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BEGIN:VEVENT
SUMMARY:Jose Figueroa-O'Farrill (University of Edinburgh)
DTSTART:20200505T114500Z
DTEND:20200505T124500Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/1
DESCRIPTION:Title: A cohomological approach to rigid supersymmetry in curve
d space\nby Jose Figueroa-O'Farrill (University of Edinburgh) as part
of Joint Theory Seminar between Vienna University of Technology and Univer
sity of Vienna\n\n\nAbstract\nApart from any intrinsic interest one might
have in supersymmetry\, supersymmetric field theories in curved space are
the subject of study because of their utility in computing exact quantitie
s in (non-supersymmetric) quantum field theory via supersymmetric localisa
tion techniques. I will review the usual methods by which we may constru
ct such theories and motivate the central question I will answer in the ta
lk: how to define a suitable notion of “Killing spinor”. The approac
h I will present is based on the observation that Killing spinors generate
a Lie superalgebra with a very particular algebraic structure\, which is
amenable to cohomological calculation. I will explain how the cohomology
calculation gives rise to the Killing spinor equation and summarise some
of the calculations that we have done in a number of different dimensions.
(This is based on ongoing collaborations with my student Andrew Beckett
(Edinburgh) and my long-term collaborators Paul de Medeiros (Stavanger) a
nd Andrea Santi (Padova).)\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gaston Giribet (Buenos Aires University)
DTSTART:20200512T114500Z
DTEND:20200512T124500Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/2
DESCRIPTION:Title: On string theory on AdS3 x M7 in the tensionless limit\nby Gaston Giribet (Buenos Aires University) as part of Joint Theory Se
minar between Vienna University of Technology and University of Vienna\n\n
\nAbstract\nIn this talk I will review old and recent results on a special
limit of string theory on AdS3 x M7 with pure NS-NS fluxes: the limit in
which the string length (l_s) equals the AdS3 radius (R). At this point of
the moduli space\, the theory exhibits special properties\, which I will
discuss. Special attention will be focused on features of correlation func
tions that are related to the non-compactness of the boundary CFT target s
pace\, and on how these features change when the point l_s=R is approached
. Also\, we briefly review recent proposals for exact realizations of AdS/
CFT correspondence at this special point.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Evgeny Skvortsov (Albert Einstein Institute)
DTSTART:20200519T114500Z
DTEND:20200519T124500Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/3
DESCRIPTION:Title: (Quantum) Higher spin gravity and applications to physic
s\nby Evgeny Skvortsov (Albert Einstein Institute) as part of Joint Th
eory Seminar between Vienna University of Technology and University of Vie
nna\n\n\nAbstract\nI will give a general overview of Higher Spin Gravities
and also discuss the recent developments\nthat give a class of models whe
re UV-divergences of Einstein gravity cancel out thanks to the higher spin
symmetry. \nAt the end I will discuss the relation between Higher Spin Gr
avities and a class of conformal field theories in three dimensions\nthat
describe the physics of many second order phase transitions in the real wo
rld and have been recently conjectured to exhibit a number\nof remarkable
dualities\, in particular the three-dimensional bosonization duality. I wi
ll show how Higher Spin Gravity can help to prove the dualities\nand how i
t makes new predictions. The relation to QCD and self-dual Yang-Mills will
also be discussed.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eran Palti (MPI Munich)
DTSTART:20200514T140000Z
DTEND:20200514T150000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/4
DESCRIPTION:Title: Scale separation\, Swampland\, and type IIA orientifold
vacua\nby Eran Palti (MPI Munich) as part of Joint Theory Seminar betw
een Vienna University of Technology and University of Vienna\n\n\nAbstract
\nI will introduce the Swampland program which aims to capture constraints
on which effective theories can be completed into quantum gravity in the
UV. I will then discuss such a proposed constraint which states that effec
tive theories in anti-de Sitter space must have an infinite tower of state
s whose mass is related to the cosmological constant. I will describe how
this is satisfied in almost all fully understood vacua of string theory. I
will then focus on a proposed counter example to the conjecture based on
four-dimensional effective theories from compactifications of type IIA str
ing theory. I will present recent results on testing such counter examples
by studying whether they can be uplifted to full ten-dimensional solution
s or not. In particular\, presenting a ten-dimensional solution which hold
s at the two-derivative level and at first order in a certain perturbative
