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BEGIN:VEVENT
SUMMARY:Dimitris Kosmopoulos (Univ. of Geneva)
DTSTART:20231031T100000Z
DTEND:20231031T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/1
DESCRIPTION:Title: Μελετώντας Βαρυτικά Κύματα με Πλάτη Σκέ
δασης/Gravitational Waves from Amplitudes\nby Dimitris Kosmopoulo
s (Univ. of Geneva) as part of NKUA HEP Seminars\n\nLecture held in Αίθ
ουσα σεμιναρίων του Τομέα (3ος όροφος).\n\nA
bstract\nΗ χρήση τεχνικών της Κβαντικής Θεωρ
ίας Πεδίου\, συγκεκριμένα η σύγχρονη εργ
αλειοθήκη των Πλατών Σκέδασης\, για την α
νάλυση βαρυτικών κυμάτων που παράγονται
από δυαδικά συστήματα έχει οδηγήσει σε
ραγδαία πρόοδο τα τελευταία χρόνια. Σε α
υτή την ομιλία θα περιγράψω αυτή την ερε
υνητική προσπάθεια\, δίνοντας ιδιαίτερη
έμφαση σε φαινόμενα συσχετισμένα με το σ
πιν των αστροφυσικών σωμάτων που δημιου
ργούν τα βαρυτικά κύματα\, καθώς και στα
πρώτα βήματα προς την περιγραφή δυαδικώ
ν συστημάτων με μεγάλη διαφορά στη μάζα (
extreme-mass-ratio inspirals) χρησιμοποιώντας Πλάτη Σ
κέδασης.\n\nRecent years have seen significant advancements in empl
oying tools from Quantum Field Theory\, specifically Scattering Amplitudes
\, to inform theoretical predictions for gravitational waveforms generated
by binary systems. In this talk I will review this effort\, emphasizing e
specially results related to the spin of the astrophysical objects in the
binary system\, as well as the first steps towards a Quantum Field Theoret
ic description of extreme-mass-ratio inspirals.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Dodelson (CERN)
DTSTART:20231211T100000Z
DTEND:20231211T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/2
DESCRIPTION:Title: Black hole bulk-cone singularities\nby Matthew Dodelson (CERN) as par
t of NKUA HEP Seminars\n\n\nAbstract\nCorrelators in field theories at fin
ite temperature have singularities on the light cone. Are there any other
singularities? In this talk I will address this question in the context of
holographic theories in the black hole phase. Two points on the AdS bound
ary can be connected by a null geodesic in the bulk\, leading to a so-call
ed bulk-cone singularity. These new singularities were previously conjectu
red by analyzing the geodesic approximation\, but we will derive them in f
ull generality by developing the technology of thermal Regge theory. The f
unctional form of the singularity leads to sharp signatures of the AdS pho
ton sphere in the boundary CFT\, including an identification of the bounda
ry dual of the angular velocity and Lyapunov exponent associated to the ph
oton sphere. I will also comment on the resolution of the singularity by s
tringy effects.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sašo Grozdanov (Univ. of Edinburgh)
DTSTART:20231204T100000Z
DTEND:20231204T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/3
DESCRIPTION:Title: Pole-skipping in a large number of spacetime dimensions and the reconstru
ction of QFT spectra\nby Sašo Grozdanov (Univ. of Edinburgh) as part
of NKUA HEP Seminars\n\n\nAbstract\nThe holographic duality provides an ex
plicit reduction of quantum field theory (QFT) calculations in the semicla
ssical large-N limit to sets of “gravitational” differential equations
whose analysis can reveal all details of the spectra of thermal QFT corre
lators. I will discuss how\, in certain cases\, a complete reconstruction
of the spectrum and of the corresponding correlator is possible from only
the knowledge of an infinite\, discrete set of pole-skipping points (a “
0/0” in the associated correlation function) traversed by a single (hydr
odynamic) mode. The main step that will enable a unique reconstruction wil
l be a series expansion of the problem in an inverse number of spacetime d
imensions\, expanded around infinity. Conceptually\, this reduces the comp
utation of a QFT correlator spectrum to performing a set of purely algebra
ic manipulations.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicolaos Toumbas (Cyprus U.)
DTSTART:20240429T090000Z
DTEND:20240429T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/4
DESCRIPTION:Title: A time dependent ER=EPR for closed FRW cosmologies\nby Nicolaos Toumb
as (Cyprus U.) as part of NKUA HEP Seminars\n\n\nAbstract\nIn this talk\,
I will discuss extensions of the static patch holographic proposal for de
Sitter space and entanglement entropy calculation prescriptions to generic
closed FRW cosmologies in arbitrary dimensions. For large classes of boun
cing and Big Bang/Big Crunch cosmologies\, the spacetime can be encoded on
two holographic screens at the apparent horizons associated to observers
at antipodal points of the spatial sphere. The leading contributions to th
e entanglement entropy between the screens arise from a minimal extremal t
rapped or anti-trapped sphere in the region between the apparent horizons.
