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Intrinsic light-quark sea

ECT* Workshop on " Flavor Structure of the Nucleon Sea" July 1st - 5 th 2013. Intrinsic light-quark sea. Wen-Chen Chang Institute of Physics, Academia Sinica, Taiwan. Outline. Very brief review of experimental results of nucleon sea Intrinsic s ea quarks in light-front 5q m odel

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Intrinsic light-quark sea

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  1. ECT* Workshop on "Flavor Structure of the Nucleon Sea" July 1st - 5th 2013 Intrinsic light-quark sea Wen-Chen Chang Institute of Physics, Academia Sinica, Taiwan

  2. Outline • Very brief review of experimental results of nucleon sea • Intrinsic sea quarks in light-front 5q model • Sea quarks in lattice-QCD • “Intrinsic gluons” • Prospects • Conclusion

  3. Strange Quark in the Nucleon:Deep-Inelastic Neutrino Scattering

  4. Strange Quark in the Nucleon CCFR, Z. Phys. C 65, 189 (1995)

  5. Strange Quark Asymmetry NuTeV, PRL 99, 192001 (2007)

  6. Strange Content from Semi-Inclusive Charged-Kaon DIS Production HERMES, PLB 666, 446 (2008)

  7. W and Z production at LHC ATLAS, PRL 109, 012001 (2012)

  8. Parton Distribution Functions of Protons

  9. Short Range Structure of Hadron Hoyer and Brodsky, AIP Conf. Proc. 221, 238 (1990)

  10. Intrinsic Sea Quarks in Light-Front 5q Fock States In the 1980’s Brodsky, Hoyer, Peterson, Sakai (BHPS) suggested the existence of “intrinsic” charm (PLB 93,451; PRD 23, 2745). • Dominant Fock state configurations have the minimal invariant mass, i.e. the ones with equal-rapidity constituents. • The large charm mass gives the c quark a larger x than the other comoving light partons, more valence-like.

  11. Intrinsic Sea Quarks in Light-Front 5q FockStates Brodsky, Hoyer, Peterson, Sakai (BHPS) PLB 93,451 (1980); PRD 23, 2745 (1981) “extrinsic” “intrinsic”

  12. Experimental Evidences of Intrinsic Charm 1% IC ISR Gunion and Vogt, hep-ph/9706252

  13. Global Fit by CTEQ Pumplin, Lai, Tung, PRD 75, 054029 (2007) No Conclusive Evidence…..

  14. Search for the lighter “intrinsic” quark sea No conclusive experimental evidence for intrinsic-charm so far The 5-quark states for lighter quarks have larger probabilities!

  15. Intrinsic Charm Quarks in Light-Front 5q Fock States Strong overlapping with extrinsic sea mc=1.5, ms=0.5, mu, md=0.3 GeV is obtained numerically. In the limit of a large mass for quark Q (charm):

  16. How to separate the “intrinsic sea” from the “extrinsic sea”?

  17. How to separate the “intrinsic sea” from the “extrinsic sea”? • Select experimental observables which have no contributions from the “extrinsic sea”

  18. How to separate the “intrinsic sea” from the “extrinsic sea”? • Select experimental observables which have no contributions from the “extrinsic sea” • Investigate the x distribution of flavor non-singlet quantities: , . 

  19.  Data of d(x)-u(x) vs. Light-Front 5q Fock States • The data are in good agreement with the 5q model after evolution from the initial scale μ to Q2=54 GeV2 • The difference of these two 5-quark components could be determined. Chang and Peng, PRL 106, 252002 (2011)

  20. How to separate the “intrinsic sea” from the “extrinsic sea”? • “Intrinsic sea” and “extrinsic sea” are expected to have different x-distributions • Intrinsic sea is “valence-like” and is more abundant at larger x • Extrinsic sea is more abundant at smaller x

  21. Data of x(s(x)+s(x)) vs. Light-Front 5q FockStates  • The x(s(x)+s(x)) are from HERMES kaon SIDIS data at <Q2>=2.5 GeV2. • The data seem to consist of two components. • Assume data at x>0.1 are originated from the intrinsic |uudss> 5-quark state.  Chang and Peng, PLB 704, 197 (2011)

  22. How to separate the “intrinsic sea” from the “extrinsic sea”? • Select experimental observables which have no contributions from the “extrinsic sea” • Investigate the x distribution of flavor non-singlet quantities: , .