expansion.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tom Rudelius (IAS)
DTSTART:20200526T140000Z
DTEND:20200526T150000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/5
DESCRIPTION:Title: Conditions for (no) eternal inflation\nby Tom Rudeli
us (IAS) as part of Joint Theory Seminar between Vienna University of Tech
nology and University of Vienna\n\n\nAbstract\nIn the first half of this t
alk\, I will present a pedagogical introduction to eternal inflation\, fea
turing necessary and sufficient conditions on scalar field potentials for
eternal inflation. In the second half\, I will speculate on possible conne
ctions between a "No Eternal Inflation" conjecture and recently-proposed d
e Sitter Swampland conjectures.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kevin Grosvenor (University of Wuerzburg)
DTSTART:20200616T114500Z
DTEND:20200616T124500Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/7
DESCRIPTION:Title: Entanglement entropy and subregion complexity in thermal
perturbations around pure-AdS\nby Kevin Grosvenor (University of Wuer
zburg) as part of Joint Theory Seminar between Vienna University of Techno
logy and University of Vienna\n\n\nAbstract\nI will discuss the computatio
n of the entanglement entropy \nand subregion complexity for spherical ent
angling regions in the AdS \nblack hole background up to third order in th
e black hole mass using \nthe "complexity equals volume" conjecture. I wil
l show that a \nreinterpretation of the conjectured relationship between F
isher \ninformation and subregion complexity in 1701.02319 suggests an \ne
xtension of the "first law of entanglement thermodynamics" to second \nord
er. By analogy to standard thermodynamics\, entanglement and \ncomplexity
play the roles of heat and work\, respectively.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ilka Brunner (LMU Munich)
DTSTART:20200623T114500Z
DTEND:20200623T124500Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/8
DESCRIPTION:Title: Flows\, defects\, and transport of D-branes\nby Ilka
Brunner (LMU Munich) as part of Joint Theory Seminar between Vienna Unive
rsity of Technology and University of Vienna\n\n\nAbstract\nI will discuss
RG flows of two dimensional supersymmetric field theories using defects.\
nIn particular\, defects provide a tool to transport D-branes between UV a
nd IR.\nThe main example will be linear sigma models with different Landau
-Ginzburg phases.\n\nThe seminar will be held via BigBlueButton. Please co
ntact the organizers for the link.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Henning Samtleben (Ecole Normale Supérieure de Lyon)
DTSTART:20200630T090000Z
DTEND:20200630T100000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/9
DESCRIPTION:Title: Kaluza-Klein spectrometer from exceptional field theory<
/a>\nby Henning Samtleben (Ecole Normale Supérieure de Lyon) as part of J
oint Theory Seminar between Vienna University of Technology and University
of Vienna\n\n\nAbstract\nI present new tools for the computation of Kalu
za-Klein mass spectra associated with compactifications around various bac
kground geometries relevant for string theory. This includes geometries wi
th little to no remaining symmetries\, hardly accessible to standard metho
ds. The new tools build on exceptional field theory\, the duality covarian
t formulation of supergravity. Among the applications I discuss the tachyo
nic Kaluza-Klein modes arising at higher levels in the spectrum of the non
-supersymmetric SO(3) × SO(3)-invariant AdS4 vacuum of 11-dimensional sup
ergravity.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jarkko Peuron (ECT\, Trento)
DTSTART:20200721T110000Z
DTEND:20200721T120000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/10
DESCRIPTION:Title: Heavy quark diffusion in an overoccupied gluon plasma\nby Jarkko Peuron (ECT\, Trento) as part of Joint Theory Seminar betwee
n Vienna University of Technology and University of Vienna\n\n\nAbstract\n
We extract the heavy-quark diffusion coefficient \\kappa and the resulting
momentum broadening in a far-from-equilibrium non-Abelian plasma. We find
several features in the time dependence of the momentum broadening: a sho
rt initial rapid growth of \, followed by linear growth with time due to L
angevin-type dynamics and damped oscillations around this growth at the pl
asmon frequency. We show that these novel oscillations are not easily expl
ained using perturbative techniques but result from an excess of gluons at
low momenta. These oscillation are therefore a gauge invariant confirmati
on of the infrared enhancement we had previously observed in gauge-fixed c
orrelation functions. We argue that the kinetic theory description of such
systems becomes less reliable in the presence of this IR enhancement.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edgar Shaghoulian (Cornell)
DTSTART:20201006T120000Z
DTEND:20201006T130000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/11
DESCRIPTION:Title: Looking for islands\nby Edgar Shaghoulian (Cornell)
