This book covers a very broad spectrum of experimental and theoretical activity in particle physics, from the searches for the Higgs boson and physics beyond the Standard Model, to detailed studies of Quantum Chromodynamics, the B-physics sectors and the properties of hadronic matter at high energy density as realised in heavy-ion collisions. Starting with a basic introduction to the Standard Model and its most likely extensions, the opening section of the book presents an overview of the theoretical and phenomenological framework (...) of hadron collisions, and current theoretical models of frontier physics. In part II, discussion of the theory is supplemented by chapters on the detector capabilities and search strategies, as well as an overview of the main detector components, the initial calibration procedures and physics samples, and early LHC results. Part III completes the volume with a description of the physics behind Monte Carlo event generators, and a broad introduction to the main statistical methods used in high energy physics. LHC Phenomenology covers all of these topics at a pedagogical level, with the aim of providing young particle physicists with the basic tools required for future work on the various LHC experiments. It will also serve as a useful reference text for those working in the field. (shrink)

My horoscope today says, “Focus on the small stuff.” Now, such advice does have content. It predicts that when readers interpret its words in the usual way as a guide to action, those who do what they think it recommends will, on average, feel they got more of what they wanted than those who ignored it. Even so, astrologers sure don’t make it easy for us to test their claims. If they wanted to make it easier, they would do what (...) forecasters in weather, sports, and business do: issue forecasts in a clear, standardized form. A horoscope is like a weather forecast that says, “Some rain likely nearby, soon.” It’s much easier to evaluate a forecast that a particular rain gauge has a.. (shrink)

On March 21 a suit was filed in Federal District Court in Hawaii asking for a temporary restraining order prohibiting the European Center for Nuclear Research (CERN) in Geneva from turning on the world’s largest particle accelerator, the Large Hadron Collider (LHC), this summer. The suit contends that the collider could produce a tiny black hole or an exotic object called a “strangelet,” either of which might swallow up Earth and perhaps more.

Članak je usmjeren ususret paradigmi nove fizike koju treba iznijeti LHC, ali s kritičkim prosuđivanjem toga razvoja pomoću Kuhnovih teza i epistemologije povezanih s modernom fizikom. Promišljanja i prosudbe nove filozofije niču iz LHC-fizike, koja se tumači kao »science universelle« . LHC, kao najveći sudarivač čestica u svijetu do sada, nije motiviran time da uništi Boga niti bilo koju vjeru u svijetu, već za otkrivanje novih čestica s njihovim interakcijama i kozmologijom u Prirodi, baš onoliko koliko pružaju LHC-scenariji na Tera-elektron-volt (...) skali. Polazeći od ponovnog otkrića fizike Standardnog modela i otkrića Higgsovih bozona, nova fizika na LHC-u ide mogućim putovima u skladu s problemom hijerarhije u suvremenoj fizici. K tome još, SM nije konačna teorija i upućuje se prema ne-standardnoj fizici poput supersimetrije , dodanih dimenzija na TeV-skali s kozmološkim posljedicama te ostale scenarije. Ne-standardna fizika, teorija i pokus, predviđa se otvorenom pa je formuliran novi princip agnostičkog eksperimentalizma kao najprikladniji filozofski princip, jer se ne mogu sva opažanja znati/predvidjeti na LHC-u. Čak i ako eksperimentalni program LHC-a krene u krivome smjeru, mnoge će mogućnosti izroniti iz Pandorine kutije fizike. Tada će filozofska promišljanja postati vrlo važna, napose Kuhnovi pogledi kao i naš AE princip te noviji mediteranski razvoj filozofije. Uostalom, standardna paradigma kao i nova fizika na LHC-u ne opisuju svijet u kojemu danas živimo.A paper is aiming towards a new physics paradigm to be brought by the LHC with a critical assessing on that development by the Kuhnian theses and epistemology related to modern physics. Thinking and critical assessments on the new philosophy arise up from the LHC physics, which is interpreted as the ‘science universelle’ . The LHC as the world’s largest particle collider as ever been was not motivated neither to destroy God nor any religion in the World, but to investigate new particles with their interactions and cosmology of the Nature inasmuch as it has proposed by the LHC scenarios on the Tera-electron-Volt scale. Starting from the rediscovery of the Standard Model and discovery of the Higgs bosons, the new physics at the LHC goes by the possible roads according to the Hierarchy Problem in contemporary physics. However, the SM is not a final theory by inquiring a Non-Standard physics, such as Supersymmetry , Extra Dimensions on the TeV scale with cosmological implications, and other scenarios. A Non-Standard physics, both theory and experiment, is foreseen to be open and a novel view of agnostic experimentalism was formulated to be the best philosophical principle, since we can’t know/predict everything to be observed in the LHC. Even if experimental programme of the LHC wouldn’t go in the right way, then many possibilities may emerge from the Pandora’s Box of physics. Then, philosophical considerations would become very important, particularly Kuhn’s views on it including our AE principle and new Mediterranean development of philosophy, respectively. After all, either standard paradigm or the new physics of the LHC doesn’t describe the world in which we live. (shrink)

