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SUMMARY:Kantaro Ohmori (Simons Center for Geometry and Physics)
DTSTART;VALUE=DATE-TIME:20200515T030000Z
DTEND;VALUE=DATE-TIME:20200515T040000Z
DTSTAMP;VALUE=DATE-TIME:20201204T173339Z
UID:EASW/1
DESCRIPTION:Title: 1+1d adjoint QCD and non-invertible topological lines\n
by Kantaro Ohmori (Simons Center for Geometry and Physics) as part of East
Asian String Webinars\n\n\nAbstract\nIn ‘90s\, it is claimed that the Q
CD with massless adjoint quark in 1+1-dimensions is confined\, although na
ively the fermions cannot screen the Wilson line in the fundamental repres
entation. In this talk\, we will see that the confinement can be explained
from the topological line operators live in the theory. In particular\, n
on-invertible topological lines\, which do not correspond to a symmetry\,
play a crucial role. Based on a ongoing work with Zohar Komargodski\, Kons
tantinos Roumpedakis and Sahand Seifnashri.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chang-Tse Hsieh (Kavli IPMU)
DTSTART;VALUE=DATE-TIME:20200529T030000Z
DTEND;VALUE=DATE-TIME:20200529T040000Z
DTSTAMP;VALUE=DATE-TIME:20201204T173339Z
UID:EASW/2
DESCRIPTION:Title: Anomaly of the electromagnetic duality of Maxwell theor
y\nby Chang-Tse Hsieh (Kavli IPMU) as part of East Asian String Webinars\n
\n\nAbstract\nEvery physicist knows that the classical electromagnetism is
described by Maxwell's equations and that it is invariant under the elect
romagnetic duality S: (E\, B) → (B\, −E). However\, the properties of
the electromagnetic duality in the quantum theory might not be as well kno
wn to physicists and are in fact not very well understood in the literatur
e. Recently\, we uncovered a feature of Maxwell theory in the situation wh
ere going around nontrivial paths in the spacetime involves the action of
the duality transformation\, namely that it has a quantum anomaly. We foun
d that the anomaly of this system in a particular formulation is 56 times
that of a Weyl fermion. Our result reproduces\, as a special case\, the kn
own anomaly of the all-fermion electrodynamics — a version of the Maxwel
l theory where particles of odd (electric or magnetic) charge are fermions
— discovered in the last few years.\n
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BEGIN:VEVENT
SUMMARY:Miranda Cheng (Univ. of Amsterdam/National Taiwan University)
DTSTART;VALUE=DATE-TIME:20200612T030000Z
DTEND;VALUE=DATE-TIME:20200612T040000Z
DTSTAMP;VALUE=DATE-TIME:20201204T173339Z
UID:EASW/3
DESCRIPTION:Title: Quantum Modularity from 3-Manifolds\nby Miranda Cheng (
Univ. of Amsterdam/National Taiwan University) as part of East Asian Strin
g Webinars\n\n\nAbstract\nQuantum modular forms are functions on rational
numbers that have rather mysterious weak modular properties. Mock modular
forms and false theta functions are examples of holomorphic functions on t
he upper-half plane which lead to quantum modular forms. Inspired by the 3
d-3d correspondence in string theory\, a new topological invariants named
homological blocks for (in particular plumbed) three-manifolds have been p
roposed a few years ago. My talk aims to explain the recent observations o
n the quantum modular properties of the homological blocks\, as well as th
e relation to logarithmic vertex algebras. The talk will be based on a ser
ies of work in collaboration with Sungbong Chun\, Boris Feigin\, Francesca
Ferrari\, Sergei Gukov\, Sarah Harrison\, and Gabriele Sgroi.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:João Penedones (École Polytechnique Fédérale de Lausanne)
DTSTART;VALUE=DATE-TIME:20200626T080000Z
DTEND;VALUE=DATE-TIME:20200626T090000Z
DTSTAMP;VALUE=DATE-TIME:20201204T173339Z
UID:EASW/4
DESCRIPTION:Title: Nonperturbative Mellin Amplitudes\nby João Penedones (
École Polytechnique Fédérale de Lausanne) as part of East Asian String
Webinars\n\n\nAbstract\nI will argue that nonperturbative CFT correlation
functions admit a Mellin amplitude representation. I will discuss the main
properties of Mellin amplitudes: subtractions\, analyticity\, unitarity\,
Polyakov conditions and polynomial boundedness at infinity. These can be
used to write dispersion relations for Mellin amplitudes. Combining crossi
ng\, dispersion relations and Polyakov conditions I will write down a set
