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BEGIN:VEVENT
SUMMARY:Michele Del Zotto (Uppsala)
DTSTART:20220308T150000Z
DTEND:20220308T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/1
DESCRIPTION:Title: Global structures from the infrared\nby Michele Del Zotto (Uppsa
la) as part of Symmetry Seminar\n\n\nAbstract\nQuantum field theories with
identical local dynamics can admit different choices of global structure\
, leading to different partition functions and spectra of extended operato
rs. Recent work has determined the structure of such choices via stringy g
eometric methods for various classes of Lagrangian and non-Lagrangian theo
ries. In this talk I will discuss a purely field theoretical counterpart o
f this analysis\, showing that global structures can be captured from a ca
reful analysis of the infrared Coulomb-like phases. Our results confirm an
d extend the many results obtained within geometric engineering about the
global structures of Argyres-Douglas theories\, 5d SCFTs and 6d SCFTs.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Justin Kaidi (SCGP)
DTSTART:20220315T140000Z
DTEND:20220315T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/2
DESCRIPTION:Title: Kramers-Wannier-like duality defects in (3+1)d gauge theories\nb
y Justin Kaidi (SCGP) as part of Symmetry Seminar\n\n\nAbstract\nI will in
troduce a class of non-invertible topological defects in (3+1)d gauge theo
ries whose fusion rules are the higher-dimensional analogs of those of the
Kramers-Wannier defect in the (1+1)d critical Ising model. As in the lowe
r-dimensional case\, the presence of such non-invertible defects implies s
elf-duality under a particular gauging of the discrete (higher-form) symme
tries. I will illustrate this by means of the examples of SO(3) Yang-Mills
at θ=π\, as well as SU(2)N=4 SYM at τ=i.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ho Tat Lam (MIT)
DTSTART:20220412T150000Z
DTEND:20220412T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/3
DESCRIPTION:Title: Non-invertible Condensation\, Duality and Triality Defects in 3+1d\nby Ho Tat Lam (MIT) as part of Symmetry Seminar\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Du Pei (Harvard)
DTSTART:20220419T150000Z
DTEND:20220419T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/4
DESCRIPTION:Title: On Symmetries of 2d TQFTs and the Equivariant Verlinde Formula\n
by Du Pei (Harvard) as part of Symmetry Seminar\n\n\nAbstract\nIn this tal
k\, we will discuss (generalized) symmetries of 2d semisimple TQFTs. We wi
ll show that\, in a special basis\, the 0-form symmetries always act as pe
rmutations while 1-form symmetries act by phases. This leads to an explici
t description of the gauging of these symmetries. These results can be use
d to better understand compactifications of 6d (2\,0) theories. In particu
lar\, we will use it to generalize the equivariant Verlinde formula to the
case of general Lie groups\, which leads to many predictions for the geom
etry of Hitchin moduli spaces.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ibrahima Bah (JHU)
DTSTART:20220322T150000Z
DTEND:20220322T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/5
DESCRIPTION:by Ibrahima Bah (JHU) as part of Symmetry Seminar\n\nAbstract:
TBA\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ibou Bah (JHU)
DTSTART:20220405T150000Z
DTEND:20220405T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/6
DESCRIPTION:Title: Geometry of decoupled fields\nby Ibou Bah (JHU) as part of Symme
try Seminar\n\n\nAbstract\nAbstract: In this talk I will discuss aspects o
f flipped fields that appear in the engineering of 4d SCFTs from compactif
ications of 6d (1\,0) SCFTs of A_(N-1) type. By studying various ways of
constructing the anomaly polynomial for the 4d theory\, it is possible to
account for flipped fields when the 6d SCFT is compactified on a Riemann s
urface. I will also discuss their geometric origin and their role along t
he RG flow.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Apoorv Tiwari (KTH)
DTSTART:20220426T150000Z
DTEND:20220426T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/7
DESCRIPTION:Title: Topological Holography: Unifying Conventional and Unconventional Qua
ntum Phase Transitions\nby Apoorv Tiwari (KTH) as part of Symmetry Sem
inar\n\n\nAbstract\nIn this talk\, I will describe an approach that uses a
n auxiliary D+1-dimensional topological order\, typically a topological ga
uge theory\, to extract non-perturbative statements about the quantum phas
es and phase transitions realized in D-dimensional quantum systems with a
fixed global symmetry structure. I will exemplify this approach for D=1 an
d for the case where the symmetry structure corresponds to a finite Abelia
n group.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lorenzo di Pietro (Trieste)
DTSTART:20220503T150000Z
DTEND:20220503T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/8
DESCRIPTION:Title: Factorization and Global symmetry in holography\nby Lorenzo di P
ietro (Trieste) as part of Symmetry Seminar\n\n\nAbstract\nBased on 2203.0
9537. In the context of toy models of holography arising from 3d Chern-Sim
ons theory\, I will describe an approach in which\, rather than summing ov
er bulk geometries\, one gauges a one-form global symmetry of the bulk the
ory. This ensures that the bulk theory has no global symmetries\, and it m
akes the partition function on spacetimes with boundaries coincide with th
at of a modular-invariant 2d CFT on the boundary. In particular\, on wormh
ole geometries one finds a factorized answer for the partition function\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dongmin Gang (Seoul)
DTSTART:20220510T150000Z
DTEND:20220510T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/9
DESCRIPTION:Title: Infrared phases of 3D class R theories\nby Dongmin Gang (Seoul)
as part of Symmetry Seminar\n\n\nAbstract\nWe study IR phases of 3D class
R theory associated to closed non-hyperbolic 3-manifolds. Non-hyperbolic 3
-manifolds can be obtained by performing Dehn fillings on 1-cusped hyperb
olic 3-manifolds along exceptional slopes. In 3D-3D correspondence\, the `
exceptional' Dehn filling corresponds to the gauging of an SU(2) flavor sy
mmetry in a superconformal field theory associated to a 1-cusped 3-manifol
d with `small' Chern-Simons levels. With several explicit examples\, we an
alyze various interesting non-perturbative IR phenomena (such as spontan
eous SUSY breaking\, generation of mass gap and supersymmetry enhancement
) from the `exceptional' gaugings. Interestingly\, distinguished featur
es of the IR phases can be captured by simple topological properties of no
n-hyperbolic 3-manifolds. We also find that 3D class R theories associated
to certain classes of atoroidal non-hyperbolic manifolds always exhibit s
upersymmetry enhancement at low energy and actually flow to 3D rank 0 N=4
SCFTs with trivial vacuum moduli space.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ben Gripaios (Cambridge)
DTSTART:20220726T150000Z
DTEND:20220726T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/10
DESCRIPTION:Title: Generalized symmetries of topological field theories\nby Ben Gr
ipaios (Cambridge) as part of Symmetry Seminar\n\n\nAbstract\nI describe j
oint work\, with Oscar Randal-Williams and Joseph Tooby-Smith\, studying g
eneralized symmetries in a simplified arena in which the usual quantum fie
ld theories of physics are replaced with topological field theories and th
e smooth structure with which the symmetry groups of physics are usually e
ndowed is forgotten. Doing so allows many questions of physical interest t
o be answered using the tools of homotopy theory. We study both global and
gauge symmetries\, as well as two types of `t Hooft anomaly. Our approach
also allows some insight into earlier work on symmetries (generalized or
not) of topological field theories.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yunqin Zheng (IPMU)
DTSTART:20220621T150000Z
DTEND:20220621T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/11
DESCRIPTION:by Yunqin Zheng (IPMU) as part of Symmetry Seminar\n\nAbstract
: TBA\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Craig Lawrie (DESY)