The picture amounts to a time-dependent\, cosmological realization of the
ER=EPR conjecture. For the Big Crunch contracting cases\, the screens dis
entangle with the geometrical bridge between them closing off when the min
imal extremal trapped sphere hits the Big Crunch singularity at a time bef
ore the collapse of the Universe.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Achilleas Lazopoulos (ETH\, Zurich)
DTSTART:20240122T100000Z
DTEND:20240122T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/5
DESCRIPTION:Title: Ενεργός θεωρία πεδίου για το Καθιερωμέν
ο Μοντέλο/Developments in Standard Model Effective Field Theory\nby Achilleas Lazopoulos (ETH\, Zurich) as part of NKUA HEP Seminars\n\n
Lecture held in TBA.\n\nAbstract\nΠερίληψη:\n\nΗ μη ανακά
λυψη\, μέχρι τώρα\, καινούριων σωματιδίων
στο LHC υποδηλώνει ότι\, αν υπάρχουν τέτοι
α σωματίδια στην TeV κλίμακα\, η επίδρασή
τους στις μετρήσεις στο LHC θα είναι μόνο
έμμεση. Η Ενεργός Θεωρία Πεδίου για το Κα
θιερωμένο Μοντέλο (ΕΘΠΚΜ) είναι ένα πολύ
δημοφιλές θεωρητικό εργαλείο για την πα
ραμετροποίηση παρόμοιων επιδράσεων\, κα
ι τη διαμεσολάβηση ανάμεσα στη θεωρία κα
ι τα πειραματικά δεδομένα. Σ’αυτό το σεμ
ινάριο θα περιγράψω σύντομα την ΕΘΠΚΜ κα
ι μερικές θεωρητικές προκλήσεις που αντ
ιμετωπίζουμε σε ένα και δύο loops\, στην πρ
οσπάθειά μας να κάνουμε τη θεωρητική περ
ιγραφή ακριβέστερη. \n\n---\n\nAbstract:\n\nThe lack of d
irect discoveries at the LHC implies that if there is new physics at the T
eV scale\, its effects will only influence collider observables indirectly
. The Standard model effective field theory (SMEFT) is a very popular theo
retical tool to parametrise the effects of new physics models\, and theref
ore mediate between theory and experimental data. I will briefly describe
the SMEFT and some recent theoretical challenges at one and two loops\, as
we strive to make the theoretical description more precise.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Elias Kiritsis (Univ. of Crete)
DTSTART:20231109T090000Z
DTEND:20231109T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/6
DESCRIPTION:Title: Holographic cosmological reheating [Canceled]\nby Elias Kiritsis (Uni
v. of Crete) as part of NKUA HEP Seminars\n\nLecture held in Αίθουσ
α συνεδριάσεων του Τμήματος Φυσικής ΕΚΠ
Α (2ος όροφος).\n\nAbstract\nAccording to the inflationary theory
of cosmology\, most elementary particles in the current universe were cre
ated during a period of reheating after inflation. We self-consistently c
ouple the Einstein-inflaton equations to a strongly coupled quantum field
theory (QFT) which is holographic.\n\nWe solve for the cosmological evolut
ion and show that this leads to an inflating universe\, a fast reheating p
hase and finally a universe dominated by the QFT in thermal equilibrium.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nana Geraldine Cabo Bizet (Univ. de Guanajuato)
DTSTART:20231120T100000Z
DTEND:20231120T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/8
DESCRIPTION:Title: Non-Abelian T-dualities in (0\,2) gauged linear sigma models\nby Nana
Geraldine Cabo Bizet (Univ. de Guanajuato) as part of NKUA HEP Seminars\n
\n\nAbstract\nWe consider U(1) two dimensional gauged linear sigma models
with (0\,2) supersymmetry and global symmetries. We implement T-duality by
gauging the global symmetries and adding Lagrange multipliers\, via the R
oček-Verlinde procedure. First\, we find Abelian T-duals\, which match th
e mirror symmetry case. Then\, we implement general non-Abelian T-duality
for models arising from a reduction of (2\,2) supersymmetry\; including i
nstanton corrections. We study the case of CP1 target space with SU(2) gl
obal symmetry\, obtaining as a dual space the disk. We determine the non-A
belian SU(2)xSU(2) dual of CP1xCP1\, which consists of two copies of the
disk. We fully solve the equations of motion leading to non-Abelian T-dual
ity\, improving with respect to the studies for (2\,2) supersymmetry.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dimitrios Katsinis (NKUA)
DTSTART:20240108T100000Z
DTEND:20240108T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/9
DESCRIPTION:Title: Generating solutions of sigma models efficiently\nby Dimitrios Katsin
is (NKUA) as part of NKUA HEP Seminars\n\nLecture held in Αίθουσα
σεμιναρίων Τομέα Β.\n\nAbstract\nWe review the dressing me
thod for the construction solutions of non linear sigma models given a kno
wn solutions. Specializing in the case of the O(N) model\, we show that gi
ven a solution having appropriate free parameters\, it is possible to appl
y the dressing method systematically (i.e. without solving any equation) b
y taking advantage of the Pohlmeyer reduction and by rescaling the free pa
rameters. In this context the dressing method acts as a non linear superpo
sition rule\, merging a genuine solution of the sigma model with a "virtua
l" one. Talk based on 2011.04610\, 2201.02493\, 2201.10554 and work in pro
gress.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Carlos Núñez (Swansea Uni.)
DTSTART:20240212T100000Z
DTEND:20240212T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/10
DESCRIPTION:Title: Aspects of gauge-strings duality\nby Carlos Núñez (Swansea Uni.) a
s part of NKUA HEP Seminars\n\n\nAbstract\nI will start with a pedagogical
introduction of Duality (in Physics) and AdS/CFT as an application of the
se ideas. After that and more technically\, I will discuss how one can use
some techniques developed by string theorists to study non perturbative a
spects of Quantum Field Theories that undergo phenomena like confinement\,
symmetry breaking\, screening\, etc. The examples discussed will be taken
from the papers I published in the last year.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shai Chester (Imperial College London)
DTSTART:20240304T100000Z
DTEND:20240304T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/11
DESCRIPTION:Title: Bootstrapping N = 4 SYM for all N and coupling\nby Shai Chester (Imp
erial College London) as part of NKUA HEP Seminars\n\n\nAbstract\nWe combi
ne supersymmetric localization with the numerical conformal bootstrap to b
ound the scaling dimension and OPE coefficient of the lowest-dimension ope
rator in N = 4 SU( N) super-Yang-Mills theory for a wide range of N and Ya
ng-Mills couplings g. We find that our bounds are approximately saturated
by weak coupling results at small g. Furthermore\, at large N our bounds i
nterpolate between integrability results for the Konishi operator at small
g and strong-coupling results\, including the first few stringy correctio
ns\, for the lowest-dimension double-trace operator at large g. In particu
lar\, our scaling dimension bounds describe the level splitting between th
e single- and double-trace operators at intermediate coupling.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Congkao Wen (QMUL)
DTSTART:20240115T100000Z
DTEND:20240115T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/12
DESCRIPTION:Title: Exact integrated correlators in N=4 super Yang-Mills\nby Congkao Wen
(QMUL) as part of NKUA HEP Seminars\n\n\nAbstract\nOver the past few year
s\, it has been shown that\, when integrating out the spacetime dependence
with a certain integration measure\, some four-point correlation function
s in four-dimensional maximally supersymmetric Yang-Mills theory (N=4 SYM)
can be computed exactly. These physical observables are often called inte
grated correlators\, which are functions of (complexified) Yang-Mills coup
ling\, and transform under the S-duality of N=4 SYM. In this talk\, I will
review some of the recent developments regarding the integrated correlato