A lot of attention has been devoted to the study of discoveries in high energy physics, but less on measurements aiming at improving an existing theory like the standard model of particle physics, getting more precise values for the parameters of the theory or establishing relationships between them. This paper provides a detailed and critical study of how measurements are performed in recent HEP experiments, taking examples from differential cross section measurements with the ATLAS detector at the LHC. This study (...) will be used to provide an elucidation of the concept of event used in HEP, in order to determine what constitutes an observation and what does not. It will highlight the essential place taken by theory-ladenness in order to produce observational facts, and will show how uncertainty and sensitivity estimates constitute an operational approach to robustness, inside the practice of science, avoiding potential circularity problem traditionally implied by theory-ladenness. This is in contrast to robustness analyses typically considered in the literature. A careful analysis of systematic uncertainty estimates and of statistical tests used to set empirical conclusions from the observations will however demonstrate that quantitative statements obtained from these statistical tests cannot be more than simple guiding arguments for the production of knowledge, but do not determine it. This indicates that the frontier between theory and observation is blurry and that the dichotomy theory-experiment should be revised. (shrink)

The Large Hadronic Collider (LHC), which is to be the world’s highest energy particle accelerator, is currently being constructed at the CERN laboratory in Geneva, Switzerland. The machine was designed to be high enough in energy to produce a completely new type of particle, the Higgs boson, which is considered to be the missing puzzle-piece in the Standard Model of particle interactions. According to current theoretical thinking, it is the Higgs particle that gives mass to all the other particles, quarks, (...) leptons, etc., in the current bestiary of fundamental particles. (shrink)

In this column, however, I'm not going to talk about my own experiment here, but about CERN's fast-track plans for building a new and more powerful particle accelerator, the Large Hadronic Collider or LHC. The LHC is to come into operation around 1999. It is the principal competition for the SSC, the huge U. S. accelerator presently under construction in and around Waxahachie, Texas. [See my AV column "The Coming of the SSC", Analog March, 1988 for a description of that (...) project.]. (shrink)

Im Herbst des Jahres 20– breiten sich Gerüchte aus, dass am Genfer Kernforschungszentrum CERN, den gegenteiligen Versicherungen führender Teilchenphysiker zum Trotz, stabile schwarze Löcher erzeugt wurden. Daraufhin kommt es vielerorts zu Plünderungen. Auch vermelden zahlreiche Firmen und öffentliche Arbeitgeber, dass ein erheblicher Anteil der Belegschaft nicht am Arbeitsplatz erschienen ist. Rund um den Globus fragen sich Menschen ob der Hiobsbotschaften aus Genf: Steht nun der Weltuntergang tatsächlich kurz bevor? In der Sendung „Kontrovers“ im Deutschlandfunk diskutieren ein Teilchenphysiker, eine Juristin, ein (...) Wissenschaftsjournalist und ein Philosoph diese Ereignisse. Wir freuen uns, hier einen Mitschnitt der Sendung vorab veröffentlichen zu können. (shrink)

