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BEGIN:VEVENT
SUMMARY:Barton Zwiebach (MIT)
DTSTART:20211029T130000Z
DTEND:20211029T143000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/1
DESCRIPTION:by Barton Zwiebach (MIT) as part of SFT@Cloud Journal Club\n\n
Abstract: TBA\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Carlo Maccaferri (INFN\, Turin)
DTSTART:20211112T140000Z
DTEND:20211112T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/2
DESCRIPTION:by Carlo Maccaferri (INFN\, Turin) as part of SFT@Cloud Journa
l Club\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nathan Berkovits (ICTP-SAIFR)
DTSTART:20211203T140000Z
DTEND:20211203T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/3
DESCRIPTION:Title: Applications of the N=1 d=4 spacetime-supersymmetric version of op
en superstring field theory\nby Nathan Berkovits (ICTP-SAIFR) as part
of SFT@Cloud Journal Club\n\n\nAbstract\nI will first review the version o
f open superstring field theory based on the hybrid formalism which has ma
nifest N=1 d=4 spacetime supersymmetry. I will then discuss two recent app
lications including the equations of motion for higher-spin massive fields
in an electromagnetic background and the computation of stringy correctio
ns to the self-dual d=4 instanton solution.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ashoke Sen (ICTS-TIFR\, Bengaluru)
DTSTART:20220127T140000Z
DTEND:20220127T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/4
DESCRIPTION:Title: D-instanton amplitudes\nby Ashoke Sen (ICTS-TIFR\, Bengaluru)
as part of SFT@Cloud Journal Club\n\n\nAbstract\nI'll describe the general
procedure for computing D-instanton amplitudes in string theory\, with a
special focus on type II string theories compactified on Calabi-Yau manifo
lds.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yuji Okawa (Institute of Physics\, University of Tokyo)
DTSTART:20220210T140000Z
DTEND:20220210T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/5
DESCRIPTION:Title: Renormalization of one-loop scattering amplitudes in scarlar field
theories via homotopy algebras\nby Yuji Okawa (Institute of Physics\,
University of Tokyo) as part of SFT@Cloud Journal Club\n\n\nAbstract\nWhe
n actions are written in terms of homotopy algebras such as $A_\\infty$ al
gebras and $L_\\infty$ algebras\, expressions of on-shell scattering ampli
tudes in perturbation theory are universal for both string field theories
and ordinary field theories. In this talk\, we describe the renormalizatio
n of one-loop scattering amplitudes in $\\phi^3$ theory using an $A_\\inft
y$ algebra.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ivo Sachs (LMU\, Munich)
DTSTART:20220224T140000Z
DTEND:20220224T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/6
DESCRIPTION:by Ivo Sachs (LMU\, Munich) as part of SFT@Cloud Journal Club\
n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Raghu Mahajan (Stanford University)
DTSTART:20220407T130000Z
DTEND:20220407T143000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/7
DESCRIPTION:Title: Semiclassical evaluation of the vacuum sphere and the FZZT disk pa
th integrals in noncritical string theory\nby Raghu Mahajan (Stanford
University) as part of SFT@Cloud Journal Club\n\n\nAbstract\nWe compute th
e vacuum sphere and the FZZT disk partition functions in noncritical strin
g theory in the semiclassical limit. The worldsheet theory consists of the
$(2\,p)$ minimal model\, the Liouville field and the usual bc ghosts. The
semiclassical limit is the limit of large p\, in which the central charge
of the Liouville sector goes to plus infinity\, and the path integral can
be done via the saddle point method. The main conceptual point is that th
e unfixed $PSL(2\,C)$ and $PSL(2\,R)$ gauge groups are spontaneously broke
n by the saddle point configuration of the Liouville field\, which removes
the usual obstacles in computing these path integrals in critical string
theory. The quantity $sphere/disk^2$ is free of all normalization ambiguit
ies and we find a precise numerical match between the string theory answer
and the answer from the dual double-scaled one-matrix integral. (This tal
k is based on work with Douglas Stanford and Cynthia Yan.)\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Oliver Schlotterer (Uppsala university)
DTSTART:20220519T130000Z
DTEND:20220519T143000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/8
DESCRIPTION:Title: Recent developments in superstring loop amplitudes\nby Oliver
Schlotterer (Uppsala university) as part of SFT@Cloud Journal Club\n\n\nAb
