Part 1: A Dostoeyevskijan Hero.- An Archimedes from Sicily studies in Rome.- A Certain Interest in Pure Science.- Ten short papers.- Part 2: Power for the Italian School.- The 1937 Chance.- Landing in Naples.- Part 3: A Legacy from the Grand Inquisitor.- The Mystery of the Missing Papers.- Fortunes and Misfortunes of a Famous Director.- Part 4: Investigation of a Disappearance.- Before March 26.- In Search for a Missing Professor.- The Last Chapter.- Epilogue.

This textbook provides an introduction to radiation, the principles of interaction between radiation and matter, and the exploitation of those principles in the design of modern radiation detectors. Both radiation and detectors are given equal attention and their interplay is carefully laid out with few assumptions made about the prior knowledge of the student. Part I is dedicated to radiation, broadly interpreted in terms of energy and type, starting with an overview of particles and forces, an extended review of common natural and man-made sources of radiation, and an introduction to particle accelerators. Particular attention is paid to real life examples, which place the types of radiation and their energy in context. Dosimetry is presented from a modern, user-led point of view, and relativistic kinematics is introduced to give the basic knowledge needed to handle the more formal aspects of radiation dynamics and interaction. The explanation of the physics principles of interaction between radiation and matter is given significant space to allow a deeper understanding of the various technologies based on those principles. Following an introduction to the ionisation mechanism, detectors are introduced in Part II, grouped according to the physical principle that underpins their functionality, with chapters covering gaseous detectors, semiconductor detectors, the scintillation process and light detectors. The final two chapters describe the phenomenology of showers and the design of calorimeters, and cover additional phenomena including Cherenkov and transition radiation and the detection of neutrinos. An appendix offers the reader a useful review of statistics and probability distributions. The mathematical formalism is kept to a minimum throughout and simple derivations are presented to guide the reasoning and facilitate understanding of the working principles. The book is unique in its wide scope and introductory level, and is suitable for undergraduate and graduate students in physics and engineering. The reader will acquire an awareness of how radiation and its exploitation are becoming increasingly relevant in the modern world, with over 140 experimental figures, detector schematics and photographs helping to relate the material to a broader research context.

This is a comprehensive textbook designed for graduate and advanced undergraduate students. Both authors rely on more than 20 years of teaching experience in renowned Physics Engineering courses to write this book addressing the students' needs. Kinetics and Spectroscopy of Low Temperature Plasmas derives in a full self-consistent way the electron kinetic theory used to describe low temperature plasmas created in the laboratory with an electrical discharge, and presents the main optical spectroscopic diagnostics used to characterize such plasmas. The chapters with the theoretical contents make use of a deductive approach in which the electron kinetic theory applied to plasmas with basis on the electron Boltzmann equation is derived from the basic concepts of Statistical and Plasma Physics. On the other hand, the main optical spectroscopy diagnostics used to characterize experimentally such plasmas are presented and justified from the point of view of the Atomic and Molecular Physics. Low temperature plasmas (LTP) are partially ionized gases with a broad use in many technological applications such as microelectronics, light sources, lasers, biology and medicine. LTPs lead to the production of atomic and molecular excited states, chemically reactive radicals, and activated surface sites, which are in the origin, among others, of the deposition of thin films, advanced nanotechnology products, solar cells, highly efficient combustion motors, and treatment of cancer cells.

This book illustrates a theory well suited to tracking codes, which the author has developed over the years. Tracking codes now play a central role in the design and operation of particle accelerators. The theory is fully explained step by step with equations and actual codes that the reader can compile and run with freely available compilers. In this book, the author pursues a detailed approach based on finite "s"-maps, since this is more natural as long as tracking codes remain at the centre of accelerator design. The hierarchical nature of software imposes a hierarchy that puts map-based perturbation theory above any other methods. The map-based approach, perhaps paradoxically, allows ultimately an implementation of the Deprit-Guignard-Schoch algorithms more faithful than anything found in the standard literature. This hierarchy of methods is not a personal choice: it follows logically from tracking codes overloaded with a truncated power series algebra package. After defining abstractly and briefly what a tracking code is, the author illustrates most of the accelerator perturbation theory using an actual code: PTC. This book may seem like a manual for PTC; however, the reader is encouraged to explore other tools as well. The presence of an actual code ensures that readers will have a tool with which they can test their understanding. Codes and examples will be available from various sites since PTC is in MAD-X (CERN) and BMAD (Cornell).

