# Effective Theories of Quantum Phases of Matter

Europe/Stockholm
122:026 (Nordita, Stockholm)

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Description

### Venue

Nordita, Stockholm, Sweden

### Scope

Physical systems look different when observed at different resolutions: what appears as a continuum liquid to the naked eye becomes a cluster of jiggling atoms when observed at the resolution of an electron microscope. Effective field theory provides a description of physics in terms of degrees of freedom appropriate to a given resolution. Over the last couple of decades, physicists have developed effective field theory tools which, to a large extent, unify fields as diverse as atomic and condensed-matter physics, particle and nuclear physics, and cosmology. Numerous physical phenomena, first predicted and studied in high-energy physics, have found their realization in novel materials. On the other hand, the richness of condensed-matter physics provides a lasting source of inspiration for new developments in high-energy physics and cosmology. Extremely useful in general, the effective field theory tools become indispensable for quantum phases of matter whose low-energy physics is driven by collective excitations, either due to the presence of spontaneous symmetry breaking or due to strong microscopic interactions.

Despite the common interest in effective field theory techniques, it is rare that experts from different fields come together to share their results, which in some cases are obscured by the jargon particular to each community. This lack of communication sometimes leads to replication of results and increases time spent searching unfamiliar literature when some approach is not well-known in a particular field, even though it might be frequently used in another. This could be greatly improved by providing a common environment where scientists from different disciplines can share their expertise.

This four-week program aims to provide such a meeting ground, to cherish and strengthen interdisciplinary connections between different sub-fields of theoretical physics. We will do so by bringing together practitioners working on effective theories of quantum phases of matter across several branches of physics. Our goal is to map out important open problems with broad relevance and look for new directions towards their solution, to reinvigorate existing collaborations and foster new connections.

### Schedule

[Timetable - available from start of the program]

There will be one to two presentations every day, leaving ample time for informal discussions and collaboration. We plan to cover four main topics, each spanning over roughly one week, with the tentative schedule as outlined below. However, the participants are encouraged to self-organize, welcome to blend the topics, and bring in their own: it is the intention that experts on different branches of physics get to meet each other!

Week 1 (6-10 May 2019): Topology in effective field theories. Topology plays an indispensable role in the effective field theory approach. Topological terms such as Chern-Simons, Wess-Zumino and theta-terms are special because their coefficients are quantized and thus cannot be changed smoothly. This provides a pathway to distinguish (and sometime fully classify) different phases of matter, and the last decade has seen an explosion of new activities directed towards applying topology to quantum phases of matter. In most cases topological terms are tied to quantum anomalies and are responsible for new forms of dissipationless transport. Spin systems and quantum Hall fluids are paradigmatic quantum phases of matter governed by topological terms. More recently these terms have been identified in a wide range of novel systems, from quark-gluon plasma in high-energy physics to topological insulators and Weyl semimetals in condensed-matter physics.

Week 2 (13-17 May 2019): Dualities in effective field theories. A duality relates two theories that at first sight might look unrelated to each other. Since the discovery of the boson-vortex duality, dualities have become a standard tool for development of effective field theories and contributed with deep insights in physics of superconductors, superfluids, quantum Hall fluids and spin liquids. In high-energy physics, exact and approximate dualities have been studied for a long time, especially in the context of supersymmetric theories and string theory. Motivated in part by the developments in condensed-matter physics, new dualities in non-supersymmetric theories have recently attracted considerable interest. In recent years, a number of new dualities involving Dirac fermions have been discovered and their implications are now being thoroughly studied by members of both communities.

Week 3 (20-24 May 2019): Broken symmetry and Nambu-Goldstone bosons. The paradigm of spontaneous symmetry breaking underlies much of our understanding of the fundamental laws of nature. A wave of renewed interest in this classical topic has occurred in the last decade, with particular emphasis on the subtleties of broken symmetries in the nonrelativistic setting. Upon the initial works on classification of Nambu-Goldstone bosons for internal symmetries, the main focus is now gradually shifting towards spacetime symmetries and more detailed properties of Nambu-Goldstone bosons such as their scattering amplitudes. These developments have been of special interest in cosmology, where effective theories of spontaneously broken time translation invariance are used to capture general properties of the cosmological evolution and perturbations.

