engLiang, ZLiu, CHyperon polarization in $\nu_{\mu}$ charged current interaction at the NOMAD energiesParticle Physics - Phenomenologyhep-ph/0204323We show that, in $\nu_\mu N\to \mu^-\Lambda X$ at the NOMAD energies, it is impossible to separate the products of the fragmentation of the struck quark from those of the nucleon remnant. The latter has a large contribution even in the current fragmentation region and has to be taken into account in calculating $\Lambda$ polarization using different pictures. Based on this, we make a rough estimation for the longitudinal $\Lambda$ polarization in $\nu_{\mu} N \to \mu^- \Lambda X$ at the NOMAD energies. A comparison with the data is given and predictions for $\nu_\mu N\to\mu^-\Sigma^+X$ are presented.2002-04-28http://cds.cern.ch/record/549388http://cds.cern.ch/record/549388oai:cds.cern.ch:549388 doi:10.1103/PhysRevD.65.113012engLiang, ZXu, QHyperon polarization in e^-p --> e^-HK with polarized electron beamsParticle Physics - Phenomenologyhep-ph/0204322We apply the picture proposed in a recent Letter for transverse hyperon polarization in unpolarized hadron-hadron collisions to the exclusive process e^-p --> e^-HK such as e^-p-->e^-\Lambda K^+, e^-p --> e^-\Sigma^+ K^0, or e^-p--> e^-\Sigma^0 K^+, or the similar process e^-p\to e^-n\pi^+ with longitudinally polarized electron beams. We present the predictions for the longitudinal polarizations of the hyperons or neutron in these reactions, which can be used as further tests of the picture.2002-04-28http://cds.cern.ch/record/54938710.1103/PhysRevD.65.113012http://cds.cern.ch/record/549387oai:cds.cern.ch:549387Comments: 15 pages, 2 figures. submitted to Phys. Rev. D doi:10.1016/S0375-9474(01)01161-7engPopov, B AMeasurement of the $\Lambda$ hyperon polarization in $\nu_{\mu}$ charged current interactions in the NOMAD experimentParticle Physics - ExperimentThe Lambda hyperon polarization in nu /sub mu / charged current interactions has been measured in the NOMAD experiment. The event sample (8087 reconstructed Lambda 's) is more than an order of magnitude larger than that of previous bubble chamber experiments, while the quality of the event reconstruction is comparable. We observe a negative polarization along the W-boson direction which is enhanced in the target fragmentation region: P/sub x/(x/sub F/<0) =-0.21+or-0.04(stat)+or-0.02(sys). In the current fragmentation region we find P/sub x/(x/sub F/>0)=-0.09+or-0.06(stat)+or-0.03(sys). These results provide a test of different models describing the nucleon spin composition and the spin transfer mechanisms. We also observe a significant transverse polarization (in the direction orthogonal to the Lambda production plane) for the first time in a neutrino experiment: P/sub y/=-0.22+or-0.03(stat)+or-0.01(sys). The dependence of the absolute value of P/sub y/ on the Lambda transverse momentum with respect to the hadronic jet direction is in qualitative agreement with the results from unpolarized hadron-hadron experiments. The dependence of the Lambda polarization on the type of target nucleon in nu /sub mu / scattering has been also studied. (11 refs).2001http://cds.cern.ch/record/53681110.1016/S0375-9474(01)01161-7http://cds.cern.ch/record/536811oai:cds.cern.ch:536811 chi Liu Chun Xiu Liang Zuo Tang Spin transfer in high-energy hadronization processes and polarization of hyperon in the lepton-induced reactions Particle Physics - Phenomenology We show that measuring the polarization of the hyperon in the lepton induced reactions is an ideal way to study the spin transfer in high- energy hadronization processes. After a brief summary of the polarization of the initial quark or antiquark in these reactions, we give the calculation method of the polarization of the hyperon. As an example, we calculate polarizations of different hyperons in e/sup + /e/sup -/ annihilation at LEP energies and compare these results with the available data. The results show that measurements of such polarizations should provide important information about the question of which picture of spin structure of baryon is more suitable in describing the spin effects in the high-energy fragmentation processes. (17 refs). 