# Simons Collaboration on Special Holonomy in Geometry, Analysis and Physics Third Annual Meeting

• Organized by
• Robert Bryant, Ph.D.Duke University
Date & Time

Location

Gerald D. Fischbach Auditorium
160 5th Ave
New York, NY 10010 United States

View Map

Monday August 12, 2019

Participation is by invitation only. All participants must register.

Simons Collaboration on Special Holonomy in Geometry, Analysis and Physics Homepage »

The study of the geometry of higher dimensional spaces, important in many applications, both theoretical and applied, has led to an understanding of their properties in terms of *holonomy*, a way of describing global effects of curvature, and those geometric spaces with constrained (i.e., 'reduced') holonomy have come to play a fundamental role in partial differential equations, algebraic geometry, calculus of variations, topology, and theoretical physics, often revealing surprising connections between these subjects that are yielding new insights in both mathematics and physics.

This annual meeting of the Simons Collaboration on Special Holonomy in Geometry, Analysis, and Physics will highlight and explain the fundamental progress in the theory of spaces with special holonomy that has been made in the first three years of the Collaboration and will describe the goals of our continuing research program as well as the challenges that lie ahead.

• Agenda

#### THURSDAY, SEPTEMBER 12

 8:30 AM CHECK-IN & BREAKFAST 9:30 AM Robert Bryant | An Overview of the Progress and Goals of the Special Holonomy Simons Collaboration 10:30 AM BREAK 11:00 AM Bobby Acharya | Some recent progress in the Physics of Special Holonomy Spaces: Dark matter, Gauge theories and The String Landscape 12:00 PM LUNCH 1:30 PM Simon Donaldson | $$G_2$$ Geometry and Adiabatic Limits 2:30 PM BREAK 2:30 PM Mark Haskins | Recent Developments in Special and Exceptional Holonomy Metrics 4:00 PM BREAK 4:30 PM Johannes Nordstrom | Topology in Special Holonomy 5:30 PM DAY ONE CONCLUDES

#### FRIDAY, SEPTEMBER 13

 8:30 AM CHECK-IN & BREAKFAST 9:30 AM Simon Salamon | Twistor Spaces and Special Holonomy 10:30 AM BREAK 11:00 AM Sakura Schaefer-Nameki | Higgs Bundles and M Theory 12:00 PM LUNCH 1:00 PM Aleksander Doan | From Gauge Theory to Calibrated Geometry and Back 2:00 PM MEETING CONCLUDES
• Abstracts

#### Thursday, September 12

Robert Bryant
An Overview of the Progress and Goals of the Special Holonomy Simons Collaboration

This talk will serve as an introduction to the meeting, including background on the area of special holonomy and an overview of the fundamental existence results, progress made by our collaboration (and others) and what we see as the major goals and challenges in current research in special holonomy.

Bobby Acharya
Some recent progress in the Physics of Special Holonomy Spaces: Dark matter, Gauge theories and The String Landscape

Acharya will survey recent progress in understanding the physics of special holonomy spaces as models for the extra dimensions of space in string/M theory. He will begin by briefly reviewing how special holonomy spaces can aid our understanding of particle physics and cosmology and how recent progress may help shape our picture of the dark sector of the universe. The talk will then go on to apply recent progress on the construction of a class of G2-holonomy spaces as circle bundles over Calabi-Yau’s (Foscolo, Haskins, Nordstrom) to M theory/Type IIA duality and, in particular, to four-dimensional gauge theories. Finally Acharya surveys some recent progress in physics related to the conjecture “stable, compact Ricci flat manifolds have special holonomy” and how it can shape our understanding of the String Landscape.

Simon Donaldson
$$G_2$$ Geometry and Adiabatic Limits

The main focus of the talk will be $$G_2$$ manifolds with co-associative fibrations and in particular the “adiabatic limit” when the fibers become very small and the structure can be described by solutions of a version of the maximal submanifold equation. Donaldson will discuss progress in the development of this theory and prospects for the future. In particular, he will explain the connection with boundary value problems for $$G_2$$ structures and descriptions, in part conjectural, of calibrated submanifolds in the adiabatic limit.

Recent Developments in Special and Exceptional Holonomy Metrics

In this talk, Haskins will give an overview of some of the main recent developments in the construction of metrics with special and exceptional holonomy, concentrating on the progress made by members of the collaboration on resolving some long-standing open questions. He will indicate some of the symbiotic relationships that have developed between the two better understood cases of hyperKaehler 4-manifolds and Calabi-Yau 3-folds, and the more challenging case of 7-manifolds with holonomy $$G_2$$.