Large scale experiments at CERN’s Large Hadron Collider rely heavily on computer simulations, a fact that has recently caught philosophers’ attention. CSs obviously require appropriate modeling, and it is a common assumption among philosophers that the relevant models can be ordered into hierarchical structures. Focusing on LHC’s ATLAS experiment, we will establish three central results here: with some distinct modifications, individual components of ATLAS’ overall simulation infrastructure can be ordered into hierarchical structures. Hence, to a good degree of approximation, hierarchical (...) accounts remain valid at least as descriptive accounts of initial modeling steps. In order to perform the epistemic function Winsberg Model-based reasoning in scientific discovery. Kluwer Academic/plenum Publishers, New York, pp 255–269, 1999) assigns to models in simulation—generate knowledge through a sequence of skillful but non-deductive transformations—ATLAS’ simulation models have to be considered part of a network rather than a hierarchy, in turn making the associated simulation modeling messy rather than motley. Deriving knowledge-claims from this ‘mess’ requires two sources of justification: holistic validation :253–262, 2010; in Carrier M, Nordmann A Science in the context of application. Springer, Berlin, pp 115–130, 2011), and model coherence. As it turns out, the degree of model coherence sets HEP apart from other messy, simulation-intensive disciplines such as climate science, and the reasons for this are to be sought in the historical, empirical and theoretical foundations of the respective discipline. (shrink)

We start by remarks on the scientific and societal context of today's theoretical physics. Major classes of models for physics to be explored at the LHC are then reviewed. This leads us to propose an LHC timeline and a list of potential effects on theoretical physics and the society. We then explore three conceptual questions connected with the LHC physics: symmetry (and symmetry breaking), effective field theory, and fine tuning.

This paper provides an account of the nature of creativity in high-energy physics experiments through an integrated historical and philosophical study of the current and planned attempts to measure the self-coupling of the Higgs boson by two experimental collaborations at the Large Hadron Collider and the planned High Luminosity Large Hadron Collider. A notion of creativity is first identified broadly as an increase in the epistemic value of a measurement outcome from an unexpected transformation, and narrowly as a condition for (...) knowledge of the measurement of the self-coupling of the Higgs. Drawing upon Tal’s model-based epistemology of measurement this paper shows how without change to ‘readings’ a transformation to the model of the measurement process can increase the epistemic value of the measurement outcome. Such transformations are attributed to the creativity of the experimental collaboration. Creativity, in this context, is both a product, a creative and improved model, and the distributed collaborative process of transformation to the model of the measurement process. For the case of the planned measurements at the HL-LHC, where models of the measurement process perform the epistemic function of prediction, creativity is included in the models of the measurement process, both as projected quantified creativity and as an assumed property of the future collaborations. (shrink)

According to the received view Feynman diagrams are a bookkeeping device in complex perturbative calculations. Thus, they do not provide a representation or model of the underlying physical process. This view is in apparent tension with scientific practice in high energy physics, which analyses its data in terms of “channels”. For example the Higgs discovery was based on the observation of the decay H → γγ – a process which can be easily represented by the corresponding Feynman diagrams. I take (...) issue with this tension and show that on closer analysis the story of the Higgs discovery should be told differently. (shrink)

Along three measurements at the Large Hadron Collider (LHC), a high energy particle accelerator, we analyze procedures and consequences of exploratory experimentation (EE). While all of these measurements fulfill the requirements of EE: probing new parameter spaces, being void of a target theory and applying a broad range of experimental methods, we identify epistemic differences and suggest a classification of EE. We distinguish classes of EE according to their respective goals: the exploration where an established global theory cannot provide the (...) details of a local phenomenon, exploration of an astonishing discovery and exploration to find a new entity. We find that these classes also differ with respect to the existence of an identifiable target and their impact on the background theory. The characteristics distinguish EE from other kinds of experimentation, even though these different kinds have not yet been systematically studied. The formal rigor and precision of LHC physics facilitates to analyze concept formation in its early state. In particular we emphasize the importance for nil–results for conceptualization and argue that conceptualization can also be achieved from nil–results only. (shrink)

