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Spin Effects Correlated with 6q-Component in the Deuteron

Spin Effects Correlated with 6q-Component in the Deuteron. L.S. Zolin, Yu.K. Pilipenko Joint Institute for Nuclear research (Dubna). Outline. Introduction SR NN-correlations in nuclei, Fermi- motion or MQC ? Evidence for MQC in nuclei in IE and HE spin expts.

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Spin Effects Correlated with 6q-Component in the Deuteron

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  1. Spin Effects Correlated with 6q-Component in the Deuteron L.S. Zolin, Yu.K. Pilipenko Joint Institute for Nuclear research (Dubna) Spin-2006_ Kyoto_Zolin L.

  2. Outline • Introduction • SR NN-correlations in nuclei, Fermi- motion or MQC ? • Evidence for MQC in nuclei in IE and HE spin expts. • dAYπXin cumulative regime as tool to study the deuteron core spin structure • SSA in dAYπXand ppYπX • Azz(x) of HERMES (b1-data) vs Ayy(x) of Dubna • Ayy(Pt) indAYπXand orbital mom. of 6q in D-state • Conclusion Spin-2006_ Kyoto_Zolin L.

  3. Structure of nuclei at short internucleonic distances is connected with phenomenon of existing of short range nucleon correlations which manifests themselves as few nucleon clusters. When wave functions of nucleons are overlapped ( rNN < 0.7 fm) they can be treated as multiquark configurations MQC. ( In case of deuteron the deuteron core can be considered as the 6q-system). MQC existence is confirmed by EMC-effect. They are responsible for such phenomena as subthreshold meson production at E < 1 GeV and production of high momentum cumulative secondaries in NA-,AA- collisions at high energies. An alternative explanation in frame work of nucleon meson models of NN-forces is by means of Fermi motion in nuclei. Experiments with spin observables can help toresolvewhich of two approaches is more founded. Spin-2006_ Kyoto_Zolin L.

  4. Spin observables were studied most intensively at intermediate energies with detail comparison of data and calculations at use of 2NF’s and 3NF’s. Analysis of intermediate energy data made it is clear that 1) necessary to find theoretical approach of correct treatment of relativistic effects and QDF when one probes the NF’s core, 2) the spin effects are very sensitive to structure of short range NF’s. [ M.Lacombe et al., PR C65,034004 (2002) , the analysis - up to 350 MeV.]. Data at higher energies confirms the same: SR NNF’s cannot be understood without detail knowledge of nucleon substructure and structure of SR NN-correlations in nuclei. Spin-2006_ Kyoto_Zolin L.

  5. HE-region: DIS experiments and nucleus fragmentation Information on SR NN-correlations in nuclei can be extracted : a) in DIS experiments with light nuclei, available rNN-scale is limited by low cross sections of (e,)A-reactions ; b) in reactions of nuclei fragmentationwith use h-probes (NA,pA), very low rNN are available (up to 0.2 fm) but interpretation is difficult due to distortion carried in by strong interacting probe. Let to discuss the results obtained at fragmentation of polarized deuterons with energies from 1 to 3.65 GeV/n , which permit to study the deuteron spin structure up to internal momenta k=1 GeV/c . Spin-2006_ Kyoto_Zolin L.

  6. Dubna andSaclaymeasurements of thetensor analyzing powerT20 and the polarization transferko at deuteron breakup revealed significant deviations from IA calculations at k>0.25 GeV/c. These discrepancies raise a question: is DWF constructed with realistic NNP not correct at rNN ≤ 0.4÷0.5 fm? Spin-2006_ Kyoto_Zolin L.