Week 4 (27-31 May 2019): Interplay of geometry and spacetime symmetries. The role of spacetime geometry in effective theories is yet another exciting avenue of current research. Recent years have seen the discovery of a number of deep relations between various geometric responses (such as the Wen-Zee terms and Hall viscosity) and the electromagnetic response (Hall conductivity). New ideas based on the classical Newton-Cartan geometry have also led to an elegant framework for the construction of effective theories of quantum phases of matter, which respects manifestly nonrelativistic general coordinate invariance. Thursday 30 May 2019 is a public holiday in Sweden.

### Application

Registration to the program is now closed.

### Accommodation

Nordita offers free accommodation to all accepted participants in one of its partner facilities, the default being the Stockholm apartment hotel BizApartments.

Please be aware that unfortunately, scammers sometimes approach participants claiming to be able to provide accommodation and asking for credit card details. Please do not give this information to them. For successful applicants, Nordita will be in touch via email regarding accommodation. If you are in any doubt about the legitimacy of an approach, please get in contact with the organisers.

• Monday, May 6
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Downfall of chiral magnetic wave 1h
Speaker: Shovkovy
• 2:00 PM 3:00 PM
Chiral anomaly and axial gauge fields in Weyl semimetals 1h
Speaker: Vozmediano
• 3:00 PM 3:30 PM
coffee 30m
• Tuesday, May 7
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Transport phenomena due to conformal anomaly 1h
Speaker: Chernodub
• 1:30 PM 2:30 PM
Merons and theta-vacuum effects in the 2-d O(3) model 1h
Speaker: Wiese
• 2:30 PM 3:00 PM
coffee 30m
• 3:00 PM 4:00 PM
Colloquium: Quantum field theory, past, present and future 1h
Speaker: Zee
• Wednesday, May 8
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Classification of topological terms in effective field theories 1h
Speaker: Gripaios
• 2:00 PM 3:00 PM
Beyond the Tenfold Way: Non-Abelian Topology in Noninteracting Metals 1h
Speaker: Bzdusek
• 3:00 PM 3:30 PM
coffee 30m
• 6:00 PM 7:00 PM
reception 1h
• Thursday, May 9
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Fracton-elasticity duality 1h
• 2:00 PM 3:00 PM
Orthogonal fermions: deconfined criticality and Fermi-surface reconstruction with symmetry breaking 1h
Speaker: Gazit
• 3:00 PM 3:30 PM
coffee 30m
• 3:30 PM 4:00 PM
Boundary central charge from bulk Hall viscosity - chiral superfluids 30m
Speaker: Golan
• 4:00 PM 4:30 PM
Theory of diffusive fluctuations 30m
Speaker: Delacretaz
• Friday, May 10
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Effective field theory for rotating QCD matter 1h
Speaker: Yamamoto
• 2:00 PM 3:00 PM
Survival of the quantum anomalous Hall effect in orbital magnetic fields as a consequence of the parity anomaly 1h
Speaker: Hankiewicz
• 3:00 PM 3:30 PM
coffee 30m
• Monday, May 13
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Fixed point collisions and tensorial order parameters in Luttinger semimetals and some popular field theories 1h
Speaker: Herbut
• 2:00 PM 3:00 PM
Dirac fermions and critical phenomena: exponents, emergent symmetries and dualities 1h
Speaker: Scherer
• 3:00 PM 3:30 PM
coffee 30m
• Tuesday, May 14
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Disordered and deconfined: exotic quantum criticality with Dirac fermions 1h
Speaker: Maciejko
• 2:00 PM 3:00 PM
Duality and metallic criticality 1h
Speaker: Mulligan
• 3:00 PM 3:30 PM
coffee 30m
• Wednesday, May 15
• 10:30 AM 11:00 AM
break 30m
• 11:00 AM 12:00 PM
Effective field theories and defects in quantum Hall valley nematics 1h
Speaker: Parameswaran
• 2:00 PM 3:00 PM
Collective modes in FQH phases 1h