This thesis provides an introduction to the physics of the Standard Model and beyond, and to the methods used to analyse Large Hadron Collider (LHC) data. The 'hierarchy problem', astrophysical data and experiments on neutrinos indicate that new physics can be expected at the now accessible TeV scale. This work investigates extensions of the Standard Model with gravitons and gravitinos (in the context of supergravity). The production of these particles in association with jets is studied as one of the most (...) promising avenues for researching new physics at the LHC. Advanced simulation techniques and tools, such as algorithms allowing the computation of Feynman graphs and helicity amplitudes are first developed and then employed. (shrink)

With the author(s)’ decision to opt for Open Choice the copyright of the article changed on 26 May 2021 to ©The Author(s) 2021 and the article is forthwith distributed under a Creative Commons Attribution.

The recent discovery of the Higgs at 125 GeV by the ATLAS and CMS experiments at the LHC has put significant pressure on a principle which has guided much theorizing in high energy physics over the last 40 years, the principle of naturalness. In this paper, I provide an explication of the conceptual foundations and physical significance of the naturalness principle. I argue that the naturalness principle is well-grounded both empirically and in the theoretical structure of effective field theories, and (...) that it was reasonable for physicists to endorse it. Its possible failure to be realized in nature, as suggested by recent LHC data, thus represents an empirical challenge to certain foundational aspects of our understanding of QFT. In particular, I argue that its failure would undermine one class of recent proposals which claim that QFT provides us with a picture of the world as being structured into quasi-autonomous physical domains. (shrink)

It has been suggested that particle physics has reached the "dawn of the post-naturalness era." I provide an explanation of the current shift in particle physicists' attitude towards naturalness. I argue that the naturalness principle was perceived to be supported by the theories it has inspired. The potential coherence between major beyond the Standard Model (BSM) proposals and the naturalness principle led to an increasing degree of credibility of the principle among particle physicists. The absence of new physics at the (...) Large Hadron Collider (LHC) has undermined the potential coherence and has led to the principle's loss of significance. (shrink)

The collection provides an analysis of the concept of beauty in the evaluation of experiments. What properties do practicing experimenters value? How have the aesthetic properties of scientific experiments changed over the years? Secondly, the volume looks at the role that aesthetic factors, including negative values such as ugliness, as well as experiences of the sublime and the profound, play in the construction of an experiment and its reception. Thirdly, the chapters provide in-depth historical case studies from the Royal Society, (...) which also allows for a study of the depiction of scientific experiment in artworks, as well as contemporary examples from the LHC and cases of AI-designed experiments. Finally, it offers a exploration of the commonalities between how we learn from experiments on the one hand, and the cognitive value of artworks on the other. (shrink)

The requirement of naturalness has long served as an influential constraint on model-building in theoretical particle physics. Yet there are many ways of understanding what, precisely, this requirement amounts to, from restrictions on the amount of fine-tuning that a model can exhibit, to prohibitions on sensitive dependence between physics at different scales, to the requirement that dimensionless parameters defining the Lagrangian of a theory all be of order one unless they are protected by a symmetry. This workshop aims to clarify (...) the relationships among these concepts of naturalness and their connection to the hierarchy problem, as well as to assess arguments for and against imposing various forms of naturalness as a requirement on particle physics model-building. (shrink)

The requirement of naturalness has long served as an influential constraint on model-building in theoretical particle physics. Yet there are many ways of understanding what, precisely, this requirement amounts to, from restrictions on the amount of fine-tuning that a model can exhibit, to prohibitions on sensitive dependence between physics at different scales, to the requirement that dimensionless parameters defining the Lagrangian of a theory all be of order one unless they are protected by a symmetry. This workshop aims to clarify (...) the relationships among these concepts of naturalness and their connection to the hierarchy problem, as well as to assess arguments for and against imposing various forms of naturalness as a requirement on particle physics model-building. (shrink)

