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Hyperon polarization in hh/hA collisions and related problems

Hyperon polarization in hh/hA collisions and related problems. 梁作堂 (Liang Zuo-tang) 山东大学 (Shandong University). Introduction The physical picture Results for single-spin left-right asymmetries Results for hyperon polarizations in hh / hA collisions Further tests. Introduction.

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Hyperon polarization in hh/hA collisions and related problems

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  1. Hyperon polarization in hh/hA collisions and related problems 梁作堂 (Liang Zuo-tang) 山东大学(Shandong University) • Introduction • The physical picture • Results for single-spin left-right asymmetries • Results for hyperon polarizations in hh/hA collisions • Further tests. 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  2. Introduction Two classes of puzzling spin effects in inclusive h-h reactions • Single-spin left-right asymmetries in e.g. p()+p(0)+X • Hyperon polarization in unpolarized h+h or h+A collisions • For p()+p+X, • For p+pH+X, Question: Relation between PH and AN? 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  3. Single Spin Left-Right Asymmetry Experimental Results: • AN is non-zero for large xF and moderate p. • AN depends on the flavor of the produced hadron. • AN depends on the flavor of the polarized incident hadron. 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  4. Hyperon Polarization in Unpolarized h-h Collisions P in - +p+X, compared with P in p+p+X. Experimental Results -P in K- +p+X, compared with P in p+p+X. The same characteristics as those for AN! 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  5. A Physical Picture (i) Hadrons in fragmentation regions are products of direct fusions of valence quark(s) with sea- or anti-sea-quark(s), i.e. (ii) In the direct fusion processes (a) and (b), i.e. in qv+(..)h(qv..), there exists a spin-dependent interaction so the cross section can be written as, (iii) The direct fusion process is accompanied by , and the associatively produced M and B move in opposite transverse direction. (iv) SU(6) wave-function is used to related the spin of qvand that of B which contains this qv. (v) Spins of qsand qs-bar in the associated direct-fusion processes and are anti-aligned. 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  6. A simple working model for ANin p()+ph+X First, take h=meson as an example. In this case, points (i) and (ii) are relevant. Direct Fusion: , contributing to AN p+p+X includes Others: no contribution to AN The number density: c.m.s. energy squared Energy-momentum conservation demands For 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  7. Results for AN AN for lepton-pair production: clear test of the picture! Liang & Meng, Z. Phys.A (1992). Boros, Liang & Meng, Phys.Rev.Lett. (1993). 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  8. Energy dependence FNAL E704 Pinc=200GeV BNL E925 Pinc=22GeV Dong and Liang, PRD (2004) 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  9. Results for AN in p()+p+X Two contributing direct fusion processes: Test of point (iii). FNAL E704 Pinc=200GeV Boros and Liang, PRD (1996) 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  10. Results for PH in h+hH+X Class I: only (b) qv+qsqsH is contributing, i.e. the produced hyperon has one common valence quark with the projectile. Points (i), (ii) and (iv) are relevant. E.g.: p+p-+X dominated by : p+p+X dominated by : K-+p+X dominated by : The existence of PH in h+h/AH+X. 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  11. Dong and Liang, PRD (2004). 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  12. Results for PH in h+hH+X Class II: both (b) qv+qsqsHand (c) qvqv+qsH are contributing. The produced hyperon has two common valence quark with the projectile. Points (i), (ii), (iii), (iv) and (v) are relevant. E.g.: p+p+X. are contributing. type of correlation (ii): (Spin of K+)= 0 (v): anti-alignment of the spins of ss and ss-bar 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  13. Liang and Boros, PRL (1997). 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  14. Dong and Liang, PRD (2004). 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  15. Tests of (V): spins of qs and qs-bar are anti-aligned (1) Lambda polarization in pp pK+ Liang and Boros, PRD (2000). Only the following processes contribute |P| inpppK+ takes the maximum among different channels of pp X, and P=-C=-0.6. Consistent with the data from CERN R608, P=-0.620.04. 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  16. Tests of (v): spins of qs and qs-bar are anti-aligned (2) P in e-pe-K+ with polarized electron beam Liang and Xu, PRD (2002). Only the following processes contribute Consistent with the recent results by CLAS! 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  17. Tests of (V): spins of qs and qs-bar are anti-aligned (3) Predictions forPH e-pe-HK with polarized electron beam Three cases: 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  18. Polarizations of different baryons in 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  19. Tests of (iv): spin transfer in qh+X (1) PHin e+e-Z0 q0q0-bar H+X Max of |P| SU(6) DIS Boros,Liang, PRD(98) SU(6) agrees with the data not worse than DIS! 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  20. Tests of (iv): spin transfer in qh+X (2) PHin • Predictions have been made. • Data are available, but statistics is too low, energy is two low. • Further measurements at COMAPSS? Liu, Xu and Liang, PRD(2001); Liang and Liu, PRD(2002). 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  21. Tests of (iv): spin transfer in qh+X (3) Prediction for PHin p+pH+X at high pT and high energies. Xu, Liu and Liang, PRD(2002) Sigma polarization in more suitable to test different models for spin transfer in qh+X, since: • The polarization is much higher; • Decay contribution is smaller; • Influence from the difference in parametrization of p.d.f. is smaller. Waiting for the Results from RHIC! 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  22. Tests of (iv): spin transfer in qh+X (4) Spin alignment of V in high energy reactions Data from OPAL unpolarized: 00 =1/3. 00: probability for V to be in the helicity 0 state. 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  23. Tests of (iv): spin transfer in qh+X (4) Spin alignment of V in high energy reactions Xu and Liang, PRD(2002) Measurements from COMPASS!? 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  24. Tests of (iv): spin transfer in qh+X (4) Spin alignment of V in high energy reactions Xu and Liang, PRD(2003) Measurements at RHIC!? 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

  25. Summary and outlook A physical picture is proposed to relate hyperon polarization in unpolarized hh/hA collisions to the left-right asymmetry in singly polarized hh collisions. Reasonable agreements with the available data have been obtained. Tests of different ingredients of the picture have been proposed, compared with the available data. They can be further tested by future experiments. Thanks ! 梁作堂(Liang Zuo-tang)，山东大学(Shandong University)

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