) 298;Altarelli G.,Phys. Rep.,81 (1982) 1.
Altarelli G. andRoss G. G.,Phys. Lett. B,212 (1988) 391.
Brodsky S. J., Burkardt M. andSchmidt I.,Perturbative constraints on the shape of polarized quarks and gluons distributions, SLAC-PUB-6087.
Forte S.,Nucl. Phys. B,331 (1990) 1;Forte S.,Polarized structure functions: theory and phenomenology, talk at theTennessee International Symposium on Radiative Corrections, June 1994, CERN-TH 7453/94.
Particle Data Group,Phys. Rev. D,45 (1992).
Close F. E. andRoberts R. G.,Phys. Lett. B,316 (1993) 165.
Virchaux M.,Nucleon structure functions, inQCD 20 Years Later, edited byP. M. Zerwas andH. A. Kastrup (World Scientific) 1992;Altarelli G.,Annu. Rev. Nucl. Part. Sci.,39 (1989) 357.
Paccanoni F.,Note on DGLAP evolution equation, talk at theInternational Workshop Hadrons 94, Uzhgorod (Ukraine), September 7–11, 1994, edited byG. Bugrij, L. Jenkovszky andE. Martinov; Ball R. D. andForte R.,Phys. Lett. B,335 (1994) 77.
Bass S. D. andLandshoff P. V.,Phys. Lett. B,336 (1994) 537.
Close F. E. andRoberts R. G.,Phys. Lett. B,336 (1994) 257.
Mulders P. J. andPollock S. J.,Evolution of the spin of the nucleon, NIKHEF-94-P9, HEP-PH 9412287.
Altarelli G. andRidolfi G.,Understanding the proton spin structure: a status report, talk at theQCD ’94 Workshop, Montpellier, France, July 1994, CERN-TH 7415/94;Ellis J. andKarliner M.,Spin structure functions, CERN-TH 7022/93; plenary talk at theXIII International Conference on Particles and Nuclei, PANIC ’93, Perugia, Italy;Ellis J. andKarliner M.,Phys. Lett. B,341 (1995) 397.
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Bertini, M., Giffon, M. & Predazzi, E. A phenomenological model for the spin-dependent structure functions. Nuov Cim A 109, 61–75 (1996). https://doi.org/10.1007/BF02734429
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DOI: https://doi.org/10.1007/BF02734429