12 from Neutral Currents to Weak Vector Bosons
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The Story of Large Electron Positron Collider 1
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Publications of the IAS Fellows GENERAL ç ARTICLE The Story of Large Electron Positron Collider 1. Fundamental Constituents of Matter S N Ganguli I nt roduct ion The story of the large electron positron collider, in short LEP, is linked intimately with our understanding of na- ture'sfundamental particlesand theforcesbetween them. We begin our story by giving a brief account of three great discoveries that completely changed our thinking Som Ganguli is at the Tata Institute of Fundamental and started a new ¯eld we now call particle physics. Research, Mumbai. He is These discoveries took place in less than three years currently participating in an during 1895 to 1897: discovery of X-rays by Wilhelm experiment under prepara- Roentgen in 1895, discovery of radioactivity by Henri tion for the Large Hadron Becquerel in 1896 and the identi¯cation of cathode rays Collider (LHC) at CERN, Geneva. He has been as electrons, a fundamental constituent of atom by J J studying properties of Z and Thomson in 1897. It goes without saying that these dis- W bosons produced in coveries were rewarded by giving Nobel Prizes in 1901, electron-positron collisions 1903 and 1906, respectively. X-rays have provided one at the Large Electron of the most powerful tools for investigating the struc- Positron Collider (LEP). During 1970s and early ture of matter, in particular the study of molecules and 1980s he was studying crystals; it is also an indispensable tool in medical diag- production and decay nosis. -
The Standard Model Part II: Charged Current Weak Interactions I
Prepared for submission to JHEP The Standard Model Part II: Charged Current weak interactions I Keith Hamiltona aDepartment of Physics and Astronomy, University College London, London, WC1E 6BT, UK E-mail: [email protected] Abstract: Rough notes on ... Introduction • Relation between G and g • F W Leptonic CC processes, ⌫e− scattering • Estimated time: 3 hours ⇠ Contents 1 Charged current weak interactions 1 1.1 Introduction 1 1.2 Leptonic charge current process 9 1 Charged current weak interactions 1.1 Introduction Back in the early 1930’s we physicists were puzzled by nuclear decay. • – In particular, the nucleus was observed to decay into a nucleus with the same mass number (A A) and one atomic number higher (Z Z + 1), and an emitted electron. ! ! – In such a two-body decay the energy of the electron in the decay rest frame is constrained by energy-momentum conservation alone to have a unique value. – However, it was observed to have a continuous range of values. In 1930 Pauli first introduced the neutrino as a way to explain the observed continuous energy • spectrum of the electron emitted in nuclear beta decay – Pauli was proposing that the decay was not two-body but three-body and that one of the three decay products was simply able to evade detection. To satisfy the history police • – We point out that when Pauli first proposed this mechanism the neutron had not yet been discovered and so Pauli had in fact named the third mystery particle a ‘neutron’. – The neutron was discovered two years later by Chadwick (for which he was awarded the Nobel Prize shortly afterwards in 1935). -
Discovery of Weak Neutral Currents∗
Discovery of Weak Neutral Currents∗ Dieter Haidt Emeritus at DESY, Hamburg 1 Introduction Following the tradition of previous Neutrino Conferences the opening talk is devoted to a historic event, this year to the epoch-making discovery of Weak Neutral Currents four decades ago. The major laboratories joined in a worldwide effort to investigate this new phenomenon. It resulted in new accelerators and colliders pushing the energy frontier from the GeV to the TeV regime and led to the development of new, almost bubble chamber like, general purpose detectors. While the Gargamelle collaboration consisted of seven european laboratories and was with nearly 60 members one of the biggest collaborations at the time, the LHC collaborations by now have grown to 3000 members coming from all parts in the