Lattice Field Theory: Scientific Goals and Computing Needs
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Localization at Large N †
NORDITA-2013-97 UUITP-21/13 Localization at Large N † J.G. Russo1;2 and K. Zarembo3;4;5 1 Instituci´oCatalana de Recerca i Estudis Avan¸cats(ICREA), Pg. Lluis Companys, 23, 08010 Barcelona, Spain 2 Department ECM, Institut de Ci`enciesdel Cosmos, Universitat de Barcelona, Mart´ıFranqu`es,1, 08028 Barcelona, Spain 3Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-106 91 Stockholm, Sweden 4Department of Physics and Astronomy, Uppsala University SE-751 08 Uppsala, Sweden 5Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow, Russia [email protected], [email protected] Abstract We review how localization is used to probe holographic duality and, more generally, non-perturbative dynamics of four-dimensional N = 2 supersymmetric gauge theories in the planar large-N limit. 1 Introduction 5 String theory on AdS5 × S gives a holographic description of the superconformal N = 4 Yang- arXiv:1312.1214v1 [hep-th] 4 Dec 2013 Mills (SYM) through the AdS/CFT correspondence [1]. This description is exact, it maps 5 correlation functions in SYM, at any coupling, to string amplitudes in AdS5 × S . Gauge- string duality for less supersymmetric and non-conformal theories is at present less systematic, and is mostly restricted to the classical gravity approximation, which in the dual field theory corresponds to the extreme strong-coupling regime. For this reason, any direct comparison of holography with the underlying field theory requires non-perturbative input on the field-theory side. There are no general methods, of course, but in the basic AdS/CFT context a variety of tools have been devised to gain insight into the strong-coupling behavior of N = 4 SYM, †Talk by K.Z. -
18. Lattice Quantum Chromodynamics
18. Lattice QCD 1 18. Lattice Quantum Chromodynamics Updated September 2017 by S. Hashimoto (KEK), J. Laiho (Syracuse University) and S.R. Sharpe (University of Washington). Many physical processes considered in the Review of Particle Properties (RPP) involve hadrons. The properties of hadrons—which are composed of quarks and gluons—are governed primarily by Quantum Chromodynamics (QCD) (with small corrections from Quantum Electrodynamics [QED]). Theoretical calculations of these properties require non-perturbative methods, and Lattice Quantum Chromodynamics (LQCD) is a tool to carry out such calculations. It has been successfully applied to many properties of hadrons. Most important for the RPP are the calculation of electroweak form factors, which are needed to extract Cabbibo-Kobayashi-Maskawa (CKM) matrix elements when combined with the corresponding experimental measurements. LQCD has also been used to determine other fundamental parameters of the standard model, in particular the strong coupling constant and quark masses, as well as to predict hadronic contributions to the anomalous magnetic moment of the muon, gµ 2. − This review describes the theoretical foundations of LQCD and sketches the methods used to calculate the quantities relevant for the RPP. It also describes the various sources of error that must be controlled in a LQCD calculation. Results for hadronic quantities are given in the corresponding dedicated reviews. 18.1. Lattice regularization of QCD Gauge theories form the building blocks of the Standard Model. While the SU(2) and U(1) parts have weak couplings and can be studied accurately with perturbative methods, the SU(3) component—QCD—is only amenable to a perturbative treatment at high energies. -
Perturbative Algebraic Quantum Field Theory at Finite Temperature