as part of Joint Theory Seminar between Vienna University of Technology a
nd University of Vienna\n\n\nAbstract\nI will review the role of replica w
ormholes in deriving a unitary Page curve for Hawking radiation and discus
s extensions to flat spacetime and cosmology. I will also discuss general
consistency conditions that guide the search for such nontrivial saddles i
n the gravitational path integral.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yuhma Asano (Universität Wien)
DTSTART:20201103T130000Z
DTEND:20201103T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/12
DESCRIPTION:Title: M-brane Realisation in Matrix Model\nby Yuhma Asano
(Universität Wien) as part of Joint Theory Seminar between Vienna Univer
sity of Technology and University of Vienna\n\n\nAbstract\nIn this talk\,
we consider a one-dimensional matrix model\, called the BMN matrix model\,
which is considered as a non-perturbative formulation of M-theory. In the
BMN matrix model\, there are some evidences that spherical M2- and M5-bra
nes correspond to vacua of the matrix model. While it is easy to understan
d realisation of M2-brane geometries because the vacua form fuzzy 2-sphere
s\, it requires non-perturbative computation in a strongly coupled regime
to obtain realisation of M5-brane geometries. We solve this notorious prob
lem by using the supersymmetric localisation method and see how the M-bran
e geometries are successfully obtained. Intriguingly\, this result gives u
s a consistent picture of how the gravity-side spacetime in the gauge/grav
ity correspondence emerges from the matrix model.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adrien Fiorucci (Université Libre de Bruxelles (ULB))
DTSTART:20201110T130000Z
DTEND:20201110T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/13
DESCRIPTION:Title: The Λ-BMS Charge Algebra in n dimensions\nby Adrie
n Fiorucci (Université Libre de Bruxelles (ULB)) as part of Joint Theory
Seminar between Vienna University of Technology and University of Vienna\n
\n\nAbstract\nThe aim of my talk is to discuss brand-new results about the
phase space of Einstein’s gravity in arbitrary dimensions with non-vani
shing cosmological constant Λ. I will start by reviewing the solution spa
ce of asymptotically locally (A)dS spacetimes in the Starobinsky/Fefferman
-Graham gauge and the renormalization of the presymplectic current needed
when the boundary structure is allowed to fluctuate. Next\, I will discuss
the gravitational charge algebra for generic Al(A)dSnspacetimes\, without
assuming any further boundary condition than the minimal falloffs allowin
g for conformal compactification. Then I will introduce the Λ-BMSnalgebro
id arising from some boundary gauge fixing and reducing to the Generalized
BMSnalgebra in the flat limit Λ→0. The associated boundary conditions\
, equivalent to fix a foliation and a measure as universal structure on th
e boundary\, do not freeze completely the transverse metric\, leading to s
ome symplectic flux through the conformal boundary. Finally\, I will parti
cularize the framework to the n=4 case and show that one can give sense to
the flat limit of the phase space thanks to the incorporation of kinetic
corner terms in the variational principle. The result of this process is e
xactly the phase space for Generalized BMS4 symmetries in asymptotically l
ocally flat spacetimes.\n\nBased on:\n\nA. FIORUCCI\, R. RUZZICONI\,Charge
Algebra in Al(A)dSnspacetimes (Nov 2020). e-Print: 2011.02002[hep-th]\n\n
G. COMPÈRE\, A. FIORUCCI\, R. RUZZICONI\,The Λ-BMS4Charge Algebra (Apr 2
020). e-Print: 2004.10769[hep-th]\n\nG. COMPÈRE\, A. FIORUCCI\, R. RUZZIC
ONI\,Superboost transitions\, refraction memory and super-Lorentz charge a
lgebra (Sep 2018). e-Print: 1810.00377[hep-th]\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Andriot (TU Wien)
DTSTART:20201117T130000Z
DTEND:20201117T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/14
DESCRIPTION:Title: Do classical de Sitter string backgrounds exist?\nb
y David Andriot (TU Wien) as part of Joint Theory Seminar between Vienna U
niversity of Technology and University of Vienna\n\n\nAbstract\nA classica
l solution of string theory with a 4d de Sitter space-time could provide a
simple and well-controlled setting to establish a connection to cosmologi
cal models. So far however\, it has proven very difficult to find any exam
ple of such a solution. As will be recalled\, attempts in this direction a
re plagued by many no-go theorems\, or by the difficulty for concrete 10d
supergravity solutions to fit in the classical stringy regime. This situat
ion agrees with the recent claims of de Sitter swampland conjectures. Thes
e conjectures can actually be verified quantitatively\, with a surprisingl
y good agreement\, as will be shown. This may hint at a deep reason agains
t classical de Sitter background\, possibly to be found within the web of
swampland conjectures\, and the relation to the distance conjecture will b
e commented on.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Flavio Tonioni (Liverpool U.)
