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SUMMARY:Probing Unified Theories with Reduced Couplings at Future Collider
s
DTSTART;VALUE=DATE-TIME:20210729T085000Z
DTEND;VALUE=DATE-TIME:20210729T091000Z
DTSTAMP;VALUE=DATE-TIME:20211023T183139Z
UID:indico-contribution-10441-105062@indico.desy.de
DESCRIPTION:Speakers: Gregory Patellis (National Technical University of A
thens)\nThe search for renormalization group invariant relations among par
ameters to all orders in perturbation theory constitutes the basis of the
reduction of couplings concept. Reduction of couplings can be achieved in
certain N=1 supersymmetric grand unified theories and few of them can even
become finite at all loops. The resulting theories in which successful re
duction of couplings has been achieved so far include: (i) a reduced versi
on of the minimal N=1 SU(5) model\, (ii) an all-loop finite N=1 SU(5) mode
l\, (iii) a two-loop finite N=1 SU(3)^3 model and finally (vi) a reduced v
ersion of the Minimal Supersymmetric Standard Model. We present a number o
f benchmark scenarios for each model and investigate their observability a
t existing and future hadron colliders. The heavy supersymmetric spectra f
eatured by each of the above models are found to be beyond the reach of th
e 14 TeV HL-LHC. It is also found that the reduced version of the MSSM is
already ruled out by the LHC searches for heavy neutral MSSM Higgs bosons.
In turn\, the discovery potential of the 100 TeV FCC-hh is investigated a
nd found that large parts of the predicted spectrum of these models can be
tested. In this talk we will present results and updates from our recent
work (Eur.Phys.J.C 81 (2021) 2\,185: arXiv:2011.07900 [hep-ph]).\n\nhttps:
//indico.desy.de/event/28202/contributions/105062/
LOCATION:Zoom
URL:https://indico.desy.de/event/28202/contributions/105062/
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SUMMARY:Non-singular vortices with positive mass in 2+1-dimensional Einste
in gravity with AdS$_3$ and Minkowski background
DTSTART;VALUE=DATE-TIME:20210728T150500Z
DTEND;VALUE=DATE-TIME:20210728T152500Z
DTSTAMP;VALUE=DATE-TIME:20211023T183139Z
UID:indico-contribution-10441-105042@indico.desy.de
DESCRIPTION:Speakers: Ariel Edery (Bishop's University)\nWe find numerical
ly static vortex solutions where the scalar and gauge fields have a non-si
ngular profile under Einstein gravity in an AdS$_3$ background. Vortices w
ith different winding numbers $n$\, VEV $v$ and cosmological constant $\\L
ambda$ are obtained. These vortices have positive mass and are not BTZ bla
ck holes as they have no event horizon. The mass is determined in two ways
: by subtracting the numerical values of two separate asymptotic metrics a
nd via an integral that is purely over the matter fields. The mass of the
vortex increases as the cosmological constant becomes more negative and th
is coincides with the core of the vortex becoming smaller (compressed). We
then consider the vortex with gravity in asymptotically flat spacetime fo
r different values of the coupling $\\alpha=1/(16 \\pi G)$. At the origin\
, the spacetime has its highest curvature and there is no singularity. It
transitions to an asymptotic conical spacetime with angular deficit that i
ncreases significantly as $\\alpha$ decreases. For comparison\, we also co
nsider the vortex without gravity in flat spacetime. For this case\, one c
annot obtain the mass by the first method (subtracting two metrics) but re
markably\, via a limiting procedure\, one can obtain an integral mass form
ula. In the absence of gauge fields\, there is a well-known logarithmic di
vergence in the energy of the vortex. With gravity\, we present this diver
