Are There Discrete Symmetries in Relativistic Quantum Mechanics
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Intrinsic Parity of Neutral Pion
Intrinsic Parity of Neutral Pion Taushif Ahmed 13th September, 2012 1 2 Contents 1 Symmetry 4 2 Parity Transformation 5 2.1 Parity in CM . 5 2.2 Parity in QM . 6 2.2.1 Active viewpoint . 6 2.2.2 Passive viewpoint . 8 2.3 Parity in Relativistic QM . 9 2.4 Parity in QFT . 9 2.4.1 Parity in Photon field . 11 3 Decay of The Neutral Pion 14 4 Bibliography 17 3 1 Symmetry What does it mean by `a certain law of physics is symmetric under certain transfor- mations' ? To be specific, consider the statement `classical mechanics is symmetric under mirror inversion' which can be defined as follows: take any motion that satisfies the laws of classical mechanics. Then, reflect the motion into a mirror and imagine that the motion in the mirror is actually happening in front of your eyes, and check if the motion satisfies the same laws of clas- sical mechanics. If it does, then classical mechanics is said to be symmetric under mirror inversion. Or more precisely, if all motions that satisfy the laws of classical mechanics also satisfy them after being re- flected into a mirror, then classical mechanics is said to be symmetric under mirror inversion. In general, suppose one applies certain transformation to a motion that follows certain law of physics, if the resulting motion satisfies the same law, and if such is the case for all motion that satisfies the law, then the law of physics is said to be sym- metric under the given transformation. It is important to use exactly the same law of physics after the transfor- mation is applied. -
An Interpreter's Glossary at a Conference on Recent Developments in the ATLAS Project at CERN
Faculteit Letteren & Wijsbegeerte Jef Galle An interpreter’s glossary at a conference on recent developments in the ATLAS project at CERN Masterproef voorgedragen tot het behalen van de graad van Master in het Tolken 2015 Promotor Prof. Dr. Joost Buysschaert Vakgroep Vertalen Tolken Communicatie 2 ACKNOWLEDGEMENTS First of all, I would like to express my sincere gratitude towards prof. dr. Joost Buysschaert, my supervisor, for his guidance and patience throughout this entire project. Furthermore, I wanted to thank my parents for their patience and support. I would like to express my utmost appreciation towards Sander Myngheer, whose time and insights in the field of physics were indispensable for this dissertation. Last but not least, I wish to convey my gratitude towards prof. dr. Ryckbosch for his time and professional advice concerning the quality of the suggested translations into Dutch. ABSTRACT The goal of this Master’s thesis is to provide a model glossary for conference interpreters on assignments in the domain of particle physics. It was based on criteria related to quality, role, cognition and conference interpreters’ preparatory methodology. This dissertation focuses on terminology used in scientific discourse on the ATLAS experiment at the European Organisation for Nuclear Research. Using automated terminology extraction software (MultiTerm Extract) 15 terms were selected and analysed in-depth in this dissertation to draft a glossary that meets the standards of modern day conference interpreting. The terms were extracted from a corpus which consists of the 50 most recent research papers that were publicly available on the official CERN document server. The glossary contains information I considered to be of vital importance based on relevant literature: collocations in both languages, a Dutch translation, synonyms whenever they were available, English pronunciation and a definition in Dutch for the concepts that are dealt with. -
Helicity of the Neutrino Determination of the Nature of Weak Interaction