DTSTART:20220517T150000Z
DTEND:20220517T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/12
DESCRIPTION:Title: Global Structures in 6d (1\,0) SCFTs and Their Implications for 4d<
/a>\nby Craig Lawrie (DESY) as part of Symmetry Seminar\n\n\nAbstract\nWe
explore the global structure of the global symmetry group across the vast
landscape of 6d (1\,0) SCFTs. Many of the known 6d SCFTs fall into familie
s related by Higgs branch deformations\, where the deformations are associ
ated to either a nilpotent orbit\, or a homomorphism from a finite group i
nto E_8\; we determine how the flavor group can be written simply in terms
of this data. A large class of novel 4d N=2 SCFTs can be obtained by comp
actifying these 6d (1\,0) SCFTs with non-simply-connected flavor group on
a torus in the presence of a topologically non-trivial flat flavor bundle
characterized by a 't Hooft magnetic flux. We explore the properties of th
e resulting 4d theories and highlight where there is overlap with previous
ly studied constructions\, such as class S and the N=2 S-folds.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yichul Choi (Stony Brook)
DTSTART:20220531T150000Z
DTEND:20220531T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/13
DESCRIPTION:Title: Higher Berry Phase of Free Dirac Fermions\nby Yichul Choi (Ston
y Brook) as part of Symmetry Seminar\n\n\nAbstract\nThe infrared fixed poi
nt of a trivially gapped quantum field theory is described by an invertibl
e field theory\, which captures its response to various external backgroun
d fields. The set of background fields can include spacetime-dependent cou
pling constants\, in which case we call the corresponding invertible theor
y a parameterized invertible field theory. The partition function of a par
ameterized invertible field theory is called a higher Berry phase\, as it
captures the response of the theory to the adiabatic variation of the coup
ling constants across spacetime. I'll discuss a class of such parameterize
d invertible field theories arising from free Dirac fermions with spacetim
e-dependent mass parameters. The universal form of the higher Berry curvat
ure will be derived using the APS index theorem\, and an example of a nont
rivial parameterized invertible theory with a vanishing Berry curvature wi
ll be explained.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Irene Valenzuela (CERN)
DTSTART:20220628T140000Z
DTEND:20220628T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/14
DESCRIPTION:Title: What can we learn from the absence of global symmetries?\nby Ir
ene Valenzuela (CERN) as part of Symmetry Seminar\n\n\nAbstract\nIn this t
alk I will explain some of the implications that the absence of global sym
metries can have for the dynamics of the theory. I will review the reasoni
ng behind the absence of global symmetries in quantum gravity\, which is e
quivalent to requiring the absence of non-trivial topologocial operators.
I will then explain how many string theory features can be derived from th
is statement\, including completeness of the charge spectra\, the existenc
e of localised worldvolume degrees of freedom on defects and the presence
of axions.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Theo Johnson-Freyd (Perimeter)
DTSTART:20221004T140000Z
DTEND:20221004T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/15
DESCRIPTION:Title: A 4D TQFT which is not (quite) a gauge theory\nby Theo Johnson-
Freyd (Perimeter) as part of Symmetry Seminar\n\n\nAbstract\nSome people h
ave accused me of proving that every (nice enough) 4D TQFT is equivalent t
o a gauge theory. A version of this statement is true\, but only if your n
otion of "gauge theory" allows dynamical spin structures among the "gauge
fields"\, and some rather complicated terms in the Lagrangian that couple
the spin structures to the other gauge fields. That said\, many of these 4
D TQFTs also admit "dual" descriptions as true gauge theories for higher-f
orm groups. In this talk\, I will explain exactly which 4D TQFTs are equiv
alent to true (higher-group) gauge theories theories\, and present a minim
al counterexample to the belief that all 4D TQFTs are true gauge theories.
\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Maissam Barkeshli (Maryland)
DTSTART:20221011T140000Z
DTEND:20221011T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/16
DESCRIPTION:Title: Defects and higher symmetries in (3+1)D topological phases of matte
r\nby Maissam Barkeshli (Maryland) as part of Symmetry Seminar\n\n\nAb
stract\n(3+1)D topological phases of matter can host interesting classes o
f non-trivial topological defects of varying codimension\, of which the we
ll-known point charges and flux loops are special cases. The complete alge
braic structure of these defects defines a higher category\, and can be vi
ewed as an emergent higher symmetry. This plays an important role both in
the classification of phases of matter and the possible fault-tolerant log
ical operations in quantum error correcting codes. In this talk I will dis
cuss some recent progress in our understanding of the properties of invert
ible defects and higher group symmetries in (3+1)D topological phases of m
atter. Along the way I will review some progress over the past few years i
n characterizing topological phases of matter and their defects in low dim
ensions.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andrea Ferrari (Durham)
DTSTART:20221018T140000Z
DTEND:20221018T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/17
DESCRIPTION:Title: Non-invertible Symmetries and Higher Representation Theory\nby
Andrea Ferrari (Durham) as part of Symmetry Seminar\n\n\nAbstract\nThere h
as recently been a lot of excitement surrounding non-invertible global sym
metries and their potential applications. An important question is how to
systematically construct theories whose non-invertible symmetry categories
we can control well. In this talk I will suggest that higher representati
on theory can help us to answer this question when the symmetries are non-
intrinsically non-invertible. In particular\, I will explain how the topol
ogical defects obtained after gauging finite groups and 2-groups in 3 dime
nsions form the category of 2-representations of the original 2-group\, an
d how this fact can be applied to some gauge theories with disconnected ga
uge groups. The same techniques can be extended to more general higher gro
ups and subgroups in higher dimensions.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Reutter (Hamburg)
DTSTART:20221101T150000Z
DTEND:20221101T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/18
DESCRIPTION:Title: Higher fusion categories and their fusion rings\nby David Reutt
er (Hamburg) as part of Symmetry Seminar\n\n\nAbstract\nHigher fusion cate
gories are certain algebraic gadgets which capture some of the behavior of
topological operators/defects in higher-dimensional quantum field theorie
s. \n\nIn the first part of this talk\, I will give an introduction to the
basic concepts of higher fusion category theory and overview some key exa
mples. If time permits\, I will then explain how every fusion n-category C
has associated `homotopy sets' pi_k C\, defined as a certain quotient of
the set of (k+1)-codimensional operators. I will sketch how these sets pi_
k C carry a kind of fusion ring structure and how in the modular case this
fusion ring structure can be recovered from a higher-dimensional Verlinde
formula.\n\n \n\nThe first part of this talk is based on arXiv:1812.11933
(joint with Christopher Douglas)\, the second part is based on ongoing jo
int work with Theo Johnson-Freyd.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xiao-Gang Wen (MIT)
DTSTART:20221108T150000Z
DTEND:20221108T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/19
DESCRIPTION:Title: A classification of 3+1D topological orders and non-degenerate unit
ary braided fusion 2-category\nby Xiao-Gang Wen (MIT) as part of Symme
try Seminar\n\n\nAbstract\nI will discuss the microscopic definition of to
pological orders in 3d space and its connection with non-degenerate unitar
y braided fusion 2-categories (or unitary fusion 3-categories with trivial
