This thesis develops fundamental ideas and advanced techniques for studying the Higgs boson’s interactions with the known matter and force particles. The Higgs boson appears as an excitation of the Higgs field, which permeates the vacuum. Several other phenomena in our Universe, such as dark energy, dark matter, and the abundance of matter over antimatter, remain unexplained. The Higgs field may prove to be the connection between our known world and the “dark” world, and studies of the Higgs boson's interactions are essential to reveal possible new phenomena. The unique feature of this work is simultaneous measurement of the Higgs boson’s associated production (its context, to use the language of the title) and its decay (its end), while allowing for multiple parameters sensitive to new phenomena. This includes computer simulation with Monte Carlo techniques of the complicated structure of the Higgs boson interactions, the matrix-element calculation of per-event likelihoods for optimal observables, and advanced fitting methods with hundreds of intricate components that cover all possible parameters and quantum mechanical interference. This culminates in the most advanced analysis of LHC data in the multi-parameter approach to Higgs physics in its single golden four-lepton decay channel to date. Optimization of the CMS detector’s silicon-based tracking system, essential for these measurements, is also described.
This book provides a comprehensive overview of the field of Higgs boson physics. It offers the first in-depth review of the complete results in connection with the discovery of the Higgs boson at CERN’s Large Hadron Collider and based on the full dataset for the years 2011 to 2012. The fundamental concepts and principles of Higgs physics are introduced and the important searches prior to the advent of the Large Hadron Collider are briefly summarized. Lastly, the discovery and first mensuration of the observed particle in the course of the CMS experiment are discussed in detail and compared to the results obtained in the ATLAS experiment.
Despite the great success of the standard model of electroweak and strong interactions to describe the phenomena observed in high energy physics experiments, the mechanism by which the elementary particles are endowed with their masses is yet to be unraveled. Does nature choose the Higgs mechanism of spontaneous symmetry breaking as predicted by the standard model, or do we need some alternative explanation? The purpose of the workshop is to capture new trends and ideas in this exciting area of fundamental physics, and to explore the potential of recent (LEPI), present (HERA, LEPII, SLC, Tevatron), and future (FMC, LHC, NLC) colliding-beam experiments to shed light on the Higgs puzzle. Contents:Analysis of the Z0 Resonant Amplitude in General Rξ Gauges and Related Problems (A Sirlin)Searches for Higgs Bosons at LEP2 and Status of ALEPH Four-Jet Events (P Janot)Aspects of Higgs Physics at the ILC (R Settles)Higgs Physics at a Muon Collider (J F Gunion)Radiative Corrections in the MSSM Higgs Sector (W Hollik)Unification or Compositeness? (P Langacker & J Erler)The Higgs Puzzle — What Can We Learn from Electroweak Phase Transition? (M E Shaposhnikov)Future Directions in Higgs Phenomenology (H E Haber)and other papers Readership: Physicists and postgraduate students in high energy physics. keywords:Higgs;Higgs Bosons;Muon Collider;Electroweak;Phenomenology
This volume provides a detailed description of the seminal theoretical construction in 1964, independently by Robert Brout and Francois Englert, and by Peter W. Higgs, of a mechanism for short-range fundamental interactions, now called the Brout-Englert-Higgs (BEH) mechanism. It accounts for the non-zero mass of elementary particles and predicts the existence of a new particle - an elementary massive scalar boson. In addition to this the book describes the experimental discovery of this fundamental missing element in the Standard Model of particle physics. The H Boson, also called the Higgs Boson, was produced and detected in the Large Hadron Collider (LHC) of CERN near Geneva by two large experimental collaborations, ATLAS and CMS, which announced its discovery on the 4th of July 2012.This new volume of the Poincaré Seminar Series, The H Boson, corresponds to the nineteenth seminar, held on November 29, 2014, at Institut Henri Poincaré in Paris.
This thesis presents innovative contributions to the CMS experiment in the new trigger system for the restart of the LHC collisions in Run II, as well as original analysis methods and important results that led to official publications of the Collaboration. The author's novel reconstruction algorithms, deployed on the Field-Programmable Gate Arrays of the new CMS trigger architecture, have brought a gain of over a factor 2 in efficiency for the identification of tau leptons, with a very significant impact on important H boson measurements, such as its decays to tau lepton pairs and the search for H boson pair production. He also describes a novel analysis of HH → bb tautau, a high priority physics topic in a difficult channel. The original strategy, optimisation of event categories, and the control of the background have made the result one of the most sensitive concerning the self-coupling of the Higgs boson among all possible channels at the LHC.