rs.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Roberts (APCTP)
DTSTART:20240123T100000Z
DTEND:20240123T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/13
DESCRIPTION:Title: Monodromy Defects in QFT and Holography\nby Matthew Roberts (APCTP)
as part of NKUA HEP Seminars\n\nLecture held in TBA.\n\nAbstract\nWith an
aim to further quantify non-pertubative defects in quantum field theory\,
we study two-dimensional magnetic defects in four dimensional SUSY quantum
field theories which preserve a two-dimensional superconformal symmetry a
long the defect. These can be thought of as an infrared limit of a magneti
c solenoid. On general grounds such magnetic defects support localized chi
ral edge states\, and in our system we generically preserve a (0\,2) super
symmetry. We compute various physical observables such induced currents ro
tating around the solenoid\, as well as central charges of the defect\, as
a function of the monodromies. Time permitting\, we also comment on the a
nalagous case of one dimensional defects in three dimensional QFTs.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Geoffrey Compère (Brussels U. and Intl. Solvay Inst.\, Brussels)
DTSTART:20240326T100000Z
DTEND:20240326T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/14
DESCRIPTION:Title: Memory effects in de Sitter and the Lambda-BMS group\nby Geoffrey Co
mpère (Brussels U. and Intl. Solvay Inst.\, Brussels) as part of NKUA HEP
Seminars\n\n\nAbstract\nI will first review the features of the displacem
ent memory effect in asymptotically flat spacetimes. I will contrast the a
symptotic structure of future infinity in de Sitter spacetime to the one o
f null infinity in asymptotically flat spacetimes and explain how a genera
lization of the BMS group of asymptotic symmetries\, the Lambda-BMS group\
, arises in de Sitter. I will then explain how to solve for the linear gra
viton field in de Sitter for a localized quadrupolar source and derive the
de Sitter memory effect and its relationship to the Lambda-BMS group. I w
ill prove that the analysis invalidates the dS4/CFT3 conjecture.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mehrdad Mirbabayi (ICTP)
DTSTART:20240311T100000Z
DTEND:20240311T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/15
DESCRIPTION:Title: An Observer's Measure of De Sitter Entropy\nby Mehrdad Mirbabayi (IC
TP) as part of NKUA HEP Seminars\n\n\nAbstract\nThe two-point correlation
function of a massive field\, measured along an observer's worldline in de
Sitter (dS)\, decays exponentially in time. Meanwhile\, every dS observer
is surrounded by a horizon and the holographic interpretation of the hori
zon entropy S_dS suggests that the correlation function should stop decayi
ng\, and start behaving erratically at late times. We find evidence for th
is expectation in Jackiw-Teitelboim gravity by finding a topologically non
trivial saddle\, which is suppressed by exp(-S_dS)\, and which gives a con
stant contribution to the norm squared of the correlator. This constant mi
ght have the interpretation of the late-time average over all microscopic
theories that have the same low-energy effective description. Based on arx
iv-2311.07724.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Erik Tonni (SISSA)
DTSTART:20240527T090000Z
DTEND:20240527T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/17
DESCRIPTION:Title: Aspects of Entanglement Hamiltonians\nby Erik Tonni (SISSA) as part
of NKUA HEP Seminars\n\n\nAbstract\nThe reduced density matrix of a spatia
l subsystem can be written as the exponential of the entanglement (modular
) Hamiltonian\, hence this operator contains a lot of information about th
e entanglement of the corresponding spatial bipartition. For some particul
ar models\, states and bipartitions\, this operator is local\, but in gene
ral it is expected to be non-local. \nWe discuss some entanglement Hamilto
nians in two-dimensional conformal field theory and\, in the case of free
fermions\, also how to obtain them from lattice calculations. The modular
conjugation is closely related to the modular Hamiltonian. We discuss the
geometric action of this operator in two-dimensional conformal field theor
y and its holographic gravitational counterpart in terms of geodesic bit t
hreads.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michele Redi (INFN\, Florence)
DTSTART:20240408T090000Z
DTEND:20240408T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/18
DESCRIPTION:Title: The meso-inflationary axion scenario\nby Michele Redi (INFN\, Floren
ce) as part of NKUA HEP Seminars\n\n\nAbstract\nIn this talk I will descri
be a new scenario for the QCD axion where the Peccei-Quinn symmetry is bro
ken after the beginning of visible inflation. This regime interpolates bet
ween popular pre-inflationary and post-inflationary axion scenarios with d
ifferent phenomenological features from both. In particular in some region
of parameters the PQ symmetry breaking is visible after QCD confinement\,
modifying the axion dark matter abundance and with novel predictions for
axion mini-clusters. I will then show\, using the stochastic formalism of
inflation\, that the meso-inflationary regime is realized even in the simp
lest scenario\, the KSVZ axion\, when the decay constant of the axion is c
omparable to the Hubble scale during inflation for specific values of the
quartic coupling.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Αντωνία Παρασκευoπούλου (Max Planck Inst. Mun
ich & LMU Munich)
DTSTART:20240513T090000Z
DTEND:20240513T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/19
DESCRIPTION:Title: Is M-theory emergent?\nby Αντωνία Παρασκευoπούλο
υ (Max Planck Inst. Munich & LMU Munich) as part of NKUA HEP Seminars\n\
nLecture held in High Energy Group seminar room\, 3rd floor.\n\nAbstract\n
In this talk\, I will present recent progress in the Swampland Program\, w
hich I will briefly introduce\, focusing primarily on one of its less esta
blished conjectures\, usually referred to as the Emergence Proposal. This
postulates that the low energy effective action of a quantum gravity theor
y may be obtained by integrating out light towers of states appearing in v
arious asymptotic regions of the moduli space. In doing so\, I will review
certain subtleties regarding the species scale\, considered to be the ene
rgy scale where the effective description of gravity breaks down and will
serve as the scale distinguishing perturbative from non-perturbative degre
es of freedom. I will then proceed to motivate why the Emergence Proposal
seems to be naturally realized in the (not yet completely understood) deco
mpactification limit to M-theory by reviewing recent calculations of highe
r derivative couplings and independent arguments. The talk will be based o
n: 2309.11551\, 2404.01371\, 2404.05801.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Grumiller (TU Wien)
DTSTART:20240521T090000Z
DTEND:20240521T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/20
DESCRIPTION:Title: Carroll black holes\nby Daniel Grumiller (TU Wien) as part of NKUA H
EP Seminars\n\n\nAbstract\nAfter laying dormant for about half a century\,
Carroll symmetries recently attracted considerable attention\, in part be
cause conformal Carroll symmetries are equivalent to the BMS symmetries fo
und in asymptotically flat spacetimes and thus play a key role in flat spa
ce holography. Making Carroll symmetries local yields Carroll gravity\, wh
ich I shall review. We define Carroll black holes as solutions of Carroll
gravity that exhibit Carroll thermal properties and have a Carroll extrema