DTSTART:20201124T130000Z
DTEND:20201124T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/15
DESCRIPTION:Title: Misaligned Supersymmetry and Anti-D-branes\nby Flav
io Tonioni (Liverpool U.) as part of Joint Theory Seminar between Vienna U
niversity of Technology and University of Vienna\n\n\nAbstract\nIn this ta
lk\, I will review the concept of misaligned supersymmetry and discuss its
relationship with anti-D-branes in type II string theories. Misaligned su
persymmetry characterises a variety of non-supersymmetric string models: e
ven if the particle spectrum lacks a one-by-one matching between particles
with a different spin\, there exist theories in which an infinite oscilla
tion between fermionic and bosonic surpluses at each mass level results in
a net cancellation that allows for a finite one-loop cosmological constan
t. Such a scenario is often discussed with regard to closed-string theorie
s\, but I will show that the spectrum of an anti-D-brane on top of an orie
ntifold plane presents essentially the same properties. Anti-D-branes are
crucial tools in many phenomenological string-theory realisations of featu
res such as supersymmetry breaking and de Sitter uplifting\, and I will co
mment on how an understanding of the effects of their infinite tower of st
ates is related to their low-energy descriptions.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Laurent Freidel
DTSTART:20201208T130000Z
DTEND:20201208T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/16
DESCRIPTION:Title: Quantum gravity at the corner\nby Laurent Freidel a
s part of Joint Theory Seminar between Vienna University of Technology and
University of Vienna\n\n\nAbstract\nIn this talk\, I will present a new p
erspective on the non-perturbative\nquantization of gravity based on the c
oncept of corner symmetries associated with local subregions.\nAfter intro
ducing the corner algebra for various formulations of general relativity\,
I will illustrate its physical content in 4d metric and tetrad gravity. I
will also present the formalism of edge modes\, whose role is to restore
gauge-invariance at boundaries while preserving non-trivial charges. If t
ime permits\, I'll show our recent progress on the representation theory o
f these algebras. I will also describe the relationship that these results
entertain with standard loop gravity\, asymptotic quantization\, and the
concept of holography.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Severin Lüst (Harvard)
DTSTART:20201215T130000Z
DTEND:20201215T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/17
DESCRIPTION:Title: The Tadpole Problem\nby Severin Lüst (Harvard) as
part of Joint Theory Seminar between Vienna University of Technology and U
niversity of Vienna\n\n\nAbstract\nI will discuss string theory compactifi
cations where a large number of moduli is stabilized by fluxes. I will pre
sent a conjecture which rules out the stabilization of all complex-structu
re moduli in F-theory at a generic point in moduli space by fluxes that sa
tisfy the tadpole cancellation condition. Evidence for this conjecture com
es from K3xK3 compactifications. Using evolutionary algorithms we found th
at moduli stabilization needs fluxes whose charge is slightly smaller than
1/2 of the number of moduli and larger than what is allowed by tadpole ca
ncellation. I will furthermore comment on possible implications on de Sitt
er vacua obtained by antibrane uplift in long warped throats.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joshua Kames-King (University of Bonn)
DTSTART:20210119T130000Z
DTEND:20210119T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/21
DESCRIPTION:Title: Deformations of JT Gravity and KdV Equations\nby Jo
shua Kames-King (University of Bonn) as part of Joint Theory Seminar betwe
en Vienna University of Technology and University of Vienna\n\n\nAbstract\
nRecently\, it was shown that the duality of double-scaled matrix models a
nd JT gravity can be extended to include surfaces with conical defects.\nW
e show that the thermal partition function of this deformed theory may be
written as the free energy of topological gravity around a shifted expansi
on point.\nBy use of the KdV equation we furnish an off-shell de- scriptio
n for both the single and multi-boundary cases of the partition function.\
nWe also rewrite the deformed partition function as a low temperature expa
nsion\, which allows for a convenient calculation of contributions up to a
desired order.\nWe use this approach to demonstrate the existence of a Ha
wking-Page phase transition between connected and disconnected surfaces fo
r this instance of JT gravity.\nFurthermore\, we calculate the spectral fo
rm factor and compare with the standard JT case.\nWe conclude by commentin
g on the dS2 case.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Prateek Agrawal (Oxford U.)