stract\nIn this talk\, I will review motivations\, results\, and strategie
s for loop amplitudes in superstring theories. Based on chiral splitting o
f correlation functions of closed-string vertex operators\, a simplified r
esult will be presented for two-loop five-point amplitudes involving massl
ess type-II states.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edward Witten (IAS Princeton)
DTSTART:20220310T140000Z
DTEND:20220310T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/9
DESCRIPTION:Title: No Ensemble Averaging Below the Black Hole Threshold\nby Edwar
d Witten (IAS Princeton) as part of SFT@Cloud Journal Club\n\n\nAbstract\n
In the AdS/CFT correspondence\, amplitudes associated to connected bulk ma
nifolds with disconnected boundaries have presented a longstanding mystery
. A possible interpretation is that they reflect the effects of averaging
over an ensemble of boundary theories. But in examples in dimension D≥3\
, an appropriate ensemble of boundary theories does not exist. Here we sha
rpen the puzzle by identifying a class of "sub-threshold" observables that
we claim do not show effects of ensemble averaging. These are amplitudes
that do not involve black hole states. To support our claim\, we explore t
he example of D=3\, and show that connected solutions of Einstein's equati
ons with disconnected boundary never contribute to sub-threshold observabl
es. To demonstrate this requires some novel results about the renormalized
volume of a hyperbolic three-manifold\, which we prove using modern metho
ds in hyperbolic geometry. Why then do any observables show apparent ensem
ble averaging? We propose that this reflects the chaotic nature of black h
ole physics and the fact that the Hilbert space describing a black hole do
es not have a large N limit.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nima Arkani-Hamed (IAS\, Princeton)
DTSTART:20220421T130000Z
DTEND:20220421T143000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/10
DESCRIPTION:Title: On Unitarity of Tree-Level String Amplitudes\nby Nima Arkani-
Hamed (IAS\, Princeton) as part of SFT@Cloud Journal Club\n\n\nAbstract\nF
our-particle tree-level scattering amplitudes in string theory are magical
ly consistent with unitarity\, reflected in the non-trivial fact that bene
ath the critical dimension\, the residues of the amplitudes on massive pol
es can be expanded in partial waves with all positive coefficients. While
this follows (rather indirectly) from the no-ghost theorem\, the simplicit
y of the statement and its fundamental importance for the physical consist
ency of string theory begs for a more direct and elementary understanding.
In this note we take a step in this direction by presenting a new express
ion for the partial wave coefficients of string amplitudes\, given by surp
risingly simple double/triple contour integrals for open/closed strings. T
his representation allows us to directly prove unitarity of all superstrin
g theories in $D \\leq 6$ spacetime dimensions\, and can also be used to d
etermine various asymptotics of the partial waves at large mass levels.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hiroshi Kunitomo (Kyoto University)
DTSTART:20220602T120000Z
DTEND:20220602T133000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/11
DESCRIPTION:Title: Open-closed Homotopy Algebra in Superstring Field Theory\nby
Hiroshi Kunitomo (Kyoto University) as part of SFT@Cloud Journal Club\n\n\
nAbstract\nWe construct open-closed superstring interactions based on the
open-closed homotopy algebra structure. It provides a classical open super
string field theory on general closed-superstring field backgrounds descri
bed by classical solutions of the nonlinear equations of motion of the clo
sed superstring field theory.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Atakan Hilmi Fırat (MIT)
DTSTART:20220505T130000Z
DTEND:20220505T143000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/12
DESCRIPTION:Title: D-instanton Induced Superpotential\nby Atakan Hilmi Fırat (M
IT) as part of SFT@Cloud Journal Club\n\n\nAbstract\nIn this talk\, I will
explain how one can fix the normalization of the D-instanton contribution
to the superpotential in type II string theory on Calabi-Yau orientifolds
using string field theory and show such normalization is holomorphic func
tion of the moduli. Along the way I will sketch the proof for a folk theo
rem relating D-instantons to space-filling D-branes on Calabi-Yau's. Lastl
y\, I will argue for the absence of multi-instanton contribution to the su