l surface\, notions explained in my talk. [arXiv:2308.10947]\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Γεώργιος Λιναρδόπουλος (Asia-Pacific Center f
or Theoretical Physics)
DTSTART:20240520T090000Z
DTEND:20240520T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/21
DESCRIPTION:Title: B-type anomaly coefficients of holographic defects\nby Γεώργι
ος Λιναρδόπουλος (Asia-Pacific Center for Theoretical Physi
cs) as part of NKUA HEP Seminars\n\nLecture held in High Energy Group semi
nar room\, 3rd floor.\n\nAbstract\nEven dimensional conformal field theori
es (CFTs) develop conformal/Weyl anomalies which inflict a (non-vanishing)
expectation value on the trace of the energy-momentum/stress tensor. The
presence of boundaries in CFTs gives rise to extra anomaly coefficients an
d extra central charges\, which show up in both even and odd dimensions an
d can be used to classify defect CFTs\, much like central charges are used
to classify pure CFTs.\n\nThis talk is about the computation of boundary
anomaly coefficients in (codimension-1) holographic defect CFTs. These are
described by domain wall versions of N = 4 SYM that are holographically d
ual to the D3-D5 and the D3-D7 probe-brane systems. Starting from the expl
icit expression of the improved energy-momentum tensor of N = 4 SYM\, we w
ill determine its two and three-point functions in the presence of the dom
ain walls and extract the boundary anomaly coefficients\, to leading order
in perturbation theory. In the same process\, we will also determine the
two and three-point function of the corresponding displacement operators.\
n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Georgios Palkanoglou (University of Guelp and TRIUMF)
DTSTART:20240708T090000Z
DTEND:20240708T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/22
DESCRIPTION:Title: Εξωτική πυρηνική υπερρευστότητα σε πυρ
ήνες και πυρηνική ύλη\nby Georgios Palkanoglou (Univ
ersity of Guelp and TRIUMF) as part of NKUA HEP Seminars\n\n\nAbstract\nΤ
α πυρηνικά υπερρευστά δημιουργούνται απ
ο την συμπύκνωση ζευγών νουκλεονίων\, κα
ι η υπαρξή τους τόσο στους πυρήνες όσο κα
ι στην εκτεταμένη πυρηνική ύλη\, έχει πλέ
ον εδραιωθεί\, φέροντας ποιοτικά αποτελέ
σματα στο φάσμα και τις μάζες πυρηνών κα
θώς και στις θερμικές και περιστροφικές
ιδιότητες των αστέρων νετρονίων. Ωστόσo\,
η ακριβής τους δομή παραμένει ένα σημαν
τικό πρόβλημα της πυρηνικής θεωρίας. Σε
αυτή την ομιλία\, ξεκινώντας με την πυρην
ική ύλη\, θα παρουσιάσω ακριβείς ab initio υπ
ολογισμούς μικροσκοπικών ιδιοτήτων υπέ
ρρευστης νετρονικής ύλης\, όπως η καταστ
ατική της εξίσωση και η ενέργεια ζεύξης
των ζευγών που την αποτελούν\, σε όλο το ε
ύρως πυκνοτήτων του εξωτερικού φλοιού τ
ου αστέρα νετρονίων. Αυτοί οι υπολογισμο
ί έχουν παραχθεί με τεχνικές Quantum Monte Carlo
και θα παρουσιάσω πως πρόμοιες τεχνικές
αυτή τη στιγμή εφαρμόζονται στην μελέτη
των υπερρευστών που αναμένονται σε μεγα
λύτερα βάθη στον αστέρα\, καθώς και την π
ιθανότητα ύπαρξης εξωτικών πυρηνικών υπ
ερρευστών (π.χ.\, καταστάσεις που σπάνε pari
ty και time-reversal συμμετρίες). Συνεχίζοντας σ
τους πεπρασμένους πυρήνες\, θα παρουσιάσ
ω αποτελέσματα που υποστηρίζουν την ύπα
ρξη εξωτικής υπερρευστότητας (απο ζεύγη
spin-triplet ή mixed-spin) και θα συζητήσω τις πειρα
ματικές προσπάθειες επιβεβαίωσης τους σ
ε μετρήσεις μάζας και φάσματος βαρέων πυ
ρήνων. Τέλος\, θα συζητήσω τις επιπτώσεις
όλων αυτών των υπολογισμών στη φυσική τ
ων cold atoms και πως αυτά μπορούν να οδηγήσο
υν ή/και να συμπληρώσουν την εικόνα μας γ
ια τη δομή και τις μορφές της υπέρρευστη
ς πυρηνικής ύλης.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dimitrios Tsimpis (IP2I\, Lyon)
DTSTART:20241029T100000Z
DTEND:20241029T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/23
DESCRIPTION:Title: Τhe importance of being open\nby Dimitrios Tsimpis (IP2I\, Lyon) as
part of NKUA HEP Seminars\n\n\nAbstract\nI will talk about some interesti
ng features of open cosmologies (i.e. four-dimensional spacetimes of Fried
mann-Lemaître-Robertson-Walker type with three-dimensional spatial slices
that are hyperbolic) related to compactifications of ten-dimensional supe
rgravity on certain classes of six-dimensional spaces. Based on e-Prints:
$\\href{https://arxiv.org/abs/2210.10813}{2210.10813}$\, $\\href{https://a
rxiv.org/abs/2309.03938}{2309.03938}$ and $\\href{https://arxiv.org/abs/24
05.09323}{2405.09323}$.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jorge Russo (ICREA\, Barcelona and Barcelona\, Autonoma U. and ICC
\, Barcelona U.)
DTSTART:20241111T100000Z
DTEND:20241111T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/24
DESCRIPTION:Title: On the new formulation of self-dual nonlinear electrodynamics\nby Jo
rge Russo (ICREA\, Barcelona and Barcelona\, Autonoma U. and ICC\, Barcelo
na U.) as part of NKUA HEP Seminars\n\n\nAbstract\nAn important class of t
heories of nonlinear electrodynamics (NLED) are the self-dual ones\,\nthat
is\, theories invariant under electromagnetic duality. A well-known examp
le is Born-Infeld theory. Until recently\, only a few other examples were
known. A new formulation leads to the explicit construction of the most ge
neral self-dual nonlinear electrodynamics and leads to the complete soluti
on of the causality constraints. In addition\, the construction exhibits i
n a simple way the connection between causality and energy conditions. A c
orollary is that there are no regular black holes in any causal NLED with
zero cosmological constant.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eduardo Peinado (Universidad Nacional Autónoma de México (UNAM))
DTSTART:20240905T090000Z
DTEND:20240905T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/25
DESCRIPTION:Title: Recent results in phenomenology of light gauge bosons and dark matter\nby Eduardo Peinado (Universidad Nacional Autónoma de México (UNAM)) a
s part of NKUA HEP Seminars\n\nLecture held in Nuclear and Particle Physic
s Division\, Seminar Room\, 3rd floor.\n\nAbstract\nThe Standard Model has
been confirmed with high precision across a wide range of energies in num
erous experiments. The LHC has significantly constrained new physics\, pus
hing potential discoveries to energy scales above the TeV range. Despite t
his\, a light gauge boson remains a compelling extension to the Standard M
odel\, mainly due to its testability in upcoming low-energy experiments. I
n this talk\, we will review the potential effects of light gauge bosons i
n current and future low-energy experiments\, such as CEvNS\, parity-viola
ting electron scattering\, and electron-positron annihilation. Furthermore
\, dark matter direct detection experiments provide complementary search s
trategies if the new gauge boson mediates between the dark and visible sec
tors.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Robert Harris (Fermilab)
DTSTART:20241001T090000Z
DTEND:20241001T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/26
DESCRIPTION:Title: Searches for Single and Pair-Produced Dijet Resonances at CMS\nby Ro
bert Harris (Fermilab) as part of NKUA HEP Seminars\n\nLecture held in Nuc
lear and Particle Physics Division\, Seminar Room\, 3rd floor.\n\nAbstract
\nSearches for resolved dijet resonances at CMS explore physics at high ma
ss\, and have\nplaced significant constraints on models of dark matter\, g
rand unification\, quark\ncompositeness\, dynamical symmetry breaking\, ad
ditional strong interactions\, new gauge\nbosons and extra dimensions. Con
ducted for over three decades at hadron colliders\,\nthese searches for s-
channel production of a single dijet resonance (p p $\\to$ X $\\to$ jet je
t)\,\nuse the simplest and highest mass signature of new physics with jets