GENERAL ¨ ARTICLE Helicity of the Neutrino Determination of the Nature of Weak Interaction Amit Roy Measurement of the helicity of the neutrino was crucial in identifying the nature of weak interac- tion. The measurement is an example of great ingenuity in choosing, (i) the right nucleus with a specific type of decay, (ii) the technique of res- onant fluorescence scattering for determining di- rection of neutrino and (iii) transmission through Amit Roy is currently at magnetised iron for measuring polarisation of γ- the Variable Energy rays. Cyclotron Centre after working at Tata Institute In the field of art and sculpture, we sometimes come of Fundamental Research across a piece of work of rare beauty, which arrests our and Inter-University attention as soon as we focus our gaze on it. The ex- Accelerator Centre. His research interests are in periment on the determination of helicity of the neutrino nuclear, atomic and falls in a similar category among experiments in the field accelerator physics. of modern physics. The experiments on the discovery of parity violation in 1957 [1] had established that the vi- olation parity was maximal in beta decay and that the polarisation of the emitted electron was 100%. This im- plies that its helicity was −1. The helicity of a particle is a measure of the angle (co- sine) between the spin direction of the particle and its momentum direction. H = σ.p,whereσ and p are unit vectors in the direction of the spin and the momentum, respectively. The spin direction of a particle of posi- tive helicity is parallel to its momentum direction, and for that of negative helicity, the directions are opposite (Box 1). -
Kinematic Relativity of Quantum Mechanics: Free Particle with Different Boundary Conditions
Journal of Applied Mathematics and Physics, 2017, 5, 853-861 http://www.scirp.org/journal/jamp ISSN Online: 2327-4379 ISSN Print: 2327-4352 Kinematic Relativity of Quantum Mechanics: Free Particle with Different Boundary Conditions Gintautas P. Kamuntavičius 1, G. Kamuntavičius 2 1Department of Physics, Vytautas Magnus University, Kaunas, Lithuania 2Christ’s College, University of Cambridge, Cambridge, UK How to cite this paper: Kamuntavičius, Abstract G.P. and Kamuntavičius, G. (2017) Kinema- tic Relativity of Quantum Mechanics: Free An investigation of origins of the quantum mechanical momentum operator Particle with Different Boundary Condi- has shown that it corresponds to the nonrelativistic momentum of classical tions. Journal of Applied Mathematics and special relativity theory rather than the relativistic one, as has been uncondi- Physics, 5, 853-861. https://doi.org/10.4236/jamp.2017.54075 tionally believed in traditional relativistic quantum mechanics until now. Taking this correspondence into account, relativistic momentum and energy Received: March 16, 2017 operators are defined. Schrödinger equations with relativistic kinematics are Accepted: April 27, 2017 introduced and investigated for a free particle and a particle trapped in the Published: April 30, 2017 deep potential well. Copyright © 2017 by authors and Scientific Research Publishing Inc. Keywords This work is licensed under the Creative Commons Attribution International Special Relativity, Quantum Mechanics, Relativistic Wave Equations, License (CC BY 4.0). Solutions -
Title: Parity Non-Conservation in Β-Decay of Nuclei: Revisiting Experiment and Theory Fifty Years After
Title: Parity non-conservation in β-decay of nuclei: revisiting experiment and theory fifty years after. IV. Parity breaking models. Author: Mladen Georgiev (ISSP, Bulg. Acad. Sci., Sofia) Comments: some 26 pdf pages with 4 figures. In memoriam: Prof. R.G. Zaykoff Subj-class: physics This final part offers a survey of models proposed to cope with the symmetry-breaking challenge. Among them are the two-component neutrinos, the neutrino twins, the universal Fermi interaction, etc. Moreover, the broken discrete symmetries in physics are very much on the agenda and may occupy considerable time for LHC experiments aimed at revealing the symmetry-breaking mechanisms. Finally, an account of the achievements of dual-component theories in explaining parity-breaking phenomena is added. 