perpotential in these scenarios. Based on 2204.02981.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kevin Costello (Perimeter Institute)
DTSTART:20230525T130000Z
DTEND:20230525T143000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/13
DESCRIPTION:Title: Twisted supergravity and string field theory\nby Kevin Costel
lo (Perimeter Institute) as part of SFT@Cloud Journal Club\n\n\nAbstract\n
Twisted supergravity is ordinary supergravity in a background where the su
perghost has a vev. I will review what is known about twisted supergravity
. I will also discuss some joint work with Si Li\, where we give a string
field theory inspired argument for how to quantize twisted IIB supergravi
ty.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aron Wall (DAMTP\, Cambridge University)
DTSTART:20230126T140000Z
DTEND:20230126T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/15
DESCRIPTION:Title: The Off-Shell String Effective Action\nby Aron Wall (DAMTP\,
Cambridge University) as part of SFT@Cloud Journal Club\n\n\nAbstract\nTak
ing string theory off shell requires breaking Weyl invariance on the world
sheet\, i.e. the worldsheet theory is now a QFT instead of a CFT. I will
explain Tseytlin's approach to taking the worldsheet theory off-shell in a
consistent manner\, with a particular emphasis on the subtleties involved
in calculating the sphere amplitude. This approach allows for the deriva
tion of a classical string action which gives rise to the correct equation
s of motion and S-matrix\, to all orders in perturbation theory. I will a
lso attempt to explain how the resulting off-shell effective tree amplitud
es are related to string field theory. Based on arXiv:2211.08607.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Amr Ahmadain (DAMTP\, Cambridge University)
DTSTART:20230209T140000Z
DTEND:20230209T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/16
DESCRIPTION:Title: Off-shell Strings and Black Hole Entropy\nby Amr Ahmadain (DA
MTP\, Cambridge University) as part of SFT@Cloud Journal Club\n\n\nAbstrac
t\nIn this talk\, after reviewing Tseytlin's prescriptions for constructin
g classical (sphere) off-shell effective actions\, I'll explain the underl
ying conceptual structure of the Susskind and Uglum black hole entropy arg
ument. There I will show explicitly how the classical (tree-level) effecti
ve action and entropy $S = A/4G_N$ may be calculated from the sphere diagr
ams. We also discuss the behaviour of the Susskind and Uglum entropy unde
r RG flow. Although the conical manifold smooths out under RG flow\, movi
ng towards an on-shell configuration\, the entropy doesn't change. \n\nI w
ill also compare these off-shell results with the much more popular orbifo
ld method for calculating entropy from the on-shell $C/Z_N$ background. By
considering processes involving twisted string states (basically\, the or
bifold conserves twist and hence does not allow twisted strings to pinch o
ff at the tip\, while the off-shell NLSM of a slightly smoothed-out cone o
bviously does allow this process)\, I will conclude that the orbifold back
grounds are fundamentally different from conical backgrounds at the same v
alue of inverse temperature $\\beta$---unless one allows tachyons to conde
nse on the orbifold.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hong Liu (MIT)
DTSTART:20230223T140000Z
DTEND:20230223T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/17
DESCRIPTION:Title: Subalgebra-subregion duality: emergence of space and time in holo
graphy\nby Hong Liu (MIT) as part of SFT@Cloud Journal Club\n\n\nAbstr
act\nIn holographic duality\, a higher dimensional quantum gravity system
emerges from a lower dimensional conformal field theory (CFT) with a large
number of degrees of freedom. We propose a formulation of duality for a
general causally complete bulk spacetime region\, called subalgebra-subreg
ion duality\, which provides a framework to describe how geometric notions
in the gravity system\, such as spacetime subregions\, different notions
of times\, and causal structure\, emerge from the dual CFT. Subalgebra-sub
region duality generalizes and brings new insights into subregion-subregio
n duality (or\, equivalently\, entanglement wedge reconstruction). It prov
ides a mathematically precise definition of subregion-subregion duality an
d gives an independent definition of entanglement wedges without using ent
ropy. Geometric properties of entanglement wedges\, including those that p
lay a crucial role in interpreting the bulk as a quantum error correcting
code\, can be understood from the duality as the geometrization of the add
itivity anomaly of certain algebras.\nUsing general boundary subalgebras r