Perturbative Algebraic Quantum Field Theory at Finite Temperature Dissertation zur Erlangung des Doktorgrades des Fachbereichs Physik der Universität Hamburg vorgelegt von Falk Lindner aus Zittau Hamburg 2013 Gutachter der Dissertation: Prof. Dr. K. Fredenhagen Prof. Dr. D. Bahns Gutachter der Disputation: Prof. Dr. K. Fredenhagen Prof. Dr. J. Louis Datum der Disputation: 01. 07. 2013 Vorsitzende des Prüfungsausschusses: Prof. Dr. C. Hagner Vorsitzender des Promotionsausschusses: Prof. Dr. P. Hauschildt Dekan der Fakultät für Mathematik, Informatik und Naturwissenschaften: Prof. Dr. H. Graener Zusammenfassung Der algebraische Zugang zur perturbativen Quantenfeldtheorie in der Minkowskiraum- zeit wird vorgestellt, wobei ein Schwerpunkt auf die inhärente Zustandsunabhängig- keit des Formalismus gelegt wird. Des Weiteren wird der Zustandsraum der pertur- bativen QFT eingehend untersucht. Die Dynamik wechselwirkender Theorien wird durch ein neues Verfahren konstruiert, das die Gültigkeit des Zeitschichtaxioms in der kausalen Störungstheorie systematisch ausnutzt. Dies beleuchtet einen bisher un- bekannten Zusammenhang zwischen dem statistischen Zugang der Quantenmechanik und der perturbativen Quantenfeldtheorie. Die entwickelten Methoden werden zur ex- pliziten Konstruktion von KMS- und Vakuumzuständen des wechselwirkenden, mas- siven Klein-Gordon Feldes benutzt und damit mögliche Infrarotdivergenzen der Theo- rie, also insbesondere der wechselwirkenden Wightman- und zeitgeordneten Funktio- nen des wechselwirkenden Feldes ausgeschlossen. Abstract We present the algebraic approach to perturbative quantum field theory for the real scalar field in Minkowski spacetime. In this work we put a special emphasis on the in- herent state-independence of the framework and provide a detailed analysis of the state space. The dynamics of the interacting system is constructed in a novel way by virtue of the time-slice axiom in causal perturbation theory. -
Regularization and Renormalization of Non-Perturbative Quantum Electrodynamics Via the Dyson-Schwinger Equations
University of Adelaide School of Chemistry and Physics Doctor of Philosophy Regularization and Renormalization of Non-Perturbative Quantum Electrodynamics via the Dyson-Schwinger Equations by Tom Sizer Supervisors: Professor A. G. Williams and Dr A. Kızılers¨u March 2014 Contents 1 Introduction 1 1.1 Introduction................................... 1 1.2 Dyson-SchwingerEquations . .. .. 2 1.3 Renormalization................................. 4 1.4 Dynamical Chiral Symmetry Breaking . 5 1.5 ChapterOutline................................. 5 1.6 Notation..................................... 7 2 Canonical QED 9 2.1 Canonically Quantized QED . 9 2.2 FeynmanRules ................................. 12 2.3 Analysis of Divergences & Weinberg’s Theorem . 14 2.4 ElectronPropagatorandSelf-Energy . 17 2.5 PhotonPropagatorandPolarizationTensor . 18 2.6 ProperVertex.................................. 20 2.7 Ward-TakahashiIdentity . 21 2.8 Skeleton Expansion and Dyson-Schwinger Equations . 22 2.9 Renormalization................................. 25 2.10 RenormalizedPerturbationTheory . 27 2.11 Outline Proof of Renormalizability of QED . 28 3 Functional QED 31 3.1 FullGreen’sFunctions ............................. 31 3.2 GeneratingFunctionals............................. 33 3.3 AbstractDyson-SchwingerEquations . 34 3.4 Connected and One-Particle Irreducible Green’s Functions . 35 3.5 Euclidean Field Theory . 39 3.6 QEDviaFunctionalIntegrals . 40 3.7 Regularization.................................. 42 3.7.1 Cutoff Regularization . 42 3.7.2 Pauli-Villars Regularization . 42 i 3.7.3 Lattice Regularization . 43 3.7.4 Dimensional Regularization . 44 3.8 RenormalizationoftheDSEs ......................... 45 3.9 RenormalizationGroup............................. 49 3.10BrokenScaleInvariance ............................ 53 4 The Choice of Vertex 55 4.1 Unrenormalized Quenched Formalism . 55 4.2 RainbowQED.................................. 57 4.2.1 Self-Energy Derivations . 58 4.2.2 Analytic Approximations . 60 4.2.3 Numerical Solutions . 62 4.3 Rainbow QED with a 4-Fermion Interaction . -
General Properties of QCD
Cambridge University Press 978-0-521-63148-8 - Quantum Chromodynamics: Perturbative and Nonperturbative Aspects B. L. Ioffe, V. S. Fadin and L. N. Lipatov Excerpt More information 1 General properties of QCD 1.1 QCD Lagrangian As in any gauge theory, the quantum chromodynamics (QCD) Lagrangian can be derived with the help of the gauge invariance principle from the free matter Lagrangian. Since quark fields enter the QCD Lagrangian additively, let us consider only one quark flavour. We will denote the quark field ψ(x), omitting spinor and colour indices [ψ(x) is a three- component column in colour space; each colour component is a four-component spinor]. The free quark Lagrangian is: Lq = ψ(x)(i ∂ − m)ψ(x), (1.1) where m is the quark mass, ∂ ∂ ∂ ∂ = ∂µγµ = γµ = γ0 + γ . (1.2) ∂xµ ∂t ∂r The Lagrangian Lq is invariant under global (x–independent) gauge transformations + ψ(x) → Uψ(x), ψ(x) → ψ(x)U , (1.3) with unitary and unimodular matrices U + − U = U 1, |U|=1, (1.4) belonging to the fundamental representation of the colour group SU(3)c. The matrices U can be represented as U ≡ U(θ) = exp(iθata), (1.5) where θa are the gauge transformation parameters; the index a runs from 1 to 8; ta are the colour group generators in the fundamental representation; and ta = λa/2,λa are the Gell-Mann matrices. Invariance under the global gauge transformations (1.3) can be extended to local (x-dependent) ones, i.e. to those where θa in the transformation matrix (1.5) is a x-dependent. -
Arxiv:0810.4453V1 [Hep-Ph] 24 Oct 2008
The Physics of Glueballs Vincent Mathieu Groupe de Physique Nucl´eaire Th´eorique, Universit´e de Mons-Hainaut, Acad´emie universitaire Wallonie-Bruxelles, Place du Parc 20, BE-7000 Mons, Belgium. [email protected] Nikolai Kochelev Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Moscow region, 141980 Russia. [email protected] Vicente Vento Departament de F´ısica Te`orica and Institut de F´ısica Corpuscular, Universitat de Val`encia-CSIC, E-46100 Burjassot (Valencia), Spain. [email protected] Glueballs are particles whose valence degrees of freedom are gluons and therefore in their descrip- tion the gauge field plays a dominant role. We review recent results in the physics of glueballs with the aim set on phenomenology and discuss the possibility of finding them in conventional hadronic experiments and in the Quark Gluon Plasma. In order to describe their properties we resort to a va- riety of theoretical treatments which include, lattice QCD, constituent models, AdS/QCD methods, and QCD sum rules. The review is supposed to be an informed guide to the literature. Therefore, we do not discuss in detail technical developments but refer the reader to the appropriate references. I. INTRODUCTION Quantum Chromodynamics (QCD) is the theory of the hadronic interactions. It is an elegant theory whose full non perturbative solution has escaped our knowledge since its formulation more than 30 years ago.[1] The theory is asymptotically free[2, 3] and confining.[4] A particularly good test of our understanding of the nonperturbative aspects of QCD is to study particles where the gauge field plays a more important dynamical role than in the standard hadrons. -
Nuclear Quark and Gluon Structure from Lattice QCD
Nuclear Quark and Gluon Structure from Lattice QCD Michael Wagman QCD Evolution 2018 !1 Nuclear Parton Structure 1) Nuclear physics adds “dirt”: — Nuclear effects obscure extraction of nucleon parton densities from nuclear targets (e.g. neutrino scattering) 2) Nuclear physics adds physics: — Do partons in nuclei exhibit novel collective phenomena? — Are gluons mostly inside nucleons in large nuclei? Colliders and Lattices Complementary roles in unraveling nuclear parton structure “Easy” for electron-ion collider: Near lightcone kinematics Electromagnetic charge weighted structure functions “Easy” for lattice QCD: Euclidean kinematics Uncharged particles, full spin and flavor decomposition of structure functions !3 Structure Function Moments Euclidean matrix elements of non-local operators connected to lightcone parton distributions See talks by David Richards, Yong Zhao, Michael Engelhardt, Anatoly Radyushkin, and Joseph Karpie Mellin moments of parton distributions are matrix elements of local operators This talk: simple matrix elements in complicated systems Gluon Transversity Quark Transversity O⌫1⌫2µ1µ2 = G⌫1µ1 G⌫2µ2 q¯σµ⌫ q Gluon Helicity Quark Helicity ˜ ˜ ↵ Oµ1µ2 = Gµ1↵Gµ2 q¯γµγ5q Gluon Momentum Quark Mass = G G ↵ qq¯ Oµ1µ2 µ1↵ µ2 !4 Nuclear Glue Gluon transversity operator involves change in helicity by two units In forward limit, only possible in spin 1 or higher targets Jaffe, Manohar, PLB 223 (1989) Detmold, Shanahan, PRD 94 (2016) Gluon transversity probes nuclear (“exotic”) gluon structure not present in a collection of isolated -
Simulating Quantum Field Theory with A
