A Course for Advanced Quantum Field Theory — Gauge Field Theories —
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Perturbative Renormalization and BRST
Perturbative renormalization and BRST Michael D¨utsch Institut f¨ur Theoretische Physik Universit¨at Z¨urich CH-8057 Z¨urich, Switzerland [email protected] Klaus Fredenhagen II. Institut f¨ur Theoretische Physik Universit¨at Hamburg D-22761 Hamburg, Germany [email protected] 1 Main problems in the perturbative quantization of gauge theories Gauge theories are field theories in which the basic fields are not directly observable. Field configurations yielding the same observables are connected by a gauge transformation. In the classical theory the Cauchy problem is well posed for the observables, but in general not for the nonobservable gauge variant basic fields, due to the existence of time dependent gauge transformations. Attempts to quantize the gauge invariant objects directly have not yet been completely satisfactory. Instead one modifies the classical action by adding a gauge fixing term such that standard techniques of perturbative arXiv:hep-th/0411196v1 22 Nov 2004 quantization can be applied and such that the dynamics of the gauge in- variant classical fields is not changed. In perturbation theory this problem shows up already in the quantization of the free gauge fields (Sect. 3). In the final (interacting) theory the physical quantities should be independent on how the gauge fixing is done (’gauge independence’). Traditionally, the quantization of gauge theories is mostly analyzed in terms of path integrals (e.g. by Faddeev and Popov) where some parts of the arguments are only heuristic. In the original treatment of Becchi, Rouet and Stora (cf. also Tyutin) (which is called ’BRST-quantization’), a restriction to purely massive theories was necessary; the generalization to the massless case by Lowenstein’s method is cumbersome. -
Gauge Theories of the Strong and Electroweak Interaction
Gauge Theories of the Strong and Electroweak Interaction By Prof. Dr. rer. nat. Manfred Böhm, Universität Würzburg Dr. rer. nat. Ansgar Denner, Paul Scherrer Institut Villigen Prof. Dr. rer. nat. Hans Joos, DESY Hamburg B. G.Teubner Stuttgart • Leipzig • Wiesbaden Contents 1 Phenomenological basis of gauge theories of strong, elec tromagnetic, and weak interactions 1 1.1 Elementary particles and their interactions 1 1.1.1 Leptons and quarks as fundamental constituents of matter . 2 1.1.2 Fundamental interactions 4 1.2 Elements of relativistic quantum field theory 5 1.2.1 Basic concepts of relativistic quantum field theory 6 1.2.2 Lie algebras and Lie groups 18 1.2.3 Conserved currents and charges 24 1.3 The quark model of hadrons 29 1.3.1 Quantum numbers and wave functions of hadrons in the quark model 29 1.3.2 Quark model with colour 35 1.3.3 The concept of quark dynamics—quarkonia 36 1.4 Basics of the electroweak interaction 39 1.4.1 Electroweak interaction of leptons 41 1.4.2 Electroweak interaction of hadrons 47 1.5 The quark-parton model 57 1.5.1 Scaling in deep-inelastic lepton-nucleon scattering 57 1.5.2 The parton model 63 1.5.3 Applications of the simple parton model 68 1.5.4 Universality of the parton model 72 1.6 Higher-order field-theoretical effects in QED 76 1.6.1 QED as a quantum field theory 76 Contents 1.6.2 A test of QED: the magnetic moment of the muon 78 1.7 Towards gauge theories of strong and electroweak interactions 81 References to Chapter 1 82 2 Quantum theory of Yang-Mills fields 85 2.1 Green functions and 5-matrix elements 86 2.1.1 The principles of quantum field theory 86 2.1.2 Green functions 88 2.1.3 5-matrix elements and the LSZ formula . -
Effective Potentials and the Vacuum Structure of Quantum Field Theories
