CERN–2006–015 19 December 2006 ORGANISATION EUROPÉENNE POUR LA RECHERCHE NUCLÉAIRE CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 2005 CERN–CLAF School of High-Energy Physics Malargüe, Argentina 27 February–12 March 2005 Proceedings Editors: N. Ellis M.T. Dova GENEVA 2006 CERN–290 copies printed–December 2006 Abstract The CERN–CLAF School of High-Energy Physics is intended to give young physicists an introduction to the theoretical aspects of recent advances in elementary particle physics. These proceedings contain lectures on field theory and the Standard Model, quantum chromodynamics, CP violation and flavour physics, as well as reports on cosmic rays, the Pierre Auger Project, instrumentation, and trigger and data-acquisition systems. iii Preface The third in the new series of Latin American Schools of High-Energy Physics took place in Malargüe, lo- cated in the south-east of the Province of Mendoza in Argentina, from 27 February to 12 March 2005. It was organized jointly by CERN and CLAF (Centro Latino Americano de Física), and with the strong support of CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas). Fifty-four students coming from eleven different countries attended the School. While most of the students stayed in Hotel Rio Grande, a few students and the Staff stayed at Microtel situated close by. However, all the participants ate their meals to- gether at Hotel Rio Grande. According to the tradition of the School the students shared twin rooms mixing nationalities and in particular Europeans together with Latin Americans. María Teresa Dova from La Plata University was the local director for the School. The lectures were given at the Expositions and Convention Centre, ‘Thesaurus’, an ultra-modern building, some three hundred metres from the two hotels and just across the road from the Pierre Auger Observatory central campus. The proximity of the Auger Observatory was the main reason for choosing Malargüe as the site for the School, and a special presentation on the Auger experiment, given by Alan Watson the present project spokesman, was highly appreciated by the school participants. The presentation was followed by an interesting tour of Los Leones where one of the Auger fluorescence detectors is installed and to some of the detectors of the surface array deployed in Pampa Amarilla. Our sincere thanks go to Tere who, together with the local committee, made it possible to organize the School and contributed to its success, and to Esteban Roulet, Ricardo Piegaia and Juan Tirao, who helped during the visit to the different locations which had been proposed for the School. We are also grateful to CONICET for their financial support. Our thanks are due to the lecturers and discussion leaders for their active participation in the School and for making the scientific programme so stimulating. The students, who in turn manifested their good spirits during two intense weeks, undoubtedly appreciated the personal contributions of the teaching staff in answering questions and explaining points of theory. We are very grateful to Danielle Métral for her untiring efforts in the lengthy preparations for and the day- to-day care of the School. Her continuous care of the participants and their needs was highly appreciated. We are also grateful to Andrea Aparicio for her friendly assistance with translations, accounting, and other practical problems. Our special thanks also go to Graciella Viollaz, head of the local Tourist Office, Raul Rodriguez, Mayor of Malargüe, and Celso A. Jaque, former Mayor and now National Senator, who invited the school to Malargüe, providing the local infrastructure for free. The School participants enjoyed two memorable excursions, one to Castillos de Pincheira, a natural and impressive geologic structure about thirty kilometres from the city of Malargüe, and another to Las Leñas, Argentina’s largest ski resort. On the way to Las Leñas stops were made at the Well of the Souls (‘Pozo de las Ánimas’), and the lagoon of the Enchanted Girl (‘La Niña Encantada’). However, the success of the School was to a large extent due to the students themselves. Their posters were of excellent quality both technically and in content, and throughout the School they participated actively during the lectures, in the discussion sessions, and with genuine interest in the different activities and excursions. Egil Lillestøl on behalf of the Organizing Committee v vi People in the photograph 1 Sánchez Paredes, Marcial 34 Fry, Catherine 2 Cobos-Martínez, Jesús 35 Sepúlveda, Fernando 3 González-Canales, Félix Francisco 36 Simili, Emanuele 4 Schneebeli, Matthias 37 Kharzeev, Dmitri 5 Cortes Maldonado, Ismael 38 Uranga, Llinersy 6 Nunokawa, Hiroshi 39 Bazo Alba, José Luis 7 Lillestøl, Egil 40 Castillo, Felisola