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Particles-Versus-Strings.Pdf
Particles vs. strings http://insti.physics.sunysb.edu/~siegel/vs.html In light of the huge amount of propaganda and confusion regarding string theory, it might be useful to consider the relative merits of the descriptions of the fundamental constituents of matter as particles or strings. (More-skeptical reviews can be found in my physics parodies.A more technical analysis can be found at "Warren Siegel's research".) Predictability The main problem in high energy theoretical physics today is predictions, especially for quantum gravity and confinement. An important part of predictability is calculability. There are various levels of calculations possible: 1. Existence: proofs of theorems, answers to yes/no questions 2. Qualitative: "hand-waving" results, answers to multiple choice questions 3. Order of magnitude: dimensional analysis arguments, 10? (but beware hidden numbers, like powers of 4π) 4. Constants: generally low-energy results, like ground-state energies 5. Functions: complete results, like scattering probabilities in terms of energy and angle Any but the last level eventually leads to rejection of the theory, although previous levels are acceptable at early stages, as long as progress is encouraging. It is easy to write down the most general theory consistent with special (and for gravity, general) relativity, quantum mechanics, and field theory, but it is too general: The spectrum of particles must be specified, and more coupling constants and varieties of interaction become available as energy increases. The solutions to this problem go by various names -- "unification", "renormalizability", "finiteness", "universality", etc. -- but they are all just different ways to realize the same goal of predictability. -
Evidence for a Sublattice Weak Gravity Conjecture
Evidence for a Sublattice Weak Gravity Conjecture The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Heidenreich, Ben, Matthew Reece, and Tom Rudelius. 2017. Evidence for a Sublattice Weak Gravity Conjecture. Journal of High Energy Physics 2017, 25. Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:41392811 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Open Access Policy Articles, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#OAP Prepared for submission to JHEP Evidence for a Sublattice Weak Gravity Conjecture Ben Heidenreich,a;b Matthew Reece,a and Tom Rudeliusa aDepartment of Physics, Harvard University, Cambridge, MA 02138, USA bPerimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada N2L 2Y5 E-mail: [email protected], [email protected], [email protected] Abstract: The Weak Gravity Conjecture postulates the existence of superextremal charged particles, i.e. those with mass smaller than or equal to their charge in Planck units. We present further evidence for our recent observation that in known examples a much stronger statement is true: an infinite tower of superextremal particles of different charges exists. We show that effective Kaluza-Klein field theories and perturbative string vacua respect the Sublattice Weak Gravity Conjecture, namely that a finite index sublattice of the full charge lattice exists with a superextremal particle at each site. In perturbative string theory we show that this follows from modular invariance. -
Hep-Th/0011078V1 9 Nov 2000 1 Okspotdi Atb H ..Dp.O Nryudrgrant Under Energy of Dept
CALT-68-2300 CITUSC/00-060 hep-th/0011078 String Theory Origins of Supersymmetry1 John H. Schwarz California Institute of Technology, Pasadena, CA 91125, USA and Caltech-USC Center for Theoretical Physics University of Southern California, Los Angeles, CA 90089, USA Abstract The string theory introduced in early 1971 by Ramond, Neveu, and myself has two-dimensional world-sheet supersymmetry. This theory, developed at about the same time that Golfand and Likhtman constructed the four-dimensional super-Poincar´ealgebra, motivated Wess and Zumino to construct supersymmet- ric field theories in four dimensions. Gliozzi, Scherk, and Olive conjectured the arXiv:hep-th/0011078v1 9 Nov 2000 spacetime supersymmetry of the string theory in 1976, a fact that was proved five years later by Green and myself. Presented at the Conference 30 Years of Supersymmetry 1Work supported in part by the U.S. Dept. of Energy under Grant No. DE-FG03-92-ER40701. 1 S-Matrix Theory, Duality, and the Bootstrap In the late 1960s there were two parallel trends in particle physics. On the one hand, many hadron resonances were discovered, making it quite clear that hadrons are not elementary particles. In fact, they were found, to good approximation, to lie on linear parallel Regge trajectories, which supported the notion that they are composite. Moreover, high energy scattering data displayed Regge asymptotic behavior that could be explained by the extrap- olation of the same Regge trajectories, as well as one with vacuum quantum numbers called the Pomeron. This set of developments was the focus of the S-Matrix Theory community of theorists. -