center). Then I will discuss a "physical" classification of 3+1D topolog
ical orders (and non-degenerate unitary braided fusion 2-categories or uni
tary fusion 3-categories with trivial center).\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fiona Burnell (Minnesota)
DTSTART:20221025T140000Z
DTEND:20221025T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/20
DESCRIPTION:Title: Subsystem symmetry protected phases and anomalies in higher-form ga
uge theories\nby Fiona Burnell (Minnesota) as part of Symmetry Seminar
\n\n\nAbstract\nRecent interest in systems with excitations that have sub-
dimensional mobility and conserved higher-multipole moments has motivated
an investigation of models with so-called subsystem symmetry\, in which co
nservation laws apply not to the system as a whole\, but rather to sub man
ifolds within the system\, such as families of lattice planes. I will disc
uss analogs of symmetry protection in these phases\, and its relation to a
nomalies in the corresponding field theoretical description\, which involv
es tensor gauge fields.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Javier Mangan (UPenn)
DTSTART:20221115T150000Z
DTEND:20221115T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/21
DESCRIPTION:Title: Generalized symmetries\, Noether and Weinberg-Witten\nby Javier
Mangan (UPenn) as part of Symmetry Seminar\n\n\nAbstract\nIn this talk we
describe new theorems concerning the mixing of symmetries in QFT. In part
icular\,\nwe show that generalized symmetries cannot be charged under a co
ntinuous global symmetry having a Noether\ncurrent. The results follow fro
m a finer classification of twist operators\, which naturally extends to\n
finite group global symmetries. They unravel topological obstructions to t
he strong version of Noether’s\ntheorem in QFT\, even if under general c
onditions a global symmetry can be implemented locally by twist\noperators
(weak version). We use these results to rederive Weinberg-Witten’s theo
rem within local QFT\,\ngeneralizing it in several directions. We end up d
iscussing the conditions for the strong version to hold\,\ndynamical aspec
ts of QFT’s with non-compact generalized symmetries\, scale vs conformal
invariance in QFT\nand connections with the Coleman-Mandula theorem.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christian Copetti (SISSA)
DTSTART:20221122T150000Z
DTEND:20221122T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/22
DESCRIPTION:Title: Zoology of duality defects: the view from class S\nby Christian
Copetti (SISSA) as part of Symmetry Seminar\n\n\nAbstract\nWe review know
n constructions of non-invertible duality defects for general QFTs and exp
lain their emergence in the context of theories of class S. This leads us
to defining the of "rank" of a non-invertible symmetry. We explain to comp
ute it and its impact the fusion algebra.\n\nBased on upcoming work with A
. Antinucci\, G. Galati and G. Rizi.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Yu (Perimeter)
DTSTART:20221206T150000Z
DTEND:20221206T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/23
DESCRIPTION:Title: Gauging noninvertible surface operators\, and the 2-Deligne theorem
.\nby Matthew Yu (Perimeter) as part of Symmetry Seminar\n\n\nAbstract
\nI will explain a generalization of the notion of an anomaly for a symmet
ry to a noninvertible symmetry enacted by surface operators using the fram
ework of condensation in 2-categories. I will give examples of when we hav
e reasonable control over these anomalies\, and prove theorems about the s
tructure of the 2-category obtained by condensing a suitable algebra objec
t. I will provide examples where the resulting category displays grouplik
e fusion rules and through a cohomology computation\, find the obstruction
to condensing further to the vacuum theory. I will then present the main
result of this work\, which categorifies a theorem of Deligne about the ex
istence of fibre functors for 1-categories. This work was done in collabo
ration with Thibault Decoppet.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fabio Apruzzi (Bern)
DTSTART:20221129T150000Z
DTEND:20221129T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/24
DESCRIPTION:Title: Non-invertible symmetries from holography and branes\nby Fabio
Apruzzi (Bern) as part of Symmetry Seminar\n\n\nAbstract\nGeneralised non-
invertible symmetries have emerged in past year as a new type of symmetry
in d≥ 4 QFTs. This has lead to a new understanding of certain constraint
s on the low-energy dynamics of QFTs\, such as QED\, or the standard model
. In this talk\, I will describe a systematic approach to deriving symmetr
y generators of Quantum Field Theories in holography. Central to this are
the Gauss law constraints in the Hamiltonian quantization of Symmetry Topo
logical Field Theories (SymTFTs)\, which are obtained from supergravity. C
rucially\, we realize the symmetry generators from world-volume theories o
f D-branes in holography. I will particularly focus on non-invertible symm
etries\, by presenting the application of our proposal in the holographic
setup\, dual to 4d N=1 SU(M) or PSU(M) Super-Yang Mills (SYM). In the bran
e-picture\, the fusion of non-invertible symmetries naturally arises from
the Myers effect on D-branes. In addition\, the action of the topological
non-invertible defects t’Hooft on line is modelled by the Hanany-Witten
effect. For SU and PSU SYM\, we also identify the infra-red (IR) 4d field
theory from the dual gravity description\, which describes the domain-wall
s and confining/deconfining behaviour in the IR.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lian Kong (SIQSE\, Southern University of Science and Technology)
DTSTART:20230117T140000Z
DTEND:20230117T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/25
DESCRIPTION:Title: Global Quantum Many-body Theory\nby Lian Kong (SIQSE\, Southern
University of Science and Technology) as part of Symmetry Seminar\n\n\nAb
stract\nThe program of studying the categories of topological orders or qu
antum liquids\, was initiated in 1502.01690 and 1702.00673\, where the not
ion of a morphism between two topological orders (or quantum liquids) was
introduced. This notion is different from the usual definition by a domain
wall but contains the recent idea of Symmetry TFT as special cases. In th
is talk\, I will review this notion and show how it led us immediately to
the so-called boundary-bulk relation\, then to a unified theory of both ga
pped and gapless boundaries of 2+1D topological orders and topological Wic
k rotation 1705.01087\,1905.04924\,1912.01760\, and eventually to a mathem
atical theory of gapped/gapless quantum liquids 2011.02859\, 2107.03858\,
2201.05726\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nathan Seiberg (IAS)
DTSTART:20230124T150000Z
DTEND:20230124T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/26
DESCRIPTION:Title: Symmetries and Anomalies in the Continuum and on the Lattice\nb
y Nathan Seiberg (IAS) as part of Symmetry Seminar\n\n\nAbstract\nBased on
joint work with Meng Cheng (arXiv:2211.12543)\, we will discuss some aspe
cts of global symmetries and their ‘t Hooft anomalies.\nWe will define a
notion of an emanant global symmetry. It is not a symmetry of the UV the
ory\, but unlike emergent (accidental) symmetries\, it is not violated by
any relevant or irrelevant operators in the IR theory. \nWe will present l
attice models with anomalous internal symmetries and see how the anomalies
are diagnosed on the lattice using topological defects.\nWe will also dis
cuss lattice models with anomalous lattice translation and relate them to
an anomalous emanant symmetry in the IR theory. This will connect our dis
cussion to the well-known Lieb-Schultz-Mattis theorem and to filling const
raints like Luttinger theorem.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Clay Cordova (Chicago)
DTSTART:20230214T150000Z
DTEND:20230214T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/27
DESCRIPTION:Title: Neutrino Masses from Generalized Symmetry Breaking\nby Clay Cor
dova (Chicago) as part of Symmetry Seminar\n\n\nAbstract\nWe explore gener
alized global symmetries in theories of physics Beyond the Standard Model.