. The next simplest\nsearch is pair production of resolved dijet resonance
s with identical masses\, produced\neither non-resonantly (p p $\\to$ X X
$\\to$ [j j] [j j])\, or resonantly through a massive\nintermediate state
Y that itself decays to dijet resonances (p p $\\to$ Y $\\to$ X X $\\to$ [
j j] [j j]). During Run 2 of the LHC\, such a search for resonant pair pro
duction of dijet resonances\nhas found hints of a possible new resonance a
t a mass of around 8 TeV\, which should be\neither confirmed or excluded b
y the data now accumulating during Run 3. Finally\, a new\nsearch is just
beginning for resonant production of pairs of dijet resonances with non-\n
identical masses (p p $\\to$ Y $\\to$ X Z $\\to$ [j j] [j j]). All the abo
ve searches will also be pursued with jets tagged as bottom quarks. I will
discuss these searches\, that constitute a\ncontinuing program of explora
tion of resolved dijet resonances\, pursued at CMS by a\nstrong collaborat
ion among Athens\, Fermilab\, and other institutions. At the LHC now\, and
\nat the HL-LHC for the next generation\, these searches will continue to
probe the highest\navailable mass scales for new physics in jet final stat
es\, scales that will not be surpassed\nunless and until a higher energy h
adron collider is eventually built.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Avik Banerjee (University of Crete)
DTSTART:20240916T090000Z
DTEND:20240916T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/27
DESCRIPTION:Title: Nambu-Goto equations from 3D gravity\nby Avik Banerjee (University o
f Crete) as part of NKUA HEP Seminars\n\nLecture held in Nuclear and Parti
cle Physics Division seminar room\, 3rd floor.\n\nAbstract\nIn this talk\,
I will demonstrate that the solutions of three-dimensional gravity obtain
ed by gluing two copies of a spacetime across a junction constituted of a
tensile string are in one-to-one correspondence with the solutions of the
Nambu-Goto equation in the same spacetime up to a finite number of rigid d
eformations. The non-linear Nambu-Goto equation satisfied by the average o
f the embedding coordinates of the junction emerges directly from the junc
tion conditions along with the rigid deformations and corrections due to t
he tension. Therefore\, the equivalence principle generalizes non-triviall
y to the string. Our results are valid both in three-dimensional flat and
AdS spacetimes. In the context of AdS$_3$/CFT$_2$ correspondence\, our set
up could be used to describe a class of interfaces in the conformal field
theory featuring relative time reparametrization at the interface which en
codes the solution of the Nambu-Goto equation corresponding to the bulk ju
nction.\n\nBased on 2404.02149 (accepted for publication in JHEP)\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Roberts (APCTP)
DTSTART:20241007T090000Z
DTEND:20241007T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/28
DESCRIPTION:Title: An update on holographic magnetic defects\nby Matthew Roberts (APCTP
) as part of NKUA HEP Seminars\n\n\nAbstract\nDefect CFTs provide an excit
ing new playground to study RG flows and their endpoints. After reviewing
some basics of defect CFTs\, I will present a detailed study of supersymme
tric monodromy defects (also known as magnetic defects) in four and three
dimensional systems. We will measure the response of the system to the ins
ertion of the magnetic solenoid\, and in the four dimensional case will ca
lculate new central charges which appear in the trace anomaly. We close by
commenting on new possible monotonic quantities in these new mixed dimens
ional systems.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Achilleas Porfyriadis (U. Crete)
DTSTART:20241001T110000Z
DTEND:20241001T120000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/29
DESCRIPTION:Title: Extreme Black Holes: Anabasis and Accidental Symmetry\nby Achilleas
Porfyriadis (U. Crete) as part of NKUA HEP Seminars\n\n\nAbstract\nThe nea
r-horizon region of black holes near extremality is universally AdS2-like.
In this talk I will first explain the SL(2) transformation properties of
the spherically symmetric linear perturbations of AdS2 x S2 and show how t
heir backreaction leads to the Reissner-Nordstrom black hole. This backrea
ction with boundary condition change is called an anabasis. I will then sh
ow that the linear Einstein equation near AdS2 x S2\, with or without addi
tional matter\, enjoys an accidental symmetry that may be thought of as an
on-shell large diffeomorphism of AdS2. These symmetries are able to map d
ifferent physical solutions onto each other by acting as a linearized diff
eomorphisms on perturbative solutions around AdS2.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eliezer Rabinovici (The Racah Institute of Physics)
DTSTART:20241126T100000Z
DTEND:20241126T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/30
DESCRIPTION:Title: Some Aspects of Complexity and Krylov Complexity\nby Eliezer Rabino
vici (The Racah Institute of Physics) as part of NKUA HEP Seminars\n\n\nAb
stract\nA review of the concept of Complexity as has emerged in studying l
ong time properties of systems including blackholes will be presented. Som
e emphasis will be made on describing features of a particular form of Com
plexity\, the Krylov Complexity. These include its structure when interpo
lating among various types of systems: free\, strongly integrable and chao
tic ones. Finally I will present a case where we have shown that the value
of the Krylov Complexity\, a quantum information concept\, is equal to th
e value of a geodesic in a certain background\, a geometric concept.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aristomenis Donos (Durham University)
DTSTART:20241217T100000Z
DTEND:20241217T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/31
DESCRIPTION:Title: Nearly critical superfluids and holography [CANCELED]\nby Aristomeni
s Donos (Durham University) as part of NKUA HEP Seminars\n\n\nAbstract\nI
will discuss the low energy dynamics of finite temperature systems which a
re close to a superfluid phase transition. In the regime\, the amplitude o
f the order parameter needs to be included in the description captured by
the hydrodynamics of conserved quantities and the Goldstone mode. After pr
esenting a field theoretic construction of a suitable effective theory\, I
will examine the phenomenology of suitable holographic systems.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chrysoula Markou (Pisa\, Scuola Normale Superiore)
DTSTART:20241209T100000Z
DTEND:20241209T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/33
DESCRIPTION:Title: On the deep string spectrum\nby Chrysoula Markou (Pisa\, Scuola Norm
ale Superiore) as part of NKUA HEP Seminars\n\nLecture held in Seminar Roo
m of Nuclear and Particle Physics Division.\n\nAbstract\nHow well do we un
derstand string theory? As an indicator can be thought of the degree of ou
r understanding of its spectrum. Yet\, other than comprising infinitely ma
ny physical states of arbitrarily high spin and mass\, what does the strin
g spectrum look like? Traditional methodologies can yield its state conten
t on a level-by-level basis\, a straightforward procedure which however be
comes cumbersome as the level increases. In this seminar\, we will discuss
a new\, covariant and efficient technology with which entire physical tra
jectories can be excavated. It is based on the observation that the Viraso
ro constraints in fact encode the generators of a bigger algebra\, that is
a symplectic algebra\, which commutes with the spacetime Lorentz algebra.