  7. em - probes vs h - probes It seems an answer was provided in the JLAB d(e,de’)- experiment where T20 was measured up to Q equivalent of k=0.65 GeV/c and rather good agreement with IA-predictions was observed (and with pQCD-calcul’s as well) - known DWF’s work well up to k~0.6 GeV/c. Thus, the deuteron breakup N(d,p)X permits to probe DWF at very high k (1 Gev/c is reached) but too many mechanisms affect on behavior of spin observables (FSI, 3NF, isobar excitation, rescattering and so on). D.Abbott et al., nucl-ex/0001006 Another reaction with h-probe which permits to study the deuteron spin structure at very small rNN is polarized deuteron fragmentation into high momentum pions: pol.d + N→π+X. Spin-2006_ Kyoto_Zolin L.

  8. Among hadrons probes a meson as mediator of NN-forces brings a valuable information on SR NN-forces. What sign can identify that the meson is produced at short rNN ? Pbeam = 4.5 GeV/c/nucl. One must use a meson production reaction dN→πXin the cumulative regime when themeson can be produced on strongcorrelated NN-pair only (i.e. on the d-core). The invariant variable xc is used for the cumulative reactions. It is defined by 4-mom. conservation: xc·Pd+PN=Ph+Px (Pd is 4-mom. per nucleon). xc is min. fragmenting mass (in Mn unit) to produce h . IndN→hXxc ranges up to 2. xcis some analog of xFfor a case of NA-interaction Xc →XF at E >> MN Xc/XF - 1< 0.1 at E= 9 CeV Spin-2006_ Kyoto_Zolin L.

  9. Motivation to study spin observables in the reactiondA YπXin the cumulative regime • Discriminate between two alternatives for mechanisms • of cumulative reactions: • a)based onFermimotion: NN→NNπ, IAcan be applied to calculate T20, • the prediction can be compared with data; • b) based on fragmentation 6q-component in the deuteron • with hadronization of struck quark into the meson: d→6q→(q→π)+X; • no theoretical recipe to predict a behavior spin observables, • but one can try to apply Collins or/and Sivers mechanisms • to 6q-fragmentation for data interpretation . Spin-2006_ Kyoto_Zolin L.

  10. 2) The large SSA were observed in pp→πX in beam fragmentation region at Pt > 0.5 GeV/c (FNAL) and at xF > 0.5 (BNL). Thus, one can expect a remarkable spin effectsat d-fragmentation into high momentum pions with high Pt if similar mechanisms act at fragmentation of 3q- and 6q-system. FNAL (E704), 200 GeV/c BNL, 22 GeV/c Spin-2006_ Kyoto_Zolin L.

  11. LHE experimental setup for study an inclusive meson production A(d,p)X Acceptance of the focusing spectrometer -5 sr, D(Dp/p)=2.4x10 Dp/p=2.2% Momentum range 1.5 to 6 GeV/c TOF 1,2 - correlation 9 Deuteron beam intensity Id = 2x10 d/spill TOF-bases: 28m & 21m Pzz(+) = 0.640 ± 0.033 ± 0.026 (sys) TOF-resolution s =0.2 ns Pzz(-) = -0.729 ±0.024 ± 0.029 (sys) Spin-2006_ Kyoto_Zolin L.

  12. Tensor analyzing power Ayy in dA→π(Θ)X at Pd=9 GeV/c The sign of Ayy at xc >1 is negative at allQ (contrary to DPM IA-prediction) Magnitude of Ayy increases with rise of Θ andwith rise of xc Ayy reaches –0.4 at xc=1.5 Θ-and k -dependences in A(d,π)X is contrary toA(d,p)X Spin-2006_ Kyoto_Zolin L.

  13. Transverse momentum dependence of Ayy in A(d,π)X Ayy rises in magnitudeat increase of Pt from 0.4 to 0.8 (~linearly, where is limit of such a rise?) Threshold effect is seen for SSA in pp→πX, it is due to x-dependence of quark contribution into nucleon spin. In dp→πXAyy(Pt) is tensor effect due to D-state of 6q in the deuteron core (seen at xc > 1 only). In frame of Sivers approach (PDF) Ayy(Pt)-dependence is determined, evidently, by the orbital momentum of 6q (L=2) . Spin-2006_ Kyoto_Zolin L.