of (extremal) functionals that act on the OPE data.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Tong (University of Cambridge)
DTSTART;VALUE=DATE-TIME:20200710T080000Z
DTEND;VALUE=DATE-TIME:20200710T090000Z
DTSTAMP;VALUE=DATE-TIME:20201204T173339Z
UID:EASW/5
DESCRIPTION:Title: Boundary conditions for chiral Fermions\nby David Tong
(University of Cambridge) as part of East Asian String Webinars\n\n\nAbstr
act\nI will describe boundary conditions for fermions in d=1+1 dimensions\
, using the framework of boundary conformal field theory. I will explain h
ow boundary states are classified by a mod 2 index\, related to their SPT
phase\, describe how one can follow RG flows from one boundary state to an
other\, and give a novel perspective on the Z_8 classification of d=2+1 SP
T phases.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xiangyu Cao (UC Berkeley)
DTSTART;VALUE=DATE-TIME:20200724T030000Z
DTEND;VALUE=DATE-TIME:20200724T040000Z
DTSTAMP;VALUE=DATE-TIME:20201204T173339Z
UID:EASW/6
DESCRIPTION:Title: Scrambling vs chaos\nby Xiangyu Cao (UC Berkeley) as pa
rt of East Asian String Webinars\n\n\nAbstract\nHow to characterize inform
ation scrambling in dynamical systems is a question of interest to physici
sts across energy scales. Inspired by classical chaos\, which addresses th
is question quite successfully in classical physics\, out of order time co
rrelators (OTOC) have been considered a promising approach for quantum sys
tems. In this talk\, I will first discuss the relation between scrambling
(as defined by exponential growth of OTOC) and chaos in the semiclassical
regime\, and show that they can differ qualitatively (joint work with Tian
rui Xu andThomas Scaffidi). In a second part\, I will discuss scrambling i
n a family of generalized Sachdev-Ye-Kitaev models\, which are arguably mo
re realistic\, and which allow us to clarify the behavior of the Lyapunov
exponent in non-maxically chaotic Fermi and non-Fermi liquids (joint work
with Jaewon Kim and Ehud Altman).\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Julian Sonner (U. Geneva)
DTSTART;VALUE=DATE-TIME:20200807T080000Z
DTEND;VALUE=DATE-TIME:20200807T090000Z
DTSTAMP;VALUE=DATE-TIME:20201204T173339Z
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DESCRIPTION:Title: Causal symmetry breaking: late time physics of holograp
hic quantum chaos\nby Julian Sonner (U. Geneva) as part of East Asian Stri
ng Webinars\n\n\nAbstract\nQuantum chaotic systems are often defined via t
he assertion that their spectral statistics coincides with\, or is well ap
proximated by\, random matrix theory. In this talk I will explain how the
universal content of random matrix theory emerges as the consequence of a
simple symmetry-breaking principle and its associated Goldstone modes. Wit
hin AdS/CFT this gives a universal framework to express correlations betwe
en "different universes"\, even for individual theories rather than ensemb
les. I will illustrate the bulk picture of this EFT using the example mini
mal string theory. I will end by discussing the construction of the EFT of
quantum chaos also in higher dimensional field theories\, as applicable f
or example for higher-dimensional AdS/CFT dual pairs.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Richard A. Davison (Herriot-Watt U.)
DTSTART;VALUE=DATE-TIME:20200821T080000Z
DTEND;VALUE=DATE-TIME:20200821T090000Z
DTSTAMP;VALUE=DATE-TIME:20201204T173339Z
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DESCRIPTION:Title: Relations between transport and chaos in holographic th
eories\nby Richard A. Davison (Herriot-Watt U.) as part of East Asian Stri
ng Webinars\n\n\nAbstract\nI will describe recent work illustrating genera
l relations between the transport properties and chaotic properties of qua
ntum field theories with holographic duals. I will firstly show how a simp
le analysis of near-horizon dynamics yields exact constraints on the spect
rum of collective excitations. I will then describe how this can be exploi
ted to identify a universal feature in the spectrum\, and its implications
for the collective transport properties of strongly interacting field the
ories with gravity duals.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yang Zhou (Fudan Univ.)