gence in a new light. We show that the metric acquires a logarithmic term
which is the $2+1$ dimensional realization of the Newtonian gravitational
potential when General Relativity is supplemented with a scalar field.\n\n
https://indico.desy.de/event/28202/contributions/105042/
LOCATION:Zoom
URL:https://indico.desy.de/event/28202/contributions/105042/
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SUMMARY:The strong CP problem\, the infinite volume limit\, and cluster de
composition
DTSTART;VALUE=DATE-TIME:20210729T091000Z
DTEND;VALUE=DATE-TIME:20210729T093000Z
DTSTAMP;VALUE=DATE-TIME:20211023T183139Z
UID:indico-contribution-10441-105057@indico.desy.de
DESCRIPTION:Speakers: Carlos Tamarit (Technische Universität München)\nW
hile CP violation has never been observed in the strong interactions\, the
QCD Lagrangian admits a CP-odd topological interaction proportional to th
e so called theta angle\, which weighs the contributions to the partition
function from different topological sectors. The observational bounds are
usually interpreted as demanding a severe tuning of theta against the phas
es of the quark masses\, which constitutes the so-called strong CP problem
. In this talk we challenge this view and argue that in an infinite spacet
ime the theta angle drops out of correlation functions\, so that it become
s unobservable and the CP symmetry is preserved. We arrive at this result
either by using instanton computations or by constraining the dependence o
f the partition function on the spacetime volume and the fermion masses by
imposing cluster decomposition and compatibility with the index theorem.
We further show that in large but finite spacetime volumes\, cluster decom
position can be satisfied up to volume-suppressed corrections without the
need to sum over topological sectors\, and the resulting partition functio
ns lead again to no CP violation.\n\nhttps://indico.desy.de/event/28202/co
ntributions/105057/
LOCATION:Zoom
URL:https://indico.desy.de/event/28202/contributions/105057/
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SUMMARY:Non-Hermiticity: a new paradigm for model building in particle phy
sics
DTSTART;VALUE=DATE-TIME:20210729T083000Z
DTEND;VALUE=DATE-TIME:20210729T085000Z
DTSTAMP;VALUE=DATE-TIME:20211023T183139Z
UID:indico-contribution-10441-105056@indico.desy.de
DESCRIPTION:Speakers: Peter Millington (University of Nottingham)\nNon-Her
mitian quantum theories have been applied in many other areas of physics.
In this talk\, I will review recent developments in the formulation of no
n-Hermitian quantum field theories\, highlighting features that are unique
compared to Hermitian theories. I will describe their crucial discrete s
ymmetries and how continuous symmetry properties are borne out\, including
Noether's theorem [1]\, the Goldstone theorem [2] and the Englert-Brout-H
iggs mechanism [3\,4]. As examples\, I will describe non-Hermitian deform
ations of QED\, the Higgs-Yukawa theory [5] and flavour oscillations [6]\,
illustrating the potential implications of non-Hermitian model building f
or the neutrino sector [5]. Together\, these results pave the way for a s
ystematic programme for building non-Hermitian extensions of the Standard
Model of particle physics.\n\n[1] J. Alexandre\, P. Millington\, D. Seynae
ve\, Phys. Rev. D 96\, 065027 (2017).\n[2] J. Alexandre\, J. Ellis\, P. Mi
llington\, D. Seynaeve\, Phys. Rev. D 98\, 045001 (2018). \n[3] J. Alexand
re\, J. Ellis\, P. Millington\, D. Seynaeve\, Phys. Rev. D 99\, 075024 (20
19).\n[4] J. Alexandre\, J. Ellis\, P. Millington\, D. Seynaeve\, Phys. Re
v. D 101\, 035008 (2020).\n[5] J. Alexandre\, C. M. Bender\, P. Millington
\, J. High Energy Phys. JHEP11(2015)111.\n[6] J. Alexandre\, J. Ellis\, P.