2001 http://cds.cern.ch/record/516889 http://cds.cern.ch/record/516889 engLiu, CXu, QLiang, ZHyperon polarization in semi-inclusive deeply inelastic lepton-nucleon scattering at high energyParticle Physics - Phenomenologyhep-ph/0106184We calculate the polarizations for different octet hyperons produced in the current fragmentation regions of the deeply inelastic lepton-nucleon scatterings $\mu^-N \to \mu^- HX$ and $\nu_{\mu} N \to \mu^- HX$ at high energy using different models for spin transfer in fragmentation processes. The results show that measurements of those hyperon polarizations should provide useful information to distinguish between different models in particular the SU(6) and the DIS pictures used frequently in the literature. We found, in particular, that measuring the polarization of $\Sigma^+$ produced in these processes can give a better test to the validity of the different spin transfer models.2001http://cds.cern.ch/record/504920http://cds.cern.ch/record/504920oai:cds.cern.ch:504920 eng Maggiora, M Balestra, F Bedfer, Y Bertini, R Bland, L C Brochard, F Bussa, M P Chalyshev, V Choi, S Debowski, M Dzemidzic, M Faivre, Jean-Claude Falomkin, I V Fava, L Ferrero, L Foryciarz, J Frolov, V Fröhlich, I Garfagnini, R Gill, D Grasso, A Heinz, S Ivanov, V V Jacobs, W W Kühn, W Maggiora, A Manara, A Panzieri, D Pfaff, H W Piragino, G Pontecorvo, G B Popov, A Ritman, J Salabura, P Tosello, F Vigdor, S E Zosi, G Spin observables in hyperon production Nuclear Physics The first exclusive measurements of the spin transfer parameter D sub N sub N in the reaction p-vectorp->pK sup +LAMBDA-vector has been performed at Saturne with the polarized beam and with the DISTO spectrometer. The results suggest an OBE mechanism dominated by kaon exchange. 2000 http://cds.cern.ch/record/782505 http://cds.cern.ch/record/782505 eng Belostotskii, S L Longitudinal spin transfer to the Lambda hyperon in leptoproduction XX DESY-HERMES-2001-70 2001 http://cds.cern.ch/record/733005 http://cds.cern.ch/record/733005 eng Chiang Huan Ching Lambda hyperon production mechanisms and longitudinal spin transfer at HERMES XX DESY-HERMES-2003-09 2003 http://cds.cern.ch/record/627493 http://cds.cern.ch/record/627493 engGöckeler, MHorsley, RPleiter, DRakow, P E LSchäfer, SSchäfer, ASchierholz, GA lattice study of the spin structure of the Lambda hyperonParticle Physics - Latticehep-lat/0208017DESY-02-100DESY-2002-100EDINBURGH-2002-05LU-ITP-2002-014The internal spin structure of the Lambda is of special importance for the understanding of the spin structure of hadrons in general. The comparison between the nucleon and Lambda allows for a test of the relevant flavour-symmetry breaking effects. Using nonperturbatively O(a) improved Wilson fermions in the quenched approximation we have calculated the first moments of the unpolarised, longitudinally polarised and transversity quark distribution functions in the Lambda. The results indicate that flavour symmetry breaking has little effect on the internal spin structure, in accordance with model based expectations.2002-08-13http://cds.cern.ch/record/576187http://cds.cern.ch/record/576187oai:cds.cern.ch:576187 engGöckeler, MHorsley, RPleiter, DRakow, P E LSchäfer, SSchäfer, ASchierholz, GThe spin structure of the Lambda hyperon in quenched lattice QCDParticle Physics - Latticehep-lat/0110057DESY-2001-144DESY-01-144It has been suggested to use the production of Lambda hyperons for investigating the nucleon spin structure. The viability of this idea depends crucially on the spin structure of the Lambda. Using nonperturbatively O(a) improved Wilson fermions in the quenched approximation we have studied matrix elements of two-quark operators in the Lambda. We present results for the axial vector current, which give us the contributions of the u, d, and s quarks to the Lambda spin.2001-10-12http://cds.cern.ch/record/522893http://cds.cern.ch/record/522893oai:cds.cern.ch:522893 eng Belostotskii, S L Grebenyuk, O Lambda polarization measured at HERMES and Lambda spin structure XX DESY-HERMES-99-54 1999 http://cds.cern.ch/record/732981 http://cds.cern.ch/record/732981 engYang Jian JunUp and Down Quark Contributions to Spin Content of Lambda from FragmentationParticle Physics - Phenomenologyhep-ph/0107222USM-TH-109We check the $u$ and $d$ quark contributions to the spin content of the $\Lambda$ by means of the $q\to\Lambda$ fragmentation and find that the $u$ and $d$ quarks of the $\Lambda$ are likely positively polarized. The parton distributions in the $\Lambda$ are given by a successful statistical model which can reproduce and correlate a vast body of polarized and unpolarized structure function and parton distribution data of the nucleon. With the Gribov-Lipatov relation between the quark distributions and fragmentation functions, the longitudinal spin transfer for the $\Lambda$ production in the polarized charged lepton deep inelastic scattering (DIS) process and the $\Lambda$-polarization in the neutrino (antineutrino) DIS process are predicted. The available experimental data suggests that the $u$ and $d$ quark contributions to the spin of the $\Lambda$ are positive. In addition, our results provide a collateral evidence for the SU(3) symmetry breaking in hyperon semileptonic decays of the octet baryons, which is very important