A Problem of the QCD Axion in Supergravity
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Introductory Lectures on Quantum Field Theory
Introductory Lectures on Quantum Field Theory a b L. Álvarez-Gaumé ∗ and M.A. Vázquez-Mozo † a CERN, Geneva, Switzerland b Universidad de Salamanca, Salamanca, Spain Abstract In these lectures we present a few topics in quantum field theory in detail. Some of them are conceptual and some more practical. They have been se- lected because they appear frequently in current applications to particle physics and string theory. 1 Introduction These notes are based on lectures delivered by L.A.-G. at the 3rd CERN–Latin-American School of High- Energy Physics, Malargüe, Argentina, 27 February–12 March 2005, at the 5th CERN–Latin-American School of High-Energy Physics, Medellín, Colombia, 15–28 March 2009, and at the 6th CERN–Latin- American School of High-Energy Physics, Natal, Brazil, 23 March–5 April 2011. The audience on all three occasions was composed to a large extent of students in experimental high-energy physics with an important minority of theorists. In nearly ten hours it is quite difficult to give a reasonable introduction to a subject as vast as quantum field theory. For this reason the lectures were intended to provide a review of those parts of the subject to be used later by other lecturers. Although a cursory acquaintance with the subject of quantum field theory is helpful, the only requirement to follow the lectures is a working knowledge of quantum mechanics and special relativity. The guiding principle in choosing the topics presented (apart from serving as introductions to later courses) was to present some basic aspects of the theory that present conceptual subtleties. -
D-Instanton Perturbation Theory
D-instanton Perturbation Theory Ashoke Sen Harish-Chandra Research Institute, Allahabad, India Sao Paolo, June 2020 1 Plan: 1. Overview of the problem and the solution 2. Review of basic aspects of world-sheet string theory and string field theory 3. Some explicit computations A.S., arXiv:1908.02782, 2002.04043, work in progress 2 The problem 3 String theory began with Veneziano amplitude – tree level scattering amplitude of four tachyons in open string theory World-sheet expression for the amplitude (in α0 = 1 unit) Z 1 dy y2p1:p2 (1 − y)2p2:p3 0 – diverges for 2p1:p2 ≤ −1 or 2p2:p3 ≤ −1. Our convention: a:b ≡ −a0b0 + ~a:~b Conventional viewpoint: Define the amplitude for 2p1:p2 > −1, 2p2:p3 > −1 and then analytically continue to the other kinematic regions. 4 However, analytic continuation does not always work It may not be possible to move away from the singularity by changing the external momenta Examples: Mass renormalization, Vacuum shift – discussed earlier In these lectures we shall discuss another situation where analytic continuation fails – D-instanton contribution to string amplitudes 5 D-instanton: A D-brane with Dirichlet boundary condition on all non-compact directions including (euclidean) time. D-instantons give non-perturbative contribution to string amplitudes that are important in many situations Example: KKLT moduli stabilization uses non-perturbative contribution from D-instanton (euclidean D3-brane) Systematic computation of string amplitudes in such backgrounds will require us to compute amplitudes in the presence of D-instantons Problem: Open strings living on the D-instanton do not carry any continuous momenta ) we cannot move away from the singularities by varying the external momenta 6 Some examples: Let X be the (euclidean) time direction Since the D-instanton is localized at some given euclidean time, it has a zero mode that translates it along time direction 4-point function of these zero modes: Z 1 A = dy y−2 + (y − 1)−2 + 1 0 Derivation of this expression will be discussed later. -
Holography Principle and Topology Change in String Theory 1 Abstract
