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BEGIN:VEVENT
SUMMARY:Jeremias Aguilera Damia (Centro Atomico Bariloche)
DTSTART;VALUE=DATE-TIME:20200504T183000Z
DTEND;VALUE=DATE-TIME:20200504T193000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/1
DESCRIPTION:Title: Non-Fermi liquid quantum critical points and IR diverge
ncies\nby Jeremias Aguilera Damia (Centro Atomico Bariloche) as part of Ka
danoff seminars\n\n\nAbstract\nThe study of metallic Quantum Critical Poin
ts with dynamics falling beyond the Fermi Liquid paradigm is well-motivate
d by experimental observations in Strange Metals. Even from a purely theor
etical point of view\, the description of these systems by means of a full
y consistent QFT stands as a challenging task. In this talk\, we describe
a particular Quantum Critical Point displaying Non-Fermi Liquid dynamics\
, arising by coupling a Fermi Surface to a gapless boson. We extend the de
scription to finite temperatures by proposing a mechanism to resolve the s
ingular behavior associated to static bosons\, thus leading to a consisten
t characterization of the Quantum Critical Region. We also comment on the
phenomenological implications of our results.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wen Wei Ho (Harvard)
DTSTART;VALUE=DATE-TIME:20200511T183000Z
DTEND;VALUE=DATE-TIME:20200511T193000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/2
DESCRIPTION:Title: Interacting phases of matter protected by multiple time
-translation symmetries in quasiperiodically-driven systems\nby Wen Wei Ho
(Harvard) as part of Kadanoff seminars\n\n\nAbstract\nThe discrete time-t
ranslation symmetry of a periodically-driven (Floquet) system allows for t
he existence of novel\, nonequilibrium interacting phases of matter. A wel
l-known example is the discrete time crystal\, a phase characterized by th
e spontaneous breaking of this time-translation symmetry. In this talk\, I
will show that the presence of *multiple* time-translation symmetries\, r
ealized by quasiperiodically driving a system with two or more incommensur
ate frequencies\, leads to a panoply of novel non-equilibrium phases of ma
tter\, both spontaneous symmetry-breaking ("discrete time quasi-crystals")
and topological. I will demonstrate that these phases are stable in a lon
g-lived\, 'preheating' regime\, by outlining rigorous mathematical results
establishing slow heating at high driving frequencies. As a byproduct\, I
will introduce the notion of many-body localization (MBL) in quasiperiodi
cally-driven systems.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chong Wang (Perimeter Institute)
DTSTART;VALUE=DATE-TIME:20200518T183000Z
DTEND;VALUE=DATE-TIME:20200518T193000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/3
DESCRIPTION:Title: A theory of deconfined pseudo-criticality\nby Chong Wan
g (Perimeter Institute) as part of Kadanoff seminars\n\n\nAbstract\nIt has
been proposed that the deconfined criticality in (2+1)d - the quantum pha
se transition between a Neel anti-ferromagnet and a valence-bond-solid (VB
S) - may actually be pseudo-critical\, in the sense that it is a weakly fi
rst-order transition with a generically long correlation length. The under
lying field theory of the transition would be a slightly complex (non-unit
ary) fixed point as a result of fixed points annihilation. This proposal w
as motivated by existing numerical results from large scale Monte-Carlo si
mulations as well as conformal bootstrap. However\, an actual theory of su
ch complex fixed point\, incorporating key features of the transition such
as the emergent SO(5) symmetry\, is so far absent. Here we propose a Wess
-Zumino-Witten (WZW) nonlinear sigma model with level k=1\, defined in 2+
ϵ dimensions\, with target space S^(3+ϵ) and global symmetry SO(4+ϵ). T
his gives a formal interpolation between the deconfined criticality at d=3
and the SU(2)_1 WZW theory at d=2 describing the spin-1/2 Heisenberg chai
n. The theory can be formally controlled\, at least to leading order\, in
terms of the inverse of the WZW level 1/k. We show that at leading order\,
there is a fixed point annihilation at d*≈2.77\, with complex fixed poi
nts above this dimension including the physical d=3 case. The pseudo-criti
cal properties such as correlation length\, scaling dimensions and the dri
fts of scaling dimensions as the system size increases\, calculated crudel
y to leading order\, are qualitatively consistent with existing numerics.\
n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gabriel Cuomo (EPFL)
DTSTART;VALUE=DATE-TIME:20200601T183000Z
DTEND;VALUE=DATE-TIME:20200601T193000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/4
DESCRIPTION:Title: The epsilon expansion meets semiclassics\nby Gabriel Cu
omo (EPFL) as part of Kadanoff seminars\n\n\nAbstract\nIn this talk\, I wi
ll study the scaling dimension of the lightest operator of charge n in the
U(1) model at the Wilson-Fisher fixed point in 4-ε dimensions.\nEven for
a perturbatively small fixed point coupling λ\, standard perturbation th
eory breaks down for sufficiently large λ n. Treating λ n as fixed for s
mall λ\, I will show that the scaling dimension can be successfully compu
ted through a semiclassical expansion around a non-trivial trajectory\, re
sulting in a series in the coupling whose coefficients are fixed functions
of λ n. I will discuss explicitly the computation of the first two order
s in the expansion. The result\, when expanded at small λ n\, perfectly a
grees with all available diagrammatic computations. The asymptotic at larg