This proceedings volume contains talks and poster presentations from the International Symposium "Self-Organization in Complex Systems: The Past, Present, and Future of Synergetics", which took place at Hanse-Wissenschaftskolleg, an Institute of Advanced Studies, in Delmenhorst, Germany, during the period November 13 - 16, 2012. The Symposium was organized in honour of Hermann Haken, who celebrated his 85th birthday in 2012. With his fundamental theory of Synergetics he had laid the mathematical-physical basis for describing and analyzing self-organization processes in a diversity of fields of research. The quest for common and universal principles of self-organization in complex systems was clearly covered by the wide range of interdisciplinary topics reported during the Symposium. These extended from complexity in classical systems and quantum systems over self-organisation in neuroscience even to the physics of finance. Moreover, by combining a historical view with a present status report the Symposium conveyed an impression of the allure and potency of this branch of research as well as its applicability in the future.
In this book, the interaction between the Higgs boson and the top quark is studied with the CMS detector at the LHC via the search for the associate production of the Higgs boson with one (tH) or two (ttH) top quarks. These processes are very rare and thus a high particle selection efficiency by the trigger system is essential. The selection of hadronically decaying tau leptons, expected from the Higgs boson decays, is tackled in the first part, where the trigger is optimized for Run 2 and Run 3 and a novel machine-learning based trigger for the High-Luminosity LHC is developed. The second part presents the analysis of tH and ttH where the Higgs boson decays into tau leptons, W or Z bosons with Run 2 data. The presence of multiple particles in the final state leads to the use of multivariant discriminants based on machine learning and the Matrix Element Method. The sophisticated methods used and the unprecedented amount of data result in the most precise cross section measurements to date.
The Standard Model of electroweak and strong interactions contains a scalar field which permeates all of space and matter, and whose properties provide the explanation of the origin of the masses. Commonly referred to as the Higgs field, it assumes in the physical vacuum a non-vanishing classical expectation value to which the masses of not only the vector bosons, but all the other known fundamental particles (quarks and leptons) are proportional. This volume presents a concise summary of the phenomenological properties of the Higgs boson.
If the new boson is indeed the Higgs particle, its discovery represents an important milestone in the history of particle physics. However, despite the pressure to award Nobel Prizes to physicists associated with the Higgs boson, John Moffat argues that there still remain important data analyses to be performed before uncorking the champagne. John Moffat is Professor Emeritus of Physics at the University of Toronto and a senior researcher at the Perimeter Institute for Theoretical Physics. Well-known for his outside-the-box research on topics such as dark matter, dark energy, and the varying speed of light cosmology (VSL), his new book takes a critical look at the hype surrounding the Higgs boson. In the process, he presents a cogent and often entertaining history of particle physics and an exploration of alternative theories of particle physics that do not feature the Higgs boson, including his own. He gives a detailed and personal description of how theoretical physicists come up with new theories, and emphasizes how carefully experimental physicists must interpret the complex data now coming out of accelerators like the Large Hadron Collider (LHC). The book does not shy away from controversial topics such as the sociology of particle physics. There is immense pressure on projects like the $9 billion LHC to come up with positive results in order to secure funding for the future. Yet to date, the Higgs boson may be the only positive result to emerge from the LHC experiments. The searches for dark matter particles, mini-black holes, extra dimensions, and supersymmetric particles have all come up empty-handed, with serious consequences for theoretical physics, including string theory and gravity theory. John Moffat is also the author of Reinventing Gravity (2008) and Einstein Wrote Back (2010).
Winner of the prestigious 2013 Royal Society Winton Prize for Science Books “A modern voyage of discovery.” —Frank Wilczek, Nobel Laureate, author of The Lightness of Being The Higgs boson is one of our era’s most fascinating scientific frontiers and the key to understanding why mass exists. The most recent book on the subject, The God Particle, was a bestseller. Now, Caltech physicist Sean Carroll documents the doorway that is opening—after billions of dollars and the efforts of thousands of researchers at the Large Hadron Collider in Switzerland—into the mind-boggling world of dark matter. The Particle at the End of the Universe has it all: money and politics, jealousy and self-sacrifice, history and cutting-edge physics—all grippingly told by a rising star of science writing.
This thesis describes a novel and robust way of deriving a Hamiltonian of the interacting boson model based on microscopic nuclear energy density functional theory. Based on the fact that the multi-nucleon induced surface deformation of finite nucleus can be simulated by effective boson degrees of freedom, observables in the intrinsic frame, obtained from self-consistent mean-field method with a microscopic energy density functional, are mapped onto the boson analog. Thereby, the excitation spectra and the transition rates for the relevant collective states having good symmetry quantum numbers are calculated by the subsequent diagonalization of the mapped boson Hamiltonian. Because the density functional approach gives an accurate global description of nuclear bulk properties, the interacting boson model is derived for various situations of nuclear shape phenomena, including those of the exotic nuclei investigated at rare-isotope beam facilities around the world. This work provides, for the first time, crucial pieces of information about how the interacting boson model is justified and derived from nucleon degrees of freedom in a comprehensive manner.