This thesis represents a unique mix of theoretical work discussing the Lorentz theory of gravity and experimental work searching for supersymmetry with the Compact Muon Solenoid experiment at the Large Hadron Collider. It begins by reviewing a set of widely-discussed theoretical solutions to the cosmological constant problem, including a natural solution provided by the recently developed Lorentz gauge theory of gravity. The Schwartzschild metric, de Sitter space, and quantum versions of the theory are also discussed. The thesis then looks to supersymmetry for an alternative solution. The idea behind supersymmetry is reviewed and an experimental search for supersymmetry is presented. A major contribution was to estimate one of the most significant backgrounds in this search, which arises from top-antitop quark pair production or W boson production in association with multiple jets where the W boson decays into the hadronically-decaying tau leptons and neutrinos. This background was estimated through a novel method involving kinematically analogous events but including a well-measured muon. This search significantly extends limits on supersymmetric partners of gluons from previous searches.

This biography explores the life and career of the Italian physicist Enrico Fermi, which is also the story of thirty years that transformed physics and forever changed our understanding of matter and the universe: nuclear physics and elementary particle physics were born, nuclear fission was discovered, the Manhattan Project was developed, the atomic bombs were dropped, and the era of "big science" began.It would be impossible to capture the full essence of this revolutionary period without first understanding Fermi, without whom it would not have been possible. Enrico Fermi: The Obedient Genius attempts to shed light on all aspects of Fermi's life - his work, motivation, influences, achievements, and personal thoughts - beginning with the publication of his first paper in 1921 through his death in 1954. During this time, Fermi demonstrated that he was indeed following in the footsteps of Galileo, excelling in his work both theoretically and experimentally by deepening our understanding of the Pauli exclusion principle, winning the Nobel Prize for his discovery of the fundamental properties of slow neutrons, developing the theory of beta decay, building the first nuclear reactor, and playing a central role in the development of the atomic bomb. Interwoven with this fascinating story, the book details the major developments in physics and provides the necessary background material to fully appreciate the dramatic changes that were taking place. Also included are appendices that provide a timeline of Fermi's life, several primary source documents from the period, and an extensive bibliography. This book will enlighten anyone interested in Fermi's work or the scientific events that led to the physics revolution of the first half of the twentieth century.

This fourteenth volume in the Poincare Seminar Series is devoted to Niels Bohr, his foundational contributions to understanding atomic structure and quantum theory and their continuing importance today. This book contains the following chapters: - Tomas Bohr, Keeping Things Open; - Olivier Darrigol, Bohr's Trilogy of 1913; -John Heilbron, The Mind that Created the Bohr Atom; - Serge Haroche & Jean-Michel Raimond, Bohr's Legacy in Cavity QED; - Alain Aspect, From Einstein, Bohr, Schroedinger to Bell and Feynman: a New Quantum Revolution?; - Antoine Browaeys, Interacting Cold Rydberg Atoms: A Toy Many-Body System; - Michel Bitbol & Stefano Osnaghi, Bohrs Complementarity and Kants Epistemology. Dating from their origin in lectures to a broad scientific audience these seven chapters are of high educational value. This volume is of general interest to physicists, mathematicians and historians.

In this book, renowned scientists describe the various techniques used to detect and characterize extrasolar planets, or exoplanets, with a view to unveiling the "tricks of the trade" of planet detection to a wider community. The radial velocity method, transit method, microlensing method, and direct imaging method are all clearly explained, drawing attention to their advantages and limitations and highlighting the complementary roles that they can play in improving the characterization of exoplanets' physical and orbital properties. By probing the planetary frequency at different distances and in different conditions, these techniques are helping astrophysicists to reconstruct the scenarios of planetary formation and to give robust scientific answers to questions regarding the frequency of potentially habitable worlds. Twenty years have passed since the discovery of a Jupiter-mass companion to a main sequence star other than the Sun, heralding the birth of extrasolar planetary research; this book fully conveys the exciting progress that has been achieved during the intervening period.