world. Indeed, High Energy Physics is now done on a worldwide level thanks to net working and fast communications. It seems hardly imaginable that 40 years ago there was no handy, no world wide web, no laptop, no email and program codes had to be punched on cards. Before describing the discovery of weak neutral currents as such and the cir- cumstances how it came about a brief look at the past four decades is anticipated. The history of weak neutral currents has been told in numerous reviews and spe- cialized conferences. Neutral currents have since long a firm place in textbooks. The literature is correspondingly rich - just to point out a few references [1, 2, 3, 4]. 2 Four decades Figure 1 sketches the glorious electroweak way originating in the discovery of weak neutral currents by the Gargamelle Collaboration and followed by the series of eminent discoveries. -
Introduction to Subatomic- Particle Spectrometers∗
IIT-CAPP-15/2 Introduction to Subatomic- Particle Spectrometers∗ Daniel M. Kaplan Illinois Institute of Technology Chicago, IL 60616 Charles E. Lane Drexel University Philadelphia, PA 19104 Kenneth S. Nelsony University of Virginia Charlottesville, VA 22901 Abstract An introductory review, suitable for the beginning student of high-energy physics or professionals from other fields who may desire familiarity with subatomic-particle detection techniques. Subatomic-particle fundamentals and the basics of particle in- teractions with matter are summarized, after which we review particle detectors. We conclude with three examples that illustrate the variety of subatomic-particle spectrom- eters and exemplify the combined use of several detection techniques to characterize interaction events more-or-less completely. arXiv:physics/9805026v3 [physics.ins-det] 17 Jul 2015 ∗To appear in the Wiley Encyclopedia of Electrical and Electronics Engineering. yNow at Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723. 1 Contents 1 Introduction 5 2 Overview of Subatomic Particles 5 2.1 Leptons, Hadrons, Gauge and Higgs Bosons . 5 2.2 Neutrinos . 6 2.3 Quarks . 8 3 Overview of Particle Detection 9 3.1 Position Measurement: Hodoscopes and Telescopes . 9 3.2 Momentum and Energy Measurement . 9 3.2.1 Magnetic Spectrometry . 9 3.2.2 Calorimeters . 10 3.3 Particle Identification . 10 3.3.1 Calorimetric Electron (and Photon) Identification . 10 3.3.2 Muon Identification . 11 3.3.3 Time of Flight and Ionization . 11 3.3.4 Cherenkov Detectors . 11 3.3.5 Transition-Radiation Detectors . 12 3.4 Neutrino Detection . 12 3.4.1 Reactor Neutrinos . 12 3.4.2 Detection of High Energy Neutrinos . -
Measurement of Neutrino-Nucleon Neutral-Current Elastic Scattering Cross-Section at Sciboone
Measurement of Neutrino-Nucleon Neutral-Current Elastic Scattering Cross-section at SciBooNE Hideyuki Takei Thesis submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Science at Tokyo Institute of Technology February, 2009 2 Abstract In this thesis, results of neutrino-nucleon neutral current (NC) elastic scattering analysis are presented. Neutrinos interact with other particles only with weak force. Measure- ment of cross-section for neutrino-nucleon reactions at various neutrino en- ergy are important for the study of nucleon structure. It also provides data to be used for beam flux monitor in neutrino oscillation experiments. The cross-section for neutrino-nucleon NC elastic scattering contains the 2 axial vector form factor GA(Q ) as well as electromagnetic form factors unlike electromagnetic interaction. GA is propotional to strange part of nucleon spin (∆ s) in Q2 → 0 limit. Measurement of NC elastic cross-section with smaller Q2 enables us to access ∆ s. NC elastic cross-sections of neutrino- nucleon and antineutrino-nucleon were measured earlier by E734 experiment at Brookheaven National Laboratory (BNL) in 1987. In this experiment, cross-sections were measured in Q2 > 0.4 GeV 2 region. Result from this experiment was the only published data for NC elastic scattering cross-section published before our experiment. SciBooNE is an experiment for the measurement of neutrino-nucleon scat- tering cross-secitons using Booster Neutrino Beam (BNB) at FNAL. BNB has energy peak at 0.7 GeV. In this energy region, NC elastic scattering, charged current elastic scattering, charged current pion production, and neutral cur- rent pion production are the major reaction branches. -
