Praxis Archives – Page 88 of 183

Greater than the sum of the parts

Agnieszka Zalewska, president of CERN Council.
Image credit: Andrzej Zalewska.

CERN was founded in 1954 with the aim of bringing European countries together to collaborate in scientific research after the horrors of the Second World War. After the end of the war, however, Europe had been divided politically by the “Iron Curtain”, and countries in the Eastern Bloc were not in a position to join CERN. Nevertheless, through personal contacts dating back to pre-war days, scientists on either side of the divide were able to keep in touch. From the start, CERN had schemes to welcome physicists from outside its member states. At the same time, the bubble-chamber experiments in particular provided a way that research groups in the East could contribute to physics at CERN from their home institutes. The groups could analyse bubble-chamber events with relatively few resources and make their mark by choosing specific areas of analysis.

In the case of my country, Poland, this contact with CERN from the 1950s provided a precious window on modern science, allowing us to maintain a good level in particle physics. The first Polish physicist was welcomed to the laboratory in 1959 and was soon followed by others when CERN awarded several scholarships to young researchers from Cracow and Warsaw. Collaboration between CERN and Polish institutes followed, and despite the difficult circumstances, physicists in Poland were able to make important contributions to CERN’s research programmes. In 1963, the country gained observer status at CERN Council, as the only country from Eastern Europe.

My association with CERN began when I was a student at the Jagellonian University in Cracow in the early 1970s, working on the analysis of events collected by the 2-m bubble chamber. During the 1960s, the experimental groups in Cracow and Warsaw had made the analysis of high-multiplicity events their speciality, and this was the topic for my doctoral thesis. The collaborative work with CERN gradually extended to electronic detectors, and from the 1970s Polish groups contributed hardware such as wire chambers to a number of experiments. The DELPHI experiment at the Large Electron–Positron (LEP) collider already used a variety of Polish contributions to both hardware and software.

It is hard today to imagine the world without the web. It was CERN’s gift to humanity

The start-up of LEP coincided with the big political changes in Eastern Europe at the end of the 1980s. Poland became the first former Eastern Bloc country to be invited to become a CERN member state, and in July 1991 my country became the 16th member of CERN – a moment of great pride. Hungary, the Czech Republic and Slovakia followed soon after.

The end of the 1980s also coincided with the development of the World Wide Web to help the large collaborations at LEP work together. It revolutionized the way we could work in our home institutions. In particular in Poland, a dedicated phone line set up in 1991 between CERN and the institutes in Cracow and Warsaw provided a “magic” link, allowing us, for example, to make changes remotely to software running underground at LEP.

It is hard today to imagine the world without the web. It was CERN’s gift to humanity – creating connections, allowing the exchange of ideas and communication between people all over the world. Developed in a scientific, non-commercial organization, the web’s international annual economic value is now estimated at €1.5 trillion. As Chris Llewellyn Smith, CERN’s director-general from 1994 to 1998, asked: how many yearly budgets of CERN have been saved because it was developed quickly in a non-commercial environment?

Now, after some four decades in particle physics, I have the enormous privilege to be president of CERN Council. I have already experienced the exceptional moment when the Israeli flag was raised for the first time at the Meyrin entrance to the laboratory, representing the first new member state to join the organization for 14 years. Other countries are at various stages in the process of accession to become member states or to attain associate membership. In discussions with the physicists from these countries, I recognize the same feelings that we had in countries like Poland in the 1960s or 1970s.

As one person said to me recently, it is not only CERN as the organization, but the idea of CERN that has such a strong appeal. It brings people together from different nationalities and cultures, people who have different ways of doing things – and this brings added value. CERN really is something where the whole is greater than the sum of the parts, as we all work together towards a common goal – a noble goal – to learn more about the universe that we inhabit.

During the past 60 years, the idea of CERN has succeeded in the goal of bringing European countries to work peacefully together, helping to bridge the divisions that existed between East and West. I sincerely believe that this “idea” will continue to inspire people around the world for years to come.

Quantum Field Theories in Two Dimensions: Collected Works of Alexei Zamolodchikov (2 volumes)/

By Alexander Belavin, Yaroslav Pugai and Alexander Zamolodchikov (ed.)
World Scientific
Hardback: £124

These two volumes contain original contributions of Alexei Zamolodchikov (1952–2007), who was a prominent theoretical physicist of his time. Volume 1 contains his work on conformal field theories, 2D quantum gravity and Liouville theory. Volume 2 includes his pioneering work on non-perturbative methods in 2D quantum field theory and on integrable models. Both volumes can be used as an advanced textbook by graduate students specializing in string theory, conformal field theory and integrable models of quantum field theory. They are also highly relevant to experts in these fields.

