Search for first-generation leptoquarks at HERA

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAM
A search for first-generation leptoquarks was performed in electron-proton and positron-proton collisions recorded with the ZEUS detector at HERA in 2003–2007 using an integrated luminosity of 366 pb-1. Final states with an electron and jets or with missing transverse momentum and jets were analyzed, searching for resonances or other deviations from the standard model predictions. No evidence for any leptoquark signal was found. The data were combined with data previously taken at HERA, resulting in a total integrated luminosity of 498 pb-1. Limits on the Yukawa coupling, λ, of leptoquarks were set as a function of the leptoquark mass for different leptoquark types within the Buchmüller-Rückl-Wyler model. Leptoquarks with a coupling λ = 0.3 are excluded for masses up to 699 GeV
This work was supported by the U.S. Department of Energy; the Italian National Institute for Nuclear Physics (INFN); the German Federal Ministry for Education and Research (BMBF), under Contract No. 05 H09PDF; the Science and Technology Facilities Council, UK; an FRGS grant from the Malaysian government; the U.S. National Science Foundation (any opinion, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation); the Polish Ministry of Science and Higher Education as a scientific project No. DPN/N188/DESY/2009; the Polish Ministry of Science and Higher Education and its grants for Scientific Research; the German Federal Ministry for Education and Research (BMBF), under Contract No. 05h09GUF, and the SFB 676 of the Deutsche Forschungsgemeinschaft (DFG); the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) and its grants for Scientific Research; the Korean Ministry of Education and Korea Science and Engineering Foundation; FNRS and its associated funds (IISN and FRIA) and by an Inter- University Attraction Poles Programme subsidised by the Belgian Federal Science Policy Office; the Spanish Ministry of Education and Science through funds provided by CICYT; the Natural Sciences and Engineering Research Council of Canada (NSERC); supported by the German Federal Ministry for Education and Research (BMBF); R. F. Presidential Grant No. 4142.2010.2 for Leading Scientific Schools, by the Russian Ministry of Education and Science through its grant for Scientific Research on High Energy Physics and under Contract No. 02.740.11.0244; the Netherlands Foundation for Research on Matter (FOM); and the Israel Science Foundation. R. Aggarwal, P. Kaur, and I. Singh were supported by the Max Planck Institute for Physics, Munich, Germany. V. Aushev, Y. Aushev, V. Bokhonov, and N. Zhmak were supported by DESY, Hamburg, Germany. A. Kotanski was supported by the research Grant No. 1 P03B 04529 (2005-2008). W. Słomin´ski was supported by the Polish National Science Centre, Project No. DEC-2011/01/BST2/03643. J. Tomaszewska was partially supported by Warsaw University, Poland. K. Gladilin and I. A. Korzhavina were supported by the Russian Foundation for Basic Research, Grant No. 11-02-91345-DFG_a