An Introduction to Singular Stochastic PDEs.
Allen-Cahn Equations, Metastability, and Regularity Structures

N. Berglund
EMS Press, EMS Series of Lectures in Mathematics (2022)
ISBN: 978-3-98547-014-3
Publisher's website

Contents

1 Introduction 1
1.1 Stochastic partial differential equations 1
1.2 Singular SPDEs 3
1.3 Regularity structures 6
1.4 About this book 7
2 A system of interacting diffusions 13
2.1 Deterministic dynamics 13
2.2 Existence and uniqueness of solutions 16
2.3 Invariant measure and reversibility 17
2.4 Large deviations 19
2.5 Metastability 20
Bibliographical notes 31
3 Allen-Cahn SPDE in one space dimension 33
3.1 Deterministic dynamics 34
3.2 Space-time white noise 37
3.3 The stochastic heat equation 41
3.4 Existence and uniqueness of solutions 47
3.5 Invariant measure 50
3.6 Large devations 54
3.7 Metastability 55
Bibliographical notes 61
4 Allen-Cahn SPDE in two space dimensions 63
4.1 The need for renormalisation 63
4.2 Wick calculus 64
4.3 Existence and uniqueness of solutions 74
4.4 Invariant measure 75
4.5 Large deviations 79
4.6 Metastability 80
Bibliographical notes 84
5 Allen-Cahn SPDE in three space dimensions 87
5.1 Failure of the previous approaches 87
5.2 Perturbation theory for the Gibbs measure 89
5.3 Regularity structures: Introduction 99
5.4 Regularity structures: Algebraic aspects 102
5.5 Regularity structures: Analytic aspects 118
5.6 Existence and uniqueness of solutions 146
5.7 Large deviations 151
Bibliographical notes 155
A Potential theory for reversible Markov chains 157
A.1 First-hitting time and capacity 157
A.2 Dirichlet principle 160
A.3 Thomson principle 161
Bibliographical notes 163
B Hopf algebras 165
B.1 Definition and examples 165
B.2 Group action 169
B.3 Comodules 173
C BPHZ renormalisation 175
C.1 Hepp sectors 176
C.2 Subdivergences 178
C.3 Zimmermann's forest formula 180
C.4 A renormalisation result 182
C.5 Decorated graphs 184
C.6 Other bounds involving singular kernels 185
D Wiener chaos expansion 189
D.1 Hermite polynolials revisited 189
D.2 Wiener chaos 190
D.3 Wick product 192
E Hints and solutions for some exercises 195
E.1 Exercises of Chapter 2 195
E.2 Exercises of Chapter 3 196
E.3 Exercises of Chapter 4 198
E.4 Exercises of Chapter 5 199
References 205
Index 217