The Conceptual Framework of Quantum Field Theory

By Anthony Duncan
Oxford University Press

Hardback: £77.50
Also available as an e-book

This book attempts to provide an introduction to quantum field theory by emphasizing conceptual issues. The aim is to build up the theory systematically from clearly stated foundations. The first section, “Origins”, consists of two historical chapters that situate quantum field theory in the larger context of modern physical theories. The three remaining sections follow a step-by-step reconstruction of this framework, beginning with a few basic assumptions: relativistic invariance, the basic principles of quantum mechanics, and the prohibition of physical action at a distance embodied in the clustering principle. Problems are included at the ends of the chapters and solutions can be requested via the publisher’s website.

Reminiscences: A Journey through Particle Physics

By Adrian Melissinos
World Scientific
Hardback: £28
E-book: £21

A personal account as a research physicist for more than 50 years in areas of particle physics and related fields, Adrian Melissinos’s insights into the ways that general research was carried out and the evolution of particle physics from 1958 to 2008 will prove interesting to science-history enthusiasts and particle physicists alike. Through this mix of personal reminiscences and professional journey, readers can relive the joy and excitement of research and teaching in small groups during those early years, while gaining a partial historical perspective of particle physics since the late 1950s.

Exploring Quantum Mechanics: A Collection of 700+ Solved Problems for Students, Lecturers, and Researchers

By Victor Galitski, Boris Karnakov, Vladimir Kogan and Victor Galitski Jr
Oxford University Press
Hardback: £95 $165
Paperback: £45 $84.99
Also available as an e-book

Mastering quantum physics is a non-trivial task and a deep understanding can only be achieved through working out real-life problems and examples. It is notoriously difficult to come up with new quantum-mechanical problems that would be solvable with a pencil and paper, within a finite amount of time. This book presents more than 700 original problems in quantum mechanics, together with detailed solutions covering all aspects of quantum science. Collected during 60 years, first by the late Victor Galitski Sr, the material is largely new to an English-speaking audience. New problems were added and the material polished by Boris Karnakov. Finally, Victor Galitski Jr, has extended the material with problems relevant to modern science.

Silicon Solid State Devices and Radiation Detection

By Claude Leroy and Pier-Giorgio Rancoita
World Scientific
Hardback: £89
E-book: £67

Using their many years of experience both in research with silicon detectors and in giving lectures at various levels, Leroy and Rancoita address the fundamental principles of interactions between radiation and matter, together with working principles and the operation of particle detectors based on silicon solid-state devices. They cover a range of fields of application of radiation detectors based on these devices, from low- to high-energy physics experiments, including those in outer space and medicine. Their book also covers state-of-the-art detection techniques in the use of such radiation detectors and their read-out electronics, including the latest developments in pixellated silicon radiation detectors and their applications.

Effective Theories in Physics: From Planetary Orbits to Elementary Particle Masses

By James D Wells
Springer Verlag
Paperback: £44.99 €52.70 $49.95
E-book: £35.99 €41.64 $39.95

This remarkable and charming book introduces the idea of effective field theories from a novel point of view, making the concepts natural and – in retrospect – inevitable. As the author makes clear, all theories are effective theories. At just 73 pages, it is easily accessible to a graduate student or a bright undergraduate. It will also be welcomed by professional physicists for its readability and clear, compelling style.

In introducing the idea of effective theories, the author begins by considering Galileo’s law for falling bodies, neglecting air resistance. Keeping the symmetries assumed for the problem – here translational invariance – and the idea that the constant downward acceleration might be an approximation to a more complete theory that involves a dependence of g on height above the ground, Wells derives the form of the leading correction by taking into account Newton’s law of gravitation without explicitly invoking the inverse square law. Such an effective theory could have been used to search for an extension to Galileo’s law or to accommodate data, even in the absence of Newton’s more complete theory of gravity. The second chapter continues the discussion of gravity, this time assuming circular orbits (and the simple harmonic oscillator) and the sorts of deviations that might be allowed for, using the ideas of effective theories to analyse deviations from perfect circularity.