This book presents a comprehensive mathematical approach for solving stochastic magnetic field problems. It discusses variability in material properties and geometry, with an emphasis on the preservation of structural physical and mathematical properties. It especially addresses uncertainties in the computer simulation of magnetic fields originating from the manufacturing process. Uncertainties are quantified by approximating a stochastic reformulation of the governing partial differential equation, demonstrating how statistics of physical quantities of interest, such as Fourier harmonics in accelerator magnets, can be used to achieve robust designs. The book covers a number of key methods and results such as: a stochastic model of the geometry and material properties of magnetic devices based on measurement data; a detailed description of numerical algorithms based on sensitivities or on a higher-order collocation; an analysis of convergence and efficiency; and the application of the developed model and algorithms to uncertainty quantification in the complex magnet systems used in particle accelerators.

Plasmaphysik gibt eine systematische EinfA1/4hrung in die Methoden zur theoretischen Beschreibung physikalischer Prozesse in ionisierten Gasen. Ausgehend vom mikroskopischen Teilchenbild werden die Gleichungen sowohl fA1/4r eine mikroskopische als auch fA1/4r eine makroskopische Beschreibung eines Plasmas abgeleitet. Soweit es ohne grAAeren mathematischen Aufwand mAglich ist, werden relativistische Effekte berA1/4cksichtigt. Besonders diskutiert wird die Frage, welche NAherung welcher Fragestellung angemessen ist.
Als Beispiele werden Fragestellungen aus der Astrophysik, der MagnetosphArenphysik, sowie Laborexperimente diskutiert. Insbesondere werden Gleichgewichtskonfigurationen, InstabilitAten und Wellen in den verschiedenen NAherungen behandelt.

This theses reports on an experimental search for an exotic hadron, +(1540) pentaquark, which is a genuine exotic hadron with a five-quark system of uuddsbar. The results of this book support that the existence of + was strongly constrained. The + pentaquark was searched for via the - p K- X reaction using a beam momentum of 2.01 GeV/c at the J-PARC hadron experimental facility, taking advantage of high-statistics and high-resolution compared with previous experiments, some of which claimed the evidence of +. In order to realize a good missing-mass resolution of 2 MeV, the beam spectrometer and superconducting kaon spectrometer were constructed. No clear peak was observed in the missing mass spectrum of the - p K- X reaction, and the upper limit of the production cross section was found to be less than 0.28 b/sr at the 90% confidence level in a mass region of 1500-1560 MeV/c2. This upper limit is an order of magnitude smaller than that of the previous KEK experiment. Compared with a theoretical calculation using the effective Lagrangian approach, the decay width of + was evaluated. The upper limits on the decay width were estimated to be 0.36 and 1.9 MeV for the + spin-parity of 1/2+ and 1/2-, respectively. These are quite small for a width of ordinary hadron resonances, and the existence of + was strongly constrained and is doubtful.

This book is about dark matter's particle nature and the implications of a new symmetry that appears when a hypothetical dark matter particle is heavy compared to known elementary particles. Dark matter exists and composes about 85% of the matter in the universe, but it cannot be explained in terms of the known elementary particles. Discovering dark matter's particle nature is one of the most pressing open problems in particle physics. This thesis derives the implications of a new symmetry that appears when the hypothetical dark matter particle is heavy compared to the known elementary particles, a situation which is well motivated by the null results of searches at the LHC and elsewhere. The new symmetry predicts a universal interaction between dark matter and ordinary matter, which in turn may be used to determine the event rate and detectable energy in dark matter direct detection experiments. The computation of heavy wino and higgsino dark matter presented in this work has become a benchmark for the field of direct detection. This thesis has also spawned a new field of investigation in dark matter indirect detection, determining heavy WIMP annihilation rates using effective field theory methods. It describes a new formalism for implementing Lorentz invariance constraints in nonrelativistic theories, with a surprising result at 1/M^4 order that contradicts the prevailing ansatz in the past 20 years of heavy quark literature. The author has also derived new perturbative QCD results to provide the definitive analysis of key Standard Model observables such as heavy quark scalar matrix elements of the nucleon. This is an influential thesis, with impacts in dark matter phenomenology, field theory formalism and precision hadronic physics.