: Our paper discusses the epistemic attitudes of particle physicists on the discovery of the Higgs boson at the Large Hadron Collider. It is based on questionnaires and interviews made shortly before and shortly after the discovery in 2012. We show, to begin with, that the discovery of a Standard Model Higgs boson was less expected than is sometimes assumed. Once the new particle was shown to have properties consistent with SM expectations – albeit with significant experimental uncertainties –, there (...) was a broad agreement that ‘a’ Higgs boson had been found. Physicists adopted a two-pronged strategy. On the one hand, they treated the particle as a SM Higgs boson and tried to establish its properties with higher precision; on the other hand, they searched for any hints of physics beyond the SM. This motivates our first philosophical thesis: the Higgs discovery, being of fundamental importance and establishing a new kind of particle, represented a crucial experiment if one interprets this notion in an appropriate sense. By embedding the LHC into the tradition of previous precision experiments and the experimental strategies thus established, underdetermination and confirmational holism are kept at bay. Second, our case study suggests that criteria of theory preference should be understood as epistemic and pragmatic values that have to be weighed in factual research practice. The Higgs discovery led to a shift from pragmatic to epistemic values as regards the mechanisms of electroweak symmetry breaking. Complex criteria, such as naturalness, combine epistemic and pragmatic different values, but are coherently applied by the community. (shrink)

The procedures of validating computer simulations of particle physicsParticle physics events at the LHCLarge Hadron Collider are summarized. Because of the strongly fluctuating particle content of LHC events and detectorDetector interactions, particle-based Monte Carlo methods are an indispensable tool for dataData analysis analysis. Simulation in particle physicsParticle physics is founded on factorizationFactorization and thus its global validation can be realized by validating each individual step in the simulation. This can be accomplished by drawing on results of previousMeasurement measurements, in situ (...) studies, and models. What is particularly important in particle physicsParticle physics is to quantify how well a simulation is validated such that a systematic uncertainty can be assigned to a measurement. The simulation is tested for a wide range of processes and agrees with dataData within the assigned uncertainties. (shrink)

"Seienlil·ic theories are maps ol`lhc natural worlti." This metaphor is often used as part ot`a dellationary argument lor a weak but relatively global version ot` scienlitic realism. a version that recognizes the place olconventions, goals. and contingencies in seientilic rcpresentationsr while maintaining that they are typically true in a clear and literal sense. By examining. in a naturalistic wayt some relationships between maps and what they map. we question the scope and valttc oi` realist constrtials ol` maps and by extension (...) ot` scicntiiic representationse Dcllationary philosophy ol` science requires more variegatecl stances. (shrink)

The discovery of the Higgs boson at LHC confirms that what we experience as empty space should actually be thought as a condensate of elementary quanta. This condensate characterizes the physically realized form of relativity and could play the role of preferred reference frame in a modern Lorentzian approach. This observation suggests a new interpretative scheme to understand the unexplained residuals in the old ether-drift experiments where light was still propagating in gaseous systems. Differently from present vacuum experiments, where anyhow (...) deviations from Special Relativity are expected to be at the limit of visibility, these now acquire a crucial importance and become consistent with the Earth’s velocity of 370 km/s which characterizes the CMB anisotropy. In the same scheme, one can also understand the difference with the other experiments where light propagates in strongly bound systems such as solid or liquid transparent media. This non-trivial level of consistency motivates a new generation of precise laser interferometry experiments which explore the same particle physics vacuum and, in this sense, are complementary to those with high-energy accelerators. (shrink)