Chapter 3 considers effective theories of classical gravity, arguing for the general expectation of perihelion precession and that something like black holes could have been predicted and the Schwarzschild radius estimated before the discovery of general relativity. Using both Lagrangian and Hamiltonian formulations of the problem, this discussion is not only enlightening but a delight to read. The presentation of effective theories in these simple contexts – requiring neither field theory nor even quantum mechanics – makes their meaning, importance and universality clearer than the usual, more advanced introductions.

Assuming some knowledge of the Standard Model, chapter 4 shows how the Fermi theory can be thought of as an effective field theory that approximates it. Here the author considers in some detail the origin of mass and in particular neutrino masses beyond the Standard Model. He then concludes with a discussion of naturalness and the hierarchy problem – all from the viewpoint of effective theories.

The fifth and final chapter is more philosophical in nature, emphasizing how and why effective theories are more than truncations of more comprehensive theory. It also looks at how one can go about choosing between theories, before closing with implications for the LHC.

I was pleasantly surprised by this book. The approach is original and makes the whole concept of effective theories clear and natural. I will be urging all of my students to take an afternoon to read this wonderful introduction – and to think carefully and deeply about the many points that the author makes so well.

À la recherche du boson de Higgs

De Christophe Grojean et Laurent Vacavant
Librio
Broché : €3

Vous n’avez rien compris au boson de Higgs ? Alors ce petit livre est peut-être fait pour vous. Il faut saluer en effet le très grand effort des auteurs pour tenter de rendre accessible à tous les concepts qui se cachent derrière l’une des plus grandes découvertes de ces dernières années.

De la relativité au mécanisme qui donne leur masse aux particules, en passant par la physique quantique, cet ouvrage aborde le plus simplement possible les notions qui permettront à chacun d’appréhender le monde complexe des particules ainsi que les lois du Modèle standard. Les nombreuses analogies – souvent drôles – aident à rendre concrets des phénomènes le plus souvent abstraits que seul le formalisme mathématique est en mesure de réellement retranscrire. Vous découvrirez notamment dans cet ouvrage pourquoi le père Noël ne peut être qu’un objet quantique vu son comportement (c’est de saison), ou encore pourquoi la recherche du boson de Higgs revient à chercher un tibia de mammouth dans un immense cimetière d’éléphants !

Bien sûr, les spécialistes et les puristes trouveront certainement des défauts à certaines analogies : nul doute que nous n’avons pas terminé de discuter sur la meilleure manière de présenter simplement le mécanisme de Higgs… L’avantage de ce petit livre, c’est aussi qu’en moins d’une centaine de pages, il aborde les grandes étapes de l’aventure du LHC en les replaçant dans le contexte historique et international. Il rend également compte des stratégies et technologies mises en œuvre dans les expériences ATLAS et CMS pour enregistrer et traiter une quantité de données vraiment phénoménale.

Je recommande donc sans hésitation la lecture de cet ouvrage pour sa concision, sa simplicité et son approche légère qui devrait ravir tous ceux dont la vue d’une simple équation est en mesure de provoquer une indigestion.

Compound Semiconductor Radiation Detectors

By Alan Owens
CRC Press
Hardback: £82
Also available as an e-book

Bringing together information scattered across many disciplines, this book summarizes the status of research in compound semiconductor radiation detectors. It examines the properties, growth and characterization of compound semiconductors as well as the fabrication of radiation sensors, with emphasis on the X- and γ-ray regimes. It explores the limitations of compound semiconductors and discusses current efforts to improve spectral performances, pointing to where future discoveries might lie. A resource for the established researcher, this book serves as a comprehensive and illustrated reference on material science, crystal growth, metrology, detector physics and spectroscopy. It can also be used as a textbook for those who are new to the field.

Lectures on LHC Physics

By Tilman Plehn

Springer
Paperback: £40.99 €47.43 $59.95
E-book: £31.99 €35.69 $39.95

Anyone trying to apply the solid knowledge of quantum field theory to actual LHC physics – in particular to the Higgs sector and certain regimes of QCD – inevitably meets an intricate maze of phenomenological know-how, common lore and intuition, often historically grown, about what works and what does not. These lectures are intended to be a brief but sufficiently detailed primer on LHC physics that will enable graduate students and any newcomer to the field to find their way through the more advanced literature, as well as helping them to start work in this timely and exciting field of research.

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