This book provides an overview of recent research highlights in the main areas of application of magnetic reconnection (MR), including planetary, solar and magnetospheric physics and astrophysics. It describes how research on magnetic reconnection, especially concerning the Earth's magnetosphere, has grown extensively due to dedicated observations from major satellite missions such as Cluster, Double Star and Themis. The accumulated observations from these missions are being supplemented by many theoretical and modelling efforts, for which large scale computer facilities are successfully being used, and the theoretical advances are also covered in detail. Opening with an introductory discussion of some fundamental issues related to magnetic reconnection, subsequent chapters address topics including collisionless magnetic reconnection, MHD structures in 3D reconnection, energy conversion processes, fast reconnection mediated by plasmoids, rapid reconnection and magnetic field topology. Further chapters consider specific areas of application such as magnetospheric dayside and tail reconnection, comparative reconnection in planetary systems and reconnection in astrophysical systems. The book offers insight into discussions about fundamental concepts and key aspects of MR, access to the full set of applications of MR as presently known in space physics and in astrophysics, and an introduction to a new related area of study dealing with the annihilation of quantum magnetic fluxes and its implications in the study on neutron star activity. The book is aimed primarily at students entering the field, but will also serve as a useful reference text for established scientists and senior researchers.

This book provides a compact yet comprehensive overview of recent developments in collisional-radiative (CR) modeling of laboratory and astrophysical plasmas. It describes advances across the entire field, from basic considerations of model completeness to validation and verification of CR models to calculation of plasma kinetic characteristics and spectra in diverse plasmas. Various approaches to CR modeling are presented, together with numerous examples of applications. A number of important topics, such as atomic models for CR modeling, atomic data and its availability and quality, radiation transport, non-Maxwellian effects on plasma emission, ionization potential lowering, and verification and validation of CR models, are thoroughly addressed. Strong emphasis is placed on the most recent developments in the field, such as XFEL spectroscopy. Written by leading international research scientists from a number of key laboratories, the book offers a timely summary of the most recent progress in this area. It will be a useful and practical guide for students and experienced researchers working in plasma spectroscopy, spectra simulations, and related fields.

This book is a complete treatment of work done to resolve the problems of position-, current-, and shape-control of plasma in tokamak-type (toroidal) devices being studied as a potential means of commercial energy production by nuclear fusion. Modelling and control are both detailed, allowing non-expert readers to understand the control problem. Starting from the magneto-hydro-dynamic equations, all the steps needed for the derivation of plasma state-space models are enumerated with frequent recall of the basic concepts of electromagnetics. The control problem is then described, beginning with the control of current and position-vertical and radial-control and progressing to the more challenging shape control. The solutions proposed vary from simple PIDs to more sophisticated MIMO controllers. The second edition of Magnetic Control of Tokamak Plasmas contains numerous updates and a substantial amount of completely new material covering areas such as: * modelling and control of resistive wall modes-the most important non-axisimmetric mode; * the isoflux approach for shape control; * a general approach for the control of limiter plasmas; * the use of inner vessel coils for vertical stabilization; and * significantly enhanced treatment of plasma-shape control at JET, including experimental results and introducing a method implemented for operation in the presence of current saturations. Whenever possible, coverage of the various topics is rounded out with experimental results obtained on currently existing tokamaks. The book also includes a presentation of the typical actuators and sensors used for control purposes in tokamaks. Some mathematical details are given in the appendices for the interested reader. The ideas formulated in this monograph will be of great practical help to control engineers, academic researchers and graduate students working directly with problems related to the control of nuclear fusion. They will also stimulate control researchers interested more generally in the advanced applications of the discipline. Advances in Industrial Control aims to report and encourage the transfer of technology in control engineering. The rapid development of control technology has an impact on all areas of the control discipline. The series offers an opportunity for researchers to present an extended exposition of new work in all aspects of industrial control.

This book presents more than 300 exercises, with guided solutions, on topics that span both the experimental and the theoretical aspects of particle physics. The exercises are organized by subject, covering kinematics, interactions of particles with matter, particle detectors, hadrons and resonances, electroweak interactions and flavor physics, statistics and data analysis, and accelerators and beam dynamics. Some 200 of the exercises, including 50 in multiple-choice format, derive from exams set by the Italian National Institute for Nuclear Research (INFN) over the past decade to select its scientific staff of experimental researchers. The remainder comprise problems taken from the undergraduate classes at ETH Zurich or inspired by classic textbooks. Whenever appropriate, in-depth information is provided on the source of the problem, and readers will also benefit from the inclusion of bibliographic details and short dissertations on particular topics. This book is an ideal complement to textbooks on experimental and theoretical particle physics and will enable students to evaluate their knowledge and preparedness for exams.

