The eleven dimensional supergravity equations, resolutions and Lefschetz fiber metrics by Xuwen Zhu B.S., Peking University (2010) Submitted to the Department of Mathematics in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mathematics at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY June 2015 c Massachusetts Institute of Technology 2015. All rights reserved. ○ Author................................................................ Department of Mathematics Apr 5, 2015 Certified by. Richard B. Melrose Simons Professor of Mathematics Thesis Supervisor Accepted by . William Minicozzi Chairman, Department Committee on Graduate Studies 2 The eleven dimensional supergravity equations, resolutions and Lefschetz fiber metrics by Xuwen Zhu Submitted to the Department of Mathematics on Apr 5, 2015, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mathematics Abstract This thesis consists of three parts. In the first part, we study the eleven dimensional supergravity equations on B7 S4 considered as an edge manifold. We compute the indicial roots of the linearized× system using the Hodge decomposition, and using the edge calculus and scattering theory we prove that the moduli space of solutions, near the Freund–Rubin states, is parameterized by three pairs of data on the bounding 6-sphere. In the second part, we consider the family of constant curvature fiber metrics for a Lefschetz fibration with regular fibers of genus greater than one. A result ofObitsu and Wolpert is refined by showing that on an appropriate resolution of the total space, constructed by iterated blow-up, this family is log-smooth, i.e. polyhomogeneous with integral powers but possible multiplicities, at the preimage of the singular fibers in terms of parameters of size comparable to the length of the shrinking geodesic. This is joint work with Richard Melrose. In the third part, the resolution of a compact group action in the sense described by Albin and Melrose is applied to the conjugation action by the unitary group on self-adjoint matrices. It is shown that the eigenvalues are smooth on the resolved space and that the trivial tautological bundle smoothly decomposes into the direct sum of global one-dimensional eigenspaces. Thesis Supervisor: Richard B. Melrose Title: Simons Professor of Mathematics 3 4 Acknowledgments First and foremost, I would like to express my sincere gratitude to my advisor, Richard Melrose, for introducing me into this field, suggesting interesting problems and pro- viding tremendous support for my Ph.D study and research. His deep insight, patient guidance and encouragement over the years has been invaluable to me. As noted be- low, this thesis is in part joint work with him. I am deeply thankful to Rafe Mazzeo for inspiring discussions, András Vasy for conversations on related problems for future works, Michael Singer for our mathemat- ical discussions and his help along the way, Robin Graham for illuminating comments on the supergravity project and Colin Guillarmou for his interest and comments on this thesis. I would like to thank Victor Guillemin and Tomasz Mrowka for agreeing to serve on my thesis committee and their help during my Ph.D study. I would also like to thank Gigliola Staffilani and David Jerison for their constant support and guidance during my five years at MIT. I am grateful to Fang Wang, Lu Wang, Linan Chen, Michael Eichmair, Chris Kottke, Ailsa Keating, Ting Zhou, Kiril Datchev, Semyon Dyatlov, Shelby Kimmel, Lenore Cowen, Emma Zbarsky, Boris Hanin, Zuoqin Wang and Dean Baskin for being great friends and mentors. To all my other friends here, I wish to express my appreciation for their support. Finally, I would like to thank my family, especially my parents, for their love, understanding and constant encouragement. 5 6 Contents 1 Introduction 11 1.1 Eleven dimensional supergravity theory on edge manifolds . 12 1.2 Resolution of the canonical fiber metrics for a Lefschetz fibration . 18 1.3 Resolution of eigenvalues . 23 2 The eleven dimensional supergravity equations on edge manifolds 27 2.1 Introduction . 27 2.1.1 Equations derived from the Lagrangian . 29 2.1.2 Edge metric and edge Sobolev space . 30 2.1.3 Poincaré–Einstein metric on B7 ................. 31 2.1.4 Main theorem . 32 2.2 Gauged operator construction . 35 2.2.1 Equations derived from Lagrangian . 35 2.2.2 Change to a square system . 37 2.2.3 Gauge condition . 37 2.3 Fredholm property of the linearized operator . 41 2.3.1 Linearization of the operator Q ................. 42 2.3.2 Indicial roots computation . 46 2.3.3 Fredholm property . 52 2.3.4 Large eigenvalues . 54 2.3.5 Individual eigenvalues with 휆 = 0; 16; 40 ............ 