e λ n reproduces the systematic large charge expansion\, recently derived
in CFT.\nSimilar results can be derived in the U(1) model in 3-ε dimensi
ons. I will briefly comment on the application of similar ideas in the cal
culation of other observables\, such as three-point functions of charged o
perators. This talk is based on https://arxiv.org/abs/1909.01269 and https
://arxiv.org/abs/1911.08505.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ki-Seok Kim (POSTECH)
DTSTART;VALUE=DATE-TIME:20200608T183000Z
DTEND;VALUE=DATE-TIME:20200608T193000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/5
DESCRIPTION:Title: Emergent holographic dual effective field theory as a m
ean-field theory with all-loop quantum corrections in the large N limit\nb
y Ki-Seok Kim (POSTECH) as part of Kadanoff seminars\n\n\nAbstract\nHologr
aphic duality conjecture states that a D-dimensional quantum field theory
can be duality-mapped into a (D+1)-dimensional quantum gravity theory\, wh
ere the quantum gravity theory is a “hologram” of the quantum field th
eory. Although this holographic duality conjecture serves as a novel non-p
erturbative theoretical framework for strongly coupled quantum field theor
ies\, the duality transformation has not been clarified until now. In this
study we propose a prescription for the holographic duality transformatio
n based on Wilsonian recursive renormalization group (RG) transformations.
As a result\, we manifest the RG flow of an effective field theory with t
he introduction of an emergent extra dimensional space\, where RG beta-fun
ctions to describe the evolution of coupling functions appear in the resul
ting effective action explicitly through the extra dimensional space. This
microscopic construction of the dual holographic mapping suggests that th
e origin of non-perturbative physics is in intertwined renormalization bet
ween dynamics and geometry.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michael Aizenman (Princeton)
DTSTART;VALUE=DATE-TIME:20200615T183000Z
DTEND;VALUE=DATE-TIME:20200615T193000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/6
DESCRIPTION:Title: Marginal triviality of the scaling limits of 4D critica
l Ising and $\\varphi^4_4$ models\nby Michael Aizenman (Princeton) as part
of Kadanoff seminars\n\n\nAbstract\nThe talk will outline the recent proo
f that the scaling limits of spin fluctuations in four-dimensional Ising-t
ype models at or near the critical point are Gaussian\, and of the similar
statement for the $\\varphi^4_4$ fields with a lattice ultraviolet cutoff
\, in the limit of infinite volume and vanishing lattice spacing (derived
jointly with H. Duminil-Copin). The proofs are enabled by the models' ra
ndom current representation\, in which the correlation functions' deviatio
n from Wick's law are expressed in terms of intersection probabilities of
random currents with prescribed sources. Examples will also be provided
of insights facilitated by this representation for two and three dimensio
ns.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sri Raghu (Stanford)
DTSTART;VALUE=DATE-TIME:20200831T183000Z
DTEND;VALUE=DATE-TIME:20200831T193000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/7
DESCRIPTION:Title: Dual perspective on quantum Hall to insulator transitio
ns\nby Sri Raghu (Stanford) as part of Kadanoff seminars\n\n\nAbstract\nQu
antum Hall to insulator transitions (QHITs) are among the oldest and most
studied examples of quantum critical phenomena. In this talk I will discu
ss problems that still remain open in this subject\, and present a dual ap
proach to QHITs based on composite fermion representations. I discuss the
mean-field and fluctuational aspects of the dual theories\, and discuss h
ow they provide a complementary understanding - and in many instances\, a
conceptual advantage - to current descriptions of QHITs based on the elec
tron representation.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shiraz Minwalla (TIFR Mumbai)
DTSTART;VALUE=DATE-TIME:20200908T150000Z
DTEND;VALUE=DATE-TIME:20200908T160000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/8
DESCRIPTION:Title: Fermi seas from Bose condensates and a bosonic exclusio
n principle in matter Chern Simons theories\nby Shiraz Minwalla (TIFR Mumb
ai) as part of Kadanoff seminars\n\n\nAbstract\nI will study Chern Simons
gauge theories in three dimensions coupled to (bosonic or fermionic) matte
r in the fundamental representation in the large N limit. I will first exp
lain how previously obtained results for the thermal free energy in these
theories can be generalized to values of the chemical potential that are l
arger than quasi particle mases. I will then use these results to find a
simple explicit formula for the occupation number for a bosonic quasiparti
cle state of any given energy and charge as a function of the temperature
and chemical potential. This formula is a generalization to finite 't Hoof
t coupling of the famous result of Bose-Einstein statistics. It implies th
e following exclusion principle for large N Chern Simons coupled bosons:
the total number of bosons occupying any single state cannot exceed the C
hern Simons level. Specializing to zero temperature I will also construct
the phase diagrams of these theories as a function of chemical potential
and the UV parameters. The phase diagram includes a Bose condensed phase\
, dual to the Fermionic Fermi sea. The runaway instability of free theorie
s at large chemical potential is cured by the bosonic exclusion principle.