ather than those associated with geometric subregions makes it possible to
find duals for general bulk spacetime regions\, including those not touch
ing the boundary. Applying subalgebra-subregion duality to a boundary stat
e describing a single-sided black hole also provides a precise way to defi
ne mirror operators.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nobuyuki Ishibashi (Tsukuba University)
DTSTART:20230309T120000Z
DTEND:20230309T133000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/18
DESCRIPTION:Title: The Fokker-Planck formalism for closed bosonic strings\nby No
buyuki Ishibashi (Tsukuba University) as part of SFT@Cloud Journal Club\n\
n\nAbstract\nEvery Riemann surface with genus $g$ and $n$ punctures admits
a hyperbolic metric if $2g-2+n>0$. Such a surface can be decomposed into
pairs of pants whose boundaries are geodesics. We construct a string field
theory for closed bosonic strings based on this pants decomposition.\n\nI
n order to do so\, we derive a recursion relation satisfied by the off-she
ll amplitudes\, using Mirzakhani's scheme for computing integrals over the
moduli space of bordered Riemann surfaces. The recursion relation can be
turned into a string field theory via the Fokker-Planck formalism. The Fok
ker-Planck Hamiltonian consists of kinetic terms and three string vertices
.\n\nUnfortunately\, the worldsheet BRST symmetry is not manifest in the t
heory thus constructed. We will show that the invariance can be made manif
est by introducing auxiliary fields.\n\nNote unusual time.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Piotr Tourkine (Université de Savoie)
DTSTART:20230323T140000Z
DTEND:20230323T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/19
DESCRIPTION:Title: Integrands\, monodromies\, and loop momentum in string amplitude<
/a>\nby Piotr Tourkine (Université de Savoie) as part of SFT@Cloud Journa
l Club\n\n\nAbstract\nMonodromy relations relate different orderings of op
en string amplitudes at tree-level. These relations originate from the mut
livaluedness of the open-string integrand and are fundamental to understan
ding the famous KLT relations\, which allow the explanation of closed-stri
ng amplitudes factorising into a product of open-string amplitudes. Upon t
he field theory limit\, this relates to the double-copy formalism\, which
has been instrumental in the progress in the calculations of gravitational
scattering amplitudes over the last 15 years.\n\nAt loop-level\, we showe
d how the monodromy relations are naturally expressed in terms of loop-mom
entum\, and they relate graphs with different orderings and topologies. Th
is raises some immediate problems: from the Feynman diagram intuition\, lo
op momenta in different graphs are not supposed to have anything to do wit
h each other\, and therefore the monodromy relations might be ambiguous.\n
\nIn this talk\, I will explain that this is not the case and that the for
malism used to introduce loop momentum\, chiral splitting\, defines a glob
al loop momentum. One consequence is that\, upon the field theory limit\,
a similar global choice exists in field theory as well. I will start by re
viewing the monodromy relations and chiral splitting\, and then I’ll ela
borate on this definition of the loop momentum and relations to the field
theory limit and double-copy procedure.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Manki Kim (MIT)
DTSTART:20230504T130000Z
DTEND:20230504T143000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/20
DESCRIPTION:Title: Some difficult problems in string compactifications and string ph
enomenology\nby Manki Kim (MIT) as part of SFT@Cloud Journal Club\n\n\
nAbstract\nIn this talk\, I will describe a few important open problems in
string phenomenology. I will describe how some of the problems may benefi
t from recent developments in string field theory.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cumrun Vafa (Harvard University)
DTSTART:20230406T130000Z
DTEND:20230406T143000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/21
DESCRIPTION:Title: String Theory and Our Universe\nby Cumrun Vafa (Harvard Unive
rsity) as part of SFT@Cloud Journal Club\n\n\nAbstract\nString theory land
scape of vacua point to new consistency conditions that a quantum gravitat
ional system must satisfy. There are only a small number of quantum field
theories that satisfy these conditions\, and all the rest belong to the `
Swampland'\, which cannot be consistently coupled to gravity. In this tal
k\, I review some of these conditions and their implications for cosmology