With its many beautiful colour pictures, this book gives fascinating insights into the unusual forms and behaviour of matter under extremely high pressures and temperatures. These extreme states are generated, among other things, by strong shock, detonation and electric explosion waves, dense laser beams, electron and ion beams, hypersonic entry of spacecraft into dense atmospheres of planets and in many other situations characterized by extremely high pressures and temperatures. Written by one of the world's foremost experts on the topic, this book will inform and fascinate all scientists dealing with materials properties and physics and also serve as an excellent introduction to plasma-, shock-wave and high-energy-density physics for students and newcomers seeking an overview. This second edition is thoroughly revised and expanded, in particular with new material on high energy-density physics, nuclear explosions and other nuclear transformation processes.

This thesis reports on investigations of a specific collective mode of nuclear vibration, the isoscalar giant monopole resonance (ISGMR), the nuclear "breathing mode", the energy of which is directly related to a fundamental property of nuclei-the nuclear incompressibility. The alpha inelastic scattering experiments reported in this thesis have been critical to answering some fundamental questions about nuclear incompressibility and the symmetry energy, quantities that are crucial to our understanding of a number of phenomena in nuclear physics and astrophysics, including collective excitations in nuclei, radii of neutron stars, and the nature of stellar collapse and supernova explosions. The work described included three sets of experiments and subsequent sophisticated data analysis, both leading to results that have been welcomed by the community and recognised as important contributions to the field.

These proceedings gather invited and contributed talks presented at the XXI DAE-BRNS High Energy Physics Symposium, which was held at the Indian Institute of Technology Guwahati in December 2014. The contributions cover many of the most active research areas in particle physics, namely (i) Electroweak Physics; (ii) QCD and Heavy Ion Physics; (iii) Heavy Flavour Physics and CP Violation; (iv) Neutrino Physics; (v) Astro-particle Physics and Cosmology; (vi) Formal Theory; (vii) Future Colliders and New Machines; and (viii) BSM Physics: SUSY, Extra Dimensions, Composites etc. The DAE-BRNS High Energy Physics Symposium, widely considered to be one of the premiere symposiums organised in India in the field of elementary particle physics, is held every other year and supported by the Board of Research in Nuclear Sciences, Department of Atomic Energy, India. Roughly 250 physicists and researchers participated in the 21st Symposium, discussing the latest advancements in the field in 18 plenary review talks, 15 invited mini-review talks and approximately 130 contributed presentations. Bringing together the essential content, the book offers a valuable resource for both beginning and advanced researchers in the field.

This thesis describes the experimental and theoretical basics of free electron laser science, serving as an excellent introduction for newcomers to this young field. Beyond that, it addresses electron-beam lifetimes in third-generation synchrotron light sources, in particular with a view to optimizing them in the forthcoming ESRF upgrade. The lifetime of the electron beam in a storage ring is a measure of how fast electrons are being lost, and is thus an essential parameter determining the required injection frequency, which in turn affects beam stability and power consumption. The main limitation on the beam lifetime in these synchrotron light sources is the Touschek effect, i.e. the single scattering between two electrons in a bunch. In this thesis a model able to predict the Touschek lifetime is presented. The model is successfully tested against measurements and used to study the influence of other parameters such as current and size of vacuum chamber. Not least, it enables the settings of sextupole magnets to be optimized.

This work represents an inventive attempt to apply recent advances in nanotechnology to identify and characterise novel polymer systems for drug delivery through the skin. Atomic force microscopy (AFM) measurements of the nanoscale mechanical properties of topical, drug-containing polymeric films enabled the author to identify optimal compositions, in terms of flexibility and substantivity, for application to the skin. To elucidate the enhanced drug release from polyacrylate films incorporating medium chain triglycerides, the author combined AFM studies with the complementary technique of Raman micro-spectroscopy. This experimental strategy revealed that the significant increase in the drug released from these films is the result of a nanoscale two-phase structure. Finally, in experiments examining the microporation of skin using femtosecond laser ablation, the author demonstrated that the threshold at which the skin's barrier function is undermined can be dramatically reduced by the pre-application of ink. The approach allows thermal damage at the pore edge to be minimised, suggesting a very real potential for substantially increasing drug delivery in a minimally invasive fashion.