Models with Z' bosons generically contain `non-invertible' chiral symmetr
ies\, whose presence indicates a natural paradigm to break this symmetry b
y an exponentially small amount in an ultraviolet completion. For example\
, in models of gauged lepton family difference\, there is a non-invertible
lepton number symmetry which protects neutrinomasses. We embed these theo
ries in gauged non-Abelian horizontal lepton symmetries\, e.g SU(3)_H\, w
here the generalized symmetries are broken non-perturbatively by the exist
ence of lepton family magnetic monopoles. In such theories\, either Majora
na or Dirac neutrino masses may be generated through quantum gauge theory
effects from the charged lepton Yukawas. These theories require no bevy of
new fields nor ad hoc additional global symmetries\, but are instead simp
le\, natural\, and predictive: the discovery of a lepton family Z' at low
energies will reveal the scale at which it emerges from a larger gauge sym
metry.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lakshya Bhardwaj (Oxford)
DTSTART:20230131T150000Z
DTEND:20230131T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/28
DESCRIPTION:Title: Non-Invertible Theta Symmetries\nby Lakshya Bhardwaj (Oxford) a
s part of Symmetry Seminar\n\n\nAbstract\nIt is by now well-known that the
symmetries of a d-dimensional quantum field theory form a fusion (d-1)-ca
tegory. This contains a fusion 1-category piece formed by genuine topologi
cal line operators and non-genuine topological local operators which is ex
tremely well understood both physically and mathematically. This talk will
discuss recent physical and mathematical understandings of a fusion 2-cat
egory piece formed by genuine topological surface operators and non-genuin
e topological line & local operators\, which contains within it the above
fusion 1-category piece. For simplest physical constructions\, the fusion
2-category can be identified with the 2-category formed by 2-representatio
ns of a finite group G. We will discuss the mathematical definition of 2-r
epresentations and provide a simple universal physical reasoning for their
appearance: namely that any QFT that can be obtained by gauging a 0-form
symmetry group G contains dual non-invertible symmetries described by surf
ace operators labeled by 2-representations of G. We refer to such universa
l symmetries as theta symmetries because they generalize the notion of the
ta angle. We will then proceed to discuss the inclusion of non-universal s
ymmetries that depend on the specifics of the QFT under consideration. We
will see that the physical reasoning involved in the discussion of univers
al theta symmetries will continue to play a major role also for non-univer
sal symmetries\, leading to the notion of "twisted theta symmetries". Many
interesting physical phenomena like symmetry fractionalization on condens
ation defects will be encountered. Towards the end of the talk\, we will b
riefly discuss the generalization of these studies to fusion 3-categories
and higher. This involves various physical and mathematical subtleties hav
ing to do with the fact that TQFTs in spacetime dimension bigger than two
form an extremely rich mathematical structure.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Emily Nardoni (Kavli IPMU)
DTSTART:20230221T140000Z
DTEND:20230221T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/29
DESCRIPTION:Title: Probing Anomalies of Non-Invertible Symmetries with Symmetry TFTs\nby Emily Nardoni (Kavli IPMU) as part of Symmetry Seminar\n\nAbstract:
TBA\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Miguel Montero (Madrid)
DTSTART:20230228T150000Z
DTEND:20230228T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/30
DESCRIPTION:Title: The Chronicles of IIBordia\nby Miguel Montero (Madrid) as part
of Symmetry Seminar\n\n\nAbstract\nWe will embark on a journey through the
realms of cobordism groups in IIB string theory\, taking into account the
duality symmetry of the theory. These cobordism groups are interesting be
cause they can be used systematically to predict new generalized symmetrie
s of IIB supergravity and the corresponding objects that break them in IIB
string theory. In this way we are able to recover many known branes and a
few unknown ones. We will describe some particularly interesting examples
\, discuss the connection to topological couplings and anomalies in IIB st
ring theory\, and time permitting\, I will comment on the likely fate of n
on-invertible symmetries in quantum gravity.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Zohar Komargodski (SCGP)
DTSTART:20230321T150000Z
DTEND:20230321T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/31
DESCRIPTION:Title: Line Operators\, RG Flows\, and One-Form Symmetry\nby Zohar Kom
argodski (SCGP) as part of Symmetry Seminar\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wenjie Ji (UCSB)
DTSTART:20230328T140000Z
DTEND:20230328T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/32
DESCRIPTION:Title: Recent progress in the symmetry/topological order correspondence\nby Wenjie Ji (UCSB) as part of Symmetry Seminar\n\n\nAbstract\nIn this
talk\, we discuss some recent progress in the symmetry/topological order c
orrespondence. The correspondence basically says that topological aspects
of a discrete symmetry in d dimensions are captured by topological data in
a topological order in d+1 dimensions. The topological aspects of symmetr
y include but are not limited to symmetry charges\, defects\, their fusion
rules as well as commutation relations. We will discuss (1) how a beyond-
Landau transition is solved using the correspondence (arXiv: 2205.06244) a
nd (2) in practice how we derive a topological order for a given symmetry
in a 1+1d conformal field theory (arXiv:2106.02069). For the latter\, two
cases are particularly interesting: (i) when the symmetry is anomalous\, (
ii) after the CFT is matched with a topological order\, there is a further
symmetry that enriches the topological order. If time allowed\, we discus
s the similarities and relations of our setting with that proposed by Free
d\, Moore\, and Teleman.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Brennan (UCSD)
DTSTART:20230404T140000Z
DTEND:20230404T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/33
DESCRIPTION:Title: Coupling a Cosmic String to a TQFT\nby Daniel Brennan (UCSD) as
part of Symmetry Seminar\n\n\nAbstract\nIn this talk we will study a mode
l that couples axion-Maxwell theory to a TQFT. Here\, we will show that th
ere are phenomenological consequences of this coupling and leave potential
ly measurable effects from the cosmological evolution of our universe.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pavel Putrov (ICTP)
DTSTART:20230411T140000Z
DTEND:20230411T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/34
DESCRIPTION:Title: Non-invertible symmetries and mixed gravitational anomalies\nby
Pavel Putrov (ICTP) as part of Symmetry Seminar\n\n\nAbstract\nIn my talk
I will describe how a presence of a mixed anomaly between a global symmet
ry and gravity can be traded off for non-invertibility of the charge opera
tors. Specifically\, I will consider the cases of U(1) and Z4 symmetries (
which include fermion parity) in 4d. I will also comment on the relevance
for the Standard Model. The talk is based on a joint work with Juven Wang.
\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ruben Verresen (Harvard)
DTSTART:20230509T140000Z
DTEND:20230509T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/35
DESCRIPTION:Title: Higgs condensates are symmetry-protected topological phases: from c
luster states to superconductors\nby Ruben Verresen (Harvard) as part
of Symmetry Seminar\n\n\nAbstract\nDeconfined phases of gauge theories are
now well-understood as spontaneously breaking higher-form symmetries. How
does the Higgs phase fit in this way of thinking? In this talk\, we will
explore how the Higgs phase does not just preserve such a higher-form symm
etry\, but is in a non-trivial symmetry-protected topological (SPT) phase.
