Pacific Journal of Mathematics Vol. 264 (2013)
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Some Stuff About the String Gerbe
Some Stuff about the String Gerbe Danny Stevenson Department of Mathematics, University of California, Riverside Riverside, CA 92521, USA email: [email protected] March 14, 2006 1 Introduction Let G be a compact, simple and simply connected Lie group and let π : P → M be a principal G bundle over a smooth manifold M. Let ν denote the universally transgressive generator of H3(G; Z) = Z and let c ∈ H4(BG; Z) = H3(G; Z) be the transgression of ν. By regarding H4(BG; Z) as a lattice in (S2g∗)G we will allow ourselves to confuse c and the basic inner product h , i on g. Recall [23] that h ,√i is the Killing form on g, normalised so that the longest root θ has length 2. In the physics literature, M is said to be string, or admit a string structure, if a certain characteristic class in H3(LM; Z) vanishes (here LM denotes the free loop space of M). This characteristic class is the obstruction to lifting the structure group of the principal LG- bundle LP → LM to LGc — the Kac-Moody group. As has been observed by several authors [12, 13, 19] the obstruction in H3(LM; Z) is closely related to the characteristic class c ∈ H4(M; Z): if M is 2-connected a lift of the structure group to LGc exists precisely when the map c: M → K(Z, 4) is null- homotopic. As is well known, if G = Spin(n) then 2c = p1. This obstruction problem on LM can be phrased in the language of homotopy theory down on M. -
A Brief Summary of My Researches
A Brief Summary of My Researches Kefeng Liu My research interest is to solve problems from mathematics and physics with simple and clean ideas, and along the way to learn and to ¯nd new math- ematical structures and theories. Localization techniques in various settings, combining with various subjects of mathematics, have played central roles in my researches. See my ICM lecture [38] for more detailed discussions. I divide my past researches into the following several parts: (1). The applications of modular invariance, the in¯nite dimensional sym- metry in Kac-Moody algebras and mathematical physics, to geometry and topology. From modular invariance we derived several quite general rigid- ity, divisibility and vanishing results about certain topological invariants of a manifold. (2). The use of the explicit expressions of heat kernels on Lie groups to study the geometry and topology of moduli spaces of flat connections on Riemann surfaces, this proves certain conjectural formulas of Witten and gives several new results including general vanishing formulas of intersection numbers. (3). The understanding of mirror symmetry and counting curves on pro- jective manifolds. My joint work with Lian and Yau solves some very general conjectures about the relationship between the numbers of algebraic curves in projective manifolds and hypergeometric series. (4). The proof of the Marino-Vafa conjecture on Hodge integrals on mod- uli spaces of Deligne-Mumford curves, which expresses the generating series of three term Hodge integrals over all genera and any number of marked points in terms of a ¯nite expression of representation of symmetric groups, or Chern-Simons knot invariants. -
A Construction of String 2-Group Modelsusing a Transgression
A Construction of String 2-Group Models using a Transgression-Regression Technique Konrad Waldorf Fakult¨at f¨ur Mathematik Universit¨at Regensburg Universit¨atsstraße 31 D–93053 Regensburg [email protected] Dedicated to Steven Rosenberg on the occasion of his 60th birthday Abstract In this note we present a new construction of the string group that ends optionally in two different contexts: strict diffeological 2-groups or finite-dimensional Lie 2-groups. It is canonical in the sense that no choices are involved; all the data is written down and can be looked up (at least somewhere). The basis of our construction is the basic gerbe of Gaw¸edzki-Reis and Meinrenken. The main new insight is that under a transgression- regression procedure, the basic gerbe picks up a multiplicative structure coming from the Mickelsson product over the loop