Óscar Alberto 8 Stark Schneebeli, Luisa Sabrina 41 Ellis, John 9 Asorey, Claudio 42 Blanco Siffert, Beatriz 10 Goy López, Silvia 43 Deplano, Caterina 11 Paniccia, Mercedes 44 Dabrowski, Anne 12 Olinto, Angela 45 Aliaga Soplín, Leonidas 13 Mello Jr., Walter 46 Vázquez-Jauregui, Eric 14 Racker, Juan 47 Tamashiro, Alejandro 15 Capa Tira, Claudio 48 Pérez, Ricardo 16 Mondragón, Miguel 49 Martínez, Santiago Andrés 17 Swain, John 50 Sommers, Paul 18 Contreras, Guillermo 51 Dova, María Teresa 19 Métral, Danielle 52 Fonseca, Sandro 20 Paulucci, Laura 53 Ellis, Nick 21 Marinho, Franciole 54 Medina, María Clementina 22 Castromonte Flores, César Manuel 55 García, Carlos 23 Almeida, Rogerio 56 Watson, Alan 24 Rangel, Murilo 57 Ramírez Rojas, Alba 25 Busca, Nicolas 58 Morales, Allan 26 Pioppi, Michele 59 Ruiz Tabasco, Julia Elizabeth 27 Gómez Dumm, Daniel 60 González Sprinberg, Gabriel 28 Moreno, Juan Cruz 61 Peinado-Rodríguez, Eduardo 29 Cabarcas, Jose Miguel 62 Helo Herrera, Juan Carlos 30 Schoch Vianna, Cristina 63 Barrett, Matthew 31 Moreno Briceño, Alexander 64 Blanco Covarrubias, Ernesto Alejandro 32 Akiba, Kazuyoshi 65 Bravo, Alberto 33 Morales Morales, Cristina vii Contents Preface E. Lillestøl ..................................................................................... v Photograph of participants . vi Introductory lectures on quantum field theory L. Álvarez-Gaumé and M.A Vázquez-Mozo ........................................................ 1 Introduction to QCD in hadronic collisions M.L. Mangano ................................................................................. 81 CP violation in meson decays Y. Nir ........................................................................................ 131 Experimental aspects of cosmic rays P. Sommers ................................................................................... 177 The Pierre Auger Observatory – why and how A.A. Watson .................................................................................. 191 Instrumentation for high-energy physics S. Stapnes .................................................................................... 209 Trigger and data acquisition N. Ellis ...................................................................................... 241 International Scientific Committee . 267 Local Organizing Committee . 267 List of Lecturers . 267 List of Discussion Leaders . 267 List of Students . 268 List of posters . 269 Photographs (montage) . 271 ix Introductory lectures on quantum field theory∗ L. Álvarez-Gaumé a and M.A. Vázquez-Mozo b; c a CERN, Geneva, Switzerland b Departamento de Física Fundamental, Universidad de Salamanca, Salamanca, Spain c Instituto Universitario de Física Fundamental y Matemáticas (IUFFyM), Universidad de Salamanca, Salamanca, Spain Abstract In these lectures we present a few topics in quantum field theory in detail. Some of them are conceptual and some more practical. They have been se- lected because they appear frequently in current applications to particle physics and string theory. 1 Introduction The audience for these lectures was composed to a large extent of students in experimental high-energy physics with an important minority of theorists. In nearly ten hours it is quite difficult to give a reasonable introduction to a subject as vast as quantum field theory. For this reason these lectures are intended to provide a review of those parts of the subject to be used later by other lecturers. Although a cursory acquaintance with the subject of quantum field theory is helpful, the only requirement necessary to follow the lectures is a working knowledge of quantum mechanics and special relativity. The guiding principle in choosing the topics (apart from to serve as introductions to later courses) was to cover some basic aspects of the theory that present conceptual subtleties: those topics one often is uncomfortable with after a first introduction to the subject. Among them we have selected the following. – The need to introduce quantum fields, with the great complexity this implies. – Quantization of gauge theories and the role of topology in quantum phenomena. We have included a brief study of the Aharonov–Bohm effect and Dirac's explanation of the quantization of the electric charge in terms of magnetic monopoles. – Quantum aspects of global and gauge symmetries and their breaking. – Anomalies. – The physical idea behind the process of renormalization of quantum field theories. – Some more specialized topics, like the creation of particles by classical fields and the very basics of supersymmetry. These notes follow closely the original presentation, with numerous clarifications. Sometimes the treatment given to some subjects has been extended, in particular the discussion of the Casimir