This sheds new light on the distinction between confined and Higgs phases
. In fact\, the remarkable properties of superconductors---which are Higgs
phases for U(1) gauge theory---can be derived as SPT properties! This is
based on the works arxiv:2010.00607\, arxiv:2211.01376 and arxiv:2303.0813
6.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Clement Delcamp (Ghent)
DTSTART:20230516T140000Z
DTEND:20230516T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/36
DESCRIPTION:Title: Higher categorical symmetries and gauging on the lattice\nby Cl
ement Delcamp (Ghent) as part of Symmetry Seminar\n\n\nAbstract\nHigher ca
tegorical symmetries have received widespread attention in recent years. T
hough exotic\, such generalised symmetries have been shown to naturally ar
ise as dual symmetries upon gauging invertible symmetries. Given an arbitr
ary two-dimensional lattice model with an ordinary symmetry\, I will prese
nt an approach to perform the (twisted) gauging of any of its sub-symmetri
es and study the resulting symmetry structure. Specialising to certain fin
ite group generalisations of the (2+1)d transverse-field Ising model\, I w
ill explicitly construct lattice symmetry operators organised into fusion
2-categories of higher representations of higher groups.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gregory Moore (Rutgers)
DTSTART:20230523T140000Z
DTEND:20230523T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/37
DESCRIPTION:Title: Finite Symmetries Of Field Theories From TQFT\nby Gregory Moore
(Rutgers) as part of Symmetry Seminar\n\n\nAbstract\nI will review some a
spects of the paper ``Topological Field Theory In Quantum Field Theory\,''
written with Dan Freed and Constantin Teleman. I will review some aspects
of finite homotopy theories\, which form the main source of examples in t
he paper\, and attempt to give a talk complementary to the several excelle
nt talks by Freed and Teleman already available online.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simone Giacomelli (Milano)
DTSTART:20230502T140000Z
DTEND:20230502T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/38
DESCRIPTION:Title: Comments on Non-invertible Symmetries in Argyres-Douglas Theories\nby Simone Giacomelli (Milano) as part of Symmetry Seminar\n\n\nAbstrac
t\nIn this seminar I discuss the presence of non-invertible symmetries in
an infinite family of superconformal Argyres-Douglas theories. This class
of theories arises from diagonal gauging of the flavor symmetry of a colle
ction of multiple copies of D_p(SU(N)) theories. The same set of theories
that we study can also be realized from 6d N=(1\,0) compactification on a
torus. The main example in this class is the (A_2\, D_4) theory\, which be
ars the same structures of non-invertible duality and triality defects as
those of N=4 super Yang-Mills with gauge algebra su(2). This result extend
s to infinitely many other Argyres-Douglas theories in the same family\, i
ncluding those with central charges a=c whose conformal manifold is one di
mensional\, and those with a\\neq c whose conformal manifold has dimension
larger than one. This conclusion is supported by examining certain specia
l cases that can be realized in terms of theories of class S.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andrea Antinucci (Sissa)
DTSTART:20230919T140000Z
DTEND:20230919T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/39
DESCRIPTION:Title: Anomalies of non-invertible self-duality symmetries: fractionalizat
ion and gauging"\nby Andrea Antinucci (Sissa) as part of Symmetry Semi
nar\n\n\nAbstract\nAnomalies of global symmetries are important tools for
constraining the dynamics of QFTs\, hence their generalization to non-inve
rtible symmetries is clearly important. Their definition and classificatio
n\, however\, are still puzzling. In this talk\, I will argue that definin
g anomalies as obstructions to gauging makes them computable using symmetr
y topological field theory (SymmTFT). I will focus on duality defects\, ar
ising in d=2n dimensional theories self-dual under gauging a finite abelia
n n-1 form symmetry. For d=2\, the classification of anomalies was already
known in the mathematical literature\, and I will demonstrate how to repr
oduce these results with techniques easily generalizable to higher dimensi
ons. In any dimension\, we find two obstructions to gauging. The first ind
icates that intrinsically non-invertible symmetries are always anomalous.
When this obstruction vanishes\, a second one can emerge\, linked to a pur
e anomaly in the global variant where the duality defect is invertible. Ca
lculating this requires extra data\, which I will argue corresponds to a c
hoice of symmetry fractionalization. Based on joint work (2308.11707) with
F. Benini\, C. Copetti\, G. Galati\, G. Rizi.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sal Pace (MIT)
DTSTART:20230926T140000Z
DTEND:20230926T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/40
DESCRIPTION:Title: Emergent generalized symmetries in ordered phases and their spontan
eous breaking.\nby Sal Pace (MIT) as part of Symmetry Seminar\n\n\nAbs
tract\nBased on recent work (arXiv:2308.05730) and upcoming work with Chen
chang Zhu\, Agnès Beaudry\, and Xiao-Gang Wen\, we will discuss (non-)inv
ertible higher-form symmetries that emerge in generic ordered phases and t
heir physical consequences. Such phases arise from spontaneously breaking
an ordinary symmetry G down to a subgroup H\, are described in the deep IR
by a nonlinear sigma model with target space G/H\, and are ubiquitous to
condensed matter and high energy physics. We will focus on two aspects of
this story: (1) when the generalized symmetry is finite\, the fusion highe
r category describing its symmetry defects\, and (2) its spontaneous break
ing\, which drives a phase transition to a nontrivial disordered phase wit
h (non-)abelian topological orders and emergent photons. We will present e
xamples for different groups G and H and construct lattice and continuum m
odels that realize the generalized symmetry's spontaneous symmetry-breakin
g phases.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kantaro Ohmori (Tokyo)
DTSTART:20231024T130000Z
DTEND:20231024T140000Z
DTSTAMP:20260404T110912Z
UID:SymSem/41
DESCRIPTION:Title: Non-supersymmetric Heterotic Branes\nby Kantaro Ohmori (Tokyo)
as part of Symmetry Seminar\n\n\nAbstract\nThe completeness conjecture sta
tes that a consistent quantum gravity theory contains dynamical objects be
aring all conceivable charges. McNamara and Vafa proposed that such charge
s can be classified by bordism classes in the operational EFT\, which indi
cates that there may be several yet-to-be-identified branes within string
theory. In this talk\, I will elucidate some of these charges as they pert
ain to heterotic string theories and subsequently explore potential worlds
heet descriptions of strings proximate to the corresponding branes.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Meng Cheng (Yale)
DTSTART:20231031T150000Z
DTEND:20231031T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/42
DESCRIPTION:Title: A defective look at quantum phases of matter\nby Meng Cheng (Ya
le) as part of Symmetry Seminar\n\n\nAbstract\nI will discuss recent devel
opments in the classification and characterization of phases of matter in
quantum many-body systems\, through the lens of topological defects of glo
bal symmetry. In the first part\, I will review how gapped phases with spa
tial symmetries can be understood using networks of background defects\, a
nd apply the construction to derive topological boundary states of (4+1)d
"beyond-cohomology" SPT phases. The second part will discuss topological p
hases in condensed matter systems with quenched disorder. Viewing disorder
ed phases as ensembles of defects\, I will describe a classification schem
e of disordered topological phases with exact and average symmetries.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/42/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marieke van Beest (SCGP)
DTSTART:20231003T140000Z
DTEND:20231003T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/43
DESCRIPTION:Title: Monopoles\, Scattering\, and Generalized Symmetries\nby Marieke
van Beest (SCGP) as part of Symmetry Seminar\n\n\nAbstract\nI will discus
s the problem of electrically charged\, massless fermions scattering off m
agnetic monopoles. The interpretation of the outgoing states has long been
a puzzle\, as they can carry fractional quantum numbers. We argue that su
ch outgoing particles live in the twisted sector of a topological co-dimen
sion 1 surface\, which ends topologically on the monopole. This surface is
in general noninvertible\, and as such the outgoing radiation not only ca
rries unconventional flavor quantum numbers\, but is trailed by a topologi
cal field theory\, which is a new prediction.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/43/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kansei Inamura (Tokyo)
DTSTART:20231017T140000Z
DTEND:20231017T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/44
DESCRIPTION:Title: Fusion surface models: 2+1d lattice models from fusion 2-categories
\nby Kansei Inamura (Tokyo) as part of Symmetry Seminar\n\n\nAbstract\
nWe will discuss a systematic way to construct (2+1)-dimensional lattice m
odels with finite generalized symmetries described by fusion 2-categories.