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server SNUTP 98-089 hep-th/9807241 Holography Principle and Topology Change in String Theory 1 Soo-Jong Rey Physics Department, Seoul National University, Seoul 151-742 KOREA abstract D-instantons of Type IIB string theory are Ramond-Ramond counterpart of Giddings-Strominger wormholes connecting two asymptotic regions of spacetime. Such wormholes, according to Coleman, might lead to spacetime topology change, third-quantized baby universes and prob- abilistic determination of fundamental coupling parameters. Utilizing correspondence between AdS5 × M5 Type IIB supergravity and d = 4 super Yang-Mills theory, we point out that topol- ogy change and sum over topologies not only take place in string theory but also are required for consistency with holography. Nevertheless, we argue that the effects of D-instanton wormholes remain completely deterministic, in sharp contrast to Coleman’s scenario. 1Work supported in part by KOSEF SRC-Program, Ministry of Education Grant BSRI 98-2418, SNU Re- search Fund and Korea Foundation for Advanced Studies Faculty Fellowship. One of the most vexing problems in quantum gravity has been the issue of spacetime topol- ogy change: whether topology of spacetime can fluctuate and, if so, spacetime of different topologies should be summed over. Any positive answer to this question would bear profound implications to the fundamental interactions of Nature. For example, in Coleman’s scenario [1] of baby universes [2], fluctuation of spacetime topology induce effective lon-local interactions and third quantization of the universe thereof 2. As a result, the cosmological constant is no longer a calculable, deterministic parameter but is turned into a quantity of probabilistic dis- tribution sharply peaked around zero. -
Andrew Thomson Dissertation.Pdf
PHENOMENOLOGY OF COMPACTIFICATIONS OF M-THEORY ON MANIFOLDS OF G2 HOLONOMY by Andrew James Thomson Supervisor: Kelly Stelle A dissertation submitted in partial fulfilment of the requirements for the degree of Master of Science of Imperial College London 24 September 2010 Contents I. Introduction 3 II. Holonomy and G2 manifolds 7 III. Chirality and singular manifolds 11 IV. Moduli stabilization and the hierarchy problem 14 V. Conclusion 17 References 19 2 I. Introduction The Standard Model is a phenomenally successful theory of particle physics, well tested at quantum mechanical level up to the TeV energy scale, and renormalizable (notwithstanding that the Higgs particle has not been observed yet) [1]. However there are several issues (or at least perceived ones) with the model. First of all, it only describes three of the four fundamental forces (the strong, electromagnetic and weak forces) in a quantum manner, leaving gravity still described only in a classical fashion; however we will not be concerned with this any further during this dissertation. The primary issue with which we will be concerned is the so-called hierarchy problem (also known as the weak-scale instability) – why there are two (electroweak and Planck) mass scales and why they are so far apart, why the electroweak scale is not modified at loop level by the Planck scale and whether there are any other scales between them. [1,2] One wonders why we should be concerned with as yet purely theoretical imperfections which have not yet manifested themselves in any experimental observations. One only has to look to the history of the standard model itself for a precedent for looking for physics beyond it – the earliest theories of the weak interaction, which were based on the interaction of four fermions at a point, broke down when calculated to higher order at the then unimaginably high energies of 300 GeV (Heisenberg 1939) before they had been violated by any observation. -
TASI 2008 Lectures: Introduction to Supersymmetry And
TASI 2008 Lectures: Introduction to Supersymmetry and Supersymmetry Breaking Yuri Shirman Department of Physics and Astronomy University of California, Irvine, CA 92697. [email protected] Abstract These lectures, presented at TASI 08 school, provide an introduction to supersymmetry and supersymmetry breaking. We present basic formalism of supersymmetry, super- symmetric non-renormalization theorems, and summarize non-perturbative dynamics of supersymmetric QCD. We then turn to discussion of tree level, non-perturbative, and metastable supersymmetry breaking. We introduce Minimal Supersymmetric Standard Model and discuss soft parameters in the Lagrangian. Finally we discuss several mech- anisms for communicating the supersymmetry breaking between the hidden and visible sectors. arXiv:0907.0039v1 [hep-ph] 1 Jul 2009 Contents 1 Introduction 2 1.1 Motivation..................................... 