group. The conclusion of the construction is a relation between multiplicative gerbes and 2-group extensions for which we use recent work of Schommer-Pries. MSC 2010: Primary 22E67; secondary 53C08, 81T30, 58H05 arXiv:1201.5052v2 [math.DG] 4 May 2012 1 Introduction The string group String(n) is a topological group defined up to homotopy equivalence as the 3-connected cover of Spin(n), for n =3 or n> 4. Concrete models for String(n) have been provided by Stolz [Sto96] and Stolz-Teichner [ST04]. In order to understand, e.g. the differential geometry of String(n), the so-called “string geometry”, it is necessary to have models in better categories than topological groups. Its 3-connectedness implies that String(n) is a K(Z, 2)-fibration over Spin(n), so that it cannot be a (finite-dimensional) Lie group. -
Fifth International Congress of Chinese Mathematicians Part 1
AMS/IP Studies in Advanced Mathematics S.-T. Yau, Series Editor Fifth International Congress of Chinese Mathematicians Part 1 Lizhen Ji Yat Sun Poon Lo Yang Shing-Tung Yau Editors American Mathematical Society • International Press Fifth International Congress of Chinese Mathematicians https://doi.org/10.1090/amsip/051.1 AMS/IP Studies in Advanced Mathematics Volume 51, Part 1 Fifth International Congress of Chinese Mathematicians Lizhen Ji Yat Sun Poon Lo Yang Shing-Tung Yau Editors American Mathematical Society • International Press Shing-Tung Yau, General Editor 2000 Mathematics Subject Classification. Primary 05–XX, 08–XX, 11–XX, 14–XX, 22–XX, 35–XX, 37–XX, 53–XX, 58–XX, 62–XX, 65–XX, 20–XX, 30–XX, 80–XX, 83–XX, 90–XX. All photographs courtesy of International Press. Library of Congress Cataloging-in-Publication Data International Congress of Chinese Mathematicians (5th : 2010 : Beijing, China) p. cm. (AMS/IP studies in advanced mathematics ; v. 51) Includes bibliographical references. ISBN 978-0-8218-7555-1 (set : alk. paper)—ISBN 978-0-8218-7586-5 (pt. 1 : alk. paper)— ISBN 978-0-8218-7587-2 (pt. 2 : alk. paper) 1. Mathematics—Congresses. I. Ji, Lizhen, 1964– II. Title. III. Title: 5th International Congress of Chinese Mathematicians. QA1.I746 2010 510—dc23 2011048032 Copying and reprinting. Material in this book may be reproduced by any means for edu- cational and scientific purposes without fee or permission with the exception of reproduction by services that collect fees for delivery of documents and provided that the customary acknowledg- ment of the source is given. This consent does not extend to other kinds of copying for general distribution, for advertising or promotional purposes, or for resale. -
Awards of ICCM 2013 by the Editors
Awards of ICCM 2013 by the Editors academies of France, Sweden and the United States. He is a recipient of the Fields Medal (1986), the Crafoord Prize Morningside Medal of Mathematics in Mathematics (1994), the King Faisal International Prize Selection Committee for Science (2006), and the Shaw Prize in Mathematical The Morningside Medal of Mathematics Selection Sciences (2009). Committee comprises a panel of world renowned mathematicians and is chaired by Professor Shing-Tung Björn Engquist Yau. A nomination committee of around 50 mathemati- Professor Engquist is the Computational and Applied cians from around the world nominates candidates based Mathematics Chair Professor at the University of Texas at on their research, qualifications, and curriculum vitae. Austin. His recent work includes homogenization theory, The Selection Committee reviews these nominations and multi-scale methods, and fast algorithms for wave recommends up to two recipients for the Morningside propagation. He is a member of the Royal Swedish Gold Medal of Mathematics, up to two recipients for the Morningside Gold Medal of Applied Mathematics, and up to four recipients for the Morningside Silver Medal of Mathematics. The Selection Committee members, with the exception of the committee chair, are all non-Chinese to ensure the independence, impartiality and integrity of the awards decision. Members of the 2013 Morningside Medal of Mathe- matics Selection Committee are: Richard E. Borcherds Professor Borcherds is Professor of Mathematics at the University of California at Berkeley. His research in- terests include Lie algebras, vertex algebras, and auto- morphic forms. He is best known for his work connecting the theory of finite groups with other areas in mathe- matics. -
