http://dx.doi.org/10.1090/pspum/078

Proceedings of Symposia in

PURE

Volume 78

From Hodge Theory to Integrability and TQFT tt* -geometry

International Workshop From TQFT to tt* and integrability May 25-29, 2007 University of Augsburg, Augsburg, Germany

Ron Y. Donagi Katrin Wendland Editors

& American Mathematical Society 3 Providence, Rhode Island 2000 Mathematics Subject Classification. Primary 14C30, 14D07, 14D21, 14N35, 53C43, 53D45, 81R12, 81T30, 81T45.

Library of Congress Cataloging-in-Publication Data International Workshop from TQFT to tt* and Integrability (2007 : Augsburg, Germany) From Hodge theory to integrability and TQFT : tt*-geometry ; International Workshop from TQFT to tt* and Integrability, May 25-29, 2007, Augsburg, Germany / Ron Y. Donagi, Katrin Wendland, editors. p. cm. — (Proceedings of symposia in pure mathematics ; v. 78) Includes bibliographical references. ISBN 978-0-8218-4430-4 (alk. paper) 1. Geometry, Algebraic—Congresses. 2. Hodge theory—Congresses. 3. Quantum field theory—Congresses. I. Donagi, Ron Y., 1956- II. Wendland, Katrin, 1970- III. Title. QA564.I618 2008 516.3'5—dc22 2008027339

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. Requests for permission for commercial use of material should be addressed to the Acquisitions Department, American Math• ematical Society, 201 Charles Street, Providence, Rhode Island 02904-2294, USA. Requests can also be made by e-mail to [email protected]. Excluded from these provisions is material in articles for which the author holds copyright. In such cases, requests for permission to use or reprint should be addressed directly to the author(s). (Copyright ownership is indicated in the notice in the lower right-hand corner of the first page of each article.) © 2008 by the American Mathematical Society. All rights reserved. The American Mathematical Society retains all rights except those granted to the United States Government. Copyright of individual articles may revert to the public domain 28 years after publication. Contact the AMS for copyright status of individual articles. Printed in the United States of America. @ The paper used in this book is acid-free and falls within the guidelines established to ensure permanence and durability. Visit the AMS home page at http://www.ams.org/ 10 9 8 7 6 5 4 3 2 1 13 12 11 10 09 08 Contents

Introduction v Universal unfoldings of Laurent polynomials and tt* structures CLAUDE SABBAH 1 From primitive forms to Frobenius manifolds KYOJI SAITO and ATSUSHI TAKAHASHI 31 Twistor structures, ££*-geometry and singularity theory CLAUS HERTLING and CHRISTIAN SEVENHECK 49 Differential geometric aspects of the tt*-equations VICENTE CORTES and LARS SCHAFER 75 Hodge theoretic aspects of mirror symmetry LUDMIL KATZARKOV, MAXIM KONTSEVICH, and TONY PANTEV 87 A weight two phenomenon for the moduli of rank one local systems on open varieties 175 Associativity for the Neumann system L.K. HOEVENAARS 215 Two-dimensional Gauge Theories and Quantum Integrable Systems ANTON A. GERASIMOV and SAMSON L. SHATASHVILI 239 Hurwitz numbers, matrix models and enumerative geometry VINCENT BOUCHARD and MARCOS MARINO 263 Background independence and the Open Topological String Wavefunction ANDREW NEITZKE and JOHANNES WALCHER 285 This page intentionally left blank Introduction

Ideas from quantum field theory and string theory have had an enormous im• pact on geometry over the last two decades. One extremely fruitful source of new mathemati