Simulating quantum field theory with a quantum computer PoS(LATTICE2018)024 John Preskill∗ Institute for Quantum Information and Matter Walter Burke Institute for Theoretical Physics California Institute of Technology, Pasadena CA 91125, USA E-mail: [email protected] Forthcoming exascale digital computers will further advance our knowledge of quantum chromo- dynamics, but formidable challenges will remain. In particular, Euclidean Monte Carlo methods are not well suited for studying real-time evolution in hadronic collisions, or the properties of hadronic matter at nonzero temperature and chemical potential. Digital computers may never be able to achieve accurate simulations of such phenomena in QCD and other strongly-coupled field theories; quantum computers will do so eventually, though I’m not sure when. Progress toward quantum simulation of quantum field theory will require the collaborative efforts of quantumists and field theorists, and though the physics payoff may still be far away, it’s worthwhile to get started now. Today’s research can hasten the arrival of a new era in which quantum simulation fuels rapid progress in fundamental physics. The 36th Annual International Symposium on Lattice Field Theory - LATTICE2018 22-28 July, 2018 Michigan State University, East Lansing, Michigan, USA. ∗Speaker. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). https://pos.sissa.it/ Simulating quantum field theory with a quantum computer John Preskill 1. Introduction My talk at Lattice 2018 had two main parts. In the first part I commented on the near-term prospects for useful applications of quantum computing. -
Two Dimensional Supersymmetric Models and Some of Their Thermodynamic Properties from the Context of Sdlcq
TWO DIMENSIONAL SUPERSYMMETRIC MODELS AND SOME OF THEIR THERMODYNAMIC PROPERTIES FROM THE CONTEXT OF SDLCQ DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Yiannis Proestos, B.Sc., M.Sc. ***** The Ohio State University 2007 Dissertation Committee: Approved by Stephen S. Pinsky, Adviser Stanley L. Durkin Adviser Gregory Kilcup Graduate Program in Robert J. Perry Physics © Copyright by Yiannis Proestos 2007 ABSTRACT Supersymmetric Discrete Light Cone Quantization is utilized to derive the full mass spectrum of two dimensional supersymmetric theories. The thermal properties of such models are studied by constructing the density of states. We consider pure super Yang–Mills theory without and with fundamentals in large-Nc approximation. For the latter we include a Chern-Simons term to give mass to the adjoint partons. In both of the theories we find that the density of states grows exponentially and the theories have a Hagedorn temperature TH . For the pure SYM we find that TH at infi- 2 g Nc nite resolution is slightly less than one in units of π . In this temperature range, q we find that the thermodynamics is dominated by the massless states. For the system with fundamental matter we consider the thermal properties of the mesonic part of the spectrum. We find that the meson-like sector dominates the thermodynamics. We show that in this case TH grows with the gauge coupling. The temperature and coupling dependence of the free energy for temperatures below TH are calculated. As expected, the free energy for weak coupling and low temperature grows quadratically with the temperature. -
Lattice QCD for Hyperon Spectroscopy
Lattice QCD for Hyperon Spectroscopy David Richards Jefferson Lab KLF Collaboration Meeting, 12th Feb 2020 Outline • Lattice QCD - the basics….. • Baryon spectroscopy – What’s been done…. – Why the hyperons? • What are the challenges…. • What are we doing to overcome them… Lattice QCD • Continuum Euclidean space time replaced by four-dimensional lattice, or grid, of “spacing” a • Gauge fields are represented at SU(3) matrices on the links of the lattice - work with the elements rather than algebra iaT aAa (n) Uµ(n)=e µ Wilson, 74 Quarks ψ, ψ are Grassmann Variables, associated with the sites of the lattice Gattringer and Lang, Lattice Methods for Work in a finite 4D space-time Quantum Chromodynamics, Springer volume – Volume V sufficiently big to DeGrand and DeTar, Quantum contain, e.g. proton Chromodynamics on the Lattice, WSPC – Spacing a sufficiently fine to resolve its structure Lattice QCD - Summary Lattice QCD is QCD formulated on a Euclidean 4D spacetime lattice. It is systematically improvable. For precision calculations:: – Extrapolation in lattice spacing (cut-off) a → 0: a ≤ 0.1 fm – Extrapolation in the Spatial Volume V →∞: mπ L ≥ 4 – Sufficiently large temporal size T: mπ T ≥ 10 – Quark masses at physical value mπ → 140 MeV: mπ ≥ 140 MeV – Isolate ground-state hadrons Ground-state masses Hadron form factors, structure functions, GPDs Nucleon and precision matrix elements Low-lying Spectrum ip x ip x C(t)= 0 Φ(~x, t)Φ†(0) 0 C(t)= 0 e · Φ(0)e− · n n Φ†(0) 0 h | | i h | | ih | | i <latexit sha1_base64="equo589S0nhIsB+xVFPhW0 -