7. Two-component neutrino In the previous parts I through III of the paper we described the theoretical background as well as the bulk experimental evidence that discrete group symmetries break up in weak interactions, such as the β−decay. This last part IV will be devoted to the theoretical models designed to cope with the parity-breaking challenge. The quality of the proposed theories and the accuracy of the experiments made to check them underline the place occupied by papers such as ours in the dissemination of symmetry-related matter of modern science. 7.1. Neutrino gauge In the general form of β-interaction (5.6) the case Ck' = ±Ck (7.1) is of particular interest. It corresponds to interchanging the neutrino wave function in the parity-conserving Hamiltonian ( Ck' = 0 ) with the function ψν' = (! ± γs )ψν (7.2) In as much as parity is not conserved with this transformation, it is natural to put the blame on the neutrino. -
MHPAEA-Faqs-Part-45.Pdf
CCIIO OG MWRD 1295 FAQS ABOUT MENTAL HEALTH AND SUBSTANCE USE DISORDER PARITY IMPLEMENTATION AND THE CONSOLIDATED APPROPRIATIONS ACT, 2021 PART 45 April 2, 2021 The Consolidated Appropriations Act, 2021 (the Appropriations Act) amended the Mental Health Parity and Addiction Equity Act of 2008 (MHPAEA) to provide important new protections. The Departments of Labor (DOL), Health and Human Services (HHS), and the Treasury (collectively, “the Departments”) have jointly prepared this document to help stakeholders understand these amendments. Previously issued Frequently Asked Questions (FAQs) related to MHPAEA are available at https://www.dol.gov/agencies/ebsa/laws-and- regulations/laws/mental-health-and-substance-use-disorder-parity and https://www.cms.gov/cciio/resources/fact-sheets-and-faqs#Mental_Health_Parity. Mental Health Parity and Addiction Equity Act of 2008 MHPAEA generally provides that financial requirements (such as coinsurance and copays) and treatment limitations (such as visit limits) imposed on mental health or substance use disorder (MH/SUD) benefits cannot be more restrictive than the predominant financial requirements and treatment limitations that apply to substantially all medical/surgical benefits in a classification.1 In addition, MHPAEA prohibits separate treatment limitations that apply only to MH/SUD benefits. MHPAEA also imposes several important disclosure requirements on group health plans and health insurance issuers. The MHPAEA final regulations require that a group health plan or health insurance issuer may -
Relativistic Quantum Mechanics 1
Relativistic Quantum Mechanics 1 The aim of this chapter is to introduce a relativistic formalism which can be used to describe particles and their interactions. The emphasis 1.1 SpecialRelativity 1 is given to those elements of the formalism which can be carried on 1.2 One-particle states 7 to Relativistic Quantum Fields (RQF), which underpins the theoretical 1.3 The Klein–Gordon equation 9 framework of high energy particle physics. We begin with a brief summary of special relativity, concentrating on 1.4 The Diracequation 14 4-vectors and spinors. One-particle states and their Lorentz transforma- 1.5 Gaugesymmetry 30 tions follow, leading to the Klein–Gordon and the Dirac equations for Chaptersummary 36 probability amplitudes; i.e. Relativistic Quantum Mechanics (RQM). Readers who want to get to RQM quickly, without studying its foun- dation in special relativity can skip the first sections and start reading from the section 1.3. Intrinsic problems of RQM are discussed and a region of applicability of RQM is defined. Free particle wave functions are constructed and particle interactions are described using their probability currents. A gauge symmetry is introduced to derive a particle interaction with a classical gauge field. 1.1 Special Relativity Einstein’s special relativity is a necessary and fundamental part of any Albert Einstein 1879 - 1955 formalism of particle physics. We begin with its brief summary. For a full account, refer to specialized books, for example (1) or (2). The- ory oriented students with good mathematical background might want to consult books on groups and their representations, for example (3), followed by introductory books on RQM/RQF, for example (4). -