ZusammenfassungDer vorliegende Artikel widmet sich der Frage, wie Spiele und spielen zur Big-Data-basierten Wissensproduktion in der Hochenergiephysik beitragen. Als Beispiel dienen Detektorkollaborationen am Large Hadron Collider (LHC) der Europäischen Organisation für Kernforschung (CERN), in denen die Autorin seit 2014 kulturanthropologische Feldforschung unternommen hat. Der ludische Aspekt der Wissensproduktion wird hier in drei verschiedenen Dimensionen analysiert: der symbolischen, der ontologischen und der epistemischen. Erstere verweist auf das CERN als Ort, an dem ein kosmologisches Wahrscheinlichkeitsspiel mithilfe von Monte-Carlo-Simulationen durchgeführt wird. Die Zweite (...) wird durch kompetitive Infrastrukturen in der Arbeitspraxis verschiedener Kollaborationsgruppen sichtbar. Die dritte Dimension entfaltet sich durch ludische Plattformen, wie etwa Online Challenges und Citizen Science Games, die zur Entwicklung von machine learning algorithmen beitragen, deren Funktion notwendig ist, um die ungeheuren Mengen an Big Data verarbeiten zu können, die durch die Experimente gesammelt werden. Das CERN wird als Ort des Deep Play beschrieben, einem von Clifford Geertz entwickeltem Konzept, das dazu beiträgt, größere soziale und kulturelle Ordnungen durch die Analyse ludischer Kollektivphänomene zu begreifen. Der Artikel setzt sich darüber hinaus mit Peter Galisons Idee der Trading Zone auseinander und schlägt vor, diese in Zeiten von Big Data als Playground (Spielplatz) zu begreifen. Die Autorin hofft damit zu einer breiteren sozio-historiografischen Diskussion in den Science and Technology Studies (STS, Wissenschafts- und Technikforschung) und nicht zuletzt der Kulturanthropologie beizutragen, indem das Ludische in den Wissenschaften als zentrales Element für das Verständnis kollaborativer Wissensproduktion begriffen wird. (shrink)

Finetuning and Naturalness are extra-empirical theory assessments that reflect our expectation how scientific theories should provide an intuitive understanding about the foundations underlying the observed phenomena. Recently, the absence of new physics at the LHC and the theoretical evidence for a multiverse of alternative physical realities, predicted by our best fundamental theories, have casted doubts about the validity of these concepts. In this essay we argue that the discussion about Finetuning should not predominantly concentrate on the desired features a fundamental (...) theory is expected to have, but rather on the question what a theory needs to qualify as fundamental in the first place. By arguing that a fundamental description of the Universe should possess zero entropy, we develop a ‘holistic’ concept for the most fundamental layer of reality: The fundamental description of the Universe is the Universe itself, understood as an entangled quantum state. Adopting a universal applicability of quantum mechanics, in this framework the behavior of subsystems can be understood as the perspectival experience of an entangled quantum Universe perceived through the “lens of decoherence”. In this picture the fundamental reality is non-local, and finetuned coincidences in effective theories may be understood in a way similar to EPR-correlations. This notion provides a fresh view on the topic of Naturalness and Finetuning since it suggests that Finetuning problems and hints for anthropic explanations are an artifact of theories building up on subsystems rather than on the fundamental description. Recent work in quantum gravity aiming at an understanding of spacetime geometry from entanglement entropy could be interpreted as a first sign of such a paradigm shift. (shrink)

Consciousness is arguably the greatest mystery in science, still being unsolved after millennia of thinking. This book is one further attempt at trying to bring new insights regarding consciousness. While certainly the mystery will continue, the ideas in this book will raise awareness regarding an aspect of the phenomenology of consciousness that has been overlooked by past thinkers, and that is the emergent structure of consciousness, which in the end will be shown to be realized by the nature of self-reference (...) of looking-back-at-itself. The great take-away from appreciating the true nature of self-refence would be the need to switch to an unformal way of thinking in doing science if the problem of consciousness is to be resolved. To unformal way of thinking means abandoning the desire to have clearly defined entities in our theories, like “energy” or “space-time” or “spin”, and instead allow for entities that cannot be formalized, to be responsible for the workings of the world. We will slowly see as the book unfolds why the need for unformal way of thinking arises. -/- Regarding the presentation style, the book is both a popular book and a rigorous presentation that goes into thorough phenomenological analyses of consciousness. The reason is that our lives themselves are both familiar and the very nature of existence. As opposed to other writings that use a more technical approach, the philosophy of this book is that a theory of consciousness should focus more on the most mundane manifestations of consciousness, like the redness of an apple or the warmish feeling of cup of hot chocolate, in order to give a clearer understanding of consciousness. Therefore, the book is full of everyday examples of conscious experiences that the reader can relate to and use them to gain deeper insights into the workings of consciousness. In the same way that LHC is the laboratory of physicists, introspection is our own laboratory, the advantage of introspection over LHC being that it is accessible to anyone. Every person can gain a deep knowledge of consciousness by simply paying close attention to his own experiences. Of course, the difficulty arises because of the huge diversity of our experiences and this might raise an apparent initial obstacle of where one is to begin his understanding of consciousness. The book is designed as a guide through the complexities of everyday experiences in the direction of sorting them out in general and clear ways of thinking, showing that consciousness needs not be something that difficult to understand if only the proper attention is given to our experiences. -/- Therefore, the book starts with a chapter about qualia, where through many examples it is shown to be a form of meaning. Then the reader is familiarized with the Self through simple thought experiments that lead to the conclusion of the unicity of the Self, and then a further logical analysis that shows the eternal existence of the Self. After these initial familiarizations with consciousness, the book goes into its core subject, that being the emergent phenomenology, in which it will be shown how consciousness is structured on a holarchy of levels and how ultimately this structuring is a result of self-reference looking-back-at-itself, consciousness being shown to be possible only because of the unformalizable nature of self-reference. (shrink)