hep-th/0407084 12 Jul 2004 Effective Potentials and the Vacuum Structure of Quantum Field Theories Kristian D. Kennaway Department of Physics and Astronomy University of Southern California Los Angeles, CA 90089-0484, USA Abstract I review some older work on the effective potentials of quantum field theories, in par- ticular the use of anomalous symmetries to constrain the form of the effective potential, and the background field method for evaluating it perturbatively. Similar techniques have recently been used to great success in studying the effective superpotentials of supersymmetric gauge theories, and one of my motivations is to present some of the older work on non-supersymmetric theories to a new audience. The Gross-Neveu model exhibits the essential features of the techniques. In particular, we see how rewriting the Lagrangian in terms of an appropriate composite background field and performing a perturbative loop expansion gives non-perturbative information about the vacuum of the theory (the fermion condensate). The effective potential for QED in a constant electromagnetic background field strength is derived, and compared to the analogous calculation in non-Abelian Yang-Mills theory. The Yang-Mills effective potential shows that the “perturbative” vacuum of Yang-Mills theory is unstable, and the true vacuum has a non-trivial gauge field background. Finally, I describe how some of the limita- tions seen in the non-supersymmetric theories are removed by supersymmetry, which arXiv:hep-th/0407084v1 12 Jul 2004 allows for exact computation of the effective superpotential in many cases. 1 Introduction Work emerging from string theory over the last few years has led to the computation of the exact low-energy effective superpotential for gauge theories with = 1 supersymmetry and N matter in various representations. -
1 Hamiltonian Quantization and BRST -Survival Guide; Notes by Horatiu Nastase
1 Hamiltonian quantization and BRST -survival guide; notes by Horatiu Nastase 1.1 Dirac- first class and second class constraints, quan- tization Classical Hamiltonian Primary constraints: φm(p; q) = 0 (1) imposed from the start. The equations of motion on a quantity g(q; p) are g_ = [g; H]P:B: (2) Define φm ∼ 0 (weak equality), meaning use the constraint only at the end of the calculation, then for consistency φ_m ∼ 0, implying [φm; H]P:B: ∼ 0 (3) The l.h.s. will be however in general a linearly independent function (of φm). If it is, we can take its time derivative and repeat the process. In the end, we find a complete set of new constrains from the time evolution, called secondary constraints. Together, they form the set of constraints, fφjg; j = 1; J. A quantity R(q; p) is called first class if [R; φj]P:B: ∼ 0 (4) for all j=1, J. If not, it is called second class. Correspondingly, constraints are also first class and second class, independent of being primary or sec- ondary. To the Hamiltonian we can always add a term linear in the constraints, generating the total Hamiltonian HT = H + umφm (5) where um are functions of q and p. The secondary constraint equations are [φm; HT ] ∼ [φm; H] + un[φm; φn] ∼ 0 (6) where in the first line we used that [un; φm]φn ∼ 0. The general solution for um is um = Um + vaVam (7) with Um a particular solution and Vam a solution to Vm[φj; φm] = and va arbitrary functions of time only. -
The Background Field Method: Alternative Way of Deriving The
HUPD-9408 YNU-HEPTh-94-104 May 1994 THE BACKGROUND FIELD METHOD: Alternative Way of Deriving the Pinch Technique’s Results Shoji Hashimoto∗ , Jiro KODAIRA† and Yoshiaki YASUI ‡ Dept. of Physics, Hiroshima University Higashi-Hiroshima 724, JAPAN Ken SASAKI§ Dept. of Physics, Yokohama National University Yokohama 240, JAPAN Abstract We show that the background field method (BFM) is a simple way of deriving the same gauge-invariant results which are obtained by the pinch technique (PT). For illustration we construct gauge-invariant self- energy and three-point vertices for gluons at one-loop level by BFM and arXiv:hep-ph/9406271v1 10 Jun 1994 demonstrate that we get the same results which were derived via PT. We also calculate the four-gluon vertex in BFM and show that this vertex obeys the same Ward identity that was found with PT. ∗Supported in part by the Monbusho Grant-in-Aid for Scientific Research No. 040011. †Supported in part by the Monbusho Grant-in-Aid for Scientific Research No. C-05640351. ‡Supported in part by the Monbusho Grant-in-Aid for Scientific Research No. 050076. §e-mail address: [email protected] 1 Introduction Formulation of a gauge theory begins with a gauge invariant Lagrangian. However, except for lattice gauge theory, when we quantize the theory in the continuum we are under compulsion to fix a gauge. Consequently, the corresponding Green’s functions, in general, will not be gauge invariant. These Green’s functions in the standard formulation do not directly reflect the underlying gauge invariance of the theory but rather obey complicated Ward identities. -