for a deeper understanding of the proton 'spin crisis'.2001-07-20http://cds.cern.ch/record/510152http://cds.cern.ch/record/510152oai:cds.cern.ch:510152 2001-05-03T22:00:00Z http://cds.cern.ch/record/498370 http://cds.cern.ch/record/498370 eng Belostotskii, S L Grebenyuk, O Transverse polarization of Lambda hyperons produced inclusively in e N scattering at HERMES XX DESY-HERMES-2001-71 2001 http://cds.cern.ch/record/733006 http://cds.cern.ch/record/733006 eng Schnell, G Longitudinal polarization of the Lambda in deep inelastic scattering of polarized positrons from nucleons XX DESY-HERMES-99-37 1999 http://cds.cern.ch/record/732977 http://cds.cern.ch/record/732977 doi:10.1103/PhysRevC.71.065209engRaue, Brian ARatio of $\sigma_L / \sigma_T$ for $p(e,e'K^+)\Lambda$ Extracted from Polarization TransferNuclear Physicsnucl-ex/0402024The ratio of longitudinal to transverse structure functions, $\sigma_L/\sigma_T$, has been extracted from recent beam-recoil transferred polarization data for the $p(\vec e,e'K^+)\vec\Lambda$ reaction. Results have been obtained for $W$=1.69, 1.84, and 2.03 GeV at an average $Q^2$ of 0.69 GeV$^2$. Our results indicate a ratio approaching zero. This is in contradiction to previously published results using a Rosenbluth separation. A similar difference between Rosenbluth and recoil polarization results has been observed in the measurement of the ratio of electric to magnetic form factors of the proton, $\mu_pG_E/G_M$.2004http://cds.cern.ch/record/72030510.1103/PhysRevC.71.065209http://cds.cern.ch/record/720305oai:cds.cern.ch:720305Comments: 14 pages, 4 figures eng Brüll, A Transverse polarization of Lambda and Antilambda hyperons in quasi-real photon nucleon scattering XX DESY-HERMES-2002-51 2002 http://cds.cern.ch/record/627480 http://cds.cern.ch/record/627480 2002http://cds.cern.ch/record/623643http://cds.cern.ch/record/623643oai:cds.cern.ch:623643 doi:10.5170/CERN-2004-011.130engAnselmino, MTransversity and Lambda polarizationParticle Physics - Phenomenologyhep-ph/0302008Two related issues are discussed, which might be easily explored by present and future COMPASS experiments. The first one deals with the new world of transversity, the fundamental polarized parton distribution so far totally unknown. The second issue concerns Lambda production in polarized semi-inclusive processes, with a measurement of the Lambda polarization, which might give novel information on distribution and fragmentation properties of polarized partons. In case of transverse polarization the detection of Lambda's gives access to a new way of measuring transversities. Also the interesting case of Lambda polarization in unpolarized processes is discussed.CERN2003-02-02http://cds.cern.ch/record/60371510.5170/CERN-2004-011.130http://cds.cern.ch/record/603715oai:cds.cern.ch:603715 eng Carman, D S First Measurement of Transferred Polarization in the Exclusive e p --> e' K+ Lambda Reaction Particle Physics - Experiment hep-ex/0212014 The first measurements of the transferred polarization for the exclusive ep --> e'K+ Lambda reaction have been performed in Hall B at the Thomas Jefferson National Accelerator Facility using the CLAS spectrometer. A 2.567 GeV electron beam was used to measure the hyperon polarization over a range of Q2 from 0.3 to 1.5 (GeV/c)2, W from 1.6 to 2.15 GeV, and over the full center-of-mass angular range of the K+ meson. Comparison with predictions of hadrodynamic models indicates strong sensitivity to the underlying resonance contributions. A non-relativistic quark model interpretation of our data suggests that the s-sbar quark pair is produced with spins predominantly anti-aligned. Implications for the validity of the widely used 3P0 quark-pair creation operator are discussed. 2002-12-06 http://cds.cern.ch/record/595577 http://cds.cern.ch/record/595577 doi:10.1063/1.1413167engKotzinian, A M$\Lambda$ polarization in the target fragmentation region of SIDISParticle Physics - ExperimentParticle Physics - Phenomenology2001http://cds.cern.ch/record/56070910.1063/1.1413167http://cds.cern.ch/record/560709oai:cds.cern.ch:560709 engNaumov, Dmitry V.Measurement of Lambda and Lambda-bar polarization in muon neutrino charged current interactions in NOMADParticle Physics - Phenomenologyhep-ph/0206032The Lambda and Lambda-bar polarizations in muon neutrino charged current interactions have been measured in the NOMAD experiment. The event sample (8087 reconstructed Lambda's and 649 Lambda-bar's) is more than an order of magnitude larger than that of previous bubble chamber experiments, while the quality of event reconstruction is comparable. For the Lambda hyperons we observe negative polarization along the W-boson direction which is enhanced in the target fragmentation region: Px(xF < 0) = -0.21 +- 0.04 (stat) +- 0.02 (sys). In the current fragmentation region we find Px(xF > 0) = -0.09 +- 0.06 (stat) +- 0.03(sys). A significant transverse polarization (in the direction orthogonal to the Lambda production plane) has been observed for the first time in a neutrino experiment: Py = -0.22 +- 0.03 (stat) +- 0.01 (sys). The dependence of the absolute value of Py on the Lambda transverse momentum with respect to the hadronic jet direction is in qualitative agreement with the results from unpolarized hadron-hadron experiments. The polarization vector of Lambda-bar hyperons measured for the first time in neutrino interactions is found to be consistent with zero.The Lambda and Lambda-bar polarizations in muon neutrino charged current interactions have been measured in the NOMAD experiment. The event sample (8087 reconstructed Lambda's and 649 Lambda-bar's) is more than an order of magnitude larger than that of previous bubble chamber experiments, while the quality of event reconstruction is comparable. For the Lambda hyperons we observe negative polarization along the W-boson direction which is enhanced in the target fragmentation region: Px(xF < 0) = -0.21 +- 0.04 (stat) +- 0.02 (sys). In the current fragmentation region we find Px(xF > 0) = -0.09 +- 0.06 (stat) +- 0.03(sys). A significant transverse polarization (in the direction orthogonal to the Lambda production plane) has been observed for the first time in a neutrino experiment: Py = -0.22 +- 0.03 (stat) +- 0.01 (sys). The dependence of the absolute value of Py on the Lambda transverse momentum with respect to the hadronic jet direction is in qualitative agreement with the results from unpolarized hadron-hadron experiments. The polarization vector of Lambda-bar hyperons measured for the first time in neutrino interactions is found to be consistent with zero.The Lambda and Lambda-bar polarizations in muon neutrino charged current interactions have been measured in the NOMAD experiment. The event sample (8087 reconstructed Lambda's and 649 Lambda-bar's) is more than an order of magnitude larger than that of previous bubble chamber experiments, while the quality of event reconstruction is comparable. For the Lambda hyperons we observe negative polarization along the W-boson direction which is enhanced in the target fragmentation region: Px(xF < 0) = -0.21 +- 0.04 (stat) +- 0.02 (sys). In the current fragmentation region we find Px(xF > 0) = -0.09 +- 0.06 (stat) +- 0.03(sys). A significant transverse polarization (in the direction orthogonal to the Lambda production plane) has been observed for the first time in a neutrino experiment: Py = -0.22 +- 0.03 (stat) +- 0.01 (sys). The dependence of the absolute value of Py on the Lambda transverse momentum with respect to the hadronic jet direction is in qualitative agreement with the results from unpolarized hadron-hadron experiments. The polarization vector of Lambda-bar hyperons measured for the first time in neutrino interactions is found to be consistent with zero.2002-06-04http://cds.cern.ch/record/557558http://cds.cern.ch/record/557558oai:cds.cern.ch:557558 engNaumov, D VLambda Polarization in Deep-Inelastic ProductionParticle Physics - Phenomenologyhep-ph/0206031We propose a model for the longitudinal polarization of Lambda baryons produced in deep-inelastic lepton scattering at any xF, based on static SU(6) quark-diquark wave functions and polarized intrinsic strangeness in the nucleon associated with individual valence quarks. Free parameters of the model are fixed by fitting the NOMAD data on the longitudinal polarization of Lambda hyperons in neutrino interactions. Our model correctly reproduces the observed dependences of Lambda polarization on the kinematic variables. Within the context of our model, the NOMAD data imply that the intrinsic strangeness associated with a valence quark has anticorrelated polarization. We also compare our model predictions with results from the HERMES and E665 experiments using charged leptons. Predictions of our model for the COMPASS experiment are also presented.2002-06-04http://cds.cern.ch/record/557557http://cds.cern.ch/record/557557oai:cds.cern.ch:557557 doi:10.1140/epjc/s2002-01025-2engEllis, John R.Kotzinian, AramNaumov, Dmitry V.Intrinsic Polarized Strangeness and Lambda Polarization in Deep-Inelastic ProductionParticle Physics - Phenomenologyhep-ph/0204206CERN-TH-2002-080CERN-TH-2002-080We propose a model for the longitudinal polarization of Lambda baryons produced in deep-inelastic lepton scattering at any xF, based on static SU(6) quark-diquark wave functions and polarized intrinsic strangeness in the nucleon associated with individual valence quarks. Free parameters of the model are fixed by fitting NOMAD