and particle physics.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Keith R. Dienes (The University of Arizona)
DTSTART:20230420T130000Z
DTEND:20230420T143000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/22
DESCRIPTION:Title: UV/IR Mixing\, EFTs\, Hidden Cancellations\, and Origami: Calcul
ating the Higgs Mass and Gauge-Coupling Running in String Theory\nby K
eith R. Dienes (The University of Arizona) as part of SFT@Cloud Journal Cl
ub\n\n\nAbstract\nIn this talk\, we shall present a non-technical method o
f understanding UV/IR mixing from a field-theoretic perspective. We will
then discuss how these ideas are ultimately realized in string theory\, pr
oviding a self-contained introduction to relevant string ideas as we proce
ed. Finally\, we shall present a fully string-theoretic framework for c
alculating one-loop Higgs masses directly from the first principles in per
turbative closed string theories. Notably\, using our framework\, we find
that a gravitational modular anomaly generically relates the Higgs mass t
o the one-loop cosmological constant\, thereby yielding a string-theoretic
connection between the two fundamental quantities\, which are known to su
ffer from hierarchy problems in the absence of spacetime supersymmetry. \n
\nWe also discuss a number of crucial issues involving the use and interpr
etation of regulators in UV/IR-mixed theories\, such as string theory\, an
d the manner in which one can extract an EFT description from such theorie
s. Finally\, we analyze the running of the Higgs mass within such an EFT d
escription and uncover the existence of a "dual IR" region which emerges a
t high energies as the consequence of an intriguing scale-inversion dualit
y symmetry. We also identify a generic stringy effective potential for th
e Higgs fields in such theories. Our results can therefore serve as the l
aunching point for a rigorous investigation of gauge hierarchy problems in
string theory.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Olaf Hohm (Humboldt University)
DTSTART:20231026T130000Z
DTEND:20231026T143000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/23
DESCRIPTION:Title: Double Copy\, Double Field Theory & Homotopy Algebras\nby Ola
f Hohm (Humboldt University) as part of SFT@Cloud Journal Club\n\n\nAbstra
ct\nThe double copy denotes a technology to relate the scattering amplitud
es of Yang-Mills theory to those of gravity. While enormously successful a
t the level of scattering amplitudes\, until recently there was no first-p
rinciple understanding of how to derive such relations. Such an understand
ing would be needed in order to describe\, for instance\, a double copy of
classical solutions. I present an approach based on homotopy algebras suc
h as L-infinity algebras that allows one to provide such a first-principle
derivation\, at least to some finite order in perturbation theory. To thi
s end I review how to formulate Yang-Mills theory as an L-infinity algebra
\, how to "strip off" color to obtain a different kind of homotopy algebra
and\, finally\, how to combine two copies of these exotic algebras to obt
ain the L-infinity algebra of gravity in the form of double field theory.\
n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Minjae Cho (Princeton University)
DTSTART:20231116T140000Z
DTEND:20231116T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/24
DESCRIPTION:Title: On the symplectic form of the open string field theory\nby Mi
njae Cho (Princeton University) as part of SFT@Cloud Journal Club\n\n\nAbs
tract\nWe explore the construction of the symplectic form on the phase spa
ce of classical solutions in open string field theory. We demonstrate its
practical application by computing the energy of open string rolling tachy
on solutions\, which agrees with Sen’s proposal based on boundary confor
mal field theory.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Georg Stettinger (Institute of Physics of The Czech Academy of Sci
ences)
DTSTART:20240125T140000Z
DTEND:20240125T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/25
DESCRIPTION:Title: Open String Field Theory with Stubs\nby Georg Stettinger (Ins
titute of Physics of The Czech Academy of Sciences) as part of SFT@Cloud J
ournal Club\n\n\nAbstract\nThere are various reasons why adding stubs to t
he vertices of open string field theory (OSFT) is \ninteresting: Not only
can the stubs tame certain singularities and make the theory more well-beh
aved\, but also the new theory shares a lot of similarities with closed st
ring field\ntheory\, which helps to improve our understanding of its struc