Pion Magnetic Polarisability Using the Background Field Method
Physics Letters B 811 (2020) 135853 Contents lists available at ScienceDirect Physics Letters B www.elsevier.com/locate/physletb Pion magnetic polarisability using the background field method ∗ Ryan Bignell , Waseem Kamleh, Derek Leinweber Special Research Centre for the Subatomic Structure of Matter (CSSM), Department of Physics, University of Adelaide, Adelaide, South Australia 5005, Australia a r t i c l e i n f o a b s t r a c t Article history: The magnetic polarisability is a fundamental property of hadrons, which provides insight into their Received 22 May 2020 structure in the low-energy regime. The pion magnetic polarisability is calculated using lattice QCD in the Received in revised form 7 October 2020 presence of background magnetic fields. The results presented are facilitated by the introduction of a new Accepted 8 October 2020 magnetic-field dependent quark-propagator eigenmode projector and the use of the background-field Available online 15 October 2020 corrected clover fermion action. The magnetic polarisabilities are calculated in a relativistic formalism, Editor: W. Haxton and the excellent signal-to-noise property of pion correlation functions facilitates precise values. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3. 1. Introduction and a hadronic Landau-level projection for the charged pion. The background-field method has previously been used to extract the The electromagnetic polarisabilities of hadrons are of funda- polarisabilities of baryons [18,19]and nuclei [20]in dynamical mental importance in the low-energy regime of quantum chromo- QCD simulations as well as the magnetic polarisability of light dynamics where they provide novel insight into the response of mesons in quenched SU(3) simulations [21–23]. -
Propagators and Path Integrals
NAT10NAAI. WSTITUUT VOOR KERNFYSICA EN NIKHEF-H/95-050 Propagators and Path Integrals J.W. van Holten NIKHEF-H, P.O. Box 41882 1009 DB Amsterdam NI, August 22, 1995 Abstract Path-integral expressions for one-particle propagators in scalar and ferinioaic field theories are derived, for arbitrary mass. This establishes a direct connection between field theory and specific classical point-particle models. The role of world-line rep&rametroation invaiiance of the classical action avnd the implementation of the corresponding BB5T-symmetry in the qutntuin theory are discussed. The presence of classical world-line supersymrnetry is shown to lead t/> an unwanted doubling of states for massive spin-1/2 particles. The origin of this phenomenon is traced to a 'hidden' topologies! fermionic excitation. A different formulation of the pseudo-classical mechan- ics using a bosonic representation of 71 is shown to remove those extra states at the expense of losing manifest supersymmetry. PilKHEf SECTIE - H POSTBUS 4188',!, 1009 DB A^STERDfW •UL ? 0 NJ 0 1 KS002045549 R: FI NL96FG754 DEOOSS87924 1 Introduction Because of their conceptual simplicity, path-integral methods [1, 2] often provide convenient procedures to obtain insight in field theoretical problems. In recent work by Strassler, McKeon, Schmidt, Schubert and others [3]-[7] world-line path integrals have been applied to a reformulation of standard Feynman perturbation theory from which useful information on the structure of perturbative Green's functions is extracted. Some of these results were actually first derived in the particle-limit of string theory [8]. A basic question in this context is the representation of propagators in quantum field theory by path integrals for relativistic particles of various kind. -
UNIVERSIDADE ESTADUAL DE CAMPINAS Instituto De F´Isica Gleb Wataghin