58 6 2.3.6 Individual eigenvalues with 휆 = 0; 16; 40 ............ 61 2.3.7 Boundary data for the linear operator . 62 7 2.4 Nonlinear equations: application of the implicit function theorem . 67 2.4.1 Domain defined with parametrization . 68 2.4.2 Regularity of the solution . 72 2.5 Edge operators . 75 2.5.1 Edge vector fields and edge differential operators . 75 2.5.2 Hybrid Sobolev space . 76 2.6 Computation of the indicial roots . 77 2.6.1 Hodge decomposition . 77 2.6.2 Indicial roots . 78 3 Resolution of the canonical fiber metrics for a Lefschetz fibration 87 3.1 The plumbing model . 92 3.2 Global resolution and outline . 98 3.3 Bounds on (훥 + 2)−1 ........................... 100 3.4 Formal solution of (훥 + 2)u = f ..................... 106 3.5 Polyhomogeneity for the curvature equation . 111 4 Group resolution 115 4.1 Introduction . 115 4.2 Proof of the theorem . 117 8 List of Figures 1-1 Degenerating surfaces with a geodesic cycle shrinking to a point . 19 1-2 Lefschetz fibration : M Z ...................... 20 ! 1-3 The metric resolution . 22 2-1 Indicial roots of the linearized supergravity operator on C ...... 48 9 10 Chapter 1 Introduction Microlocal analysis has a lot of applications in partial differential equations and anal- ysis of problems with geometry and physics background. In this thesis, we apply microlocal techniques and the theory of pseudo-differential operators to two problems on noncompact and singular manifolds. The first one is the eleven dimensional su- pergravity equations on edge manifolds for which I give a characterization of all the solutions near the Freund–Rubin solution [47]. The second project, in collaboration with Richard Melrose, we work on the complete expansion of the constant scalar curvature fiber metric in the case of a Lefschetz fibration [31], which arises natu- rally as the singular behavior across the divisors introduced in the Deligne–Mumford compactification of the moduli space of Riemann surfaces. To get information of operators in a singular geometry setting, people study the Schwarz kernel and the behavior of the model operators on the double space. To study the behavior of the kernel and construct parametrices on this double space, blow up action is introduced [34, 32] and this approach has been utilized to solve many geometric problems [35, 26, 27, 24, 44]. The third part of this thesis contains an example of resolutions, which is an application of the resolution of a compact group action on a compact manifold described by Albin and Melrose [1], to the case of U(n) action on self-adjoint matrices [48]. 11 1.1 Eleven dimensional supergravity theory on edge manifolds Supergravity theories arise as the representations of super Lie algebras in various di- mensions. They can be viewed as low energy approximations to string theory with classical equations of motion. In particular, the case of dimension eleven has been studied by physicists since the 1970s [43, 42, 6, 2]. It was shown that there is a unique system in eleven dimensions and the theories in lower dimensions can be ob- tained from it through dimension reduction [37]. Since it is related to the AdS/CFT correspondence and brane dynamics, this subject has recently attracted more atten- tion [3, 45]. We are interested in a particular case, namely, the bosonic sector of eleven dimen- sional supergravity theory. The nonlinear system couples a metric g (gravity) and a 4-form F (extra field), and is derived from a Lagrangian constructed on the eleven dimensional manifold X = B7 S4: × Z 1 Z Z 1 L(g; F ) = RdVg ( F F + A F F ) (1.1) X − 2 X ^ * X 3 ^ ^ where A satisfies dA = F . The first term is the classical Einstein–Hilbert action term, while the second and the third terms are, respectively, of Yang–Mills and Chern- Simons type for a field. The supergravity system, the variational equation for (1.1) is 1 훾1훾2훾3 1 훾1훾2훾3훾4 R훼훽 = (F훼훾 훾 훾 F F훾 훾 훾 훾 F g훼훽) 12 1 2 3 훽 − 12 1 2 3 4 d F = 1 F F (1.2) * − 2 ^ dF = 0: As a special case, there is a family of solutions to the full system given by the product of a scaled spherical metric on S4 and an Einstein metric h on B7 with Ricci curvature satisfying Ric(h) = c2h. The product solutions are given by − 9 g = h g 4 ;F = cdV 4 ; c R: (1.3) × c2 S S 8 2 12 In particular for c = 6 these are known as Freund–Rubin solutions [11] with 1=4 of the standard S4 metric and an Einstein metric on H7. When we restrict the search of solutions to a product metric, the following theorem by Graham–Lee [15] showed that the existence of Poincaré–Einstein solutions near the hyperbolic metric prescribed by data at conformal infinity: Theorem 1.1 ([6]). Let M = Bn+1 be the unit ball and h^ the standard metric on Sn.