Strings, Boundary Fermions and Coincident D-Branes
Strings, boundary fermions and coincident D-branes Linus Wulff Department of Physics Stockholm University Thesis for the degree of Doctor of Philosophy in Theoretical Physics Department of Physics, Stockholm University Sweden c Linus Wulff, Stockholm 2007 ISBN 91-7155-371-1 pp 1-85 Printed in Sweden by Universitetsservice US-AB, Stockholm 2007 Abstract The appearance in string theory of higher-dimensional objects known as D- branes has been a source of much of the interesting developements in the subject during the past ten years. A very interesting phenomenon occurs when several of these D-branes are made to coincide: The abelian gauge theory liv- ing on each brane is enhanced to a non-abelian gauge theory living on the stack of coincident branes. This gives rise to interesting effects like the natural ap- pearance of non-commutative geometry. The theory governing the dynamics of these coincident branes is still poorly understood however and only hints of the underlying structure have been seen. This thesis focuses on an attempt to better this understanding by writing down actions for coincident branes using so-called boundary fermions, orig- inating in considerations of open strings, instead of matrices to describe the non-abelian fields. It is shown that by gauge-fixing and by suitably quantiz- ing these boundary fermions the non-abelian action that is known, the Myers action, can be reproduced. Furthermore it is shown that under natural assump- tions, unlike the Myers action, the action formulated using boundary fermions also posseses kappa-symmetry, the criterion for being the correct supersym- metric action for coincident D-branes. -
Notas De Física CBPF-NF-007/10 February 2010
ISSN 0029-3865 CBPF - CENTRO BRASILEIRO DE PESQUISAS FíSICAS Rio de Janeiro Notas de Física CBPF-NF-007/10 February 2010 A criticaI Iook at 50 years particle theory from the perspective of the crossing property Bert Schroer Ministét"iQ da Ciência e Tecnologia A critical look at 50 years particle theory from the perspective of the crossing property Dedicated to Ivan Todorov on the occasion of his 75th birthday to be published in Foundations of Physics Bert Schroer CBPF, Rua Dr. Xavier Sigaud 150 22290-180 Rio de Janeiro, Brazil and Institut fuer Theoretische Physik der FU Berlin, Germany December 2009 Contents 1 The increasing gap between foundational work and particle theory 2 2 The crossing property and the S-matrix bootstrap approach 7 3 The dual resonance model, superseded phenomenology or progenitor of a new fundamental theory? 15 4 String theory, a TOE or a tower of Babel within particle theory? 21 5 Relation between modular localization and the crossing property 28 6 An exceptional case of localization equivalence: d=1+1 factorizing mod- els 35 7 Resum´e, some personal observations and a somewhat downbeat outlook 39 8 Appendix: a sketch of modular localization 47 8.1 Modular localization of states . 47 8.2 Localized subalgebras . 51 CBPF-NF-007/10 CBPF-NF-007/10 2 Abstract The crossing property, which originated more than 5 decades ago in the after- math of dispersion relations, was the central new concept which opened an S-matrix based line of research in particle theory. Many constructive ideas in particle theory outside perturbative QFT, among them the S-matrix bootstrap program, the dual resonance model and the various stages of string theory have their historical roots in this property. -
A Brief Introduction to the Weak Gravity Conjecture Eran Palti Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
Letters in High Energy Physics LHEP-176, 2020 A Brief Introduction to the Weak Gravity Conjecture Eran Palti Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel Abstract The Weak Gravity Conjecture proposes that a theory with a gauge field that is coupled to gravity must have charged matter on which gravity acts as the weakest force. It also proposes that there is an intrinsic cutoff on such an effective theory, which corresponds to a tower of charged states, that is set by the strength of the gauge coupling (in Planck units). This article is a brief introduction to the Weak Gravity Conjecture, covering aspects of the motivations for it as well as various extensions and refinements. Keywords: Swampland, Quantum Gravity, String Theory gauge fields for simplicity), with gauge coupling g, there must DOI: 10.31526/LHEP.2020.176 exist at least one particle with quantized charge q and mass m which satisfies the bound p 1. INTRODUCTION m ≤ 2gqMp . (4) There are four known forces in the universe: the strong and The bound (4) is termed the Electric WGC. This is to dif- weak forces, electromagnetism, and gravity. The known fun- ferentiate it from a related bound termed the Magnetic WGC. damental matter particles are all charged under at least two The simplest way to introduce this second bound is through the of these forces. For example, the right-handed electron carries electromagnetic dual of (4) [1]. Under electromagnetic duality electromagnetic charge and gravitational charge. These charges the gauge coupling g is exchanged for its inverse g−1, while the can be deduced from the Coulomb forces that two electrons feel electrically charged particle is exchanged for a monopole with when placed a distance r apart. -