This enables constructing trajectories deeper inside the spectrum as “c
lones” of simpler ones\, upon suitably dressing the latter\, depending o
n the “depth” of the trajectory we aim to reach.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Manuela Kulaxizi (Trinity Coll.\, Dublin)
DTSTART:20250210T100000Z
DTEND:20250210T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/34
DESCRIPTION:Title: Comments on the bulk phase shift (eikonal phase)\nby Manuela Kulaxiz
i (Trinity Coll.\, Dublin) as part of NKUA HEP Seminars\n\n\nAbstract\nWe
discuss the phase shift of a light particle moving in an AdS black hole ge
ometry in the context of holography. When the impact parameter is beyond a
critical value\, the particle does not return to the boundary. We discuss
ways of interpreting this in the context of the dual CFT.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Markus B. Fröb (U. Leipzig)
DTSTART:20250310T100000Z
DTEND:20250310T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/35
DESCRIPTION:Title: Modular Hamiltonians\, relative entropy and the entropy-area law in de S
itter spacetime\nby Markus B. Fröb (U. Leipzig) as part of NKUA HEP S
eminars\n\n\nAbstract\nIn a very general setting\, entropy quantifies the
amount of information about a system that an observer has access to. Howev
er\, in contrast to quantum mechanics\, in quantum field theory naive meas
ures of entropy are divergent. To obtain finite results\, one needs to con
sider measures such as relative entropy\, which can be computed from the m
odular Hamiltonian using Tomita--Takesaki theory.\n\nIn this talk\, I will
explain the connection between the quantum-mechanical expressions for (re
lative) entropy\, the modular Hamiltonian and Tomita--Takesaki theory. I t
hen present two examples of modular Hamiltonians that were recently derive
d: one for conformal fields in diamond regions of conformally flat spaceti
mes (including de Sitter)\, and one for fermions of small mass in diamond
regions of two-dimensional Minkowski spacetime. I will give results for th
e relative entropy between the de Sitter vacuum state and a coherent excit
ation thereof in diamonds and wedges\, and show explicitly that the result
satisfies the expected properties for a relative entropy. Finally\, I wil
l use thermodynamic relations to determine the local temperature that is m
easured by an observer\, and consider the backreaction of the coherent exc
itation on the geometry to prove an entropy-area law for de Sitter spaceti
me.\n\nBased on arXiv:2308.14797\, 2310.12185\, 2311.13990 and 2312.04629.
\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Diego Trancanelli (Università di Modena)
DTSTART:20250513T090000Z
DTEND:20250513T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/36
DESCRIPTION:Title: Conformal defects and RG flows in ABJM\nby Diego Trancanelli (Univer
sità di Modena) as part of NKUA HEP Seminars\n\n\nAbstract\nDefects play
a central role in many contexts\, from condensed matter to quantum gravity
. The situations in which the bulk theory is conformal and the defect inhe
rits part of this symmetry -- the so-called defect conformal field theorie
s (dCFTs) -- have recently received a lot of attention\, also thanks to n
ew powerful methods to tackle them\, like supersymmetric localization\, in
tegrability or the bootstrap. A dCFT may be deformed by turning on margina
lly relevant operators\, which trigger RG flows connecting different fixed
points. A natural arena where this phenomenon can be explored are 3-dimen
sional Chern-Simons theories coupled to matter. These are in fact known to
display a plethora of Wilson loops that can be used to define 1-dimension
al dCFTs living on their contours. In this talk we discuss a few examples
from an intricate web of RG flows connecting the dCFTs defined on the BPS
and non-BPS Wilson loops of ABJM theory. We compute the anomalous dimensio
ns of the deforming operators\, establish g-theorems along the flows\, and
also discuss the role played by cohomological anomalies and framing.\n\nB
ased on: 2211.16501\, 2305.01647\, 2312.13283\, 2410.10970\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andreas Mantziris (Universidade do Porto)
DTSTART:20250520T090000Z
DTEND:20250520T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/37
DESCRIPTION:Title: Gravitational waves from a curvature-induced phase transition of a Higgs
-portal dark matter sector\nby Andreas Mantziris (Universidade do Port
o) as part of NKUA HEP Seminars\n\n\nAbstract\nOur latest study (2407.1884
5) investigates the possibility of generating gravitational waves (GWs) fr
om a curvature-induced phase transition of a non-minimally coupled scalar
field acting as dark matter\, with a portal interaction to the Higgs field
. This analysis is conducted within a dynamical spacetime framework\, spec
ifically during the transition from inflation to kination\, while also exa
mining the potential for triggering Electroweak symmetry breaking through
this mechanism.\n\nA comprehensive exploration of inflationary scales is c
arried out\, considering both positive and negative values of the non-mini
mal coupling. The study further accounts for phenomenological and observat
ional constraints on the Beyond Standard Model (BSM) couplings\, ensuring
consistency when the scalar field serves as spectator dark matter. Notably
\, kination enhances the GW amplitudes\, significantly restricting the via
ble parameter space. While the resulting GW spectra typically reside at hi
gh frequencies for standard high-scale inflation\, certain regions of para
meter space allow for potential detection in future experiments\, offering
a testable link between early universe dynamics\, dark matter physics\, a
nd gravitational wave cosmology.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Georgios Tringas (Lehigh University)
DTSTART:20250610T090000Z
DTEND:20250610T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/38
DESCRIPTION:Title: Scale-separation from O-planes\nby Georgios Tringas (Lehigh Universi
ty) as part of NKUA HEP Seminars\n\n\nAbstract\nOrientifold planes play a
crucial role in flux compactifications of string theory\, and we demonstra
te their deep connection to achieving scale-separated solutions. Specifica
lly\, we show that when an orientifold plane contributes at leading order
to the non-zero value of the scalar potential\, then either the weak coupl
ing limit or the large volume limit implies scale separation\, meaning tha
t the Kaluza-Klein tower mass decouples from the inverse length scale of t
he lower-dimensional theory. Notably\, in the supergravity limit\, such so
lutions are inherently scale-separated. This result is independent of the
spacetime dimension and the dimensionality of the Op-plane as long as p <
7. Similarly\, we show that parametric scale separation is not possible fo
r isotropic compactifications with a leading curvature term that generical
ly arise in the AdS/CFT context. We classify all possible flux compactific
ation setups in both type IIA and type IIB string theory for Op-planes wit
h 2 ≤ p ≤ 6 and present their universal features. While the parametric
ally controlled scale-separated solutions are all AdS\, we also find setup