data on the longitudinal polarization of Lambda hyperons in neutrino collisions. Our model correctly reproduces the observed dependences of Lambda polarization on the kinematic variables. Within the context of our model, the NOMAD data imply that the intrinsic strangeness associated with a valence quark has anticorrelated polarization. We also compare our model predictions with results from the HERMES and E665 experiments using charged leptons. Predictions of our model for the COMPASS experiment are also presented.We propose a model for the longitudinal polarization of Lambda baryons produced in deep-inelastic lepton scattering at any xF, based on static SU(6) quark-diquark wave functions and polarized intrinsic strangeness in the nucleon associated with individual valence quarks. Free parameters of the model are fixed by fitting NOMAD data on the longitudinal polarization of Lambda hyperons in neutrino collisions. Our model correctly reproduces the observed dependences of Lambda polarization on the kinematic variables. Within the context of our model, the NOMAD data imply that the intrinsic strangeness associated with a valence quark has anticorrelated polarization. We also compare our model predictions with results from the HERMES and E665 experiments using charged leptons. Predictions of our model for the COMPASS experiment are also presented.2002-04-17http://cds.cern.ch/record/54752110.1140/epjc/s2002-01025-2http://cds.cern.ch/record/547521oai:cds.cern.ch:547521 engAnselmino, MBoer, DD'Alesio, UMurgia, FTransverse Lambda polarization in inclusive processesParticle Physics - Phenomenologyhep-ph/0201076A formalism proposed to study transverse Lambda polarization in unpolarized hadronic processes, based on a generalized pQCD factorization theorem, is extended to semi-inclusive DIS. Analytical expressions and examples of numerical estimates are given.2002-01-10http://cds.cern.ch/record/535101http://cds.cern.ch/record/535101oai:cds.cern.ch:535101 engArestov, YPolarization transfer in SIDIS for Lambda productionOther Fields of Physicsphysics/0111106Polarization transfer from the longitudinally polarized positron to the final-state quark is considered for the underlying QCD subprocesses giving rise to the reaction e+(pol) + p --> e+ + Lambda(pol) + X at the HERMES energy.2001-11-13http://cds.cern.ch/record/526616http://cds.cern.ch/record/526616oai:cds.cern.ch:526616 engAnselmino, MBoer, DD'Alesio, UMurgia, FTransverse Lambda polarization in semi-inclusive DISParticle Physics - Phenomenologyhep-ph/0109186DFTT-2001-28INFNCA-TH-2001-08Extending a previous description of Lambda and Lambda-bar polarization in unpolarized p-p interactions, within a pQCD factorization scheme with new polarizing fragmentation functions, we give predictions for the transverse polarization of Lambda's and Lambda-bar's in semi-inclusive DIS, both with neutral and charged currents. Comparison with existing data is not yet significant, but more experimental results are expected in the near future.2001-09-20http://cds.cern.ch/record/520384http://cds.cern.ch/record/520384oai:cds.cern.ch:520384 doi:10.1142/9789812778345_0094engAnselmino, MBoglione, MD'Alesio, UMurgia, FLongitudinal Lambda polarization in polarized semi-inclusive DISParticle Physics - Phenomenologyhep-ph/0106256We calculate, within pQCD parton model at leading orders, the expression of the longitudinal polarization of Lambda baryons produced in polarized semi-inclusive DIS, including weak interaction effects. We present some numerical estimates in few cases for which data are or will soon be available and discuss how to gather new information on polarized fragmentation functions.2001-06-22http://cds.cern.ch/record/51792210.1142/9789812778345_0094http://cds.cern.ch/record/517922oai:cds.cern.ch:517922Comments: LaTeX, 4 pages, 2 ps figures, uses sprocl.sty and epsfig.sty; Talk delivered by U. D'Alesio at the IX International Workshop on Deep Inelastic Scattering (DIS2001), Bologna, 27 April - 1 May, 2001 doi:10.1142/9789812778345_0093engAnselmino, MBoer, DD'Alesio, UMurgia, FTransverse Lambda polarization in unpolarized semi-inclusive DISParticle Physics - Phenomenologyhep-ph/0106254The long-standing problem of transverse Lambda polarization in high-energy collisions of unpolarized hadrons can be tackled by considering new, spin and k_T-dependent quark fragmentation functions for an unpolarized quark into a polarized, spin-1/2 hadron. Simple phenomenological parameterizations of these new "polarizing fragmentation functions", which describe quite well the experimental data on Lambda and Lambda-bar hyperons produced in p-A processes, are utilized and extended here to give predictions for transverse Lambda polarization in semi-inclusive