  23.   Data of x(d(x)+u(x)-s(x)-s(x)) vs. Light-Front 5q FockStates   • The d(x)+u(x) from CTEQ 6.6. • The s(x)+s(x) from HERMES kaon SIDIS data at <Q2>=2.5 GeV2.  Chang and Peng, PLB 704, 197 (2011)

  24. Extraction of various 5q-components for light quarks

  25. Light-front 5q model: Intrinsic sea

  26. Constituent 5q model Riska and Zou, PLB 636, 265 (2006)

  27. Constituent 5q model Kiswandhi, Lee, Yang, PLB 704, 373 (2011)

  28. Extended Chiral Constituent 5q model(complete configurations) Strong interplays among different components with (very) large cancellations. An and Saghai, PRC 85, 055203 (2012); 1306.3041 (2013)

  29. Comparison of 5q Probabilities    

  30. Diagrams of Nucleon Hadronic Tensor in Path-Integral Formalism Disconnected Diagram Connected Diagram

  31. Connected and Disconnected Sea Liu and Dong, PRL 72, 1790 (1994)  • qds(x)=qds(x), where q=u, d, s; s(x)=s(x) • uds(x)=dds(x) • qcs(x)=qcs(x), where q=u, d • Origin of u(x)d(x): ucs(x)dcs(x) • Small-x behaviors: • qvalence(x) , qcs(x)  x-1/2 • qds(x)  x-1         How do we separate these two components?

  32. Ratio of Momentum Fraction between s and u in DI by Lattice QCD Connected Insertion (CI) Doi, et al. PoS LATTICE2008:163, 2008 Disconnected Insertion (DI)

  33. Connected Sea Liu, Chang, Cheng and Peng, PRL 109, 252002 (2012)

  34. Small-x Behaviors of CS and DS • Small-x behavior: • Valence and CS x-1/2 • DS x-1 Liu, Chang, Cheng and Peng, PRL 109, 252002 (2012)

  35. Moments of Nucleon Sea Liu, Chang, Cheng and Peng, PRL 109, 252002 (2012)

  36. Lattice QCD: Connected sea

  37. “Connected, Disconnected Sea” VS.“Intrinsic, Extrinsic sea”

  38. CCFR [Z. Phys. C 65, 189 (1995)] How consistent are data of CCFR and HERMES?

  39. Very little Q2 variation for data of x >= 0.1 .

  40. Reasonable agreement between CCFR and HERMES1998.

  41. There is essential difference between CCFR and HERMES2013. LO and NLO difference?

  42. Arbitrary normalization Peaks at x>0.1

  43. Intrinsic Gluons? http://www.physics.adelaide.edu.au/theory/staff/leinweber/VisualQCD/Nobel/ChargeAPE5LQanimXs30.gif

  44. How to separate the “intrinsic gluon” from the “extrinsic gluon”? • Select experimental observables which have no contributions from the “extrinsic gluon” There is no “flavor non-singlet” quantities for gluon. • “Intrinsic gluon” and “extrinsic gluon” are expected to have different x-distributions.

  45. Intrinsic Gluon DistributionStanley Brodsky, Ivan Schmidt, Phys. Lett. B234 (1990) 144 • The “radiated” (or extrinsic) gluon form QCD evolution is completely incoherent; there is no diagram where gluons connect one quark to another. • The bound-state wavefunctionitself generate gluons. The intrinsic gluon distribution is connected to the transverse part of bound-state potential.

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