DTSTART;VALUE=DATE-TIME:20200904T030000Z
DTEND;VALUE=DATE-TIME:20200904T040000Z
DTSTAMP;VALUE=DATE-TIME:20201204T173339Z
UID:EASW/9
DESCRIPTION:Title: Reflected entropy for an evaporating black hole\nby Yan
g Zhou (Fudan Univ.) as part of East Asian String Webinars\n\n\nAbstract\n
Black hole information paradox is a problem over 40 years. Recent progress
shows hint towards a new understanding of the black hole interior as part
of the Hawking radiation\, which they called island. In particular the is
land formula for the Von Neumann entropy of Hawking radiation is consisten
t with unitarity. In this talk I will discuss how to extract more informat
ion of the island by computing the correlation in Hawking radiation. In pa
rticular we study reflected entropy (as a correlation measure of mixed sta
tes) and propose a quantum extremal surface for reflected entropy. Based o
n that\, we find a formula for reflected entropy with island cross section
as its area term in gravitational system.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yang-Hui He (University of Oxford)
DTSTART;VALUE=DATE-TIME:20200918T080000Z
DTEND;VALUE=DATE-TIME:20200918T090000Z
DTSTAMP;VALUE=DATE-TIME:20201204T173339Z
UID:EASW/10
DESCRIPTION:Title: Universes as Bigdata: Superstrings\, Calabi-Yau Manifo
lds and Machine-Learning\nby Yang-Hui He (University of Oxford) as part of
East Asian String Webinars\n\n\nAbstract\nWe review how historically the
problem of string phenomenology lead theoretical physics first to algebrai
c/diffenretial geometry\, and then to computational geometry\, and now to
data science and AI.\nWith the concrete playground of the Calabi-Yau lands
cape\, accumulated by the collaboration of physicists\, mathematicians and
computer scientists over the last 4 decades\, we show how the latest tech
niques in machine-learning can help explore problems of physical and mathe
matical interest.\n
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BEGIN:VEVENT
SUMMARY:Daniel Baumann (Univ. of Amsterdam)
DTSTART;VALUE=DATE-TIME:20200417T030000Z
DTEND;VALUE=DATE-TIME:20200417T040000Z
DTSTAMP;VALUE=DATE-TIME:20201204T173339Z
UID:EASW/11
DESCRIPTION:Title: The Cosmological Bootstrap\nby Daniel Baumann (Univ. of
Amsterdam) as part of East Asian String Webinars\n\n\nAbstract\nThe past
decade has seen an explosion of progress in our understanding of scatterin
g amplitudes in gauge theory and gravity. New bootstrap methods have revea
led hidden symmetries and new mathematical structures that are completely
invisible in the standard approach of Lagrangians and Feynman diagrams. In
spired by these developments\, the bootstrap philosophy has recently been
applied to cosmology. In this talk\, I will describe our work on the boots
trapping of cosmological correlations. \n\nThe talk will have two parts: I
n the first part\, I will describe the conceptual foundations of the "cosm
ological bootstrap” as developed together with Arkani-Hamed\, Lee and Pi
mentel in [arXiv:1811.00024]. In the second part\, I will describe the ext
ension of these ideas to massless particles with spin\, where locality pro
vides important new constraints. This is work to appear with Duaso Pueyo\,
Joyce\, Lee and Pimentel.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tadashi Takayanagi (Yukawa Institute for Theoretical Physics\, Kyo
to University)
DTSTART;VALUE=DATE-TIME:20200501T030000Z
DTEND;VALUE=DATE-TIME:20200501T040000Z
DTSTAMP;VALUE=DATE-TIME:20201204T173339Z
UID:EASW/12
DESCRIPTION:Title: Holographic Pseudo Entropy\nby Tadashi Takayanagi (Yuka
wa Institute for Theoretical Physics\, Kyoto University) as part of East A
sian String Webinars\n\n\nAbstract\nIn this talk\, we will study a general
ization of holographic entanglement entropy. This quantity is defined by a
mininal area surface in an asymptotically AdS space with Euclidean time-d
ependence. We will give its CFT counterpart\, which we call pseudo entropy
. We will also provide quantum information theoretic interpretations of th
is quantity in several specific examples of qubit systems\, which help us
to understand our results of pseudo entropy in CFTs and gravity duals.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Justin Kaidi (Simons Center\, Stony Brook)
DTSTART;VALUE=DATE-TIME:20201204T030000Z
DTEND;VALUE=DATE-TIME:20201204T040000Z
DTSTAMP;VALUE=DATE-TIME:20201204T173339Z
UID:EASW/13
DESCRIPTION:Title: Adventures in Non-Supersymmetric String Theory\nby Just
in Kaidi (Simons Center\, Stony Brook) as part of East Asian String Webina
rs\n\n\nAbstract\nIt has long been known that there exist strings with sup
ersymmetry on the world sheet\, but not in spacetime. These include the we
ll-known Type 0 strings\, as well as a series of seven heterotic strings\,
all of which are obtained by imposing unconventional GSO projections. Bes
ides these classic examples though\, relatively little is known about the
full space of non-SUSY theories. One of the reasons why non-SUSY strings h
ave remained understudied is the fact that nearly all of them have closed
string tachyons\, and hence do not admit ten-dimensional flat space as a s
table vacuum. The goal of this talk is two-fold. First\, using recent adva
nces in condensed matter theory\, we will reinterpret GSO projections in t
erms of topological phases of matter\, thereby providing a framework for t
he classification of non-SUSY strings. Having done so\, we will show that
for all non-SUSY theories in which a tachyon exists\, it can be condensed
to give a stable lower-dimensional vacuum. In many cases\, these stable va
cua will be two-dimensional string theories already known in the literatur
e.\n
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