Charged Current Anti-Neutrino Interactions in the Nd280 Detector
CHARGED CURRENT ANTI-NEUTRINO INTERACTIONS IN THE ND280 DETECTOR BRYAN E. BARNHART HIGH ENERGY PHYSICS UNIVERSITY OF COLORADO AT BOULDER ADVISOR: ALYSIA MARINO Abstract. For the neutrino beamline oscillation experiment Tokai to Kamioka, the beam is clas- sified before oscillation by the near detector complex. The detector is used to measure the flux of different particles through the detector, and compare them to Monte Carlo Simulations. For this work, theν ¯µ background of the detector was isolated by examining the Monte Carlo simulation and determining cuts which removed unwanted particles. Then, a selection of the data from the near detector complex underwent the same cuts, and compared to the Monte Carlo to determine if the Monte Carlo represented the data distribution accurately. The data was found to be consistent with the Monte Carlo Simulation. Date: November 11, 2013. 1 Bryan E. Barnhart University of Colorado at Boulder Advisor: Alysia Marino Contents 1. The Standard Model and Neutrinos 4 1.1. Bosons 4 1.2. Fermions 5 1.3. Quarks and the Strong Force 5 1.4. Leptons and the Weak Force 6 1.5. Neutrino Oscillations 7 1.6. The Relative Neutrino Mass Scale 8 1.7. Neutrino Helicity and Anti-Neutrinos 9 2. The Tokai to Kamioka Experiment 9 2.1. Japan Proton Accelerator Research Complex 10 2.2. The Near Detector Complex 12 2.3. The Super-Kamiokande Detector 17 3. Isolation of the Anti-Neutrino Component of Neutrino Beam 19 3.1. Experiment details 19 3.2. Selection Cuts 20 4. Cut Descriptions 20 4.1. Beam Data Quality 20 4.2. -
1989-1990 Eight College Teachers Participated in the Training
SATYENDRA NATH BOSE NATIONAL CENTRE FOR BASIC SCIENCES Calcutta ANNUAL REPORT April 1, 1989 to March 31,1990 Objectives The objectives of the S N Bose National Centre for Basic Sciences established in June 1986 as a registered society functioning under the umbrella of the Department of Science & Technology, Government of India, are : To foster, encourage and promote the growth of advanced studies in selected branches of basic sciences ; To conduct original research in theoretical and mathematical sciences and other basic sciences in frontier areas, including challenging theoretical studies of future applications ; To provide a forum of personal contacts and intellectual interaction among scientists within the country and also between them and scientists abroad ; To train young scientists for research in basic sciences. Governing Body The present Governing Body of the Centre consists of the following members : 1 Dr V Gowariker Secretary Chairman Department of Science & Technology Government of India, New Delhi 2 Professor C N R Rao Direct or Member Indian Institute of Science Bangalore 3 Professor C S Seshadri Dean Member School of Mathematics SPIC, Science Foundation Madras Professor J V Narlikar Director Member Inter-Universit y Centre for Astronomy & Astrophysics Pune Shri B K Chaturvedi Joint Secretary & Financial Adviser Member Department of Science & Technology Government of India, New Delhi Shri T C Dutt Chief Secretary Member Government of West Bengal Calcutta Professor C K Mzjumdar Director Member S N Bose National Centre for Basic Sciences Calcutta Dr J Pal Chaud huri Administrative Officer Non-member-Secretary S N Bose National Centre for Basic Sciences Calcutta At the moment the Centre operates from a rented house located at DB 17, Sector I, Salt Lake City, Calcutta 700 064. -
The Weak Interaction