UNIVERSIDADE ESTADUAL DE CAMPINAS Instituto de F´ısica Gleb Wataghin CLARA TEIXEIRA FIGUEIREDO ASPECTS OF DYNAMICAL MASS GENERATION WITHIN THE FORMALISM OF SCHWINGER-DYSON EQUATIONS Aspectos da gera¸c~ao de massa din^amica dentro do formalismo das equa¸c~oesde Schwinger-Dyson CAMPINAS 2020 Clara Teixeira Figueiredo Aspects of dynamical mass generation within the formalism of Schwinger-Dyson equations Aspectos da gera¸c~ao de massa din^amica dentro do formalismo das equa¸c~oes de Schwinger-Dyson Tese apresentada ao Instituto de F´ısica \Gleb Wataghin" da Universidade Estadual de Campinas como parte dos requisitos exigidos para a obten¸c~ao do t´ıtulo de Doutora em Ci^encias, na ´area de F´ısica. Thesis presented to the \Gleb Wataghin" Institute of Physics of the University of Campinas in par- tial fulfillment of the requirements for the degree of Doctor of Science, in the area of Physics. Orientador: Arlene Cristina Aguilar Este exemplar corresponde a` versao~ fi- nal da tese defendida pela aluna Clara Teixeira Figueiredo e orientada pela Profa. Dra. Arlene Cristina Aguilar. Campinas 2020 Ficha catalográfica Universidade Estadual de Campinas Biblioteca do Instituto de Física Gleb Wataghin Lucimeire de Oliveira Silva da Rocha - CRB 8/9174 Figueiredo, Clara Teixeira, 1991- F469a FigAspects of dynamical mass generation within the formalism of Schwinger- Dyson equations / Clara Teixeira Figueiredo. – Campinas, SP : [s.n.], 2020. FigOrientador: Arlene Cristina Aguilar. FigTese (doutorado) – Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin. Fig1. QCD não perturbativa. 2. Schwinger-Dyson, Equações de. 3. Geração de massa dinâmica. I. Aguilar, Arlene Cristina, 1977-. II. -
BRST Quantization of Yang-Mills Theory: a Purely Hamiltonian Approach on Fock Space
PHYSICAL REVIEW D 97, 074006 (2018) BRST quantization of Yang-Mills theory: A purely Hamiltonian approach on Fock space Hans Christian Öttinger* ETH Zürich, Department of Materials, Polymer Physics, HCP F 47.2, CH-8093 Zürich, Switzerland (Received 1 March 2018; published 3 April 2018) We develop the basic ideas and equations for the BRST quantization of Yang-Mills theories in an explicit Hamiltonian approach, without any reference to the Lagrangian approach at any stage of the development. We present a new representation of ghost fields that combines desirable self-adjointness properties with canonical anticommutation relations for ghost creation and annihilation operators, thus enabling us to characterize the physical states on a well-defined Fock space. The Hamiltonian is constructed by piecing together simple BRST invariant operators to obtain a minimal invariant extension of the free theory. It is verified that the evolution equations implied by the resulting minimal Hamiltonian provide a quantum version of the classical Yang-Mills equations. The modifications and requirements for the inclusion of matter are discussed in detail. DOI: 10.1103/PhysRevD.97.074006 I. INTRODUCTION The purpose of this paper is to show in the context of BRST quantization is a pivotal tool in developing Yang-Mills theories how all the above facets can be theories of the fundamental interactions, where the acro- handled entirely within the Hamiltonian approach, where nym BRST refers to Becchi, Rouet, Stora [1] and Tyutin explicit constructions on a suitable Fock space allow for a [2]. This method for handling constraints in the quantiza- maximum of intuition. The focus on Fock space implies a (quantum) particle interpretation rather than a field tion of field theories usually requires a broad viewpoint idealization. -
Implementation of General Background Electromagnetic Fields on a Periodic Hypercubic Lattice
Implementation of general background electromagnetic fields on a periodic hypercubic lattice The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Davoudi, Zohreh, and William Detmold. "Implementation of general background electromagnetic fields on a periodic hypercubic lattice." Phys. Rev. D 92, 074506 (October 2015). © 2015 American Physical Society As Published http://dx.doi.org/10.1103/PhysRevD.92.074506 Publisher American Physical Society Version Final published version Citable link http://hdl.handle.net/1721.1/99362 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. PHYSICAL REVIEW D 92, 074506 (2015) Implementation of general background electromagnetic fields on a periodic hypercubic lattice † Zohreh Davoudi* and William Detmold Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA (Received 12 August 2015; published 19 October 2015) Nonuniform background electromagnetic fields, once implemented in lattice quantum chromodynamics calculations of hadronic systems, provide a means to constrain a large class