DTSTART:20210126T130000Z
DTEND:20210126T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/22
DESCRIPTION:Title: Topological Gravity as the Early Phase of our Universe<
/a>\nby Prateek Agrawal (Oxford U.) as part of Joint Theory Seminar betwee
n Vienna University of Technology and University of Vienna\n\n\nAbstract\n
I will present a scenario motivated by string dualities and the swampland
where the early universe is described by a topological phase of gravity. M
any cosmological puzzles can be explained in terms of the topological natu
re of this phase. To obtain phenomenological predictions\, a concrete real
ization of this scenario using Witten's four dimensional topological gravi
ty will be presented. In this model\, the CMB power spectrum is controlle
d by conformal anomaly coefficients. The model predicts the absence of ten
sor modes in the CMB fluctuations and significant non-Gaussianities in 4-
and higher point functions.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shahin Sheikh Jabbari (IPM)
DTSTART:20210112T100000Z
DTEND:20210112T110000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/24
DESCRIPTION:Title: Temperature of Black Holes in Horndeski Gravity Theorie
s\nby Shahin Sheikh Jabbari (IPM) as part of Joint Theory Seminar betw
een Vienna University of Technology and University of Vienna\n\n\nAbstract
\nHorndeski theories are the most general family of scalar-tensor gravity
with second order equations of motion. In these theories speeds of propag
ation of gravitons and photons are in general different and gravitons mov
e on an effective metric different than the one seen by photons. These the
ories admit black hole solutions with the peculiar feature that they do no
t satisfy the first law with the entropy given by the Wald formula. We arg
ue that the issue with the first law stems from the fact that black hole t
emperature is not given by the surface gravity of the black hole metric\,
but with the surface gravity of the effective metric seen by gravitons. Th
e modified temperature\, with the entropy unambiguously computed by the so
lution phase space method\, yields the correct first law. We discuss far-r
eaching implications of our results for black hole thermodynamics beyond t
he Horndeski theories.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marc Geiller (ENS Lyon)
DTSTART:20210216T130000Z
DTEND:20210216T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/25
DESCRIPTION:Title: A new look at symmetries of 3d gravity\nby Marc Gei
ller (ENS Lyon) as part of Joint Theory Seminar between Vienna University
of Technology and University of Vienna\n\n\nAbstract\nI will review the an
alysis of boundary symmetries in first order 3d gravity\, and explain how
the study of the boundary current algebra and the Sugawara construction ac
tually leads to two dual notions of diffeomorphism charges. This provides
a new understanding of the relationship between the second order and first
order formulations\, and of the existence of finite distance asymptotic (
or symplectic) symmetries in topological theories. This analysis is perfor
med on the most general theory of first order 3d gravity\, which also enab
les to understand the duality between curvature and torsion\, as well as t
he relationship with chiral and massive gravity.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christoph Nega (University of Bonn)
DTSTART:20210209T130000Z
DTEND:20210209T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/26
DESCRIPTION:Title: Analytic Structure of Banana Feynman Integrals\nby
Christoph Nega (University of Bonn) as part of Joint Theory Seminar betwee
n Vienna University of Technology and University of Vienna\n\n\nAbstract\n
In this talk I will introduce the so called banana Feynman integrals and e
xplain their analytic properties in dimensional regularization.\nThese Fey
nman integrals have a natural interpretation as relative periods of a comp
lete intersection Calabi-Yau manifold\, whose dimension is the loop order
minus one of the banana integral.\nIn particular\, we find that the leadin
g logarithmic structure in the high energy regime\, which corresponds to t
he point of maximal unipotent monodromy\, is determined by a novel Gamma-c
lass evaluation in the ambient space of the mirror CY and the mirror CY it
self.\nMoreover\, we provide simple closed all loop formulas for the Frobe
nius kappa-constants at the physical threshold in terms of zeta values.\nI
will also give a short outlook how the above structures evolve in the exp
ansion in the dimensional regularization parameter.\nFinally\, I comment o
n the situation in the non-equal mass case.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Klaus Sibold
DTSTART:20210323T130000Z
DTEND:20210323T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/27
DESCRIPTION:Title: Perturbative Quantization of Einstein-Hilbert Gravity\nby Klaus Sibold as part of Joint Theory Seminar between Vienna Univer
sity of Technology and University of Vienna\n\n\nAbstract\nIn a perturbati
ve approach Einstein-Hilbert gravity is quantized about a \nflat backgroun
d. In order to render the model power counting \nrenormalizable\, higher o
rder curvature terms are added to the action.\nThey serve as Pauli-Villars
type regulators and require an expansion in \nthe number of fields in add
ition to the standard expansion in the number \nof loops.\nRenormalization
is then performed within the BPHZL scheme\, which \nprovides the action p
rinciple to construct the Slavnov-Taylor identity \nand invariant differen
tial operators.\nAfter removal of the regulators\, the final physical stat
e space of the \nEinstein-Hilbert theory is realized via the quartet mecha
nism of Kugo \nand Ojima.\nRenormalization group and Callan-Symanzik equat
ion are derived for the \nGreen functions and\, formally\, also for the S-
matrix.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Roberto Emparan (Barcelona U.)