\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alex Maloney (McGill)
DTSTART;VALUE=DATE-TIME:20200914T183000Z
DTEND;VALUE=DATE-TIME:20200914T193000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/9
DESCRIPTION:Title: Gravity from Averaging CFTs\nby Alex Maloney (McGill) a
s part of Kadanoff seminars\n\n\nAbstract\nI will explore the idea that ce
rtain theories of gravity in Anti-de Sitter space are dual to an average o
ver an ensemble of quantum theories\, rather than to a specific quantum th
eory. I will describe an average over Narain’s family of two-dimensiona
l conformal field theories which describe free bosons on a torus\, and com
pute the partition function using the Siegel-Weil formula. The result tak
es the form of a sum over geometries as one would expect in a theory of gr
avity. But the gravitational theory looks more like a Chern-Simons theory
than like Einstein gravity.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hong Liu (MIT)
DTSTART;VALUE=DATE-TIME:20200921T183000Z
DTEND;VALUE=DATE-TIME:20200921T193000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/10
DESCRIPTION:Title: Entanglement entropies of equilibrated pure states in q
uantum many-body systems and replica wormholes\nby Hong Liu (MIT) as part
of Kadanoff seminars\n\n\nAbstract\nWe develop a universal approximation f
or the Renyi entropies of a pure state at late times in non-integrable sys
tems\, which macroscopically resembles an equilibrium density matrix. The
resulting expressions are fully determined by properties of the associated
equilibrium density matrix\, and are hence independent of the details of
the initial state\, while also being manifestly consistent with unitary ti
me-evolution. For equilibrated pure states in gravity systems\, such as th
ose involving black holes\, this approximation gives a prescription for ca
lculating entanglement entropies using Euclidean path integrals which is c
onsistent with unitarity and hence can be used to address the information
loss paradox of Hawking. Applied to recent models of evaporating black hol
es and eternal black holes coupled to baths\, it provides a derivation of
replica wormholes\, and elucidates their mathematical and physical origins
. In particular\, it shows that replica wormholes can arise in a system wi
th a fixed Hamiltonian\, without the need for ensemble averages.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mark Van Raamsdonk (University of British Columbia)
DTSTART;VALUE=DATE-TIME:20200928T183000Z
DTEND;VALUE=DATE-TIME:20200928T193000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/11
DESCRIPTION:Title: Towards Microscopic Models of Big Bang Cosmology\nby Ma
rk Van Raamsdonk (University of British Columbia) as part of Kadanoff semi
nars\n\n\nAbstract\nIn this talk\, we review an approach to describing cos
mological physics using ordinary AdS/CFT\, where the cosmological physics
is the effective description of an end-of-the-world brane which cuts off t
he second asymptotic region of a two-sided black hole. The worldvolume geo
metry of the brane is an FRW big-bang/big-crunch spacetime. In favorable c
ircumstances\, the brane acts as a Randall-Sundrum Planck brane so that gr
avity localizes. We describe a microscopic construction for such an end-of
-the-world brane with localized gravity in AdS/CFT\, starting from N=4 SYM
theory. We suggest specific microscopic states of N=4 SYM theory that may
encode the physics in a four-dimensional cosmological spacetime.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simon Caron-Huot (McGill)
DTSTART;VALUE=DATE-TIME:20201005T203000Z
DTEND;VALUE=DATE-TIME:20201005T213000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/12
DESCRIPTION:Title: Dispersion relations for S-matrices and CFTs\nby Simon
Caron-Huot (McGill) as part of Kadanoff seminars\n\n\nAbstract\nDispersion
relations are statements of causality. They give sum rules connecting lo
w and high energies. They are great. I will review some recently derived
consequences of causality and how they relate to dispersion relations. I
will then discuss a surprising equivalence between three seemingly distinc
t dispersion relations in CFTs (in position space\, Mellin space\, and ana
lytic functionals)\, and a lesson for flat-space gravity.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Julian Sonner (University of Geneva)
DTSTART;VALUE=DATE-TIME:20201012T183000Z
DTEND;VALUE=DATE-TIME:20201012T193000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/13