Proton! Physics Under the Direction of Guido Energy Physics Under the Direction of We’Ll Even Print Your Abstract! Mueller
P R O T O N Physics Report on Things of Note January 2006 -- Vol. 5 No. 1 Physics Department Year-End Awards Announced Featured Publication(s) Each December, the Department holds an Awards Ceremony during the Annual Holiday Party, to recognize staff and faculty who have achieved superior perfor- T. S. Nunner, B. M. Ander- mance, and to announce the Graduate Student Awards which recognize outstand- sen, A. Melikyan, and P. J. ing graduate students from the past year. Hirschfeld. “Dopant-Modulated Pair Physics Teacher of the Year (2005) Interaction in Cuprate Super- Stephen Hill conductors.” Phys. Rev. Lett. 95, 177003 (2005). Physics Employee Excellence Awards (2005) Yvonne Dixon and Greg Labbe B. Abbott et al. (LIGO Scien- tific Collaboration). Graduate Student Awards (2005) “Upper Limits on a Stochastic Background of Gravitational Tom Scott Memorial Award : TA of the Year for the Introductory Waves.” James Ira Thorpe Labs : Sung-Soo Kim Phys. Rev. Lett. 95, 221101 (2005) This award is made annually to a se- This award recognizes Sung-Soo’s nior graduate student, in experimental commitment to his students and to the Submit your article to be featured physics, who has shown distinction in educational atmosphere in the labora- in this section. Whether it’s just research. Ira is a 2nd year graduate tory setting. Sung-Soo is a 4th year been submitted or accepted, we’d student working in experimental astro- student working in theoretical high like to feature it in the proton! physics under the direction of Guido energy physics under the direction of We’ll even print your abstract! Mueller. -
High Resolution Search for Dark Matter Axions in Milky Way Halo Substructure
HIGH RESOLUTION SEARCH FOR DARK MATTER AXIONS IN MILKY WAY HALO SUBSTRUCTURE By LEANNE DELMA DUFFY A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2006 ACKNOWLEDGMENTS This work is based on research performed by the Axion Dark Matter eX- periment (ADMX). I am grateful to my ADMX collaborators for their efforts, particularly in running the experiment and providing the high resolution data. Without these efforts, this work would not have been possible. I thank my advisor, Pierre Sikivie, for his support and guidance thoughout graduate school. It has been a priviege to collaborate with him on this and other projects. I also thank Dave Tanner for his assistance and advice on this work. I would like to thank the other members of my advisory committee, Jim Fry, Guenakh Mitselmakher, Pierre Ramond, Richard Woodard and Fred Hamann, for their roles in my progress. I am also grateful to the other members of the University of Florida Physics Department who have contributed to my graduate school experience. I am especially grateful to my family and friends, both near and far, who have supported me through this long endeavor. Special thanks go to Lisa Everett and Ethan Siegel. ii TABLE OF CONTENTS page ACKNOWLEDGMENTS ............................. ii LIST OF TABLES ................................. v LIST OF FIGURES ................................ vi ABSTRACT .................................... viii CHAPTER 1 INTRODUCTION .............................. 1 2 AXIONS .................................... 7 2.1 Introduction ............................... 7 2.2 The Strong CP Problem ........................ 7 2.3 The Axion ................................ 11 2.3.1 Introduction ........................... 11 2.3.2 The Peccei-Quinn Solution to the Strong CP Problem ... -
The Early Years of String Theory: a Personal Perspective
CALT-68-2657 THE EARLY YEARS OF STRING THEORY: A PERSONAL PERSPECTIVE John H. Schwarz California Institute of Technology Pasadena, CA 91125, USA Abstract arXiv:0708.1917v3 [hep-th] 3 Apr 2009 This article surveys some of the highlights in the development of string theory through the first superstring revolution in 1984. The emphasis is on topics in which the author was involved, especially the observation that critical string theories provide consistent quantum theories of gravity and the proposal to use string theory to construct a unified theory of all fundamental particles and forces. Based on a lecture presented on June 20, 2007 at the Galileo Galilei Institute 1 Introduction I am happy to have this opportunity to reminisce about the origins and development of string theory from 1962 (when I entered graduate school) through the first superstring revolution in 1984. Some of the topics were discussed previously in three papers that were written for various special events in 2000 [1, 2, 3]. Also, some of this material was reviewed in the 1985 reprint volumes [4], as well as the string theory textbooks [5, 6]. In presenting my experiences and impressions of this period, it is inevitable that my own contributions are emphasized. Some of the other early contributors to string theory have presented their recollections at the Galileo Galilei Institute meeting on “The Birth of String Theory” in May 2007. Since I was unable to attend that meeting, my talk was given at the GGI one month later. Taken together, the papers in this collection should -