DTSTART:20210427T120000Z
DTEND:20210427T130000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/30
DESCRIPTION:Title: Digging traversable wormholes\nby Roberto Emparan (
Barcelona U.) as part of Joint Theory Seminar between Vienna University of
Technology and University of Vienna\n\n\nAbstract\nIn recent years there
have appeared several constructions of traversable wormholes\, in four and
other dimensions\, which only involve physically acceptable\, controllabl
e ingredients. They connect in deep ways many aspects of gravity\, quantum
field theory\, and quantum information. I will discuss several features o
f these constructions\, with a focus on traversability\, connectivity betw
een multiple mouths\, and the (im)possibility of time travel.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:James Gray (Virginia Tech)
DTSTART:20210302T130000Z
DTEND:20210302T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/31
DESCRIPTION:Title: Machine learning and SU(3) structures on six manifolds<
/a>\nby James Gray (Virginia Tech) as part of Joint Theory Seminar between
Vienna University of Technology and University of Vienna\n\n\nAbstract\nI
n this talk we will discuss the application of Machine Learning techniques
to obtain numerical approximations to various metrics of SU(3) structure
on Calabi-Yau manifolds. More precisely\, we will be interested in SU(3) s
tructures whose torsion classes make them suitable backgrounds for various
string compactifications. A variety of aspects of this topic will be cove
red. These will include learning moduli dependent Ricci-Flat metrics on Ca
labi-Yau threefolds and obtaining numerical approximations to torsional SU
(3) structures.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lukas Müller
DTSTART:20210309T130000Z
DTEND:20210309T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/32
DESCRIPTION:Title: Anomalous field theories as boundaries\nby Lukas M
üller as part of Joint Theory Seminar between Vienna University of Techno
logy and University of Vienna\n\n\nAbstract\nThis talk will be about the d
escription of anomalies in quantum field theory through boundary states of
certain field theories in one dimensions higher.\nI will give a gentle in
troduction to the mathematical formulation of this approach developed by F
reed and Monnier and explain its relation to more classical approaches.\nI
will discuss two concrete examples in detail\, namely the parity anomaly
of fermionic gauge theories in odd spacetime dimensions and 't Hooft anoma
lies of discrete gauge theories.\nTime permitting I will mention some open
questions related to smooth families of field theories. The talk is based
on joint work with R. J. Szabo.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mahdi Godazgar (Queen Mary University)
DTSTART:20210316T130000Z
DTEND:20210316T140000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/33
DESCRIPTION:Title: Asymptotic charges in gravity\nby Mahdi Godazgar
(Queen Mary University) as part of Joint Theory Seminar between Vienna Un
iversity of Technology and University of Vienna\n\n\nAbstract\nI will disc
uss the Hamiltonian derivation of dual BMS charges at null infinity using
the first order formalism. More generally\, I will discuss how this idea
can be used to classify asymptotic charges in gravity.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Linus Wulff (Masaryk University)
DTSTART:20210413T120000Z
DTEND:20210413T130000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/34
DESCRIPTION:Title: O(D\,D) and string alpha'-corrections\nby Linus Wul
ff (Masaryk University) as part of Joint Theory Seminar between Vienna Uni
versity of Technology and University of Vienna\n\n\nAbstract\nString theor
y on a d-dimensional torus features an O(d\,d) duality \nsymmetry. It has
been suggested that the low-energy effective action can \nbe formulated wi
th a larger O(D\,D) symmetry (D=10 or 26)\, even before \nputting the theo
ry on a torus. This approach\, which goes by the name of \nDouble Field Th
eory (DFT)\, has proven very useful. I will address the\nproblem of constr
ucting higher derivative invariants in this formalism. \nIn agreement with
the literature we find that a quadratic Riemann \ninvariant can be constr
ucted\, which can account for the first \nalpha'-correction to the bosonic
and heterotic string. However\, we find \nthat no cubic or quartic Rieman