DIS2001-06-22http://cds.cern.ch/record/51792010.1142/9789812778345_0093http://cds.cern.ch/record/517920oai:cds.cern.ch:517920Comments: LaTeX, 4 pages, 2 ps figures, uses sprocl.sty and epsfig.sty; Talk delivered by F. Murgia at the IX International Workshop on Deep Inelastic Scattering (DIS2001), Bologna, 27 April - 1 May 2001 engSofer, ALambda-lambda bar polarization correlationsParticle Physics - ExperimentCERN1993http://cds.cern.ch/record/505911http://cds.cern.ch/record/505911oai:cds.cern.ch:505911 doi:10.1016/S0550-3213(01)00181-XengAstier, P.Autiero, D.Baldisseri, A.Baldo-Ceolin, M.Banner, M.Bassompierre, G.Besson, N.Bird, I.Blumenfeld, B.Bobisut, F.Bouchez, J.Boyd, S.Bueno, A.Bunyatov, S.Camilleri, L.Cardini, A.Cattaneo, P.W.Cavasinni, V.Cervera-Villanueva, A.Chukanov, A.Collazuol, G.Conforto, G.Conta, C.Contalbrigo, M.Cousins, R.Daniels, D.Degaudenzi, H.Del Prete, T.De Santo, A.Dignan, T.Di Lella, L.do Couto e Silva, E.Dumarchez, J.Ellis, M.Fazio, T.Feldman, G.J.Ferrari, R.Ferrère, D.Flaminio, V.Fraternali, M.Gaillard, J.-M.Gangler, E.Geiser, A.Geppert, D.Gibin, D.Gninenko, S.Godley, A.Gomez-Cadenas, J.-J.Gosset, J.Gößling, C.Gouanère, M.Grant, A.Graziani, G.Guglielmi, A.Hagner, C.Hernando, J.Hubbard, D.Hurst, P.Hyett, N.Iacopini, E.Joseph, C.Juget, F.Kirsanov, M.Klimov, O.Kokkonen, J.Kovzelev, A.Krasnoperov, A.Kustov, D.Kuznetsov, V.Lacaprara, S.Lachaud, C.Lakić, B.Lanza, A.La Rotonda, L.Laveder, M.Letessier-Selvon, A.Levy, J.-M.Linssen, L.Ljubičić, A.Long, J.Lupi, A.Marchionni, A.Martelli, F.Méchain, X.Mendiburu, J.-P.Meyer, J.-P.Mezzetto, M.Mishra, S.R.Moorhead, G.F.Naumov, D.Nédélec, P.Nefedov, Yu.Nguyen-Mau, C.Orestano, D.Pastore, F.Peak, L.S.Pennacchio, E.Pessard, H.Petti, R.Placci, A.Polesello, G.Pollmann, D.Polyarush, A.Popov, B.Poulsen, C.Rico, J.Riemann, P.Roda, C.Rubbia, A.Salvatore, F.Schahmaneche, K.Schmidt, B.Schmidt, T.Sevior, M.Sillou, D.Soler, F.J.P.Sozzi, G.Steele, D.Stiegler, U.Stipčević, M.Stolarczyk, Th.Tareb-Reyes, M.Taylor, G.N.Tereshchenko, V.Toropin, A.Touchard, A.-M.Tovey, S.N.Tran, M.-T.Tsesmelis, E.Ulrichs, J.Vacavant, L.Valdata-Nappi, M.Valuev, V.Vannucci, F.Varvell, K.E.Veltri, M.Vercesi, V.Vidal-Sitjes, G.Vieira, J.-M.Vinogradova, T.Weber, F.V.Weisse, T.Wilson, F.F.Winton, L.J.Yabsley, B.D.Zaccone, H.Zuber, K.Zuccon, P.Measurement of the $\overline{\Lambda}$ polarization in $\nu_\mu$ charged current interactions in the NOMAD experimentParticle Physics - Experimenthep-ex/0103047CERN-EP-2001-028CERN-EP-2001-028We present a measurement of the polarization of $\alam$ hyperons produced in $\nu_\mu$ charged current interactions. The full data sample from the NOMAD experiment has been analyzed using the same $\vo$ identification procedure and analysis method reported in a previous paper~\cite{NOMAD-polar} for the case of $\lam$ hyperons. The $\alam$ polarization has been measured for the first time in a neutrino experiment. The polarization vector is found to be compatible with zero.We present a measurement of the polarization of Antilambda hyperons produced in nu_mu charged current interactions. The full data sample from the NOMAD experiment has been analyzed using the same V0 identification procedure and analysis method reported in a previous paper for the case of Lambda hyperons. The Antilambda polarization has been measured for the first time in a neutrino experiment. The polarization vector is found to be compatible with zero.2001-03-29http://cds.cern.ch/record/49474410.1016/S0550-3213(01)00181-Xhttp://cds.cern.ch/record/494744oai:cds.cern.ch:49474414 pages, 4 figures, submitted to Nuclear Physics B doi:10.1063/1.1384107engNaumov, Dmitry V.Measurement of Lambda polarization in muon neutrino charged current interactions in NOMADParticle Physics - Experimenthep-ph/0101325The Lambda polarization in muon neutrino charged current interactions has been measured in the NOMAD experiment. We observe negative polarization along the W - boson direction which is enhanced in the target fragmentation region: Px (xF < 0) = -0.21 +/- 0.04(stat) +/- 0.02(sys). In the current fragmentation region we find: Px (xF > 0) = -0.09 +/- 0.06(stat) +/- 0.03(sys). These results provide a test of different models describing the nucleon spin composition and the spin transfer mechanisms. A significant transverse polarization (in the direction orthogonal to the Lambda production plane) has been observed for the first time in a neutrino experiment: Py = -0.22 +/- 0.03(stat) +/- 0.01(sys). The dependence of the absolute value of Py on the Lambda transverse momentum with respect to the hadronic jet direction is in qualitative agreement with the results from unpolarized hadron-hadron experiments.The Lambda polarization in muon neutrino charged current interactions has been measured in the NOMAD