Speaker: Gromov
• 3:00 PM 3:30 PM
coffee 30m
• 6:00 PM 7:00 PM
reception 1h
• Thursday, May 16
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Comments on hydrodynamics as an effective theory 1h
Speaker: Pavel Kovtun
• 2:00 PM 3:00 PM
Particle-hole symmetry and composite fermions theories of Jain sequence 1h
Speaker: Nguyen
• 3:00 PM 3:30 PM
coffee 30m
• 3:30 PM 4:00 PM
Dirac Composite Fermions and Emergent Reflection Symmetry about Even Denominator Filling Fractions 30m
Speaker: Goldman
• 4:00 PM 4:30 PM
Duality web from 3D Euclidean Lattice 30m
Speaker: Jun Ho Son
• Friday, May 17
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Quantum particles in a random potential in high dimensions: applications to disordered Dirac equation in 3D 1h
Speaker: Gurarie
• 2:00 PM 3:00 PM
2kF charge density wave quantum critical points in metals 1h
Speaker: punk
• 3:00 PM 3:30 PM
coffee 30m
• Monday, May 20
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Goldstones, or not, in QFT and holography 1h
Speaker: argurio
• 2:00 PM 3:00 PM
Phonons and (visco-)elasticity in holography 1h
Speaker: Pujolas
• 3:00 PM 3:30 PM
coffee 30m
• Tuesday, May 21
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
A modern perspective on Nambu-Goldstone bosons 1h
Speaker: Low
• 2:00 PM 3:00 PM
Classification of Effective Field Theories using Amplitude Methods 1h
Speaker: Kampf
• 3:00 PM 3:30 PM
coffee 30m
• Wednesday, May 22
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Holographic solids at zero temperature 1h
Speaker: Penco
• 2:30 PM 3:00 PM
coffee 30m
• 3:00 PM 4:00 PM
Symmetry Obstruction to Fermi Liquid Behavior at Unitarity 1h
Speaker: Rothstein
• 6:00 PM 7:00 PM
reception 1h
• Thursday, May 23
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Spontaneously broken boost and the Goldstone continuum 1h
Speaker: Nicolis
• 2:00 PM 3:00 PM
The chiral Lagrangian at order $p^8$ 1h
Speaker: Bijnens
• 3:00 PM 3:30 PM
coffee 30m
• 3:30 PM 4:30 PM
Fluctuations in Relativistic Fluids and Hydro+ 1h
Speaker: Misha Stephanov
• Friday, May 24
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
A unified perspective on spacetime symmetry breaking 1h
Speaker: Roest
• 2:00 PM 3:00 PM
An effective theory for elastic scattering of massive Goldstones 1h
Speaker: Esposito
• 3:00 PM 3:30 PM
coffee 30m
• Monday, May 27
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Spontaneous symmetry breaking and Nambu-Goldstone modes in open classical and quantum systems 1h
Speaker: Hidaka
• 2:00 PM 3:00 PM
Holographic phonons and bad metals 1h
Speaker: arean
• 3:00 PM 3:30 PM
coffee 30m
• Tuesday, May 28
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Galilean EFT in Condensed Matter Physics 1h
Speaker: Geracie
• 2:00 PM 3:00 PM
Geometry of QH states on Riemann surfaces 1h
Speaker: Klevtsov
• 3:00 PM 3:30 PM
coffee 30m
• Wednesday, May 29
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Gauging spatial symmetries and the classification of topological crystalline phases 1h
Speaker: Else
• 2:00 PM 3:00 PM
Nambu-Goldstone modes in time-periodic condensates 1h
Speaker: Hayata
• 3:00 PM 3:30 PM
coffee 30m
• 6:00 PM 7:00 PM
reception 1h
• Thursday, May 30
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
Fluctuations in fluid dynamics 1h
Speaker: Schaefer
• 2:00 PM 3:00 PM
Bose gases near zero scattering length 1h
Speaker: Zwerger
• 3:00 PM 3:30 PM
coffee 30m
• 3:30 PM 4:00 PM
Hall viscosity of 3D Lifschitz fermions 30m
Speaker: Copetti
• 4:00 PM 4:30 PM
Goldstone theorem for spontaneously broken spacetime symmetries 30m
Speaker: Kharuk
• Friday, May 31
• 10:30 AM 11:00 AM
coffee 30m
• 11:00 AM 12:00 PM
String theory and nonrelativistic gravity 1h
Speaker: Bergshoeff
• 2:00 PM 3:00 PM
Non-relativistic supersymmetry and supergravity 1h
Speaker: Rosseel
• 3:00 PM 3:30 PM
coffee 30m