The Weak Interaction April 20, 2016 Contents 1 Introduction 2 2 The Weak Interaction 2 2.1 The 4-point Interaction . .3 2.2 Weak Propagator . .4 3 Parity Violation 5 3.1 Parity and The Parity Operator . .5 3.2 Parity Violation . .6 3.3 CP Violation . .7 3.4 Building it into the theory - the V-A Interaction . .8 3.5 The V-A Interaction and Neutrinos . 10 4 What you should know 11 5 Furthur reading 11 1 1 Introduction The nuclear β-decay caused a great deal of anxiety among physicists. Both α- and γ-rays are emitted with discrete spectra, simply because of energy conservation. The energy of the emitted particle is the same as the energy difference between the initial and final state of the nucleus. It was much more difficult to see what was going on with the β-decay, the emission of electrons from nuclei. Chadwick once reported that the energy spectrum of electrons is continuous. The energy could take any value between 0 and a certain maximum value. This observation was so bizarre that many more experiments followed up. In fact, Otto Han and Lise Meitner, credited for their discovery of nuclear fission, studied the spectrum and claimed that it was discrete. They argued that the spectrum may appear continuous because the electrons can easily lose energy by breamsstrahlung in material. The maximum energy observed is the correct discrete spectrum, and we see lower energies because of the energy loss. The controversy went on over a decade. In the end a definitive experiment was done by Ellis and Wooseley using a very simple idea. -
Cross Sections for Neutral-Current Neutrino-Nucleus Interactions: Applications for 12C and 16O
PHYSICAL REVIEW C VOLUME 59, NUMBER 6 JUNE 1999 Cross sections for neutral-current neutrino-nucleus interactions: Applications for 12C and 16O N. Jachowicz,* S. Rombouts, K. Heyde,† and J. Ryckebusch Institute for Theoretical Physics, Vakgroep Subatomaire en Stralingsfysica, Proeftuinstraat 86, B-9000 Gent, Belgium ~Received 29 September 1998; revised manuscipt received 4 February 1999! We study quasielastic neutrino-nucleus scattering on 12C and 16O within a continuum random phase ap- proximation ~RPA! model. The RPA equations are solved using a Green’s function approach with an effective Skyrme ~SkE2! two-body interaction. Besides a comparison with existing calculations, we carry out a detailed study using various methods ~Tamm-Dancoff approximation and RPA! and different forces ~SkE2 and Landau- Migdal!. We evaluate cross sections that may be relevant for neutrino nucleosynthesis. @S0556-2813~99!01606-4# PACS number~s!: 25.30.Pt, 24.10.Eq, 26.30.1k I. INTRODUCTION function approach in which the polarization propagator is approximated by an iteration of the first-order contribution Neutrinos are extremely well-suited probes to provide de- @14#. The unperturbed wave functions are generated using tailed information about the structure and properties of the either a Woods-Saxon potential or a HF calculation using a weak interaction, as they are only interacting via the weak Skyrme force. The latter approach makes self-consistent HF- forces. Moreover, being intrinsically polarized and coupling RPA calculations possible. Calculations using either a to the axial vector as well as to the vector part of the had- Skyrme or a Landau-Migdal force must give indications ronic current, neutrinos are able to reveal other and more about possible differences and sensitivity in methods to the precise nuclear structure information than, e.g., electrons do. -
How the First Neutral-Current Experiments Ended
How the first neutral-current experiments ended Peter Galison Lyman Laboratory of Physics, Harvard University, Cambridge, Massachusetts 02138 At the beginning of the 1970s there seemed little reason to believe that strangeness-conserving neutral currents existed: theoreticians had no pressing need for them and several experiments suggested that they were suppressed if they were present at all. Indeed the two remarkable neutrino experiments that eventual- ly led to their discovery were designed and built for very different purposes, including the search for the vector boson and the investigation of the parton model. In retrospect we know that certain gauge theories (notably the Weinberg-Salam model) predicted that neutral currents exist. But until 't Hooft and Veltman proved that such theories were renormalizable, little effort was made to test the new theories. After the proof the two experimental groups began to reorient their goals to settle an increasingly central issue of physics. Do neutral currents exist? We ask here: What kind of evidence and arguments persuaded the par- ticipants that they had before them a real effect and not an artifact of