Millington\, Phys. Rev. D 102\, 125030 (2020).\n\nhttps://indico.desy.de/
event/28202/contributions/105056/
LOCATION:Zoom
URL:https://indico.desy.de/event/28202/contributions/105056/
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SUMMARY:Generalizing the Ryu-Takayanagi formula to probe entanglement shad
ows of BTZ black holes
DTSTART;VALUE=DATE-TIME:20210729T081000Z
DTEND;VALUE=DATE-TIME:20210729T083000Z
DTSTAMP;VALUE=DATE-TIME:20211023T183139Z
UID:indico-contribution-10441-105043@indico.desy.de
DESCRIPTION:Speakers: Marius Gerbershagen (Universität Würzburg)\nWe def
ine a generalized entanglement measure in the context of AdS$_3$/CFT$_2$.
Compared to the ordinary entanglement entropy between spatial degrees of f
reedom dual to the area of the Ryu-Takayanagi surface\, we take into accou
nt both entanglement between spatial degrees of freedom as well as between
different fields of the boundary CFT. We then calculate this generalized
entanglement measure in a thermal state dual to the BTZ black hole in the
setting of the D1/D5 system at and close to the orbifold point. We find th
at the entanglement entropy defined in this way is dual to the length of a
geodesic with non-zero winding number. Such geodesics probe the entire bu
lk geometry\, including regions known as entanglement shadows which are no
t reached by any Ryu-Takayanagi surface. This allows us to describe region
s close to the black hole horizon in the one-sided black hole and the worm
hole growth in the case of a two-sided black hole from entanglement data i
n the boundary field theory. Therefore\, we propose that entanglement is i
n fact enough to reconstruct the full BTZ geometry from boundary data.\n\n
https://indico.desy.de/event/28202/contributions/105043/
LOCATION:Zoom
URL:https://indico.desy.de/event/28202/contributions/105043/
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SUMMARY:Massive Integrability: From Fishnet Theories to Feynman Graphs and
Back
DTSTART;VALUE=DATE-TIME:20210729T075000Z
DTEND;VALUE=DATE-TIME:20210729T081000Z
DTSTAMP;VALUE=DATE-TIME:20211023T183139Z
UID:indico-contribution-10441-105045@indico.desy.de
DESCRIPTION:Speakers: Florian Loebbert (Humboldt University Berlin)\nSince
the rise of the AdS/CFT duality\, integrability has proven to be an impor
tant tool to advance our understanding of massless QFT. In this talk we de
monstrate that integrability is also present in massive QFT in D>2 spaceti
me dimensions. We show that large classes of massive Feynman integrals are
highly constrained by an infinite dimensional Yangian symmetry. When tran
slated to momentum space\, this leads to a novel massive generalization of
conformal symmetry. Finally\, we argue that these features of Feynman int
egrals can be understood as the integrability of planar scattering amplitu
des in a massive version of the so-called fishnet theory\, which is obtain
ed as a double-scaling limit of N=4 super Yang-Mills theory on the Coulomb
branch.\n\nhttps://indico.desy.de/event/28202/contributions/105045/
LOCATION:Zoom
URL:https://indico.desy.de/event/28202/contributions/105045/
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SUMMARY:Four-loop scattering amplitudes journey into the forest
DTSTART;VALUE=DATE-TIME:20210729T073000Z
DTEND;VALUE=DATE-TIME:20210729T075000Z
DTSTAMP;VALUE=DATE-TIME:20211023T183139Z
UID:indico-contribution-10441-105058@indico.desy.de
DESCRIPTION:Speakers: Norma Selomit Ramírez Uribe (IFIC CSIC-UV)\nA cruci
al challenge in perturbative Quantum Field Theory is the description of qu
antum fluctuations at high-energy scattering processes by the calculation
of multi-loop scattering amplitudes. Aiming for improving the efficiency o
f these computations\, we delve into a new technique based on the Loop-Tre
e Duality (LTD). We analyse the multiloop topologies that appear for the f
irst time at four loops and manage to assemble them in general expression\
, the N^4MLT universal topology. Based on the fact that the LTD enables to
open any scattering amplitude in terms of convolutions of known subtopolo