These models are 2+1d analogues of the 1+1d anyon chain models and are du
bbed fusion surface models. We will also see that our models naturally ari
se from 4d topological field theories put on a slab. Examples of fusion 2-
categories include modular tensor 1-categories that describe the symmetrie
s generated by anyons. Thus\, the fusion surface models with such symmetri
es may provide natural candidates for chiral topological phases on the lat
tice.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/44/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shu-Heng Shao (Stony Broook)
DTSTART:20231010T140000Z
DTEND:20231010T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/45
DESCRIPTION:Title: Non-invertible lattice translation\nby Shu-Heng Shao (Stony Bro
ook) as part of Symmetry Seminar\n\n\nAbstract\nI will discuss non-inverti
ble symmetries in 1+1d lattice models with a tensor-product Hilbert space\
, including the transverse-field Ising model and its deformation. The Kram
ers-Wannier duality operator on the lattice mixes with the lattice transla
tion\, and obeys a different non-invertible algebra compared to the contin
uum one.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/45/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ryan Thorngren (UCLA)
DTSTART:20231107T170000Z
DTEND:20231107T180000Z
DTSTAMP:20260404T110912Z
UID:SymSem/46
DESCRIPTION:Title: NOTE UNUSUAL TIME: The Symmetry Breaking Long Exact Sequence\nb
y Ryan Thorngren (UCLA) as part of Symmetry Seminar\n\n\nAbstract\nFractio
nal or anomalous degrees of freedom at domain walls and vortices have been
an important topic in physics for 50 years. In this talk\, we will look a
t these localized modes from a new point of view\, and study the matching
problem between them and the gapped bulk modes. We will touch on recent id
eas like higher Berry phase and discuss an interacting version of the Call
ias index theorem. The talk is based on the work of my wonderful collabora
tors\, Arun Debray\, Sanath K. Devalapurkar\, Cameron Krulewski\, Yu Leon
Liu\, and Natalia Pacheco-Tallaj\, which you can find here https://arxiv.o
rg/abs/2309.16749 .\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/46/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rajath Radhakrishnan (ICTP Trieste)
DTSTART:20231121T150000Z
DTEND:20231121T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/47
DESCRIPTION:Title: Constraints on non-invertible symmetries in 2+1D\nby Rajath Rad
hakrishnan (ICTP Trieste) as part of Symmetry Seminar\n\n\nAbstract\nIn th
is talk\, I will discuss some constraints on non-invertible symmetries imp
lemented by surface operators in 2+1D QFTs. I will first consider abelian
TQFTs and argue that non-invertible surface operators exist if and only if
there are bosonic line operators. I will then discuss an extension of thi
s result to non-abelian TQFTs. This implies that all condensation defects
are invertible in a TQFT without bosonic line operators. I will give an in
dependent argument for this result using higher-gauging of line operators.
Finally\, I will discuss some implications for general 2+1D QFTs. This ta
lk is based on the paper https://arxiv.org/abs/2309.15181 with Matthew Bui
can.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/47/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xie Chen (Caltech)
DTSTART:20231128T150000Z
DTEND:20231128T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/48
DESCRIPTION:Title: Sequential circuit as string operator for topological defects\n
by Xie Chen (Caltech) as part of Symmetry Seminar\n\n\nAbstract\nBosonic p
oint charge excitations in 3+1D topological phases can condense along a li
ne and form a descendant defect called the Cheshire string. Unlike the ele
mentary flux loop excitations in the system\, Cheshire strings do not have
to appear as the boundary of a 2D disc and can exist on open-line segment
s. On the other hand\, Cheshire strings are different from trivial excitat
ions that can be created with either local unitaries in 0d or finite depth
quantum circuits in 1d and higher. In this talk\, we show that to create
a Cheshire string\, one needs the Sequential Quantum Circuit -- a linear d
epth circuit that acts sequentially along the length of the string. Once a
Cheshire string is created\, its deformation\, movement\, and fusion can
be realized by finite depths circuits. Quantum circuits hence provide a wa
y to define equivalence classes of gapped topological defects\, giving ri
se to an operational meaning of the higher category description of topolog
ical orders in 3+1D or higher.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/48/
END:VEVENT
BEGIN:VEVENT
SUMMARY:No Symmetry Seminar
DTSTART:20231114T150000Z
DTEND:20231114T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/49
DESCRIPTION:by No Symmetry Seminar as part of Symmetry Seminar\n\nAbstract
: TBA\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/49/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ryohei Kobayashi (Maryland)
DTSTART:20231205T150000Z
DTEND:20231205T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/50
DESCRIPTION:Title: Higher-group symmetry of (3+1)D Z2 gauge theory and non-Clifford lo
gical gates of toric codes\nby Ryohei Kobayashi (Maryland) as part of
Symmetry Seminar\n\n\nAbstract\nIt has recently been understood that the c
omplete global symmetry of topological gauge theories contains the structu
re of a higher-group. In this talk\, we look at the higher-group structure
of symmetry in (3+1)D Z2 gauge theory with an emergent fermion\, and poin
t out that pumping chiral p+ip topological states gives rise to a Z8 0-for
m symmetry with mixed gravitational anomaly. This ordinary symmetry mixes
with the other higher symmetries to form a 3-group structure\, which we di
scuss in detail. \nWe then see that in the context of stabilizer quantum c
odes\, one can obtain various logical non-Clifford gates of (3+1)D Z2 tori
c code (w/ emergent fermion) including the CCZ\, CS and T gates\, which ar
e all implemented by pumping a p+ip topological state through a 3d space.\
nThe talk is mainly based on a recent work with Maissam Barkeshli and Po-S
hen Hsin\, which is found in https://arxiv.org/abs/2311.05674 .\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/50/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nat Tantivasadakarn (Caltech)
DTSTART:20240116T150000Z
DTEND:20240116T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/51
DESCRIPTION:Title: Non-invertible SPT order in a group-based cluster state\nby Nat
Tantivasadakarn (Caltech) as part of Symmetry Seminar\n\n\nAbstract\nThe
one-dimensional cluster state is a paradigmatic example of a symmetry-prot
ected topological (SPT) state protected by Z2xZ2 symmetry in 1+1D. I will
show that a generalization of the cluster state to finite groups is an exa
mple of an SPT state protected by a non-invertible GxRep(G) symmetry\, bel
onging to a distinct phase from the symmetric product state. In this examp
le\, the signatures of SPT phases: protected edge modes\, string order par
ameters\, and topological response can be naturally generalized. Along the
way\, I will highlight the deep relation between the cluster state and ga
uging (the Kramers-Wannier transformation)\, the generalization of the Pau
li matrices from the group Z2 to finite groups\, and the power of tensor n
etworks to express microscopic realizations of non-invertible symmetries.