2 1.2 Weylfermions................................... 4 1.3 Afirstlookatsupersymmetry . .. 5 2 Constructing supersymmetric Lagrangians 6 2.1 Wess-ZuminoModel ............................... 6 2.2 Superfieldformalism .............................. 8 2.3 VectorSuperfield ................................. 12 2.4 Supersymmetric U(1)gaugetheory ....................... 13 2.5 Non-abeliangaugetheory . .. 15 3 Non-renormalization theorems 16 3.1 R-symmetry.................................... 17 3.2 Superpotentialterms . .. .. .. 17 3.3 Gaugecouplingrenormalization . ..... 19 3.4 D-termrenormalization. ... 20 4 Non-perturbative dynamics in SUSY QCD 20 4.1 Affleck-Dine-Seiberg -
Gravity, Scale Invariance and the Hierarchy Problem
Motivation Setup Warm-up: Dilaton+Gravity One example: Higgs+Gravity Further Examples: Higgs+Dilaton+Gravity Discussion and Outlook Backups Gravity, Scale Invariance and the Hierarchy Problem M. Shaposhnikov, A. Shkerin EPFL & INR RAS Based on arXiv:1803.08907, arXiv:1804.06376 QUARKS-2018 Valday, May 31, 2018 1 / 39 Motivation Setup Warm-up: Dilaton+Gravity One example: Higgs+Gravity Further Examples: Higgs+Dilaton+Gravity Discussion and Outlook Backups Overview 1 Motivation 2 Setup 3 Warm-up: Dilaton+Gravity 4 One example: Higgs+Gravity 5 Further Examples: Higgs+Dilaton+Gravity 6 Discussion and Outlook 2 / 39 Motivation Setup Warm-up: Dilaton+Gravity One example: Higgs+Gravity Further Examples: Higgs+Dilaton+Gravity Discussion and Outlook Backups Drowning by numbers The fact is that G 2 F ~ ∼ 1033, where G | Fermi constant, G | Newton constant 2 F N GN c Two aspects of the hierarchy problem (G. F. Giudice'08): \classical" \quantum": Let MX be some heavy mass scale. Then one expects 2 2 δmH;X ∼ MX : Even if one assumes that there are no heavy thresholds beyond the EW scale, then, naively, 2 2 δmH;grav: ∼ MP : 3 / 39 Motivation Setup Warm-up: Dilaton+Gravity One example: Higgs+Gravity Further Examples: Higgs+Dilaton+Gravity Discussion and Outlook Backups EFT approach and beyond A common approach to the hierarchy problem lies within the effective field theory framework: Low energy description of Nature, provided by the SM, can be affected by an unknown UV physics only though a finite set of parameters This \naturalness principle" is questioned now in light of the absence of signatures of new physics at the TeV scale. -
Aspects of Supersymmetry and Its Breaking
1 Aspects of Supersymmetry and its Breaking a b Thomas T. Dumitrescu ∗ and Zohar Komargodski † aDepartment of Physics, Princeton University, Princeton, New Jersey, 08544, USA bSchool of Natural Sciences, Institute for Advanced Study, Princeton, New Jersey, 08540, USA We describe some basic aspects of supersymmetric field theories, emphasizing the structure of various supersym- metry multiplets. In particular, we discuss supercurrents – multiplets which contain the supersymmetry current and the energy-momentum tensor – and explain how they can be used to constrain the dynamics of supersym- metric field theories, supersymmetry breaking, and supergravity. These notes are based on lectures delivered at the Carg´ese Summer School 2010 on “String Theory: Formal Developments and Applications,” and the CERN Winter School 2011 on “Supergravity, Strings, and Gauge Theory.” 1. Supersymmetric Theories In this review we will describe some basic aspects of SUSY field theories, emphasizing the structure 1.1. Supermultiplets and Superfields of various supermultiplets – especially those con- A four-dimensional theory possesses = 1 taining the supersymmetry current. In particu- supersymmetry (SUSY) if it contains Na con- 1 lar, we will show how these supercurrents can be served spin- 2 charge Qα which satisfies the anti- used to study the dynamics of supersymmetric commutation relation field theories, SUSY-breaking, and supergravity. ¯ µ Qα, Qα˙ = 2σαα˙ Pµ . (1) We begin by recalling basic facts about super- { } multiplets and superfields. A set of bosonic and Here Q¯ is the Hermitian conjugate of Q . (We α˙ α fermionic operators B(x) and F (x) fur- will use bars throughout to denote Hermitian con- i i nishes a supermultiplet{O if these} operators{O satisfy} jugation.) Unless otherwise stated, we follow the commutation relations of the schematic form conventions of [1]. -