the apparatus~ What eventually con- vinced them that their experiment was over? An answer to these questions requires an examination of the organization of the experiments, the nature of the apparatus, and the previous work of the experimentalists. Finally, some general observations are made about the recent evolution of experimental physics. CONTENTS weak interaction. Certainly the provisional advance af- I. Introduction 477 forded by such a move had many historical precedents. A II. The Experiment "Cxargamelle": from W Search to hundred years earlier Ampere unravelled many of the Neutral-Current Test 481 laws of electrodynamics by studying the interactions of III. -
Sam Treiman Was Born in Chicago to a First-Generation Immigrant Family
NATIONAL ACADEMY OF SCIENCES SAM BARD TREIMAN 1925–1999 A Biographical Memoir by STEPHEN L. ADLER Any opinions expressed in this memoir are those of the author and do not necessarily reflect the views of the National Academy of Sciences. Biographical Memoirs, VOLUME 80 PUBLISHED 2001 BY THE NATIONAL ACADEMY PRESS WASHINGTON, D.C. Courtesy of Robert P. Matthews SAM BARD TREIMAN May 27, 1925–November 30, 1999 BY STEPHEN L. ADLER AM BARD TREIMAN WAS a major force in particle physics S during the formative period of the current Standard Model, both through his own research and through the training of graduate students. Starting initially in cosmic ray physics, Treiman soon shifted his interests to the new particles being discovered in cosmic ray experiments. He evolved a research style of working closely with experimen- talists, and many of his papers are exemplars of particle phenomenology. By the mid-1950s Treiman had acquired a lifelong interest in the weak interactions. He would preach to his students that “the place to learn about the strong interactions is through the weak and electromagnetic inter- actions; the problem is half as complicated.’’ The history of the subsequent development of the Standard Model showed this philosophy to be prophetic. After the discovery of parity violation in weak interactions, Treiman in collaboration with J. David Jackson and Henry Wyld (1957) worked out the definitive formula for allowed beta decays, taking into account the possible violation of time reversal symmetry, as well as parity. Shortly afterwards Treiman embarked with Marvin Goldberger on a dispersion relations analysis (1958) of pion and nucleon beta decay, a 3 4 BIOGRAPHICAL MEMOIRS major outcome of which was the famed Goldberger-Treiman relation for the charged pion decay amplitude. -
The Standard Model Lagrangian
The Standard Model Lagrangian Elementary Particle Physics Strong Interaction Fenomenology Diego Bettoni Academic Year 2011-12 Dirac Formalism i m 0 j Conserved Current 0 0 1 1 0 i i 0 5 i 0 1 0 0 1 R L i m L D. Bettoni Fenomenologia Interazioni Forti 2 Gauge Invariance U i 1 1 igA A U U UA U Abelian D g D U D 1 W W D ig2 W i i ijk j k Non 2 g2 Abelian Gauge invariance requires the introduction of vector bosons, which act as quanta of new interactions. In gauge theories the symmetries prescribe the interactions. D. Bettoni Fenomenologia Interazioni Forti 3 The Symmetries of the Standard Model • U(1) invariance. All particles appear to have this kind of invariance, related to electromagnetism. It requires a vector boson, B, whose connection with the photon will be determined later. • SU(2) invariance. Non abelian gauge invariance (electroweak isospin). It requires three vector bosons, Wi , one for each generator of SU(2). The physical W particles have definite electromagnetic charges. 1 2 1 2 0 3 W W iW 2 W W iW 2 W W • SU(3) invariance. It requires eight vector bosons, Ga , the gluons, the quanta of the strong interaction, described by Quantum ChromoDynamics (QCD). D. Bettoni Fenomenologia Interazioni Forti 4 The Lagrangian • In order to obtain the Standard Model Lagrangian we start from the free particle Lagrangian and replace the ordinary derivative by the convariant derivative. It will contain two parts: Lgauge kinetic energies of the gauge fields Lferm covariant derivative fermion kinetic energies • Next we must specify the particles and their transformation properties under the three internal symmetries.