DESCRIPTION:Title: Causal symmetry breaking: late time physics of holograp
hic quantum chaos\nby Julian Sonner (University of Geneva) as part of Kada
noff seminars\n\n\nAbstract\nQuantum chaotic systems are often defined via
the assertion that their spectral statistics coincides with\, or is well
approximated by\, random matrix theory. In this talk I will explain how th
e universal content of random matrix theory emerges as the consequence of
a simple symmetry-breaking principle and its associated Goldstone modes. W
ithin AdS/CFT this gives a universal framework to express correlations bet
ween ``different universes’’\, including for individual theories rathe
r than ensembles. I will Illustrate the bulk picture of this EFT using the
example minimal string theory. I will end by discussing the construction
of the EFT of quantum chaos also in higher dimensional field theories\, as
applicable for example for higher-dimensional AdS/CFT dual pairs.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ryan Thorngren (Harvard CMSA)
DTSTART;VALUE=DATE-TIME:20201019T183000Z
DTEND;VALUE=DATE-TIME:20201019T193000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/14
DESCRIPTION:Title: 't Hooft Anomalies of Fermi Liquids and Luttinger's The
orem\nby Ryan Thorngren (Harvard CMSA) as part of Kadanoff seminars\n\n\nA
bstract\nLattice systems with translation symmetry and U(1) charge conserv
ation have a filling fraction\, defined as the charge per unit cell. In th
is talk I will explain how the filling fraction is captured by anomalous e
mergent symmetries in the continuum limit of such systems. This anomaly ma
tching is a generalization of Luttinger's theorem for Fermi liquids\, whic
h says that the filling fraction equals the volume enclosed by the Fermi s
urface. Luttinger's theorem is obtained by analyzing an anomalous loop-gro
up symmetry of the Fermi liquid\, which generalizes the chiral anomaly of
a Luttinger liquid in 1+1d. I will argue more generally that systems at ir
rational filling cannot have continuum limits with compact symmetry groups
.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ehud Altman (Berkeley)
DTSTART;VALUE=DATE-TIME:20201109T193000Z
DTEND;VALUE=DATE-TIME:20201109T203000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/15
DESCRIPTION:by Ehud Altman (Berkeley) as part of Kadanoff seminars\n\nAbst
ract: TBA\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Israel Klich (University of Virginia)
DTSTART;VALUE=DATE-TIME:20201026T183000Z
DTEND;VALUE=DATE-TIME:20201026T193000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/16
DESCRIPTION:by Israel Klich (University of Virginia) as part of Kadanoff s
eminars\n\nAbstract: TBA\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexander Seidel (Washington University in St. Louis)
DTSTART;VALUE=DATE-TIME:20201214T193000Z
DTEND;VALUE=DATE-TIME:20201214T203000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/17
DESCRIPTION:by Alexander Seidel (Washington University in St. Louis) as pa
rt of Kadanoff seminars\n\nAbstract: TBA\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tomaž Prosen (University of Ljubljana)
DTSTART;VALUE=DATE-TIME:20201102T193000Z
DTEND;VALUE=DATE-TIME:20201102T203000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/18
DESCRIPTION:Title: Exactly solved models of many-body quantum chaos\nby To
maž Prosen (University of Ljubljana) as part of Kadanoff seminars\n\n\nAb
stract\nOne should be amazed with the unreasonable effectiveness of random
matrix theory to describe spectral fluctuations in simple non-integrable
many-body systems\, say one dimensional spin 1/2 chains with local interac
tions. I will discuss several models of Floquet (periodically driven) quan
tum spin chains\, where the random matrix result for the spectral form fac
tor can be derived or even rigorously proven. Several other nontrivial exa
ctly solvable features of the presented models\, such as dynamical correla
tions or entanglement dynamics\, will be discussed.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Leo Radzihovsky (University of Colorado Boulder)
DTSTART;VALUE=DATE-TIME:20201207T193000Z
DTEND;VALUE=DATE-TIME:20201207T203000Z
DTSTAMP;VALUE=DATE-TIME:20201029T111650Z
UID:Kadanoff/19
DESCRIPTION:by Leo Radzihovsky (University of Colorado Boulder) as part of
Kadanoff seminars\n\nAbstract: TBA\n
END:VEVENT
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