STRING THEORY in the TWENTIETH CENTURY John H
STRING THEORY IN THE TWENTIETH CENTURY John H. Schwarz Strings 2016 { August 1, 2016 ABSTRACT String theory has been described as 21st century sci- ence, which was discovered in the 20th century. Most of you are too young to have experienced what happened. Therefore, I think it makes sense to summarize some of the highlights in this opening lecture. Since I only have 25 minutes, this cannot be a com- prehensive history. Important omitted topics include 2d CFT, string field theory, topological string theory, string phenomenology, and contributions to pure mathematics. Even so, I probably have too many slides. 1 1960 { 68: The analytic S matrix The goal was to construct the S matrix that describes hadronic scattering amplitudes by assuming • Unitarity and analyticity of the S matrix • Analyticity in angular momentum and Regge Pole The- ory • The bootstrap conjecture, which developed into Dual- ity (e.g., between s-channel and t-channel resonances) 2 The dual resonance model In 1968 Veneziano found an explicit realization of duality and Regge behavior in the narrow resonance approxima- tion: Γ(−α(s))Γ(−α(t)) A(s; t) = g2 ; Γ(−α(s) − α(t)) 0 α(s) = α(0) + α s: The motivation was phenomenological. Incredibly, this turned out to be a tree amplitude in a string theory! 3 Soon thereafter Virasoro proposed, as an alternative, g2 Γ(−α(s))Γ(−α(t))Γ(−α(u)) T = 2 2 2 ; −α(t)+α(u) −α(s)+α(u) −α(s)+α(t) Γ( 2 )Γ( 2 )Γ( 2 ) which has similar virtues. -
Antipodal Correlation on the Meron Wormhole and a Bang-Crunch Universe
PHYSICAL REVIEW D 97, 126006 (2018) Antipodal correlation on the meron wormhole and a bang-crunch universe Panagiotis Betzios* Crete Center for Theoretical Physics, Institute for Theoretical and Computational Physics, Department of Physics, University of Crete, 71003 Heraklion, Greece † Nava Gaddam Institute for Theoretical Physics and Center for Extreme Matter and Emergent Phenomena, Utrecht University, 3508 TD Utrecht, Netherlands ‡ Olga Papadoulaki Mathematical Sciences and STAG Research Centre, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom (Received 13 January 2018; published 11 June 2018) We present a covariant Euclidean wormhole solution to Einstein Yang-Mills system and study scalar perturbations analytically. The fluctuation operator has a positive definite spectrum. We compute the Euclidean Green’s function, which displays maximal antipodal correlation on the smallest three sphere at the center of the throat. Upon analytic continuation, it corresponds to the Feynman propagator on a compact bang-crunch universe. We present the connection matrix that relates past and future modes. We thoroughly discuss the physical implications of the antipodal map in both the Euclidean and Lorentzian geometries and give arguments on how to assign a physical probability to such solutions. DOI: 10.1103/PhysRevD.97.126006 I. INTRODUCTION whose few proposed resolutions suffer from closed time- like curves and other intricacies [10]. Euclidean wormholes [1–3] are extrema of the Euclidean Inspired by these questions, we -
Notes on String Theory
Notes on String Theory Universidad de Santiago de Compostela April 2, 2013 Contents 1 Strings from gauge theories 3 1.1 Introduction . .3 1.2 The dual resonance model . .3 1.3 Regge trajectories from String Theory . .7 1.4 String theory from the large Nc counting of gauge theories . .8 2 Open and Closed String Amplitudes 13 2.1 Closed string interactions . 13 2.2 S matrix and Scattering Amplitudes . 18 2.2.1 m-point amplitudes for closed strings. 18 2.2.2 4-point tachyon amplitude . 21 2.3 Open string scattering . 24 3 Gauge theory from string theory 29 3.1 Gauge theory from open strings . 29 3.2 Gauge theory from closed strings . 30 3.2.1 The Kaluza Klein reduction . 30 3.2.2 Closed strings on a circle . 31 3.2.3 Massless spectrum . 33 3.3 T- duality . 33 3.3.1 Full spectrum: T-duality for closed strings . 34 3.3.2 Enhanced gauge symmetry: . 34 4 D-branes 35 4.1 T-duality for open strings and D-branes . 35 4.1.1 D branes . 36 4.1.2 T-duality with Wilson Lines . 36 4.1.3 T-duality for type II superstrings . 37 4.2 Dynamics of D − branes ............................. 39 1 4.2.1 Born-Infeld action . 40 2 Chapter 1 Strings from gauge theories 1.1 Introduction We can safely trace the origins of strings to the early 50's, where lots of scattering experi- ments were performed involving mesons and baryons. The evidence of a parton substruc- ture, together with the impossibility to obtain the quarks as a individual final states lead to the conclusion that confinement is a built in property of non abelian gauge theories.