Introduction to Supersymmetry
Introduction to Supersymmetry Pre-SUSY Summer School Corpus Christi, Texas May 15-18, 2019 Stephen P. Martin Northern Illinois University [email protected] 1 Topics: Why: Motivation for supersymmetry (SUSY) • What: SUSY Lagrangians, SUSY breaking and the Minimal • Supersymmetric Standard Model, superpartner decays Who: Sorry, not covered. • For some more details and a slightly better attempt at proper referencing: A supersymmetry primer, hep-ph/9709356, version 7, January 2016 • TASI 2011 lectures notes: two-component fermion notation and • supersymmetry, arXiv:1205.4076. If you find corrections, please do let me know! 2 Lecture 1: Motivation and Introduction to Supersymmetry Motivation: The Hierarchy Problem • Supermultiplets • Particle content of the Minimal Supersymmetric Standard Model • (MSSM) Need for “soft” breaking of supersymmetry • The Wess-Zumino Model • 3 People have cited many reasons why extensions of the Standard Model might involve supersymmetry (SUSY). Some of them are: A possible cold dark matter particle • A light Higgs boson, M = 125 GeV • h Unification of gauge couplings • Mathematical elegance, beauty • ⋆ “What does that even mean? No such thing!” – Some modern pundits ⋆ “We beg to differ.” – Einstein, Dirac, . However, for me, the single compelling reason is: The Hierarchy Problem • 4 An analogy: Coulomb self-energy correction to the electron’s mass A point-like electron would have an infinite classical electrostatic energy. Instead, suppose the electron is a solid sphere of uniform charge density and radius R. An undergraduate problem gives: 3e2 ∆ECoulomb = 20πǫ0R 2 Interpreting this as a correction ∆me = ∆ECoulomb/c to the electron mass: 15 0.86 10− meters m = m + (1 MeV/c2) × . -
Supersymmetry and the Multi-Instanton Measure
View metadata, citation and similar papers at core.ac.uk brought to you by CORE hep-th/9708036provided by CERN Document Server Supersymmetry and the Multi-Instanton Measure Nicholas Dorey Physics Department, University of Wales Swansea Swansea SA2 8PP UK [email protected] Valentin V. Khoze Department of Physics, Centre for Particle Theory, University of Durham Durham DH1 3LE UK [email protected] and Michael P. Mattis Theoretical Division T-8, Los Alamos National Laboratory Los Alamos, NM 87545 USA [email protected] We propose explicit formulae for the integration measure on the moduli space of charge-n ADHM multi-instantons in N = 1 and N =2super- symmetric gauge theories. The form of this measure is fixed by its (su- per)symmetries as well as the physical requirement of clustering in the limit of large spacetime separation between instantons. We test our proposals against known expressions for n ≤ 2. Knowledge of the measure for all n al- lows us to revisit, and strengthen, earlier N = 2 results, chiefly: (1) For any number of flavors NF , we provide a closed formula for Fn, the n-instanton contribution to the Seiberg-Witten prepotential, as a finite-dimensional col- lective coordinate integral. This amounts to a solution, in quadratures, of the Seiberg-Witten models, without appeal to electric-magnetic duality. (2) In the conformal case NF =4,this means reducing to quadratures the previously unknown finite renormalization that relates the microscopic and effective coupling constants, τmicro and τeff. (3) Similar expressions are given for the 4-derivative/8-fermion term in the gradient expansion of N = 2 supersymmetric QCD. -
Instanton Operators in Five-Dimensional Gauge
MTH-KCL/2014-20 QMUL-PH-14-25 Instanton Operators in Five-Dimensional Gauge Theories N. Lambert a,∗, C. Papageorgakis b,† and M. Schmidt-Sommerfeld c,d,‡ aDepartment of Mathematics King’s College London, WC2R 2LS, UK bCRST and School of Physics and Astronomy Queen Mary University of London, E1 4NS, UK cArnold-Sommerfeld-Center f¨ur Theoretische Physik, LMU M¨unchen Theresienstraße 37, 80333 M¨unchen, Germany dExcellence Cluster Universe, Technische Universit¨at M¨unchen Boltzmannstraße 2, 85748 Garching, Germany Abstract We discuss instanton operators in five-dimensional Yang-Mills gauge theo- ries. These are defined as disorder operators which create a non-vanishing arXiv:1412.2789v3 [hep-th] 4 Jun 2015 second Chern class on a four-sphere surrounding their insertion point. As such they may be thought