Class 2: Operators, Stationary States
Class 2: Operators, stationary states Operators In quantum mechanics much use is made of the concept of operators. The operator associated with position is the position vector r. As shown earlier the momentum operator is −iℏ ∇ . The operators operate on the wave function. The kinetic energy operator, T, is related to the momentum operator in the same way that kinetic energy and momentum are related in classical physics: p⋅ p (−iℏ ∇⋅−) ( i ℏ ∇ ) −ℏ2 ∇ 2 T = = = . (2.1) 2m 2 m 2 m The potential energy operator is V(r). In many classical systems, the Hamiltonian of the system is equal to the mechanical energy of the system. In the quantum analog of such systems, the mechanical energy operator is called the Hamiltonian operator, H, and for a single particle ℏ2 HTV= + =− ∇+2 V . (2.2) 2m The Schrödinger equation is then compactly written as ∂Ψ iℏ = H Ψ , (2.3) ∂t and has the formal solution iHt Ψ()r,t = exp − Ψ () r ,0. (2.4) ℏ Note that the order of performing operations is important. For example, consider the operators p⋅ r and r⋅ p . Applying the first to a wave function, we have (pr⋅) Ψ=−∇⋅iℏ( r Ψ=−) i ℏ( ∇⋅ rr) Ψ− i ℏ( ⋅∇Ψ=−) 3 i ℏ Ψ+( rp ⋅) Ψ (2.5) We see that the operators are not the same. Because the result depends on the order of performing the operations, the operator r and p are said to not commute. In general, the expectation value of an operator Q is Q=∫ Ψ∗ (r, tQ) Ψ ( r , td) 3 r . -
Question 1: Kinetic Energy Operator in 3D in This Exercise We Derive 2 2 ¯H ¯H 1 ∂2 Lˆ2 − ∇2 = − R +
ExercisesQuantumDynamics,week4 May22,2014 Question 1: Kinetic energy operator in 3D In this exercise we derive 2 2 ¯h ¯h 1 ∂2 lˆ2 − ∇2 = − r + . (1) 2µ 2µ r ∂r2 2µr2 The angular momentum operator is defined by ˆl = r × pˆ, (2) where the linear momentum operator is pˆ = −i¯h∇. (3) The first step is to work out the lˆ2 operator and to show that 2 2 ˆl2 = −¯h (r × ∇) · (r × ∇)=¯h [−r2∇2 + r · ∇ + (r · ∇)2]. (4) A convenient way to work with cross products, a = b × c, (5) is to write the components using the Levi-Civita tensor ǫijk, 3 3 ai = ǫijkbjck ≡ X X ǫijkbjck, (6) j=1 k=1 where we introduced the Einstein summation convention: whenever an index appears twice one assumes there is a sum over this index. 1a. Write the cross product in components and show that ǫ1,2,3 = ǫ2,3,1 = ǫ3,1,2 =1, (7) ǫ3,2,1 = ǫ2,1,3 = ǫ1,3,2 = −1, (8) and all other component of the tensor are zero. Note: the tensor is +1 for ǫ1,2,3, it changes sign whenever two indices are permuted, and as a result it is zero whenever two indices are equal. 1b. Check this relation ǫijkǫij′k′ = δjj′ δkk′ − δjk′ δj′k. (9) (Remember the implicit summation over index i). 1c. Use Eq. (9) to derive Eq. (4). 1d. Show that ∂ r = r · ∇ (10) ∂r 1e. Show that 1 ∂2 ∂2 2 ∂ r = + (11) r ∂r2 ∂r2 r ∂r 1f. Combine the results to derive Eq. -
Quantum Physics (UCSD Physics 130)
Quantum Physics (UCSD Physics 130) April 2, 2003 2 Contents 1 Course Summary 17 1.1 Problems with Classical Physics . .... 17 1.2 ThoughtExperimentsonDiffraction . ..... 17 1.3 Probability Amplitudes . 17 1.4 WavePacketsandUncertainty . ..... 18 1.5 Operators........................................ .. 19 1.6 ExpectationValues .................................. .. 19 1.7 Commutators ...................................... 20 1.8 TheSchr¨odingerEquation .. .. .. .. .. .. .. .. .. .. .. .. .... 20 1.9 Eigenfunctions, Eigenvalues and Vector Spaces . ......... 20 1.10 AParticleinaBox .................................... 22 1.11 Piecewise Constant Potentials in One Dimension . ...... 22 1.12 The Harmonic Oscillator in One Dimension . ... 24 1.13 Delta Function Potentials in One Dimension . .... 24 1.14 Harmonic Oscillator Solution with Operators . ...... 25 1.15 MoreFunwithOperators. .. .. .. .. .. .. .. .. .. .. .. .. .... 26 1.16 Two Particles in 3 Dimensions . .. 27 1.17 IdenticalParticles ................................. .... 28 1.18 Some 3D Problems Separable in Cartesian Coordinates . ........ 28 1.19 AngularMomentum.................................. .. 29 1.20 Solutions to the Radial Equation for Constant Potentials . .......... 30 1.21 Hydrogen........................................ .. 30 1.22 Solution of the 3D HO Problem in Spherical Coordinates . ....... 31 1.23 Matrix Representation of Operators and States . ........... 31 1.24 A Study of ℓ =1OperatorsandEigenfunctions . 32 1.25 Spin1/2andother2StateSystems . ...... 33 1.26 Quantum -