experiment. We observe negative polarization along the W - boson direction which is enhanced in the target fragmentation region: Px (xF < 0) = -0.21 +/- 0.04(stat) +/- 0.02(sys). In the current fragmentation region we find: Px (xF > 0) = -0.09 +/- 0.06(stat) +/- 0.03(sys). These results provide a test of different models describing the nucleon spin composition and the spin transfer mechanisms. A significant transverse polarization (in the direction orthogonal to the Lambda production plane) has been observed for the first time in a neutrino experiment: Py = -0.22 +/- 0.03(stat) +/- 0.01(sys). The dependence of the absolute value of Py on the Lambda transverse momentum with respect to the hadronic jet direction is in qualitative agreement with the results from unpolarized hadron-hadron experiments.The Lambda polarization in muon neutrino charged current interactions has been measured in the NOMAD experiment. We observe negative polarization along the W - boson direction which is enhanced in the target fragmentation region: Px (xF < 0) = -0.21 +/- 0.04(stat) +/- 0.02(sys). In the current fragmentation region we find: Px (xF > 0) = -0.09 +/- 0.06(stat) +/- 0.03(sys). These results provide a test of different models describing the nucleon spin composition and the spin transfer mechanisms. A significant transverse polarization (in the direction orthogonal to the Lambda production plane) has been observed for the first time in a neutrino experiment: Py = -0.22 +/- 0.03(stat) +/- 0.01(sys). The dependence of the absolute value of Py on the Lambda transverse momentum with respect to the hadronic jet direction is in qualitative agreement with the results from unpolarized hadron-hadron experiments.The Lambda polarization in muon neutrino charged current interactions has been measured in the NOMAD experiment. We observe negative polarization along the W - boson direction which is enhanced in the target fragmentation region: Px (xF < 0) = -0.21 +/- 0.04(stat) +/- 0.02(sys). In the current fragmentation region we find: Px (xF > 0) = -0.09 +/- 0.06(stat) +/- 0.03(sys). These results provide a test of different models describing the nucleon spin composition and the spin transfer mechanisms. A significant transverse polarization (in the direction orthogonal to the Lambda production plane) has been observed for the first time in a neutrino experiment: Py = -0.22 +/- 0.03(stat) +/- 0.01(sys). The dependence of the absolute value of Py on the Lambda transverse momentum with respect to the hadronic jet direction is in qualitative agreement with the results from unpolarized hadron-hadron experiments.The Lambda polarization in muon neutrino charged current interactions has been measured in the NOMAD experiment. We observe negative polarization along the W - boson direction which is enhanced in the target fragmentation region: Px (xF < 0) = -0.21 +/- 0.04(stat) +/- 0.02(sys). In the current fragmentation region we find: Px (xF > 0) = -0.09 +/- 0.06(stat) +/- 0.03(sys). These results provide a test of different models describing the nucleon spin composition and the spin transfer mechanisms. A significant transverse polarization (in the direction orthogonal to the Lambda production plane) has been observed for the first time in a neutrino experiment: Py = -0.22 +/- 0.03(stat) +/- 0.01(sys). The dependence of the absolute value of Py on the Lambda transverse momentum with respect to the hadronic jet direction is in qualitative agreement with the results from unpolarized hadron-hadron experiments.The Λ0 polarization in νμ charged current interactions has been measured in the NOMAD experiment. The event sample (8087 reconstructed Λ0’s) is more than an order of magnitude larger than that of previous bubble chamber experiments, while the quality of event reconstruction is comparable. We observe negative polarization along the W-boson direction which is enhanced in the target fragmentation region: Px(xF<0)=−0.21±0.04(stat)±0.02(sys). In the current fragmentation region we find Px(xF>0)=−0.09±0.06(stat)±0.03(sys). These results provide a test of different models describing the nucleon spin composition and the spin transfer mechanisms. A significant transverse polarization (in the direction orthogonal to the Λ0 production plane) has been observed for the first time in a neutrino experiment: Py=−0.22±0.03(stat)±0.01(sys). The dependence of the absolute value of Py on the Λ0 transverse momentum with respect to the hadronic jet direction is in qualitative agreement with the results from unpolarized hadron-hadron experiments.2001-01-29http://cds.cern.ch/record/48535210.1063/1.1384107http://cds.cern.ch/record/485352oai:cds.cern.ch:485352a talk given at SPIN2000 (Osaka) symposium, October 16-21 (5 pages) Journal-ref: Published