ture and possible solutions. In this talk\, I will explain in detail how t
o implement stubs into the framework of OSFT\, resulting in an\nA-infinity
-algebra with infinitely many vertices. Moreover\, properties and examples
of cohomomorphisms that map solutions of Witten theory to solutions of th
e stubbed theory are discussed. In the second part\, I will generalize the
whole construction to the sliver frame and construct solutions of the stu
bbed theory explicitly.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aninda Sinha (Indian Institute of Science)
DTSTART:20240222T140000Z
DTEND:20240222T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/26
DESCRIPTION:Title: From Euler to Veneziano and Back\nby Aninda Sinha (Indian Ins
titute of Science) as part of SFT@Cloud Journal Club\n\n\nAbstract\nWhat l
inks Madhava\, Euler\, and string theory? I will present new QFT motivated
representations of the Euler Beta function and related functions which ma
ke appearances in string theory. Pushing the analogy between Feynman diagr
ams in quantum field theory and string theory leads to new physics inspire
d representations of Zeta functions as well as pi\, finding that the QFT f
ormulas interpolate between standard representations and faster converging
ones. The new representations sum over all channels and include contact i
nteractions very much in the spirit of quantum field theory and what is an
ticipated from string field theory\, enabling efficient level truncation.
I will briefly touch upon the status of this calculation in string field t
heory and what is missing to enable a derivation of an analytic formula us
ing string field theory.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lucien Heurtier (King's College London)
DTSTART:20240418T130000Z
DTEND:20240418T143000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/27
DESCRIPTION:Title: Exact Schwinger Proper Time Renormalisation\nby Lucien Heurti
er (King's College London) as part of SFT@Cloud Journal Club\n\n\nAbstract
\nWe derive an exact version of the Schwinger Proper Time Renormalisation
Group flow equation from first principles from the complete path integral\
, without using any perturbative expansion. We study the advantages of thi
s flow equation as compared to the canonical Exact Renormalisation Group f
low equation\, which uses a regulator in momentum space. We use our flow e
quation to recover the convexity of the effective scalar potential in the
IR limit and apply it to the study of false-vacuum decay.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alberto Ruffino (Università di Torino)
DTSTART:20240328T140000Z
DTEND:20240328T153000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/28
DESCRIPTION:Title: Quantum Stubs for String Field Theories\nby Alberto Ruffino (
Università di Torino) as part of SFT@Cloud Journal Club\n\n\nAbstract\nWe
present a systematic algebraic procedure for adding stubs to a generic qu
antum String Field Theory. This method extends the approach of adding stub
s through homotopy transfer techniques\, as pointed out by Schnabl-Stettin
ger and Erbin-Firat\, to the quantum scenario. To start with\, we pedagogi
cally apply our method to a “quantum” cubic theory and then delve into
proper solutions to the BV quantum master equation\, such as open-closed
SFT\, where we extract the explicit expression for the stubbed multi-strin
g open-closed products. We also describe how our algebraic method matches
the geometric interpretation of adding stubs\, focusing on the concrete ex
ample of the open string one-loop tadpole within the framework of open-clo
sed SFT.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michael Kroyter (Holon Institute of Technology)
DTSTART:20240425T130000Z
DTEND:20240425T143000Z
DTSTAMP:20260422T225723Z
UID:SFT_at_cloud_JC/29
DESCRIPTION:Title: On Democratic String Field Theories\nby Michael Kroyter (Holo
n Institute of Technology) as part of SFT@Cloud Journal Club\n\n\nAbstract
\nWe reexamine democratic open string field theories\, namely\, theories i
n which string fields are not constrained to a single picture number and p
icture changing is obtained as a gauge transformation. We describe several
possibilities for regular free theories and attempt to construct the lowe
st order interaction term and identify the lowest order gauge transformati
on for some of these theories. We also discuss projections over string fie
ld spaces that might be needed for a consistent off-shell implementation o
f picture changing.\n
LOCATION:https://researchseminars.org/talk/SFT_at_cloud_JC/29/
END:VEVENT
END:VCALENDAR