  14. Ayy at fragmentation of 5 GeV/c tensor polarized deuterons At low Pt (Θ~0) Ayy shows weak xc-dependence varying from +0.1 to –0.1 when Pd ranges from 5 to 9 GeV/c Spin-2006_ Kyoto_Zolin L.

  15. Vector analyzing power Ay in A(d,π)X at Pd=9 GeV/c Ay was measured with vector polarized d-beam at Θπ = 180 mrad Aychanges monotonously from 0.1 to–0.1 at increase of qπ from1.5 to 4 GeV/c (0.4 < xc < 1.7, 0.25 < Pt < 0.7) crossing zero near 3 GeV/c where xc = 1. Sign of Ay is similar for π+ and π- . Both features, sign similarity and low vector analyzing power (comparing with An in pp→πX), due to isospin I=0 of the deuteron (quark content is 3u+3d) . ip(+) , o p(-) 180 mrad [ p(-) 135 mrad. Spin-2006_ Kyoto_Zolin L.

  16. GeV deuteron fragmentation vs DIS - deuteron Dubna, A( d, p)X HERMES hep-ex/0506018, d (e.e’)X - DIS b1 Different x-regions in the deuteron are probed in these two experiments: x < 0.5at HERMES x = 0.5 to 1.6 at Dubna So far, x > 0.9 is not available in ed-DIS Spin-2006_ Kyoto_Zolin L.

  17. For a possible explanation of striking Pt-dependence of Ayy in dA -> πX one can follow C.Boros and Liang Zuo-Tang approach for explanation of SSA in inclusive high energy hadron-hadron collision processes [ hep-ph/0001330 ]. They constructed the non-perturbative model which explicitly takes the orbital motion of the valence quarks into account. Spin-2006_ Kyoto_Zolin L.

  18. Estimation of cumulative pion Ptat breakup of 6q-cluster with L=2 projection on transverse plain Absolute value of orbital moment at L=2 Labs =  sqrt(L·(L+1)) ~ 500 fm· MeV/c Orbital momentum porb~ Labs / rNN Xc = 1.5 corresponds to rNN ~ 0.4 fm and porb ~ 1.2 GeV/c. Thus, xy- projection of struck quark can rang up to pq ~ 1.2 GeV/c. At its hadronization into pion the transverce pion momentum Pt can range in the same limits. At cumulative pion emission angle of 160mrad Ayy ramped to -0.4 with Pt rise up to 0.8 GeV/c. Above estimations show that one can expect further rise of Ayy at higher Xc or saturation effect can be revealed as well. - That is a matter of the next experiment. pq pq~ Pt(π) D-beam Sd along z-axis Pzz ≠ 0 D-state L=2 Spin-2006_ Kyoto_Zolin L.

  19. Conclusion The vector Ay and tensor Ayy analyzing powers were studiedat 5 and 9 GeV/c at d-fragmentation into cumulative pions which permit to probe the deuteron core structure up to rNN ~ 0.2 fm where two correlated nucleon can be studied as 6q-system. Ay in dA->πX is small due to isospin I=0 (u,d -symmetry of pn-pair). Ayy shows a linear rise at increase Ptfrom 0.4 to 0.8GeV/c – the threshold effect similar to AN(Pt) in pp->πX Ayy(Pt)-effect can be connected with orbital momentum of 6q in D-state. Precision measurements at Pt > 0.7 GeV/c are desirable to find a limit of Ayy(Pt) rise and to clarify Pt-dependence of Ay at xc >1. Spin-2006_ Kyoto_Zolin L.

  20. Our sincere thanks to Organizing Committee of SPIN 2006 for invitation and support to take part in the Symposium. It is great pleasure for both of us to express our gratitude to collaborators from Nagoya University conducted by Prof. N. Horikawa for common efforts to perform successful experiments at Dubna polarized deuteron faсility. Spin-2006_ Kyoto_Zolin L.