No evidence of “new physics” was found so far by LHC experiments, and this situation has led some voices in the physics community to call for the abandonment of the “naturalness” criterion, while other scientists have felt the need to break a lance in its defense by claiming that, at least in some sense, it has already led to successes and therefore should not be dismissed too quickly, but rather only reflected or reshaped to fit new needs. In our paper (...) we will argue that present pro-or-contra naturalness debates miss the fundamental point that naturalness, despite contrary claims, is essentially a very hazily defined, in a sense even mythical notion which, in the course of more than four decades, has been steadily, and often not coherently, shaped by its interplay with different branches of model-building in high-energy physics and cosmology on the one side, and new incoming experimental results on the other. In our paper we will endeavor to clear up some of the physical and philosophical haze by taking a closer look back at origin of naturalness in the 1970s and 1980s, with particular attention to the early work of Kenneth Wilson. In doing this, we aim to bring to light how naturalness belongs to a long tradition of present and past physical and philosophical criteria for effectively guiding theoretical reflection and experimental practice in fundamental research. (shrink)

We discuss the relation between string theory/supergravity and the observational data in cosmology, as well as at LHC, past and future. We pay particular attention to the possibility of the future detection of primordial gravitational waves and how this might affect our understanding of fundamental physics.

Die Deutsche Forschungsgemeinschaft (DFG) hat ab 2016 eine neue Forschergruppe unter Leitung der Bergischen Universität Wuppertal eingerichtet. Sie untersucht die Forschungen an der „größten Forschungsmaschine der Welt“, dem Large Hadron Collider (LHC) am Europäischen Zentrum für Teilchenphysik CERN in Genf, aus philosophischer, historischer und soziologischer Sicht. Wissenschaftsphilosophisch sind diese Forschungen vor allem aus drei Gründen relevant: Die Philosophie interessiert sich für den Ursprung und die grundlegenden Strukturen der Welt, für die Bedingungen des Erkenntniserfolges der Elementarteilchenphysik und nicht zuletzt für die (...) mit den Erfolgen mitunter eng verbundenen theoretischen und praktischen Probleme. Die Diskussion dieser Gründe zeigt die Elementarteilchenphysik als eine lebensweltferne, zugleich aber weltbildrelevante, theoretisch wie praktisch äußerst erfolgreiche Disziplin, die dennoch nicht frei von gewichtigen offenen Fragen ist. Sie könnte ein Typus für die Gewinnung von Wissen an den Grenzen unserer Erkenntnis sein. (shrink)

One model in particular, the Standard Model Higgs, is taken to have been confirmed by the Higgs boson discovery at the LHC, even though many models are compatible with the data. Some models even provided riskier predictions and should perhaps be regarded as having been even more strongly confirmed. This paper sketches an argument demonstrating this by comparing the confirmation of the Standard Model Higgs with that of the Higgs in minimal supersymmetry. The paper then attempts to provide a way (...) of understanding this result by modelling it as a case of eliminative induction. (shrink)

