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Hyperon Production in High Energy Processes

Hyperon Production in High Energy Processes. Bo-Qiang Ma (Peking University). Outline. The Motivation Distribution and Fragmentation Functions Case Study: Case Study: Case Study: Ratio in Case Study: Production in l+A Process Conclusions.

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Hyperon Production in High Energy Processes

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  1. Hyperon Production in High Energy Processes Bo-Qiang Ma(Peking University)

  2. Outline • The Motivation • Distribution and Fragmentation Functions • Case Study: • Case Study: • Case Study: Ratio in • Case Study: Production in l+A Process • Conclusions

  3. Our View of the Protonwith history • Point-Like 1919 • Finite Size with Radius1930s-1950s • Quark Model1960s • QCD and Gluons1970s • Puzzles and Anomalies1980s-present • Quark Sea of the Nucleon • Baryon-Meson Fluctuations • Statistical Features • ……

  4. Surprises & Unknownabout the Quark Structure of Nucleon: Sea • Spin Structure: “puzzle”: where is the proton’s missing spin • Strange Content • Flavor Asymmetry • Isospin Symmetry Breaking Brodsky & Ma, PLB381(96)317 Ma, PLB 274 (92) 111 Boros, Londergan, Thomas, PRL81(98)4075

  5. Unknownabout thenucleon:valence x→1behaviors of flavor and spin • Flavor • Spin

  6. Ratio of Neutron/Proton Structure Functions

  7. Flavor Content of the Protonwith nuclear binding correction W.Melnitchouk & A.W. Thomas PLB 377(1996) 11

  8. Flavor Content of the Protonfrom DIS neutrino data analysis U.K. Yang & A. Bodek PRL 82 (1999) 2467.

  9. Quark Helicity Distributions of ProtonMeasurements at JLAB and HERMES JLAb Hall A Collaboration nucl-ex/0308011, PRL

  10. Present Statusof the Flavor and Spin Contents of the Proton • Flavor favors pQCD • Spin favors diquark model Unclear & In Contradiction!

  11. How to Test Various Theories?

  12. SU(3) Symmetry together with Proton Spin Problem

  13. The u,d sea of Lambda versus s sea of Nucleon

  14. Different flavor & spin structure in different models

  15. Spin structure in two different models

  16. Flavor structure in two different models

  17. An intuitive argument

  18. Significantly different predictions

  19. Connections between structure functions and fragmentation functions

  20. Various Processes

  21. Flavor separation

  22. Extension to Sigma Hyperon

  23. The advantage of using Sigma hyperons

  24. New Domain for Theorists and Experimenlists

  25. Spin structure of Lambda from Lambda polarization in Zº decay

  26. Diquark model and pQCD results

  27. Spin Transfer to Λ in Semi-Inclusive DIS

  28. Different predictions

  29. Ratio in DIS Production • A sensitive quantity that can provides information about the flavor structure of hyperon. B.-Q. Ma, I. Schmidt, J.-J. Yang Phys. Lett. B 574 (2003) 35

  30. The flavor structure of Lambdau/s ratio with x-dependence

  31. Different predictions

  32. Anti-Lambda production as a probe of the nuclear sea structure? • 有三类原子核模型可以解释EMC效应: 团簇模型,Pi盈余模型, 重新标度模型. • 通过考察原子核与核子荷电轻子半单举过程中末态强子anti-Lambda的产率比对x的依赖性，我们发现 anti-Lambda能够区分定性描述原子核EMC效应的三类不同原子核结构模型.

  33. Different sea behaviors in nuclei

  34. Different predictions of anti-lambda production

  35. High Energy Spin Physics Experiment@ HERMES by China Group • Yajun Mao @ PKU • Yunxiu Ye @ USTC • Bo-Qiang Ma @PKU • & students

  36. Conclusion 1: Lambda Physics

  37. Conclusion 2: Anti-Lambda Productionfor Nuclear Physics Anti-Lambda production charged lepton semi-inclusive deep inelastic scattering off nuclear target is ideal to figure out the nuclear sea content, which is differently predicted by different models accounting for the nuclear EMC effect.

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