The HERMES experiment has measured the transverse polarization of Lambda and (Lambda) over bar hyperons produced inclusively in quasireal photoproduction at a positron beam energy of 27.6 GeV. The transverse polarization P-n(Lambda) of the Lambda hyperon is found to be positive while the observed (Lambda) over bar polarization is compatible with zero. The values averaged over the kinematic acceptance of HERMES are P-n(Lambda)=0.078 +/- 0.006(stat)+/- 0.012(syst) and P-n((Lambda) over bar)=-0.025 +/- 0.015(stat)+/- 0.018(syst) for Lambda and (Lambda) over bar, respectively. The dependences of P-n(Lambda) and P-n((Lambda) over bar) on the fraction zeta of the beam's light-cone momentum carried by the hyperon and on the hyperon's transverse momentum p(T) were investigated. The measured Lambda polarization rises linearly with p(T) and exhibits a different behavior for low and high values of zeta, which approximately correspond to the backward and forward regions in the center-of-mass frame of the gamma*N reaction.

Transverse polarization of Λ and Λ̅ hyperons in quasireal photoproduction

CIULLO, Giuseppe;CONTALBRIGO, Marco;FERRETTI, Paola;FABBRI, Riccardo;LENISA, Paolo;MASOLI, Francesco Antonio;REGGIANI, DAVIDE;STANCARI, Michelle Dawn;STATERA, Marco;
2007

Abstract

The HERMES experiment has measured the transverse polarization of Lambda and (Lambda) over bar hyperons produced inclusively in quasireal photoproduction at a positron beam energy of 27.6 GeV. The transverse polarization P-n(Lambda) of the Lambda hyperon is found to be positive while the observed (Lambda) over bar polarization is compatible with zero. The values averaged over the kinematic acceptance of HERMES are P-n(Lambda)=0.078 +/- 0.006(stat)+/- 0.012(syst) and P-n((Lambda) over bar)=-0.025 +/- 0.015(stat)+/- 0.018(syst) for Lambda and (Lambda) over bar, respectively. The dependences of P-n(Lambda) and P-n((Lambda) over bar) on the fraction zeta of the beam's light-cone momentum carried by the hyperon and on the hyperon's transverse momentum p(T) were investigated. The measured Lambda polarization rises linearly with p(T) and exhibits a different behavior for low and high values of zeta, which approximately correspond to the backward and forward regions in the center-of-mass frame of the gamma*N reaction.
A., Airapetian; N., Akopov; Z., Akopov; M., Amarian; V. V., Ammosov; A., Andrus; E. C., Aschenauer; W., Augustyniak; R., Avakian; A., Avetissian; E., Avetissian; P., Bailey; V., Baturin; C., Baumgarten; M., Beckmann; S., Belostotski; S., Bernreuther; N., Bianchi; H. P., Blok; H., Bottcher; A., Borissov; M., Bouwhuis; J., Brack; A., Brull; I., Brunn; G. P., Capitani; H. C., Chiang; Ciullo, Giuseppe; Contalbrigo, Marco; G. R., Court; Ferretti, Paola; R., De Leo; L., De Nardo; E., De Sanctis; E., Devitsin; P., Di Nezza; M., Duren; M., Ehrenfried; A., Elalaoui Moulay; G., Elbakian; F., Ellinghaus; U., Elschenbroich; J., Ely; Fabbri, Riccardo; A., Fantoni; A., Fechtchenko; L., Felawka; B., Fox; J., Franz; S., Frullani; Y., Garber; G., Gapienko; V., Gapienko; F., Garibaldi; E., Garutti; D., Gaskell; G., Gavrilov; V., Gharibyan; G., Graw; O., Grebeniouk; L. G., Greeniaus; W., Haeberli; K., Hafidi; M., Hartig; D., Hasch; D., Heesbeen; M., Henoch; R., Hertenberger; W. H., A.; A., Hillenbrand; Y., Holler; B., Hommez; G., Iarygin; A., Izotov; H. E., Jackson; A., Jgoun; R., Kaiser; E., Kinney; A., Kisselev; K., Konigsmann; H., Kolster; M., Kopytin; V., Korotkov; V., Kozlov; B., Krauss; V. G., Krivokhijine; L., Lagamba; L., Lapikas; A., Laziev; Lenisa, Paolo; P., Liebing; T., Lindemann; K., Lipka; W., Lorenzon; N. C., R.; H., Marukyan; Masoli, Francesco Antonio; F., Menden; V., Mexner; N., Meyners; O., Mikloukho; C. A., Miller; Y., Miyachi; V., Muccifora; A., Nagaitsev; E., Nappi; Y., Naryshkin; A., Nass; W. D., Nowak; K., Oganessyan; H., Ohsuga; G., Orlandi; S., Potashov; D. H., Potterveld; M., Raithel; Reggiani, Davide; P. E., Reimer; A., Reischl; A. R., Reolon; K., Rith; G., Rosner; A., Rostomyan; D., Ryckbosch; I., Sanjiev; I., Savin; C., Scarlett; A., Schafer; C., Schill; G., Schnell; K. P., Schuler; A., Schwind; J., Seibert; B., Seitz; R., Shanidze; T. A., Shibata; V., Shutov; M. C., Simani; K., Sinram; Stancari, Michelle Dawn; Statera, Marco; E., Steffens; J. J., M.; J., Stewart; U., Stosslein; H., Tanaka; S., Taroian; B., Tchuiko; A., Terkulov; S., Tessarin; E., Thomas; A., Tkabladze; A., Trzcinski; M., Tytgat; G. M., Urciuoli; P. B., Van; G., van der; R., van de; D., Veretennikov; M. C., Vetterli; V., Vikhrov; M. G., Vincter; J., Visser; M., Vogt; J., Volmer; C., Weiskopf; J., Wendland; J., Wilbert; T., Wise; S., Yen; S., Yoneyama; B., Zihlmann; H., Zohrabian; P., Zupranski
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11392/520202
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