Novel forms of matter, such as states made of gluons (glueballs), multiquark mesons or baryons and hybrid mesons are predicted by low energy QCD, for which several candidates have recently been identified. Searching for such exotic states of matter and studying their production and decay properties in detail has become a flourishing field at the experimental facilities now available or being built - e.g. BESIII in Beijing, BELLE II at SuperKEKB, GlueX at Jefferson Lab, PANDA at FAIR, J-PARC and in (...) the upgraded LHC experiments, in particular LHCb. A modern primer in the field is required so as to both revive and update the teaching of a new generation of researchers in the field of QCD. These lectures on hadron spectroscopy are intended for Master and PhD students and have been originally developed for a course delivered at the Stefan Meyer Institute of the Austrian Academy of Sciences. They are phenomenologically oriented and intended as complementary material for basic courses in particle and nuclear physics. The book describes the spectra of light and heavy mesons and baryons, and introduces the fundamental properties based on symmetries. Further, it derives multiplet structures, mixing angle, decay coupling constants, magnetic moments of baryons, and predictions for multiquark states and compares these with suitable experimental data. Basic methods of calculating decay angular distributions and determining masses and widths of resonances are also presented. The appendices provide students and newcomers to the field with the necessary background information, and include a set of problems and solutions. (shrink)

Inclusive single jet production in hadron collisions is considered. It is shown that the QCD parton model predicts a nonmonotonic dependence of the inclusive cross section on the fraction of the energy deposited in the jet registered, if it is normalized on the same cross section measured at another collision energy. Specifically, if the cross section is normalized by the one measured at a higher collision energy, it possesses a minimum which depends on jet rapidity. This prediction can be tested (...) at the Fermilab Tevatron, at the CERN LHC, and at the Very Large Hadron Collider under discussion. (shrink)

Der Aachener Physiker Michael Krämer sucht am Genfer Teilchenbeschleuniger LHC nach neuen Naturgesetzen. Ein Gespräch über die aufwändige Suche nach Erkenntnis, den Wert philosophischen Reflektierens und die größten offenen Fragen der Physik.

We analyze the usage of computer simulation at the LHC and derive seven jointly necessary requirements for a simulation to be considered ’trustworthy’, such that it can be used as proxy for experiments. We show that these requirements can also be applied to systems without direct experimental access and discuss their validity for properties that have not yet been probed. While being necessary, these requirements are not sufficient. Such trustworthy simulations will be analyzed for the relative epistemic statuses of simulation (...) and material measurements, from which we argue that claims of their parity are unfounded. Instead, using credibility as a measure for epistemic status, and in view of the temporal and epistemic dependence of simulation on material measurements, we argue that the latter have a higher epistemic status than the former. We further argue that suggestions to qualify the epistemic status by ’defocussing’ on the material connection to the target system of either human or natural experiments are misleading. (shrink)

This thesis studies collider phenomenology of physics beyond the Standard Model at the Large Hadron Collider (LHC). It also explores in detail advanced topics related to Higgs boson and supersymmetry - one of the most exciting and well-motivated streams in particle physics. In particular, it finds a very large enhancement of multiple Higgs boson production in vector-boson scattering when Higgs couplings to gauge bosons differ from those predicted by the Standard Model. The thesis demonstrates that due to the loss of (...) unitarity, the very large enhancement for triple Higgs boson production takes place. This is a truly novel finding. The thesis also studies the effects of supersymmetric partners of top and bottom quarks on the Higgs production and decay at the LHC, pointing for the first time to non-universal alterations for two main production processes of the Higgs boson at the LHC-vector boson fusion and gluon-gluon fusion. Continuing the exploration of Higgs boson and supersymmetry at the LHC, the thesis extends existing experimental analysis and shows that for a single decay channel the mass of the top quark superpartner below 175 GeV can be completely excluded, which in turn excludes electroweak baryogenesis in the Minimal Supersymmetric Model. This is a major new finding for the HEP community. This thesis is very clearly written and the introduction and conclusions are accessible to a wide spectrum of readers. (shrink)