This talk is based on arXiv:2312.09272\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/51/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Riccardo Argurio (Brussels)
DTSTART:20240130T150000Z
DTEND:20240130T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/52
DESCRIPTION:Title: Spontaneous non-invertible symmetry breaking\nby Riccardo Argur
io (Brussels) as part of Symmetry Seminar\n\n\nAbstract\nGiving (almost) f
or granted the motivation for generalized symmetries\, and spontaneous sym
metry breaking\, we focus on the latter phenomenon for non-invertible symm
etries. These can be further distinguished in discrete\, rational and cont
inuous\, each case leading to different physics upon breaking. We first re
view the case of discrete axial/R-symmetry\, analyzing both supersymmetric
and non-supersymmetric cases. We then consider the case of duality and tr
iality symmetries\, and how they can be broken at the end of an RG flow. W
e finally consider the peculiar case of continuous non-invertible Nambu-Go
ldstone bosons\, that parametrize an orbifold. The talk is based on result
s from https://arxiv.org/abs/2305.17084\, https://arxiv.org/abs/2306.01414
\, https://arxiv.org/abs/2309.06491.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/52/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Giovanni Rizi (SISSA)
DTSTART:20240123T150000Z
DTEND:20240123T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/53
DESCRIPTION:Title: Non-Invertible Symmetries in Calabi-Yau Conformal Field Theories\nby Giovanni Rizi (SISSA) as part of Symmetry Seminar\n\n\nAbstract\nI w
ill discuss non-invertible symmetries arising in 2d superconformal field t
heories corresponding to Calabi-Yau non linear sigma models. Our approach
begins from a particularly symmetric point in the conformal manifold of th
e theory\, the Gepner point. Here we are able to study in detail the super
symmetric topological defect lines and show that many exactly marginal def
ormations preserve a subcategory of the symmetry at the Gepner point. This
construction provides examples of continuous families of irrational (and
interacting) CFTs with non-invertible symmetries. Finally I will discuss s
ome of the constraints those symmetries imply on correlation functions.\n\
nBased on 2312.17308 with Clay Córdova.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/53/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lea Bottini (Oxford)
DTSTART:20240206T150000Z
DTEND:20240206T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/54
DESCRIPTION:Title: Gapped phases and phase transitions from the SymTFT\nby Lea Bot
tini (Oxford) as part of Symmetry Seminar\n\n\nAbstract\nThe symmetry topo
logical field theory (SymTFT) has emerged in the past years as a key tool
to study generalized symmetries. In this talk\, I will explain how we can
use it to determine gapped infra-red phases of 2d theories that have a sym
metry S\, which in general is non-invertibile. Moreover\, I will introduce
a generalization of the usual SymTFT framework that is useful to characte
rize phase transitions between such gapped phases. The SymTFT also manifes
tly encodes the order parameters for the phases\, thus providing a general
ized version of the Landau paradigm for categorical symmetries.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/54/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Zhengdi Sun (UCLA)
DTSTART:20240213T150000Z
DTEND:20240213T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/55
DESCRIPTION:Title: Self-duality under gauging non-invertible symmetries in 2d CFT\
nby Zhengdi Sun (UCLA) as part of Symmetry Seminar\n\n\nAbstract\nIt is we
ll-known that a QFT which is self-dual under gauging invertible symmetries
generically admits a non-invertible duality defect (e.g. Kramers-Wannier
duality defect in 2d Ising CFT). In this talk\, we will discuss the self-d
uality under gauging non-invertible symmetries in 2d CFT based on the work
[arXiv:2310.19867]. We will first use the symmetry $Rep(H_8)$ as an examp
le to demonstrate how to gauge non-invertible symmetries in 2d CFT\, and t
hen report some examples of self-duality under gauging $Rep(H_8)$. Finally
\, we describe the fusion categories containing the new duality defect ari
sing from the self-duality under gauging $Rep(H_8)$.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/55/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Max Hubner (UPenn)
DTSTART:20240220T150000Z
DTEND:20240220T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/56
DESCRIPTION:Title: On the Holographic Dual of a Topological Symmetry Operator\nby
Max Hubner (UPenn) as part of Symmetry Seminar\n\n\nAbstract\nIn the conte
xt of the AdS/CFT correspondence\, we study the holographic dual of a topo
logical symmetry operator. We argue that the bulk counterpart of such an o
perator has a non-topological worldvolume action\, i.e.\, it describes a d
ynamical object. Our argument will be bottom up\, without reference to a t
op down construction\, and rely on smearing properties of entanglement wed
ge reconstruction and holographic RG flows. Further\, we will compare to e
arlier work by Harlow and Ooguri on the absence of global symmetries in as
ymptotically AdS spacetimes. Finally\, we comment on stringy versions of v
arious results. This talk is based on joint work with J. J. Heckman and C.
Murdia.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/56/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lukasz Fidkowski (Seattle)
DTSTART:20240227T150000Z
DTEND:20240227T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/57
DESCRIPTION:Title: Quantum cellular automata and quantum phases of matter\nby Luka
sz Fidkowski (Seattle) as part of Symmetry Seminar\n\n\nAbstract\nWe will
show how quantum cellular automata (QCA)\, which originated in quantum inf
ormation theory\, appear naturally in the study of symmetry protected topo
logical (SPT) phases of matter. Specifically\, they appear when one studi
es these phases in the "condensed matter" or "many-qubit model" context\,
i.e. in a Hamiltonian formalism with a tensor product Hilbert space of fin
ite dimensional site Hilbert spaces. We will connect these ideas to conti
nuum field theory notions\, and will endeavor to make the talk accessible
to high energy and low energy theorists alike.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/57/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matt Reece (Harvard)
DTSTART:20240305T150000Z
DTEND:20240305T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/58
DESCRIPTION:Title: Instanton Number as a Symmetry\nby Matt Reece (Harvard) as part
of Symmetry Seminar\n\n\nAbstract\nGauge theories in d dimensions have a
(d-5)-form generalized global symmetry whose conserved charge is instanton
number. In quantum gravity\, we expect such symmetries to always be gauge
d or explicitly broken. I will discuss examples of how both can happen: ga
uging via Chern-Simons terms or (in 4d) massless fermions\, and explicit b
reaking via magnetic monopoles (in both abelian and nonabelian gauge theor
ies). In the case d=4\, instanton number symmetry is a “(-1)-form U(1) s
ymmetry\,” a somewhat degenerate case. I will discuss several closely an
alogous properties of the cases d=4 and d>4\, to argue that we should take
the notion of (-1)-form symmetry seriously. I will comment on some implic
ations of this perspective for the Strong CP problem. This talk will draw
on multiple papers\, including https://arxiv.org/abs/2012.00009 with Ben H
eidenreich\, Jake McNamara\, Miguel Montero\, Tom Rudelius\, and Irene Val
enzuela\; https://arxiv.org/abs/2105.09950 with JiJi Fan\, Katie Fraser\,
and John Stout\; https://arxiv.org/abs/2402.00117 with Daniel Aloni\, Edua
rdo García-Valdecasas\, and Motoo Suzuki\; and other work in progress.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/58/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chong Wang (PI)
DTSTART:20240312T150000Z
DTEND:20240312T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/59
DESCRIPTION:Title: Mixed-state quantum anomaly and multipartite entanglement\nby C
hong Wang (PI) as part of Symmetry Seminar\n\n\nAbstract\nQuantum entangle
ment measures of many-body states have been increasingly useful to charact
erize phases of matter. In this talk I will explore a surprising connectio
n between mixed state entanglement and 't Hooft anomaly. More specifically
\, we consider lattice systems in d space dimensions with anomalous symmet
ry G where the anomaly is characterized by an invariant in group cohomolog
y. We show that any mixed state ρ that is strongly symmetric under G\, in
the sense that Gρ~ρ\, is necessarily (d+2)-nonseparable\, i.e. is not t
he mixture of tensor products of (d+2) states in the Hilbert space. Furthe
rmore\, such states cannot be prepared from any (d+2)-separable states usi
ng finite-depth local quantum channels\, so the nonseparability is long-ra
nged in nature. We provide proof of these results in d<2\, and plausibilit
y arguments in higher dimensions. The anomaly-nonseparability connection
thus allows us to generate simple examples of mixed states with nontrivial
long-ranged multipartite entanglement\, even in d=1.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/59/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shota Komatsu (CERN)
DTSTART:20240326T150000Z
DTEND:20240326T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/60
DESCRIPTION:Title: Non-Invertible Symmetries\, Anomalies and Scattering Amplitudes
\nby Shota Komatsu (CERN) as part of Symmetry Seminar\n\n\nAbstract\nWe sh
ow that crossing symmetry of S-matrices is modified in certain theories wi
th non-invertible symmetries or anomalies. Focusing on integrable flows to
gapped phases in two dimensions\, we find that S-matrices derived previou
sly from the bootstrap approach are incompatible with non-invertible symme
tries along the flow. We present consistent alternatives\, which however v
iolate standard crossing symmetry and obey modified rules dictated by fusi
on categories. We extend these rules to theories with discrete anomalies.\
n
LOCATION:https://stable.researchseminars.org/talk/SymSem/60/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sahand Seifnashri (IAS)
DTSTART:20240416T140000Z
DTEND:20240416T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/61
DESCRIPTION:Title: Cluster state as a non-invertible SPT phase\nby Sahand Seifnash
ri (IAS) as part of Symmetry Seminar\n\n\nAbstract\nWe study the simplest
lattice realizations of SPT phases protected by non-invertible symmetries.