of as higher-dimensional analogues of three- dimensional monopole (or ‘t Hooft) operators. We argue that they play an important role in the enhancement of the Lorentz symmetry for maximally supersymmetric Yang-Mills to SO(1, 5) at strong coupling. ∗E-mail address: [email protected] †E-mail address: [email protected] ‡E-mail address: [email protected] 1 Introduction One of the more dramatic results to come out of the study of strongly coupled string theory and M-theory was the realisation that there exist UV-complete quantum super- conformal field theories (SCFTs) in five and six dimensions [1–5]. These theories then provide UV completions to a variety of perturbatively non-renormalisable five-dimensional (5D) Yang-Mills theories. In this paper we will consider the notion of ‘instanton operators’ (or Yang operators) and explore their role in five-dimensional Yang-Mills. -
Einstein and the Kaluza-Klein Particle
ITFA-99-28 Einstein and the Kaluza-Klein particle Jeroen van Dongen1 Institute for Theoretical Physics, University of Amsterdam Valckeniersstraat 65 1018 XE Amsterdam and Joseph Henry Laboratories, Princeton University Princeton NJ 08544 Abstract In his search for a unified field theory that could undercut quantum mechanics, Einstein considered five dimensional classical Kaluza-Klein theory. He studied this theory most intensively during the years 1938-1943. One of his primary objectives was finding a non-singular particle solution. In the full theory this search got frustrated and in the x5-independent theory Einstein, together with Pauli, argued it would be impossible to find these structures. Keywords: Einstein; Unified Field Theory; Kaluza-Klein Theory; Quantization; Soli- tons 1 Introduction After having formulated general relativity Albert Einstein did not immediately focus on the unification of electromagnetism and gravity in a classical field theory - the issue that would characterize much of his later work. It was still an open question to him whether arXiv:gr-qc/0009087v1 26 Sep 2000 relativity and electrodynamics together would cast light on the problem of the structure of matter [18]. Rather, in a 1916 paper on gravitational waves he anticipated a different development: since the electron in its atomic orbit would radiate gravitationally, something that cannot “occur in reality”, he expected quantum theory would have to change not only the ”Maxwellian electrodynamics, but also the new theory of gravitation” [19]2. Einstein’s position, however, gradually changed. From about 1919 onwards, he took a strong interest in the unification programme3. In later years, after about 1926, he hoped that he would find a particular classical unified field theory that could undercut quantum theory. -
Lectures on N = 2 Gauge Theory
Preprint typeset in JHEP style - HYPER VERSION Lectures on N = 2 gauge theory Davide Gaiotto Abstract: In a series of four lectures I will review classic results and recent developments in four dimensional N = 2 supersymmetric gauge theory. Lecture 1 and 2 review the standard lore: some basic definitions and the Seiberg-Witten description of the low energy dynamics of various gauge theories. In Lecture 3 we review the six-dimensional engineering approach, which allows one to define a very large class of N = 2 field theories and determine their low energy effective Lagrangian, their S-duality properties and much more. Lecture 4 will focus on properties of extended objects, such as line operators and surface operators. Contents I Lecture 1 1 1. Seiberg-Witten solution of pure SU(2) gauge theory 5 2. Solution of SU(N) gauge theory 7 II Lecture 2 8 3. Nf = 1 SU(2) 10 4. Solution of SU(N) gauge theory with fundamental flavors 11 4.1 Linear quivers of unitary gauge groups 12 Field theories with N = 2 supersymmetry in four dimensions are a beautiful theoretical playground: this amount of supersymmetry allows many exact computations, but does not fix the Lagrangian uniquely. Rather, one can write down a large variety of asymptotically free N = 2 supersymmetric Lagrangians. In this lectures we will not include a review of supersymmetric field theory. We will not give a systematic derivation of the Lagrangian for N = 2 field theories either. We will simply describe whatever facts we need to know at the beginning of each lecture.