In this thesis, the author describes the development of a software framework to systematically construct a particular class of weakly coupled free fermionic heterotic string models, dubbed gauge models. In their purest form, these models are maximally supersymmetric (N = 4), and thus only contain superpartners in their matter sector. This feature makes their systematic construction particularly efficient, and they are thus useful in their simplicity. The thesis first provides a brisk introduction to heterotic strings and the spin-structure construction of free fermionic models. Three systematic surveys are then presented, and it is conjectured that these surveys are exhaustive modulo redundancies. Finally, the author presents a collection of metaheuristic algorithms for searching the landscape for models with a user-specified spectrum of phenomenological properties, e.g. gauge group and number of spacetime supersymmetries. Such algorithms provide the groundwork for extended generic free fermionic surveys.

In this thesis the author contributes to the analysis of neutrino beam data collected between 2010 and 2013 to identify e events at the Super-Kamiokande detector. In particular, the author improves the pion-nucleus interaction uncertainty, which is one of the dominant systematic error sources in T2K neutrino oscillation measurement. In the thesis, the measurement of e oscillation in the T2K (Tokai to Kamioka) experiment is presented and a new constraint on CP is obtained. This measurement and the analysis establish, at greater than 5 significance, the observation of e oscillation for the first time in the world. Combining the T2K e oscillation measurement with the latest findings on oscillation parameters including the world average value of 13 from reactor experiments, the constraint on the value of CP at the 90% confidence level is obtained. This constraint on CP is an important step towards the discovery of CP violation in the lepton sector.

This work focuses on new electromagnetic decay mode in nuclear physics. The first part of the thesis presents the observation of the two-photon decay for a transition where the one-photon decay is allowed. In the second part, so called quadrupole mixed-symmetry is investigated in inelastic proton scattering experiments. In 1930 Nobel-prize winner M. Goeppert-Mayer was the first to discuss the two-photon decay of an exited state in her doctoral thesis. This process has been observed many times in atomic physics. However in nuclear physics data is sparse. Here this decay mode has only been observed for the special case of a transition between nuclear states with spin and parity quantum number 0+. For such a transition, the one-photon decay - the main experimental obstacle to observe the two-photon decay - is forbidden. Furthermore, the energy sharing and angular distributions were measured, allowing conclusions to be drawn about the multipoles contributing to the two-photon transition. Quadrupole mixed-symmetry states are an excitation mode in spherical nuclei which are sensitive to the strength of the quadrupole residual interaction. A new signature for these interesting states is presented which allows identification of mixed-symmetry states independently of electromagnetic transition strengths. Furthermore this signature represents a valuable additional observable to test model predictions for mixed-symmetry states.

The Black Book of Quantum Chromodynamics is an in-depth introduction to the particle physics of current and future experiments at particle accelerators. The book offers the reader an overview of practically all aspects of the strong interaction necessary to understand and appreciate modern particle phenomenology at the energy frontier. It assumes a working knowledge of quantum field theory at the level of introductory textbooks used for advanced undergraduate or in standard postgraduate lectures. The book expands this knowledge with an intuitive understanding of relevant physical concepts, an introduction to modern techniques, and their application to the phenomenology of the strong interaction at the highest energies. Aimed at graduate students and researchers, it also serves as a comprehensive reference for LHC experimenters and theorists. This book offers an exhaustive presentation of the technologies developed and used by practitioners in the field of fixed-order perturbation theory and an overview of results relevant for the ongoing research programme at the LHC. It includes an in-depth description of various analytic resummation techniques, which form the basis for our understanding of the QCD radiation pattern and how strong production processes manifest themselves in data, and a concise discussion of numerical resummation through parton showers, which form the basis of event generators for the simulation of LHC physics, and their matching and merging with fixed-order matrix elements. It also gives a detailed presentation of the physics behind the parton distribution functions, which are a necessary ingredient for every calculation relevant for physics at hadron colliders such as the LHC, and an introduction to non-perturbative aspects of the strong interaction, including inclusive observables such as total and elastic cross sections, and non-trivial effects such as multiple parton interactions and hadronization. The book concludes with a useful overview contextualising data from previous experiments such as the Tevatron and the Run I of the LHC which have shaped our understanding of QCD at hadron colliders.