n invariants can be constructed. This \nsuggests that the quartic Riemann
terms arising at order alpha'^3 in \nstring theory do not have a DFT embed
ding.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jie Gu
DTSTART:20210420T120000Z
DTEND:20210420T130000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/35
DESCRIPTION:Title: Resurgence and BPS invariants\nby Jie Gu as part of
Joint Theory Seminar between Vienna University of Technology and Universi
ty of Vienna\n\n\nAbstract\nAsymptotic series abound in physics. Borel res
ummation and resurgence theory are among the powerful tools to deal with t
hem. The former provides a way to convert asymptotic series to numbers\, \
nthe latter reveals that different asymptotic series at different saddle p
oints are related to each other by Stokes automorphism characterised by St
okes constants. We argue that the Stokes constants can be treated \nas new
invariants of the system\, and in many cases can be interpreted as counti
ng BPS states. We support this statement with examples in Seiberg-Witten t
heory\, complex Chern-Simons theory\, and topological string theory.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Johannes Thürigen
DTSTART:20210518T120000Z
DTEND:20210518T130000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/36
DESCRIPTION:Title: BPHZ renormalization in combinatorially non-local field
theory\nby Johannes Thürigen as part of Joint Theory Seminar between
Vienna University of Technology and University of Vienna\n\n\nAbstract\nC
ombinatorial non-locality occurs in various field theories such as non-com
mutative field theory\, matrix and tensor theories or the group field theo
ry approach to quantum gravity. Though interactions in such theories are n
ot point-like\, they are still local in the sense that for any divergent F
eynman diagram there is a unique counter term vertex\, described in genera
l by a graph. This allows to generalize the renormalization Hopf algebra o
f Feynman graphs to a Hopf algebra of 2-graphs which gives a concise algor
ithm for applying Zimmermann’s forest formula to amplitudes in any renor
malizable non-local field theory.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jun Nishimura
DTSTART:20210615T120000Z
DTEND:20210615T130000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/37
DESCRIPTION:by Jun Nishimura as part of Joint Theory Seminar between Vien
na University of Technology and University of Vienna\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Claudia de Rham (Imperial)
DTSTART:20210525T140000Z
DTEND:20210525T150000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/38
DESCRIPTION:Title: Positivity with Gravity\nby Claudia de Rham (Imperi
al) as part of Joint Theory Seminar between Vienna University of Technolog
y and University of Vienna\n\n\nAbstract\nIn standard effective field theo
ries\, the notion of causality is intrinsically linked with that of sublum
inality and with a set of positivity constraints to be imposed on the low-
energy scattering amplitudes. I will highlight how the presence of gravity
leads to a more subtle relation between causality\, (sub)luminality and p
ositivity bounds. These considerations are relevant for putting constraint
s on cosmological and gravitational effective field theories and I will pr
ovide explicit criteria to be satisfied so as to ensure causality and a st
andard high energy completion in gravitational effective field theories.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Petr Kravchuk (IAS Princeton)
DTSTART:20210504T120000Z
DTEND:20210504T130000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/39
DESCRIPTION:Title: CFTs and Wightman axioms in general dimensions\nby
Petr Kravchuk (IAS Princeton) as part of Joint Theory Seminar between Vien
na University of Technology and University of Vienna\n\n\nAbstract\nIn Con
formal Field Theory\, one is often concerned with computing local correlat
ion functions from the spectrum of local operators and their OPE coefficie
nts.\nIn general quantum field theories\, we expect these correlation func
tions to satisfy Wightman and Osterwalder-Schrader axioms.\nIn this talk\,
I will explain that Wightman axioms are not obvious for CFT correlation f
unctions and then present a proof for correlators up to four points.\nIn t
he process I will also briefly review the classic results relating Wightma
n and O-S axioms\, which have caveats that are important in the CFT setup.