s that allow for dS vacua. We prove that flux quantization prevents these
dS vacua from arising in a regime of parametric control.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dimitrios Tsimpis (IP2I\, Lyon)
DTSTART:20251027T100000Z
DTEND:20251027T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/39
DESCRIPTION:Title: Universal cosmologies\nby Dimitrios Tsimpis (IP2I\, Lyon) as part of
NKUA HEP Seminars\n\n\nAbstract\nUniversal cosmologies are exact solution
s of 10d type IIA supergravity containing a 4d Friedmann-Lemaître-Roberts
on-Walker factor\, that can also be repackaged as solutions of 4d models\,
i.e. as 4d consistent truncations. We extend the dynamical system analysi
s of universal cosmologies\, beyond the case of a single exponential poten
tial. For an open universe (negative 3d spatial curvature)\, these models
generally possess many desirable features: parametric control of e-folds\,
late-time acceleration from potentials with steep exponentials (i.e. in a
ccordance with swampland bounds)\, small string-loop and α′-corrections
\, scale separation and/or absence of decompactification.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aristomenis Donos (Durham University)
DTSTART:20250909T110000Z
DTEND:20250909T120000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/40
DESCRIPTION:Title: The Effective theory of Critical Superfluids\nby Aristomenis Donos (
Durham University) as part of NKUA HEP Seminars\n\n\nAbstract\nThe dynamic
s of nearly critical superfluids have been extensively studied in the past
\, in the context of statistical mechanics. I will discuss a covariant eff
ective description which includes the hydrodynamics of the normal phase fl
uid at wavelengths comparable to the correlation length. I will observe th
at the construction by Khalatnikov and Lebedev in 1978 was missing a term
important to find agreement with holographic calculations.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Panagiotis Charalambous (SISSA\, Trieste and INFN\, Trieste)
DTSTART:20251007T090000Z
DTEND:20251007T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/41
DESCRIPTION:Title: Null infinity at the edge of a black hole\nby Panagiotis Charalambou
s (SISSA\, Trieste and INFN\, Trieste) as part of NKUA HEP Seminars\n\nLec
ture held in online.\n\nAbstract\nNull hypersurfaces are lightlike surface
s that naturally emerge when asking questions like “what is an asymptoti
cally flat spacetime?” or “what is a black hole?”. This gives rise t
o the concepts of “null infinities” and “event horizons”. In this
talk\, I will highlight the observation that all spacetimes that are asymp
totically flat near null infinity can be mapped through spatial inversions
onto the geometry near an extremal\, non-expanding and non-rotating horiz
on located at a finite distance. This mapping is conformal\, ensuring the
dissimilar physics on each type of null surface\, but also emphasizing the
ir similarities. Typically\, the conformally related asymptotic geometries
do not reside in the same spacetime. When they do\, however\, the finite-
distance horizon is a true black hole event horizon\, and the correspondin
g spatial inversions become conformal isometries of the spacetime that exc
hange the two null surfaces. The prototypical example of this situation is
the four-dimensional extremal Reissner-Nordström black hole\, equipped w
ith the characteristic Couch-Torrence inversion conformal isometry. This c
orrespondence then enforces matching conditions between near-horizon and n
ear–null-infinity data\, leading\, in particular\, to the identification
between infinite towers of conserved quantities: the near-horizon Aretaki
s constants and the near–null-infinity Newman-Penrose constants. I will
also present hints of a broader relationship between disconnected null hyp
ersurfaces under less restrictive boundary conditions\, extending beyond e
xtremal\, static horizons to include rotating or even non-extremal cases.\
n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marios Galanis (Stanford University)
DTSTART:20250930T090000Z
DTEND:20250930T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/42
DESCRIPTION:Title: Superradiant interactions of cosmic relics and how to look for them\
nby Marios Galanis (Stanford University) as part of NKUA HEP Seminars\n\n\
nAbstract\nIn this talk I will do three things. First\, I will outline the
conditions under which the interaction rate of inelastic processes with a
system consisting of N targets scales as N^2. Second\, I will present com
putations of interaction rates for several weakly interacting particles\,
including the cosmic neutrino background and axion dark matter\, and will
explain the underlying physics. Third\, I will present a concrete experime
ntal protocol using Nuclear Magnetic Resonance that can extract these effe
cts through quantum observables not relying on net energy transfer. This p
rotocol has the potential to significantly accelerate axion and dark photo
n dark matter searches and extend the reach of existing axion experiments
to probe QCD axion-nuclear spin couplings. More broadly\, it paves the way
for detecting coherent inelastic interactions from other cosmic relics---
most notably the cosmic neutrino background---and establishes nuclear-spin
-based systems as a new class of quantum\, ultra-low-threshold detectors.\
n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/42/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Giuseppe Bevilacqua (INPP Demokritos)
DTSTART:20251021T090000Z
DTEND:20251021T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/43
DESCRIPTION:Title: The Next To Next Challenge: towards numerical two-loop amplitude reducti
on\nby Giuseppe Bevilacqua (INPP Demokritos) as part of NKUA HEP Semin
ars\n\n\nAbstract\nThe Large Hadron Collider (LHC) started its first beam
in 2008. The data collected so far led to the discovery and characterisati
on of the Higgs boson and allowed important precision tests of the Standar
d Model. In parallel to that\, continuous efforts are being made to shed l
ight on possible New Physics up to the energy frontier. Accurate synergy b
etween theory and experiment - and comparable precision on both sides - is
key to foster discoveries. From the theory side\, the path to precision r
uns through several directions. In several cases\, two-loop scattering amp
litudes are the bottleneck. In this talk I will discuss ongoing efforts to
wards integrand-level reduction of two-loop helicity amplitudes. First I w
ill describe a method for extracting the coefficients of the reduction. I
will elaborate on the advantages\, but also on the challenges\, of perform
ing numerical computations of two-loop integrands in the context of dimens
ional regularisation. Finally I will discuss work underway to develop a nu
merical framework to achieve this goal.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/43/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Μαρία Γεροντίδου (NKUA)
DTSTART:20250915T103000Z
DTEND:20250915T120000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/44
DESCRIPTION:Title: Μετρητές Νετρονίων: Θεμελιώδης Έρευνα
και Εφαρμογές\nby Μαρία Γεροντίδου (NKUA) a