gies\, we obtained the dual representation of the universal N^4MLT topolog
y and determined the internal causal structure of the entire amplitude. Re
markably\, we verified the causal conjecture for the N^4MLT family and pre
sent explicit causal representations of selected configurations\, allowing
a more efficient numerical implementation due to the absence of non-causa
l singularities.\n\nhttps://indico.desy.de/event/28202/contributions/10505
8/
LOCATION:Zoom
URL:https://indico.desy.de/event/28202/contributions/105058/
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SUMMARY:The Higgs field in brane-worlds
DTSTART;VALUE=DATE-TIME:20210728T152500Z
DTEND;VALUE=DATE-TIME:20210728T154500Z
DTSTAMP;VALUE=DATE-TIME:20211023T183139Z
UID:indico-contribution-10441-105054@indico.desy.de
DESCRIPTION:Speakers: Grégory Moreau (IJCLab\, Université Paris-Saclay)\
nThe problematic huge hierarchy between the usual 4-dimensional Planck mas
s scale of gravity and the ElectroWeak symmetry breaking scale can interes
tingly disappear at some point-like location along extra space-like dimens
ions where the effective gravity scale is reduced down to the TeV scale. F
ield theories with point-like particle locations (3-dimensional brane-worl
ds) or point-like interactions deserve special care. In particular it can
be shown that\, in contrast with usual literature\, brane-scalar fields
– like the Standard Model Higgs boson – interacting with fermions in t
he whole space (bulk) do not need to be regularized if rigorous 4- or 5-di
mensional treatments are applied: standard regularization introduces a fin
ite width wave function for scalar fields localized along extra dimensions
. The variational calculus of least action principle must also be applied
strictly to derivate the fermion (Kaluza-Klein) masses and couplings\, in
particular by distinguishing the natural and essential boundary conditions
: the higher-dimensional model – based in particular on extra compact sp
aces of type interval or circle (orbifold) – must be defined either comp
letely through the action expression [necessity then for new specific bran
e terms bilinear in the fermion fields] or partially from additional so-ca
lled essential boundary conditions. Besides\, the correct action integrand
definition requires to introduce improper integrals in order to remain co
mpatible with the fermion wave function discontinuities induced by point-l
ike Higgs interactions. These presented new brane-Higgs treatments have ph
enomenological impacts and in particular the relaxing of previously obtain
ed strong bounds on Kaluza-Klein masses\, induced by flavour changing reac
tions generated through exchanges of the Higgs field.\n\nhttps://indico.de
sy.de/event/28202/contributions/105054/
LOCATION:Zoom
URL:https://indico.desy.de/event/28202/contributions/105054/
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SUMMARY:Black hole metamorphosis: what happens after half evaporation?
DTSTART;VALUE=DATE-TIME:20210728T144500Z
DTEND;VALUE=DATE-TIME:20210728T150500Z
DTSTAMP;VALUE=DATE-TIME:20211023T183139Z
UID:indico-contribution-10441-105041@indico.desy.de
DESCRIPTION:Speakers: Sebastian Zell (EPFL - Ecole Polytechnique Federale
Lausanne (CH))\nHawking's calculation of particle production by a black ho
le is based on the semi-classical approximation\, in which back-reaction o
n the metric is not taken into account. This leaves open the question of h
ow the black hole evolves as a result of evaporation. In an attempt to ans
wer it\, we construct a simple analogue system\, which shares the informat
ion storage properties of a black hole such as its Bekenstein-Hawking entr
opy. We find indications that at the latest after losing half of the mass\
, a black hole undergoes a metamorphosis leading to a drastic deviation fr
om Hawking evaporation. As two likely possibilities for the subsequent evo
lution\, it can either become extremely long lived or decay via a new clas
sical instability. The first option would open up a new window for small p
rimordial black holes as viable dark matter candidates.\n\nhttps://indico.