On the String 2-Group
On the String 2-Group Urs Schreiber∗ May 3, 2006 Oberseminar Topologie Universit¨atBonn, May 2, 2006 Abstract We try to convey the main idea for 1. • what the String-group StringG is • and how it is the nerve of a 2-group StrG; 2. as well as • what a StrG-2-bundle is • and how it is “the same” as a StringG-bundle. The first point is due to [10, 9], which will be reviewed in section 2. The second point has been addressed in [8] using the language of bundle gerbes. In section 3 we review this, using a 2-functorial language which is natural with respect to the 2-group nature of StrG. A commented bibliography is given in section 1. Contents 1 Motivation 2 2 The String 2-Group 3 2.1 2-Groups . 4 2.2 StringG ................................ 6 3 String 2-Bundles 9 3.1 2-Bundles . 9 3.2 Transition Bundles . 15 4 Outlook: String Connections 19 ∗e-mail: urs.schreiber at math.uni-hamburg.de 1 1 Motivation The main motivation for the following discussion has its origin in theoretical physics. Elementary particles with spin are described by sections of spin bundles. From the physical point of view, the necessity of a spin structure on spacetime may be deduced from a certain global anomaly for the path integral of a single, point-like, fermion. The path integral (albeit a somewhat heuristic device) can be regarded as a single valued function on the space of configurations of the particle, only if the (first and) second Stiefel-Whitney class of spacetime vanishes. -
String Structures Associated to Indefinite Lie Groups
String structures associated to indefinite Lie groups Hisham Sati1 and Hyung-bo Shim2 1Division of Science and Mathematics, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, UAE 2Department of Mathematics, University of Pittsburgh, Pittsburgh, PA 15260, USA April 2, 2019 Abstract String structures have played an important role in algebraic topology, via elliptic genera and elliptic cohomology, in differential geometry, via the study of higher geometric structures, and in physics, via partition functions. We extend the description of String structures from connected covers of the definite-signature orthogonal group O(n) to the indefinite-signature orthogonal group O(p, q), i.e. from the Riemannian to the pseudo-Riemannian setting. This requires that we work at the unstable level, which makes the discussion more subtle than the stable case. Similar, but much simpler, constructions hold for other noncompact Lie groups such as the unitary group U(p, q) and the symplectic group Sp(p, q). This extension provides a starting point for an abundance of constructions in (higher) geometry and applications in physics. Contents 1 Introduction 2 2 The Postnikov tower, Whitehead tower, and variants 4 2.1 ThePostnikovtower ............................... ..... 4 2.2 TheWhiteheadtower ............................... .... 5 2.3 Avariantview .................................... ... 7 2.4 Computationalaspects. ....... 8 2.5 Special case: higher connected covers of classifying spaces and obstructions . 10 3 Applications 13 arXiv:1504.02088v2 [math-ph] 31 Mar 2019 3.1 Special orthogonal groups SO(n) and SO(p,q)...................... 13 3.2 IndefiniteSpingroups ............................. ...... 14 3.3 IndefiniteStringgroups . ....... 17 3.4 String structure associated to indefinite unitary and symplectic groups . 21 3.5 Relation to twisted structures . -
Advanced Lectures in Mathematics (ALM)
