Award Abstract # 1953945
Probabilistic and Analytic Aspects of the Loewner Energy

NSF Org: DMS
Division Of Mathematical Sciences
Recipient: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
Initial Amendment Date: April 15, 2020
Latest Amendment Date: May 9, 2022
Award Number: 1953945
Award Instrument: Standard Grant
Program Manager: Tomek Bartoszynski
tbartosz@nsf.gov
 (703)292-4885
DMS
 Division Of Mathematical Sciences
MPS
 Directorate for Mathematical and Physical Sciences
Start Date: July 1, 2020
End Date: June 30, 2023 (Estimated)
Total Intended Award Amount: $172,713.00
Total Awarded Amount to Date: $172,713.00
Funds Obligated to Date: FY 2020 = $172,713.00
History of Investigator:
  • Scott Sheffield (Principal Investigator)
    sheffield@math.mit.edu
  • Yilin Wang (Former Principal Investigator)
Recipient Sponsored Research Office: Massachusetts Institute of Technology
77 MASSACHUSETTS AVE
CAMBRIDGE
MA  US  02139-4301
(617)253-1000
Sponsor Congressional District: 07
Primary Place of Performance: Massachusetts Institute of Technology
77 Massachusetts Avenue
Cambridge
MA  US  02139-4301
Primary Place of Performance
Congressional District:
07
Unique Entity Identifier (UEI): E2NYLCDML6V1
Parent UEI: E2NYLCDML6V1
NSF Program(s): PROBABILITY
Primary Program Source: 01002021DB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s):
Program Element Code(s): 126300
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.049

ABSTRACT

This project concerns research in the areas of probability and complex analysis. The Loewner energy is a quantity measuring the roundness of a simple planar loop. It arises from the asymptotic behaviors of the Schramm-Loewner evolution (SLE), a model of random fractal curves. SLE plays a central role in random conformal geometry and two-dimensional statistical mechanics that study the macroscopic geometry of systems with given information on the microscopic level. Surprisingly, this probabilistically motivated Loewner energy can be described using fundamental concepts from seemingly disparate branches of mathematics and mathematical physics, including geometric function theory, Teichmüller theory, conformal field theory, and string theory. These links suggest deep connections between random conformal geometry and those branches. This research project aims at revealing these connections and exploring how the variety of perspectives around the Loewner energy can bring new insights to probability theory and other fields. The results are expected also to reveal new facets of the mathematical architecture underlying theoretical physics.

The Loewner energy of a Jordan curve is defined as the Dirichlet energy of its driving function via the Loewner differential equation. Finite energy curves can, therefore, be viewed as the Cameron-Martin space of SLE, which has a multiple of Brownian motion as driving function. This definition of both Loewner energy and SLE depends strongly on the parametrization of the curves. However, an equivalent and intrinsic description of the Loewner energy was discovered using determinants of Laplacians and is known to be the Kähler potential of the Weil-Petersson metric on the universal Teichmüller space. This research project first aims to provide similar intrinsic descriptions of SLE loops via the canonical measures on the welding homeomorphisms, then studies generalizations of the Loewner energy to other scenarios involving multi-chords or higher genus surfaces, analytic identities inspired by results from random conformal geometry, and the relation to minimal surfaces in the hyperbolic 3-space.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

Note:  When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

Ang, Morris and Park, Minjae and Wang, Yilin "Large deviations of radial SLE$_{\infty }$" Electronic Journal of Probability , v.25 , 2020 https://doi.org/10.1214/20-EJP502 Citation Details
Wang, Yilin "Large deviations of Schramm-Loewner evolutions: A survey" Probability Surveys , v.19 , 2022 https://doi.org/10.1214/22-PS9 Citation Details

PROJECT OUTCOMES REPORT

Disclaimer

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

The aim of the project was to advance the mathematical understanding of the
analytic and probabilistic aspects of the Loewner energy, in particular, how it
links random conformal geometry, complex analysis and Teichmuller theory. The
project was developed from previous results by Y. Wang (original PI) who showed
the Loewner energy to be the large deviation rate function of SLE0+ and also the
Kahler potential of the Weil-Petersson Teichmuller space. In addition to providing
support for conference travel and for graduate students in this area, the project
resulted in the following mathematical results.
1. A study of the radial SLE_\infty large deviations [1] and an expression for the
 rate function as a geometrically defined quantity associated with foliations on the
 Riemann sphere [3]. These results revealed unexpected symmetries of the rate
 function.
2. A study of the large deviations of SLE0+ [2], confirming conjectures in relating
 the multichordal Loewner energy to determinants of Laplacians and Brownian loop
 measure, which also led to an unexpected link to real rational functions and
 provided a new proof of the Shapiro-Shapiro conjecture on enumerative geometry. 
3. A result relating the Loewner energy to the renormalized energy of moving
 frames on the sphere [5].
4. An identification of a a subclass of Weil-Petersson quasicircles (piecewise
 geodesic Jordan curve) for which both the Loewner driving function and the Kahler
 structure have simple expression. Moreover, this class coincides with the family of
 Jordan curves optimizing the Loewner energy under the constraint of passing
 through given points [6]. We used shear coordinates to describe this class and
 gave characterizations of the Weil-Petersson metric tensor and symplectic form
 in terms of shears [7].
5. A holographic expression of the Loewner energy expressed as a renormalized
 volume in the hyperbolic 3-space.
To disseminate the results obtained from the project and to reach a broader
 readership, a survey paper reviewing the results on various large deviation
 principles of SLE was published [4].
[1] Large deviations of radial SLE infinity
Morris Ang, Minjae Park, Yilin Wang
Electron. J. Probab., Vol. 25, paper no. 102, 1-13 (2020)​

[2] Large deviations of multichordal SLE0+, real rational functions, and zeta-regularized determinants of Laplacians
Eveliina Peltola, Yilin Wang
J. Eur. Math. Soc. (JEMS), published online.

[3] The Loewner-Kufarev energy and foliations by Weil-Petersson quasicircles
Fredrik Viklund, Yilin Wang (submitted)

[4] Large deviations of Schramm-Loewner evolutions: A survey
Yilin Wang
Probability Surveys, vol. 19: 351-403 (2022)

[5] The Loewner Energy via Moving Frames and Surfaces of Finite Renormalised Area Bounding Weil-Petersson Curves
Alexis Michelat, Yilin Wang (submitted)

[6] Piecewise geodesic Jordan curves I: weldings, explicit computations, and Schwarzian derivatives
Don Marshall, Steffen Rohde, Yilin Wang (preprint)

[7] Circle homeomorphisms with square summable diamond shears
Dragomir Saric, Yilin Wang, Catherine Wolfram (submitted)

[8] Universal Liouville action as a renormalized volume and its gradient flow
Martin Bridgeman, Kenneth Bromberg, Franco Vargas Pallete, Yilin Wang (preprint)

 

 


Last Modified: 08/08/2023
Modified by: Scott R Sheffield

Please report errors in award information by writing to: awardsearch@nsf.gov.

Print this page

Back to Top of page