\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Charles Marteau (British Columbia U.)
DTSTART:20210511T120000Z
DTEND:20210511T130000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/40
DESCRIPTION:Title: From baby universes to black holes in 2d flat space gra
vity\nby Charles Marteau (British Columbia U.) as part of Joint Theory
Seminar between Vienna University of Technology and University of Vienna\
n\n\nAbstract\nIn this talk I will discuss a simple model of 2d flat gravi
ty that derives from the CGHS model. Its simplicity allows one to compute
exactly the Euclidean gravitational path integral. When one allows for mor
e than one thermal boundary\, the model is dual to an ensemble of theories
\, I will discuss this ensemble in detail. The ensemble description is equ
ivalent to a description in terms of baby universe Hilbert space in which
one can build the so-called alpha-states\, states in which the theory is n
ow dual to only one theory. I will end the presentation by describing how
this 2d model appears as a universal sector in the near-horizon dynamics o
f non-extremal black holes.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dieter Lüst (LMU Munich)
DTSTART:20210608T120000Z
DTEND:20210608T130000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/41
DESCRIPTION:Title: The swampland at a large number of space-time dimension
s\nby Dieter Lüst (LMU Munich) as part of Joint Theory Seminar betwee
n Vienna University of Technology and University of Vienna\n\n\nAbstract\n
In this talk we discuss some aspects of swampland constraints - \nespecia
lly the swampland distance conjecture - in a large number of space-time di
mensions D.\nWe analyze Kaluza-Klein (KK) states at large D and find that
some KK spectra possess an interesting dependence on D.\nOn the basis of t
hese observations we propose a new large dimension conjecture.\nWe apply
it to KK states of compactifications to anti-de Sitter backgrounds where i
t predicts an upper bound on the dimension of space-time as a function of
its characteristic radius.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Abhiram Kidambi (Kavli IPMU\, University of Tokyo)
DTSTART:20210629T110000Z
DTEND:20210629T120000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/42
DESCRIPTION:Title: Generalized Siegel-Weil formula\, Chern-Simons invarian
ts and 3d gravity\nby Abhiram Kidambi (Kavli IPMU\, University of Toky
o) as part of Joint Theory Seminar between Vienna University of Technology
and University of Vienna\n\n\nAbstract\nA recent discovery in holography
is the idea of a dual not of a particular CFT but rather of an ensemble of
CFT's and its gravitational interpretation. In this talk\, I will explain
the case of the generalization of the recent work of Maloney-Witten and A
fkhami-Jeddi et.al. Following a pedagogical introduction to the number the
ory requirements\, I will talk about the holographic duality that follows
from considering the average over toroidal CFTs with unequal left and righ
t moving central charges.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/42/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Elias Kiritsis
DTSTART:20210713T120000Z
DTEND:20210713T130000Z
DTSTAMP:20260404T111213Z
UID:JointTheorySeminar/43
DESCRIPTION:Title: Emergent gravity from hidden sectors and TT deformation
s\nby Elias Kiritsis as part of Joint Theory Seminar between Vienna Un
iversity of Technology and University of Vienna\n\n\nAbstract\nWe investig
ate emergent gravity extending the paradigm of the AdS/CFT correspondence.
\nThe emergent graviton is associated to the (dynamical) expectation value
of the energy-momentum tensor.\nWe derive the general effective descripti
on of such dynamics\, and apply it to the case where a hidden theory gener
ates gravity that is coupled to the Standard Model.\nIn the linearized des
cription\, generically\, such gravity is massive with the presence of an e
xtra scalar degree of freedom.\nThe propagators of both the spin-two and s
pin-zero modes are positive and well defined.\nThe associated emergent gra
vitational theory is a bi-gravity theory\, as is (secretly) the case in ho
lography.\nThe background metric on which the QFTs are defined\, plays the
role of dark energy and the emergent theory has always as a solution the
original background metric.\nIn the case where the hidden theory is hologr
aphic\, the overall description yields a higher-dimensional bulk theory co
upled to a brane.\nThe effective graviton on the brane has four-dimensiona
l characteristics both in the UV and IR and is always massive.\n
LOCATION:https://stable.researchseminars.org/talk/JointTheorySeminar/43/
END:VEVENT
END:VCALENDAR