in AIP Conf.Proc.570:489-493,2001 engBourrely, CSoffer, JDeep Inelastic Scattering of Leptons and Hadrons in the QCD Parton Model and Experimental TestsParticle Physics - Phenomenologyhep-ph/0101195CPT-4092We present the basic aspects of deep inelastic phenomena in the framework of the QCD parton model. After recalling briefly the standard kinematics, we discuss the physical interpretation of unpolarized and polarized structure functions in terms of parton distributions together with several important sum rules. We also make a rapid survey of the experimental situation together with phenomenological tests, in particular concerning various QCD predictions. In the summary, we try to identify some significant open questions, to clarify where we stand and to see what we expect to learn in the future.2001-01-17http://cds.cern.ch/record/483903http://cds.cern.ch/record/483903oai:cds.cern.ch:483903 doi:10.1016/j.physletb.2003.08.069engMa Bo QiangSchmidt, IvanYang Jian JunRatio of $\bar{\Lambda}/\Lambda$ in Semi-inclusive ElectroproductionParticle Physics - Phenomenologyhep-ph/0403010USM-TH-140It is shown that the $\bar{\Lambda}/\Lambda$ cross section ratio in semi-inclusive electroproduction of $\Lambda$ and $\bar{\Lambda}$ hyperons in deep inelastic scattering of charged lepton on a nucleon target, can provide useful information on the quark to $\Lambda$ fragmentation functions. This ratio is calculated explicitly in a quark-diquark model, a pQCD based analysis, and an SU(3) symmetry model, with three different options for the contribution from the unfavored fragmentation functions. The $x$-dependence of this ratio is sensitive to the ratio of unfavored fragmentation functions over favored fragmentation functions, $D_{\bar{u}}^{\Lambda}(z)/D_{u}^{\Lambda}(z)$, whereas the $z$-dependence is sensitive to the flavor structure of the fragmentation functions, i.e., the ratio $D_u^{\Lambda}(z)/D_s^{\Lambda}(z)$. Future measurements by the HERMES Collaboration at DESY can discriminate between various cases.2004-02-29http://cds.cern.ch/record/72045110.1016/j.physletb.2003.08.069http://cds.cern.ch/record/720451oai:cds.cern.ch:720451Comments: 11 latex files, 6 figures doi:10.1103/PhysRevD.64.014017doi:10.1103/PhysRevD.64.099901engMa, B QSchmidt, ISoffer, JYang Jian JunHelicity and Transversity Distribution of Nucleon and $\Lambda$-Hyperon from $\Lambda$ FragmentationParticle Physics - Phenomenologyhep-ph/0103136CPT-4045USM-TH-97It is shown that $\Lambda$-hyperon fragmentation in charged lepton deep inelastic scattering (DIS) on a polarized nucleon target can provide sensitive information concerning the quark helicity and transversity distributions for both nucleon and $\Lambda$-hyperon at large $x$. Numerical predictions are given for the spin transfers of the produced $\Lambda$, when the target nucleon is polarized either longitudinally or transversely, and with the nucleon and $\Lambda$ quark distributions evaluated both in an SU(6) quark-spectator-diquark model and in a perturbative QCD (pQCD) based model. It is also shown that the predicted spin transfers have different behaviors for proton and neutron targets, and this can provide sensitive tests of different predictions for the quark helicity and transversity distributions of the $d$ valence quark of the proton at large $x$.2001-03-13http://cds.cern.ch/record/49121310.1103/PhysRevD.64.01401710.1103/PhysRevD.64.099901Nuclear Physics - Theoryhttp://cds.cern.ch/record/491213oai:cds.cern.ch:491213Comments: 17 latex pages, 4 figures, published in PRD64, 014017 (2001), Erratum added concerning a wrong comparison with data, published in PRD64, 099901 (2001) engYang Jian Jun$q \to \Lambda$ Fragmentation Function and Nucleon Transversity Distribution in a Diquark ModelParticle Physics - Phenomenologyhep-ph/0111382USM-TH-117Based on a simple quark-diquark model, we propose a set of unpolarized, longitudinally polarized and transversely polarized fragmentation functions for the $\Lambda$ by fitting the unpolarized $\Lambda$ production data in $e^+ e ^- $ annihilation. It is found that the helicity structure of the obtained $\Lambda$ fragmentation functions is supported by the all available experimental data on the longitudinal $\Lambda$ polarization. Within the same framework of the diquark model, the nucleon transversity distributions are presented and consistent descriptions of the available HERMES data on the azimuthal spin asymmetries in pion electroproduction are obtained. Furthermore, the spin transfers to the transversely polarized $\Lambda$ in the charged lepton DIS on a transversely polarized nucleon target are predicted for future experiments.2001-11-28http://cds.cern.ch/record/528574http://cds.cern.ch/record/528574oai:cds.cern.ch:528574