Eur. Phys. J. C (2007) 49: 395-410
https://doi.org/10.1140/epjc/s10052-006-0140-3

Regular Article - Experimental Physics

Study of inclusive strange-baryon production and search for pentaquarks in two-photon collisions at LEP

¹ III. Physikalisches Institut, RWTH, 52056, Aachen, Germany
² National Institute for High Energy Physics, NIKHEF, and University of Amsterdam, 1009 DB, Amsterdam, The Netherlands
³ University of Michigan, Ann Arbor, MI, 48109, USA
⁴ Laboratoire d’Annecy-le-Vieux de Physique des Particules, LAPP, IN2P3-CNRS, BP 110, 74941, Annecy-le-Vieux CEDEX, France
⁵ Institute of Physics, University of Basel, 4056, Basel, Switzerland
⁶ Louisiana State University, Baton Rouge, LA, 70803, USA
⁷ Institute of High Energy Physics, IHEP, 100039, Beijing, P.R. China
⁸ University of Bologna and INFN-Sezione di Bologna, 40126, Bologna, Italy
⁹ Tata Institute of Fundamental Research, Mumbai (Bombay), 400 005, India
¹⁰ Northeastern University, Boston, MA, 02115, USA
¹¹ Institute of Atomic Physics and University of Bucharest, 76900, Bucharest, Romania
¹² Central Research Institute for Physics, Hungarian Academy of Sciences, 1525, Budapest 114, Hungary
¹³ Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
¹⁴ Panjab University, Chandigarh, 160 014, India
¹⁵ KLTE-ATOMKI, 4010, Debrecen, Hungary
¹⁶ UCD School of Physics, University College Dublin, Belfield, Dublin 4, Ireland
¹⁷ INFN Sezione di Firenze and University of Florence, 50125, Florence, Italy
¹⁸ European Laboratory for Particle Physics, CERN, 1211, Geneva 23, Switzerland
¹⁹ FBLJA Project, World Laboratory, 1211, Geneva 23, Switzerland
²⁰ University of Geneva, 1211, Geneva 4, Switzerland
²¹ University of Hamburg, 22761, Hamburg, Germany
²² Chinese University of Science and Technology, USTC, Hefei, Anhui, 230 029, P.R. China
²³ University of Lausanne, 1015, Lausanne, Switzerland
²⁴ Institut de Physique Nucléaire de Lyon, IN2P3-CNRS, Université Claude Bernard, 69622, Villeurbanne, France
²⁵ Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, CIEMAT, 28040, Madrid, Spain
²⁶ Florida Institute of Technology, Melbourne, FL, 32901, USA
²⁷ INFN-Sezione di Milano, 20133, Milan, Italy
²⁸ Institute of Theoretical and Experimental Physics, ITEP, Moscow, Russia
²⁹ INFN-Sezione di Napoli and University of Naples, 80125, Naples, Italy
³⁰ Department of Physics, University of Cyprus, Nicosia, Cyprus
³¹ Radboud University and NIKHEF, 6525 ED, Nijmegen, The Netherlands
³² California Institute of Technology, Pasadena, CA, 91125, USA
³³ INFN-Sezione di Perugia and Università Degli Studi di Perugia, 06100, Perugia, Italy
³⁴ Nuclear Physics Institute, St. Petersburg, Russia
³⁵ Carnegie Mellon University, Pittsburgh, PA, 15213, USA
³⁶ INFN-Sezione di Napoli and University of Potenza, 85100, Potenza, Italy
³⁷ Princeton University, Princeton, NJ, 08544, USA
³⁸ University of Californa, Riverside, CA, 92521, USA
³⁹ INFN-Sezione di Roma and University of Rome, “La Sapienza”, 00185, Rome, Italy
⁴⁰ University and INFN, Salerno, 84100, Salerno, Italy
⁴¹ University of California, San Diego, CA, 92093, USA
⁴² Central Lab. of Mechatronics and Instrumentation, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria
⁴³ The Center for High Energy Physics, Kyungpook National University, 702-701, Taegu, Republic of Korea
⁴⁴ National Central University, Chung-Li, Taiwan
⁴⁵ Department of Physics, National Tsing Hua University, Tsing Hua, Taiwan
⁴⁶ Purdue University, West Lafayette, IN, 47907, USA
⁴⁷ Paul Scherrer Institut, PSI, 5232, Villigen, Switzerland
⁴⁸ DESY, 15738, Zeuthen, Germany
⁴⁹ Eidgenössische Technische Hochschule, ETH Zürich, 8093, Zürich, Switzerland

^* e-mail: Salvatore.Mele@cern.ch

Received: 11 July 2006
Revised: 22 September 2006
Published online: 2 December 2006

Abstract

Measurements of inclusive production of the Λ, Ξ^- and Ξ^*(1530) baryons in two-photon collisions with the L3 detector at LEP are presented. The inclusive differential cross sections for Λ and Ξ^- are measured as a function of the baryon transverse momentum, p_t, and pseudo-rapidity, η. The mean number of Λ, Ξ^- and Ξ^*(1530) baryons per hadronic two-photon event is determined in the kinematic range 0.4 GeV<p_t<2.5 GeV, |η|<1.2. Overall agreement with the theoretical models and Monte Carlo predictions is observed. A search for inclusive production of the pentaquark θ⁺(1540) in two-photon collisions through the decay θ⁺→pK⁰ _S is also presented. No evidence for production of this state is found.