  21. BACK UP 1 Spin-2006_ Kyoto_Zolin L.

  22. We can shortly review data with polarized deuterons at E<1 GeV and E>1 GeV to conclude where successful and where not explanation of observables behavior at disregard of quark degrees of freedom (QDF) in nuclei. At intermediate energies (E < 1 GeV) study in a number of laboratories (IUCF,KVI,RIKEN,RCNP) was concentrated on search of evidence of a three nucleon forces (3NF) because discrepancies of 2NF calculations and data take place in cross section minimum at large c.m. angles. Spin-2006_ Kyoto_Zolin L.

  23. How much addition of 3NFs can improve an accordance of calculations and exp. data? K.Sekiguchi et al., PR 0,014001(2004) ’ ’ 3NFs (2π exchange) improve the description of CS and some spin observables, but not always 3NFs are needed but their spindependent part has some defects IUCF-groupconclusion: 3NFs are not successful in explanation of discrepancy between 2N-calculations and data at large angles (B.v.Przewoski et al. nucl-ex/0411011) p + d elast. at 135 MeV/nucleon Spin-2006_ Kyoto_Zolin L.

  24. The first evidence of impotence of the deuteron nucleon model to explane data of deuteron induced reactions in GeV-region In 1982-83 Dubna (dp-breakup) and SLAC (ed-scatt.) data showed that the nucleon mom. distribution in the deuteron Nd(k) deviates from IA-predictions based on standard DWF at k  0.25 GeV/c. Similar problem was reviled with p(d,p)d It was as a surprise because the deuteron breakup N(d,p)X and backward elastic scattering p(d,p)d are the reactions where a pole mechanism (ONE) should dominate and IA calculations seems to be well based. Spin observablesshown increasing deviations at the same k  0.25 GeV/c. From Proc. of the Intern. Symp. “Dubna Deuteron-93”,p.71, Dubna,1993 Spin-2006_ Kyoto_Zolin L.

  25. GeV polarized deuteron beams is effective tool to study the deuteron spin structure in the region of deuteron core Single spin asymmetry (SSA) in the reaction with polarized deuterons can be studied without use of expensive polarized target with the large dilution factor. At fragmentation of high momentum deuterons one can test what is internal momentum limit (rNN) for use of the nucleon model of the deuteron at disregard of nucleon substructure. As it was demonstrated by spin experiments at intermediate energies the spin effects are very sensitive to structure of the short range NN-forces. Spin-2006_ Kyoto_Zolin L.

  26. Ayy at fragmentation of 5 GeV/c tensor polarized deuterons • Ayy at Pd=5 GeV/c was measured to clarify an energy dependence in A(d,p)X (black points) • A(d,p)X against A(d,p)XEd-dependence of Ayy -- is weak in d-breakup A(d,p)X (Ayy is defined by nucleon momentum distribution in the deuteron) -- isremarkable in A(d,p)X (contradicts with NN->NNpproduction mechanism) • Ayy-sign: in A(d,p)X ds( ) > ds( ) Ayy>0 . in A(d,p)X ds( ) < ds( ) Ayy<0 -form of nucleon density distribution in D-state Multiquark fragmentation model: the cumul. meson is produced at hadronization of quark-spectator which has a high mom.(x>1) as result of momentum randomization in 6q. Preferable direction of randomization is along spinaxis: in orbit. mom. plane a constituent movement is regulated by rotation. The result is Ayy(p) < 0 Spin-2006_ Kyoto_Zolin L.

  27. Completeness of data set of spin observables riched in the lastpd-scattering experiments can be illustrated by the IUCF-data(B.v.Przewoski et al. nucl-ex/0411011) • Ay for p & d, Aji and 10 of 12 spin correlation coefficients in p+d –elastic • 2N-force Faddeev calculations with CD-Bonn & AV18 NNP’s within/without 3NFs • IUCF-group conclusion is less optimistic comparing with the pronounced in other experiments: • 3NFs are not successful in explanation of discrepancy between 2N-calculations and data at large angles ’ ’ Spin-2006_ Kyoto_Zolin L.

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