We show that the well-known 1+1d cluster model has a Rep(D8) non-invertib
le symmetry\, thereby identifying it as a non-invertible SPT phase. We als
o find commuting Pauli Hamiltonians for the remaining two Rep(D8) SPT phas
es\, matching the classification in field theory and mathematics. Finally\
, we determine the projective algebra and edge modes at the interfaces bet
ween these three non-invertible SPT phases.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/61/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jingxiang Wu (Oxford)
DTSTART:20240430T140000Z
DTEND:20240430T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/62
DESCRIPTION:Title: MTC[M3\, G]: 3d Topological Order Labeled by Seifert Manifolds\
nby Jingxiang Wu (Oxford) as part of Symmetry Seminar\n\n\nAbstract\nWe pr
opose a correspondence between topological order in 2+1d\, i.e.\nmodular t
ensor categories (MTCs) and Seifert three-manifolds together\nwith a choic
e of ADE gauge group G. The correspondence defines for\nevery Seifert man
ifold and choice of G a fusion category\, which we\nconjecture to be modul
ar whenever the Seifert manifold has trivial\nfirst homology group with co
efficients in the center of G. The\nconstruction determines the spins of
anyons and their S-matrix\, and\nprovides a constructive way to determine
the R- and F-symbols from\nsimple building blocks. We explore the possibil
ity that this\ncorrespondence provides an alternative classification of MT
Cs\, which\nis put to the test by realizing all MTCs (unitary or non-unita
ry) with\nrank $r\\leq 5$ in terms of Seifert manifolds and a choice of Li
e group\nG.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/62/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hao Zhang (IPMU)
DTSTART:20240528T130000Z
DTEND:20240528T140000Z
DTSTAMP:20260404T110912Z
UID:SymSem/63
DESCRIPTION:Title: K-theoretic Global Symmetry in String-constructed QFT and T-duality
\nby Hao Zhang (IPMU) as part of Symmetry Seminar\n\n\nAbstract\nWe pr
opose that generalized symmetries in some string-constructed QFTs are give
n by twisted K-theory\, so as to be manifestly consistent under T-duality.
We thus have even-form and odd-form symmetries determined by the twisted
K-theory as D-brane charges on the asymptotic boundary ∂X of internal ge
ometry X with twist class N. For these QFTs\, "p-form symmetries" are no l
onger separately well-defined for individual p\, but instead mixed up. We
discuss 6D ADE-type (2\,0) SCFTs and some 6d (1\,0) LSTs as examples\, and
demonstrate their twisted K-theoretic symmetries to be consistent with T-
duality.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/63/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Arkya Chatterjee (MIT)
DTSTART:20240514T140000Z
DTEND:20240514T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/64
DESCRIPTION:Title: Phases and Phase Transitions of Spin Chains with Non-invertible Sym
metries\nby Arkya Chatterjee (MIT) as part of Symmetry Seminar\n\n\nAb
stract\nNon-invertible symmetries are often emergent at low-energies\nin g
apless states of quantum matter. It is useful to construct lattice\nmodels
that have these as exact symmetries in order to provide a\nUV-complete se
tting in which they are well-controlled. To that end\, we\npropose to stud
y one-dimensional Hamiltonians defined on tensor\nproduct Hilbert spaces w
ith finite on-site dimension -- referred to as\n"spin chains" in short --
with exact non-invertible symmetries. We\nfocus on two concrete examples:
a spin chain with (invertible) S_3\nsymmetry and one with (non-invertible)
Rep(S_3) symmetry. These models\nare largely analytically tractable and d
emonstrate all spontaneous\nsymmetry breaking (SSB) phases of these symmet
ries. With the aid of\ntensor network algorithms\, we systematically study
the phase\ntransitions between these SSB phases. Both models possess\n(in
trinsically) non-invertible self-duality symmetries\, for which we\nprovid
e sequential circuit implementations. On the self-dual manifold\nin parame
ter space\, we discover an incommensurate gapless phase with\nan anomalous
U(1) symmetry which emanates from lattice translation.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/64/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xingyang Yu (Virginia Tech)
DTSTART:20240521T150000Z
DTEND:20240521T160000Z
DTSTAMP:20260404T110912Z
UID:SymSem/65
DESCRIPTION:Title: 2D Non-invertible Symmetries and Anomalies from String Theory\n
by Xingyang Yu (Virginia Tech) as part of Symmetry Seminar\n\n\nAbstract\n
We investigate a string theory perspective for non-invertible symmetries i
n 2D QFTs. In particular\, we discuss how symmetry topological field theor
ies (SymTFTs) and anomalies of non-invertible symmetries arise from top do
wn. Our primary focus is on an infinite class of 2D QFTs from Calabi-Yau 4
-folds probed by D1-branes. We derive 3D SymTFTs from IIB string theory an
d show the resulting 2D QFTs can exhibit non-invertible symmetries with a
wrapped brane origin. These non-invertible symmetries can suffer from ano
malies\, which are able to be translated into branes patterns ``at infinit
y''. Explicit examples are provided to illustrate our idea.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/65/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tyler Ellison (Yale)
DTSTART:20240618T140000Z
DTEND:20240618T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/66
DESCRIPTION:by Tyler Ellison (Yale) as part of Symmetry Seminar\n\nAbstrac
t: TBA\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/66/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Apoorv Tiwari (NBI)
DTSTART:20240625T140000Z
DTEND:20240625T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/67
DESCRIPTION:Title: Fermionic Non-Invertible Symmetries in (1+1)d\nby Apoorv Tiwari
(NBI) as part of Symmetry Seminar\n\n\nAbstract\nI will describe fermioni
c non-invertible symmetries in (1+1)d\, which are generalized global symme
tries that mix fermion parity symmetry with other invertible and non-inver
tible internal symmetries. Mathematically\, such symmetries are described
by fusion π-supercategories with a choice of fermion parity. Using the
formalism of the Symmetry Topological Field Theory (SymTFT)\, I will pre
sent the Landau paradigm for categorical fermionic symmetries. This ta
lk is based on arXiv:2405.09754\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/67/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michael Gutperle (UCLA)
DTSTART:20240709T140000Z
DTEND:20240709T150000Z
DTSTAMP:20260404T110912Z
UID:SymSem/68
DESCRIPTION:Title: Non-invertible symmetries in S_N orbifold CFTs and holography\n
by Michael Gutperle (UCLA) as part of Symmetry Seminar\n\n\nAbstract\nThis
talk is based on two recent papers (arxiv:2405.15693 and 2406.10967) by Y
. Li\, D. Rathore\, K. Roumpedakis and M. Gutperle. We construct non-inve
rtible defects in S_N symmetric orbifolds and discuss the spectrum of def
ect operators\, Ward-identities\, entanglement entropy in the presence of
defects as well as a proposal for a world sheet dual of the topological de
fects in the AdS/CFT dual of the symmetric orbifold.\n
LOCATION:https://stable.researchseminars.org/talk/SymSem/68/
END:VEVENT
END:VCALENDAR