Quantization of the Free Electromagnetic Field: Photons and Operators G
Quantization of the Free Electromagnetic Field: Photons and Operators G. M. Wysin [email protected], http://www.phys.ksu.edu/personal/wysin Department of Physics, Kansas State University, Manhattan, KS 66506-2601 August, 2011, Vi¸cosa, Brazil Summary The main ideas and equations for quantized free electromagnetic fields are developed and summarized here, based on the quantization procedure for coordinates (components of the vector potential A) and their canonically conjugate momenta (components of the electric field E). Expressions for A, E and magnetic field B are given in terms of the creation and annihilation operators for the fields. Some ideas are proposed for the inter- pretation of photons at different polarizations: linear and circular. Absorption, emission and stimulated emission are also discussed. 1 Electromagnetic Fields and Quantum Mechanics Here electromagnetic fields are considered to be quantum objects. It’s an interesting subject, and the basis for consideration of interactions of particles with EM fields (light). Quantum theory for light is especially important at low light levels, where the number of light quanta (or photons) is small, and the fields cannot be considered to be continuous (opposite of the classical limit, of course!). Here I follow the traditinal approach of quantization, which is to identify the coordinates and their conjugate momenta. Once that is done, the task is straightforward. Starting from the classical mechanics for Maxwell’s equations, the fundamental coordinates and their momenta in the QM sys- tem must have a commutator defined analogous to [x, px] = i¯h as in any simple QM system. This gives the correct scale to the quantum fluctuations in the fields and any other dervied quantities. -
Dirac Equation
Particle Physics Dr. Alexander Mitov µ+ µ+ e- e+ e- e+ µ- µ- µ+ µ+ e- e+ e- e+ µ- µ- Handout 2 : The Dirac Equation Dr. A. Mitov Particle Physics 45 Non-Relativistic QM (Revision) • For particle physics need a relativistic formulation of quantum mechanics. But first take a few moments to review the non-relativistic formulation QM • Take as the starting point non-relativistic energy: • In QM we identify the energy and momentum operators: which gives the time dependent Schrödinger equation (take V=0 for simplicity) (S1) with plane wave solutions: where •The SE is first order in the time derivatives and second order in spatial derivatives – and is manifestly not Lorentz invariant. •In what follows we will use probability density/current extensively. For the non-relativistic case these are derived as follows (S1)* (S2) Dr. A. Mitov Particle Physics 46 •Which by comparison with the continuity equation leads to the following expressions for probability density and current: •For a plane wave and «The number of particles per unit volume is « For particles per unit volume moving at velocity , have passing through a unit area per unit time (particle flux). Therefore is a vector in the particle’s direction with magnitude equal to the flux. Dr. A. Mitov Particle Physics 47 The Klein-Gordon Equation •Applying to the relativistic equation for energy: (KG1) gives the Klein-Gordon equation: (KG2) •Using KG can be expressed compactly as (KG3) •For plane wave solutions, , the KG equation gives: « Not surprisingly, the KG equation has negative energy solutions – this is just what we started with in eq.