One important unifying theme has been the more systematic study of special or exceptional holonomy metrics in either highly collapsed regimes or close to a suitable adiabatic limit: codimension one (circle) collapse of $$G_2$$ holonomy metrics underpins the physical limit where M theory is modeled by Type IIA string theory; collapsed Calabi-Yau metrics with fibers close to flat tori appear in connection with degenerations of complex structure; K3 fibrations of Calabi-Yau 3-folds or coassociative K3 fibrations of $$G_2$$ manifolds with small fiber size also both appear naturally. The latter adiabatic limit will be discussed in more detail in Simon Donaldson’s talk.

Johannes Nordstrom
Topology in Special Holonomy

Nordstrom will discuss what scant information has been available about obstructions to the existence of $$G_2$$-holonomy metrics on closed $$7$$-manifolds and then go on to explain some recent progress on the topology of known and recently constructed examples. Many of these $$7$$-manifolds belong to classes where diffeomorphism classification results have been proved or are within reach, making it possible to map out a portion of the landscape of closed $$G_2$$-manifolds. In particular, we can exhibit phenomena such as homeomorphic, but not diffeomorphic, examples and the non-connectedness of the moduli space of $$G_2$$-metrics on specific $$7$$-manifolds.

#### Friday, September 13th

Simon Salamon
Twistor Spaces and Special Holonomy

Adaptations of Penrose’s twistor theory to the Riemannian setting have played a role in the construction and study of metrics with special holonomy. The original idea was to encode conformal structures by objects from complex and algebraic geometry. After explaining this background, the talk will focus on a circle quotient of a well-known metric with holonomy $$G_2$$ that fibers over the 4-sphere, investigated by Atiyah and Witten in the context of M-theory. The Gibbons-Hawking ansatz reduces the $$G_2$$ space to R^6 endowed with a singular SU(3) structure invariant by a diagonal action of SO(3). The talk will describe some key features of this reduction (obtained jointly with Acharya and Bryant).

Sakura Schaefer-Nameki
Higgs Bundles and M Theory

Schaefer-Nameki develops a systematic way to study the gauge theory sector of M-theory on $$G_2$$-holonomy manifolds in terms of Higgs bundles. The framework is derived from a topological twist of 7d Super-Yang Mills on an associative three-cycle.

Solutions to the BPS equations are studied using Morse-Bott theory and supersymmetric Quantum Mechanics à la Witten. This framework provides a dictionary between the gauge theory data in 4-D and the local $$G_2$$ geometry. As a key application, Schaefer-Nameki develop the Higgs bundles for the twisted connected sum $$G_2$$ manifolds and study the deformations, which yield 4-D chiral matter spectra.

Aleksander Doan
From Gauge Theory to Calibrated Geometry and Back

Twenty years ago, Donaldson and Thomas proposed to define invariants of special holonomy manifolds using the equations of gauge theory. In the first part of Doan’s talk, he will discuss the basic ideas behind this fascinating proposal and survey some recent advances made by the Simons Collaboration. He will then focus on Calabi-Yau manifolds, in particular on a joint project with Thomas Walpuski, whose goal is to define new invariants of Calabi-Yau three-folds using gauge theory and pseudo-holomorphic curves.

• Ground Transportation

For those who are attending the Special Holonomy: Progress and Open Problems meeting at the Simons Center for Geometry and Physics, a shuttle will be available to take participants from Stony Brook to New York City on Wednesday afternoon.

• Travel

#### Air and Train

##### Group A
The foundation will arrange and pay for all air and train travel to the conference for those in Group A. Please provide your travel specifications by clicking the registration link above. If you are unsure of your group, please refer to your invitation sent via email.
##### Group B
The foundation will arrange and pay for hotel only for those in Group B. If you are unsure of your group, please refer to your invitation sent via email.

#### Personal Car

For participants in Groups A & B driving to Manhattan, the Roger Hotel offers valet parking. Please note there are no in-and-out privileges when using the hotel’s garage, therefore it is encouraged that participants walk or take public transportation to the Simons Foundation.
• Hotel

Participants in Groups A & B who require accommodations are hosted by the foundation for a maximum of three nights at The Roger hotel. Any additional nights are at the attendee’s own expense.

The Roger New York
New York, NY 10016
(between 30th and 31st Streets)

• Contacts

Travel and Hotel Assistance
Cecilia Sas, Protravel International
simons.foundation@protravelinc.com
646-747-9304

Registration and General Meeting Assistance
Emily Klein
MPS Event Coordinator, Simons Foundation
eklein@simonsfoundation.org
(646) 751-1262

• Reimbursement and Travel Policy

Any expenses not directly paid for by the Simons Foundation are subject to reimbursement based on the foundation’s travel policy. An email will be sent within a week following the conclusion of the meeting with further instructions on submitting your expenses via the foundation’s web-based expense reimbursement platform.

Receipts are required for any expenses over \$50 USD and are due within 30 days of the conclusion of the meeting. Should you have any questions, please contact Emily Klein.

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