Advanced Lectures in Mathematics (ALM) ALM 1: Superstring Theory ALM 2: Asymptotic Theory in Probability and Statistics with Applications ALM 3: Computational Conformal Geometry ALM 4: Variational Principles for Discrete Surfaces ALM 6: Geometry, Analysis and Topology of Discrete Groups ALM 7: Handbook of Geometric Analysis, No. 1 ALM 8: Recent Developments in Algebra and Related Areas ALM 9: Automorphic Forms and the Langlands Program ALM 10: Trends in Partial Differential Equations ALM 11: Recent Advances in Geometric Analysis ALM 12: Cohomology of Groups and Algebraic K-theory ALM 13: Handbook of Geometric Analysis, No. 2 ALM 14: Handbook of Geometric Analysis, No. 3 ALM 15: An Introduction to Groups and Lattices: Finite Groups and Positive Definite Rational Lattices ALM 16: Transformation Groups and Moduli Spaces of Curves ALM 17: Geometry and Analysis, No. 1 ALM 18: Geometry and Analysis, No. 2 Advanced Lectures in Mathematics Volume XVIII Geometry and Analysis No. 2 Editor: Lizhen Ji International Press 浧䷘㟨十⒉䓗䯍 www.intlpress.com HIGHER EDUCATION PRESS Advanced Lectures in Mathematics, Volume XVIII Geometry and Analysis, No. 2 Volume Editor: Lizhen Ji, University of Michigan, Ann Arbor 2010 Mathematics Subject Classification. 58-06. Copyright © 2011 by International Press, Somerville, Massachusetts, U.S.A., and by Higher Education Press, Beijing, China. This work is published and sold in China exclusively by Higher Education Press of China. All rights reserved. Individual readers of this publication, and non-profit libraries acting for them, are permitted to make fair use of the material, such as to copy a chapter for use in teaching or research. -
Higher Gauge Theory – I
Higher Gauge Theory { I John C. Baez joint work with: Toby Bartels, Alissa Crans, James Dolan, Aaron Lauda, Urs Schreiber, Danny Stevenson. Barrett Lectures Saturday April 29th, 2006 1 G 3+ f1 D f2 Notes and references at: http://math.ucr.edu/home/baez/barrett/ 1 The Big Idea Using n-categories, instead of starting with a set of things: ¢ ¡¢ ¡ ¦ ¥¦ ¥ ¤ £¤ £ we can now start with a category of things and processes: ¨ §¨ § © © or a 2-category of things, processes, and processes be- tween processes: ... and so on. 2 I'll illustrate this with examples from higher gauge the- ory. This describes not only how particles transform as they move along paths in spacetime: but also how strings transform as they trace out surfaces: ... and so on. Where ordinary gauge theory uses groups, which are special categories: higher gauge theory uses 2-groups: which are special 2-categories. Where ordinary gauge theory uses bundles, higher gauge theory uses 2-bundles. Everything gets ‘categorified’! But first let's back up a bit.... 3 The Fundamental Groupoid Defining the fundamental group of a space X requires us to pick a basepoint ∗ 2 X. This is a bit ad hoc, and no good when X has several components. Sometimes it's better to use the fundamental groupoid of X. This is the category Π1(X) where: • objects are points of X: •x • morphisms are homotopy classes of paths in X: γ x • ( • y We compose homotopy classes of paths in the obvious way. Composition is associative, and every point has an identity path 1x : x ! x. -
View This Volume's Front and Back Matter
AMS/IP Studies in Advanced Mathematics S.-T. Yau, Series Editor Fifth International Congress of Chinese Mathematicians Part 2 Lizhen Ji Yat Sun Poon Lo Yang Shing-Tung Yau Editors American Mathematical Society • International Press Fifth International Congress of Chinese Mathematicians https://doi.org/10.1090/amsip/051.2 AMS/IP Studies in Advanced Mathematics Volume 51, Part 2 Fifth International Congress of Chinese Mathematicians Lizhen Ji Yat Sun Poon Lo Yang Shing-Tung Yau Editors American Mathematical Society • International Press Shing-Tung Yau, General Editor 2000 Mathematics Subject Classification. Primary 05–XX, 08–XX, 11–XX, 14–XX, 22–XX, 35–XX, 37–XX, 53–XX, 58–XX, 62–XX, 65–XX, 20–XX, 30–XX, 80–XX, 83–XX, 90–XX. All photographs courtesy of International Press. Library of Congress Cataloging-in-Publication Data International Congress of Chinese Mathematicians (5th : 2010 : Beijing, China) p. cm. (AMS/IP studies in advanced mathematics ; v. 51) Includes bibliographical references. ISBN 978-0-8218-7555-1 (set : alk. paper)—ISBN 978-0-8218-7586-5 (pt. 1 : alk. paper)— ISBN 978-0-8218-7587-2 (pt. 2 : alk. paper) 1. Mathematics—Congresses. I. Ji, Lizhen, 1964– II. Title. III. Title: 5th International Congress of Chinese Mathematicians. QA1.I746 2010 510—dc23 2011048032 Copying and reprinting. Material in this book may be reproduced by any means for edu- cational and scientific purposes without fee or permission with the exception of reproduction by services that collect fees for delivery of documents and provided that the customary acknowledg- ment of the source is given. This consent does not extend to other kinds of copying for general distribution, for advertising or promotional purposes, or for resale. -