Gluon and Ghost Propagator Studies in Lattice QCD at Finite Temperature
Gluon and ghost propagator studies in lattice QCD at finite temperature DISSERTATION zur Erlangung des akademischen Grades doctor rerum naturalium (Dr. rer. nat.) im Fach Physik eingereicht an der Mathematisch-Naturwissenschaftlichen Fakultät I Humboldt-Universität zu Berlin von Herrn Magister Rafik Aouane Präsident der Humboldt-Universität zu Berlin: Prof. Dr. Jan-Hendrik Olbertz Dekan der Mathematisch-Naturwissenschaftlichen Fakultät I: Prof. Stefan Hecht PhD Gutachter: 1. Prof. Dr. Michael Müller-Preußker 2. Prof. Dr. Christian Fischer 3. Dr. Ernst-Michael Ilgenfritz eingereicht am: 19. Dezember 2012 Tag der mündlichen Prüfung: 29. April 2013 Ich widme diese Arbeit meiner Familie und meinen Freunden v Abstract Gluon and ghost propagators in quantum chromodynamics (QCD) computed in the in- frared momentum region play an important role to understand quark and gluon confinement. They are the subject of intensive research thanks to non-perturbative methods based on DYSON-SCHWINGER (DS) and functional renormalization group (FRG) equations. More- over, their temperature behavior might also help to explore the chiral and deconfinement phase transition or crossover within QCD at non-zero temperature. Our prime tool is the lattice discretized QCD (LQCD) providing a unique ab-initio non- perturbative approach to deal with the computation of various observables of the hadronic world. We investigate the temperature dependence of LANDAU gauge gluon and ghost prop- agators in pure gluodynamics and in full QCD. The aim is to provide a data set in terms of fitting formulae which can be used as input for DS (or FRG) equations. We concentrate on the momentum range [0:4;3:0] GeV. The latter covers the region around O(1) GeV which is especially sensitive to the way how to truncate the system of those equations. -
Quantum Mechanics of Topological Solitons
Imperial College London Department of Physics Quantum mechanics of topological solitons David J. Weir September 2011 Supervised by Arttu Rajantie Submitted in part fulfilment of the requirements for the degree of Doctor of Philosophy in Physics of Imperial College London and the Diploma of Imperial College London 1 Declaration I herewith certify that all material in this dissertation which is not my own work has been properly acknowledged. David J. Weir 3 Abstract Topological solitons { are of broad interest in physics. They are objects with localised energy and stability ensured by their topological properties. It is possible to create them during phase transitions which break some sym- metry in a frustrated system. They are ubiquitous in condensed matter, ranging from monopole excitations in spin ices to vortices in superconduc- tors. In such situations, their behaviour has been extensively studied. Less well understood and yet equally interesting are the symmetry-breaking phase transitions that could produce topological defects is the early universe. Grand unified theories generically admit the creation of cosmic strings and monopoles, amongst other objects. There is no reason to expect that the behaviour of such objects should be classical or, indeed, supersymmetric, so to fully understand the behaviour of these theories it is necessary to study the quantum properties of the associated topological defects. Unfortunately, the standard analytical tools for studying quantum field theory { including perturbation theory { do not work so well when applied to topological defects. Motivated by this realisation, this thesis presents numerical techniques for the study of topological solitons in quantum field theory. Calculations are carried out nonperturbatively within the framework of lattice Monte Carlo simulations.