of electromagnetic properties of hadrons and nuclei, from their higher electromagnetic moments and charge radii to their electromagnetic form factors. We show how nonuniform fields can be constructed on a periodic hypercubic lattice under certain conditions and determine the precise form of the background Uð1Þ gauge links that must be imposed on the quantum chromodynamics gauge-field configurations to maintain periodicity. Once supplemented by a set of quantization conditions on the background-field parameters, this construction guarantees that no nonuniformity occurs in the hadronic correlation functions across the boundary of the lattice. -
BRST Formulation of the Gupta-Bleuler Quantization Method
NL90C0266 MATIONAAL INSTITUUT VOOR KERNFYSICA EN HOCE-EMERGIEFYSICA March 1990 NIKHEF-H/90-7 BRST Formulation of the Gupta-Bleuler Quantization Method Z. Hastowicz *, J. Kowalski-Glikman \ J. Lukierski *. J.W, van Hotten t Abstract In this paper we show, how an algebra of mixed flits and second class constrain»» can ba transformed Into an algebra of the Gupta-Bleuler type, consisting of holomorphlc ar.d anti* hotomorphic constraints. We perform its quantization by BRST methods. We construct a second* level BRST operator n by Introducing a new ghost sector (the second-level ghosts), in addition to the ghosts of the standard BRST operator. We find an Inner product In this ghost sector such that the operator li ts hermltean. The physical states, as defined by the non-hermitsan holomorphlc constraints, are shown to be given in terms of the cohomology of this hermitean BRST charge. * Mstttuf tor TtwofHemt Pttyttca. UMvmrtlty of Wrodmw. ut Cybutokltgo «. Wnetmw. Poimnd • CHEAP, PO BOM 4IM?, 1009 DB Amstfdmm. Th» Nethftmnda. bit/ft rt00J)/fcf>«M.flSM»*itf f NSOHEF^ PO BOM 41*62. 1009 OB Amstontom. Thm Netherlands, bitnét 11ë&nikh*tli.nikh*t.nl NIKHEF SECTIE-H POSTBUS 41H3, 100» L«B AMSTERDAM 1 Introduction BRST-methods [1, 2} have become a powerful tool in the quantization of constrained systems. Not only do they provide a method for establishing the consistency of the covariant quantization procedure of gauge theories , such as used in the path-integral formulation of Yang-Mills theory [3], they also have become important in the elucidation of the canonical structure of constrained systems [4, 5, 6, 7] like relativistic point-particles and strings |8], In spite of all the past successes of the method, there still doesn't exist a completely unified and unique prescription for the application of BUST' methods to arbitrary constrained systems and surprises keep turning up when studying new systems with new types of gauge-invariances. -
BRST Quantization of Matrix Chern-Simons Theory
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server BRST quantization of Matrix Chern-Simons Theory Etera R. Livine∗ Centre de Physique Th´eorique, Campus de Luminy, Case 907, 13288 Marseille cedex 9, France Lee Smolin† Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada N2J 2W9 and Department of Physics, University of Waterloo December 5, 2002 Abstract The BRST quantization of matrix Chern-Simons theory is carried out, the symmetries of the theory are analyzed and used to constrain the form of the effective action. ∗e.mail: [email protected] ye.mail:[email protected] 1 The cubic matrix models[1, 2, 3, 4] were invented as a possible approach to the problem of formulating string or theory in a background invariant framework. They also provide a matrix formulation of certain quantumM deformed extensions of loop quantum gravity[2, 5, 6]. The basic philosophy that motivates these theories is that quantum and classical theories of gravity which are background independent can, in most if not all of the known cases, be constructed by modifying topological field theories. The idea is then to construct matrix models that extend a matrix form of Chern-Simons theory[1, 2]. The quantization of these theories faces certain issues due to the fact that the action is presented in a first order form, which means that they define theories on phase spaces rather than configuration spaces. These theories also have gauge symmetries and constraints that must be taken into account correctly. In this letter we present an approach to quantization based on the standard BRST method.