Morningside Medals, the Chern Prizes, and the International Cooperation Awards Excerpts from the 2010 ICCM Booklet
Morningside Medals, the Chern Prizes, and the International Cooperation Awards excerpts from the 2010 ICCM booklet A fundamental domain is related to the concept of a group, which can be used to express symmetry in Morningside medals of mathematics and mathematics. During the late 19th century, infinite dis- applied mathematics crete group was studied but only until the 20th century, The Morningside Medal of Mathematics is awarded to did it become a main subject area in mathematics. This outstanding mathematicians of Chinese descent to en- field of study is not only important in geometry but also courage them in their pursuit of mathematical truth. Up in number theory. Practically all the famous develop- to six medals, two gold and four silver, are awarded every ments in modern number theory are related to concepts three years at the International Congress of Chinese of fundamental domain and discrete group. Morningside Medals of Mathematics Selection Committee The selection committee for the Morningside Medal of Mathematics is chaired by Professor Shing-Tung Yau. A The Morningside Gold Medal awarded to Kefeng Liu in 2004 Mathematicians. The Morningside Medals also carry a cash award of US $25,000 for each of the gold medalists; and US $ 10,000 for each of the silver medalists. A com- mittee of internationally renowned mathematicians, chaired by Professor Shing-Tung Yau, selects the medal- ists. In addition to the name of medalists, each gold and silver medal has the image of a Möbius band and a fun- damental domain. They were chosen not only for the The Morningside Silver Medals awarded to Daqing Wan and simplicity of the image, but also because of their signifi- Chin-Lung Wang in 2001 cant contributions to the development of mathematics in 20th century. -
New Publications Offered by The
New Publications Offered by the AMS To subscribe to email notification of new AMS publications, please go to http://www.ams.org/bookstore-email. Algebra and Algebraic Analysis Geometry Differentiable Quantum Bounded Measures and the Symmetric Domains Malliavin Calculus Leonid L. Vaksman Vladimir I. Bogachev, Moscow Translated by Olga Bershtein and State University, Russia Sergey D. Sinel’shchikov This book provides the reader with the principal concepts and results related This book provides exposition of the to differential properties of measures basic theory of quantum bounded on infinite dimensional spaces. In the symmetric domains. The area became finite dimensional case such properties are described in terms of active in the late 1990s at a junction of densities of measures with respect to Lebesgue measure. In the noncommutative complex analysis and infinite dimensional case new phenomena arise. For the first time a extensively developing theory of quantum groups. It is well detailed account is given of the theory of differentiable measures, known that the classical bounded symmetric domains involve a initiated by S. V. Fomin in the 1960s; since then the method large number of nice constructions and results of the theory has found many various important applications. Differentiable of C∗-algebras, theory of functions and functional analysis, properties are described for diverse concrete classes of measures representation theory of real reductive Lie groups, harmonic arising in applications, for example, Gaussian, convex, stable, analysis, and special functions. In a surprising advance of the theory Gibbsian, and for distributions of random processes. Sobolev of quantum bounded symmetric domains, it turned out that many classes for measures on finite and infinite dimensional spaces are classical problems admit elegant quantum analogs.