desy.de/event/28202/contributions/105041/
LOCATION:Zoom
URL:https://indico.desy.de/event/28202/contributions/105041/
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SUMMARY:The string theory swampland in the Euclid\, SKA and Vera Rubin obs
ervatory era
DTSTART;VALUE=DATE-TIME:20210727T144000Z
DTEND;VALUE=DATE-TIME:20210727T150000Z
DTSTAMP;VALUE=DATE-TIME:20211023T183139Z
UID:indico-contribution-10441-105055@indico.desy.de
DESCRIPTION:Speakers: Cyril Renevey (LPSC\, Grenoble)\nWe explore the abil
ity of future cosmological surveys to put constraints on string theory\, t
hrough the Swampland program. String theory is sometimes thought to be unf
alsifiable due to the incredibly large amount of low energy effective vers
ions that can be derived in its framework. However\, it is well known that
constructing consistent solutions in a de-Sitter background is tremendous
ly difficult. This led to speculative conditions on the possible shape of
the potential of a dark energy scalar field. This postulate is referred to
as the "de-Sitter conjecture" and low-energy effective theories that do n
ot satisfy it are said to live in the Swampland. Future experiments\, such
as the Vera Rubin Observatory\, Euclid or SKA\, will set strong constrain
ts on the form of dark energy and we investigated their potential conflict
with the Swampland theoretical conditions. In particular\, we show that t
he expected constraints on the equation of states of dark energy might be
in strong contradiction with the de-Sitter conjecture and could therefore
put string theory under pressure. Our study is carried out for many differ
ent quintessence potentials and a very wide range of initial conditions.\n
\nhttps://indico.desy.de/event/28202/contributions/105055/
LOCATION:Zoom
URL:https://indico.desy.de/event/28202/contributions/105055/
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SUMMARY:Quantum breaking and scrambling: what 2 PI effective action can te
ach us
DTSTART;VALUE=DATE-TIME:20210727T142000Z
DTEND;VALUE=DATE-TIME:20210727T144000Z
DTSTAMP;VALUE=DATE-TIME:20211023T183139Z
UID:indico-contribution-10441-105046@indico.desy.de
DESCRIPTION:Speakers: Michael Zantedeschi (Max Planck Institute for Physik
\, Munich)\nIn this talk\, after reviewing the concept of quantum breaking
\, and its relation to scrambling\, concepts which proved fundamental for
our understanding of composite systems such as condensates\, black holes a
nd De Sitter\, I will show how to study them within the context of 2PI eff
ective action. To do so I will focus on a simple model of a one dimensiona
l condensate in which a logarithmic timescale emerges.\n\nhttps://indico.d
esy.de/event/28202/contributions/105046/
LOCATION:Zoom
URL:https://indico.desy.de/event/28202/contributions/105046/
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SUMMARY:Four-dimensional treatment of positivity bounds with gravity
DTSTART;VALUE=DATE-TIME:20210727T140000Z
DTEND;VALUE=DATE-TIME:20210727T142000Z
DTSTAMP;VALUE=DATE-TIME:20211023T183139Z
UID:indico-contribution-10441-105044@indico.desy.de
DESCRIPTION:Speakers: Anna Tokareva (University of Jyvaskyla)\nWe formulat
e Positivity Bounds for scattering amplitudes including exchange of gravit
ons in four dimensions. We generalize the standard construction through di
spersion relations to include the presence of a branch cut along the real
axis in the complex plane for the Maldestam variable s. In general\, valid
ity of these bounds require the cancellation of divergences in the forward
limit of the amplitude. We show that this is possible only if one assumes
a Regge behavior of the amplitude at high energies. As a non-trivial fact
\, a concrete UV behaviour of the amplitude is uniquely determined by the
structure of IR divergences. We discuss also possible phenomenological app
lications of these bounds.\n\nhttps://indico.desy.de/event/28202/contribut
ions/105044/
LOCATION:Zoom
URL:https://indico.desy.de/event/28202/contributions/105044/
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