s part of NKUA HEP Seminars\n\n\nAbstract\nΠρόγραμμα σεμινα
ρίων για την θέση Επίκουρου Καθηγητή\nΠε
ιραματικής Φυσικής Στοιχειωδών Σωματιδ
ίων (APP35102)\nΤομέας Πυρηνικής Φυσικής και
Φυσικής Στοιχειωδών Σωματιδίων\, Τμήμα Φ
υσικής\, ΕΚΠΑ\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/44/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Αντώνης Αγαπητός (Peking U.\, SKLNPT)
DTSTART:20250915T120000Z
DTEND:20250915T133000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/45
DESCRIPTION:Title: Advancing LHC physics with ML: Recent CMS results in boosted topologies\
, jet tagging\, and beyond\nby Αντώνης Αγαπητός (Peking
U.\, SKLNPT) as part of NKUA HEP Seminars\n\n\nAbstract\nΠρόγραμμ
α σεμιναρίων για την θέση Επίκουρου Καθη
γητή\nΠειραματικής Φυσικής Στοιχειωδών
Σωματιδίων (APP35102)\nΤομέας Πυρηνικής Φυσι
κής και Φυσικής Στοιχειωδών Σωματιδίων\,
Τμήμα Φυσικής\, ΕΚΠΑ\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/45/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ευστάθιος Καρέντζος (Universität Bonn)
DTSTART:20250916T070000Z
DTEND:20250916T083000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/46
DESCRIPTION:Title: Ενοποιώντας Συστήματα\, Ανιχνευτές και
Ανάλυση με Μηχανική Μάθηση: Μια Ερευνητι
κή Διαδρομή στο Μιονικό Φασματόμετρο το
υ πειράματος ATLAS\nby Ευστάθιος Καρέντζο
ς (Universität Bonn) as part of NKUA HEP Seminars\n\n\nAbstract\nΠρό
γραμμα σεμιναρίων για την θέση Επίκουρο
υ Καθηγητή\nΠειραματικής Φυσικής Στοιχε
ιωδών Σωματιδίων (APP35102)\nΤομέας Πυρηνική
ς Φυσικής και Φυσικής Στοιχειωδών Σωματ
ιδίων\, Τμήμα Φυσικής\, ΕΚΠΑ\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/46/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Γεώργιος Κριντήρας (University of Kansas)
DTSTART:20250916T083000Z
DTEND:20250916T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/47
DESCRIPTION:Title: Το άλλο 95%: Αναζητώντας την προέλευση τη
ς μάζας\nby Γεώργιος Κριντήρας (University of K
ansas) as part of NKUA HEP Seminars\n\n\nAbstract\nΠρόγραμμα σε
μιναρίων για την θέση Επίκουρου Καθηγητ
ή\nΠειραματικής Φυσικής Στοιχειωδών Σωμ
ατιδίων (APP35102)\nΤομέας Πυρηνικής Φυσικής
και Φυσικής Στοιχειωδών Σωματιδίων\, Τμή
μα Φυσικής\, ΕΚΠΑ\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/47/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Στυλιανός Αγγελιδάκης (NKUA)
DTSTART:20250916T103000Z
DTEND:20250916T120000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/48
DESCRIPTION:Title: Ανακατασκευή & Συνδυασμένη Απόδοση Μιο
νίων για το Πρόγραμμα Φυσικής του ATLAS\nb
y Στυλιανός Αγγελιδάκης (NKUA) as part of NKUA HEP Sem
inars\n\n\nAbstract\nΠρόγραμμα σεμιναρίων για την
θέση Επίκουρου Καθηγητή\nΠειραματικής Φ
υσικής Στοιχειωδών Σωματιδίων (APP35102)\nΤο
μέας Πυρηνικής Φυσικής και Φυσικής Στοι
χειωδών Σωματιδίων\, Τμήμα Φυσικής\, ΕΚΠΑ
\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/48/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Δήμητρα Τσιώνου (National Taiwan University)
DTSTART:20250916T120000Z
DTEND:20250916T133000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/49
DESCRIPTION:Title: Μετρήσεις ακρίβειας με ανιχνευτές στοι
χειωδών σωματιδίων\nby Δήμητρα Τσιώνου
(National Taiwan University) as part of NKUA HEP Seminars\n\n\nAbstract\n
Πρόγραμμα σεμιναρίων για την θέση Επίκο
υρου Καθηγητή\nΠειραματικής Φυσικής Στο
ιχειωδών Σωματιδίων (APP35102)\nΤομέας Πυρην
ικής Φυσικής και Φυσικής Στοιχειωδών Σω
ματιδίων\, Τμήμα Φυσικής\, ΕΚΠΑ\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/49/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Manuela Kulaxizi (Trinity College Dublin and NKUA)
DTSTART:20251111T100000Z
DTEND:20251111T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/50
DESCRIPTION:Title: Photon trajectory beyond the critical impact parameter\nby Manuela K
ulaxizi (Trinity College Dublin and NKUA) as part of NKUA HEP Seminars\n\n
\nAbstract\nWhen a highly energetic particle traverses a black hole experi
ences a time delay and angular deflection\, which combine easily to produc
e a standard phase shift for scattering off a very massive particle. The p
icture drastically changes when the impact parameter attains values beyond
a critical one\; then the phase shift acquires a small imaginary part\, i
ndicating inelastic scattering. What happens to the original time delay an
d deflection quantities?Do their complex valued counterparts for impact pa
rameters beyond the photosphere make sense? We will investigate this quest
ion in the context of an AdS black hole and the dual CFT description.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/50/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Constantin Bachas (Ecole Nomermale Superiere & NTUA)
DTSTART:20251125T100000Z
DTEND:20251125T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/51
DESCRIPTION:Title: Holographic tension and the radiation-reaction problem\nby Constanti
n Bachas (Ecole Nomermale Superiere & NTUA) as part of NKUA HEP Seminars\n
\n\nAbstract\nI will explain how AdS/CFT allows to define two independent
notions of invariant brane tension in gravity. I will prove that supersymm
etry identifies them\, and explain the relevance of this observation for t
he old radiation-reaction problem of accelerating charges and heavy quarks
.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/51/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Grégoire Olivier Mathys (EPFL)
DTSTART:20251209T100000Z
DTEND:20251209T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/52
DESCRIPTION:Title: Averaged null energy and the renormalisation group\nby Grégoire Oli
vier Mathys (EPFL) as part of NKUA HEP Seminars\n\n\nAbstract\nThe average
d null energy operator (ANEC) is a light-ray integral of the null energy\,
which is known to have far-reaching consequences in CFT\, such as the Lor
entzian Inversion Formula. It is also closely connected to modular Hamilto
nian in QFT. In this talk\, I will discuss a new connection between the AN
EC operator and monotonicity of the renormalization group. In particular\,
I will show how the 2d c-theorem and 4d a-theorem can be derived using th
e ANEC. This derivation relies on contact terms appearing in specific ANEC
correlators. I will also review a new infinite set of constraints that ca
n be derived from the ANEC in 2d QFT. This program hints at a more general
role for light-ray operators in QFT\, which I will argue for.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/52/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gonzalo Torroba (Centro Atomico Bariloche)
DTSTART:20260210T130000Z
DTEND:20260210T140000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/53
DESCRIPTION:Title: Quantum information\, entanglement\, and RG flows in AdS\nby Gonzalo
Torroba (Centro Atomico Bariloche) as part of NKUA HEP Seminars\n\n\nAbst
ract\nQuantum information–theoretic ideas have recently provided new ins
ights into quantum field theory in curved space-times. In this talk we pre
sent a nonperturbative inequality for the entanglement entropy of quantum
field theory in rigid AdS space-time\, derived using tools from quantum in
formation theory. This result implies the irreversibility of renormalizati
on group flows in AdS in 1+1\, 2+1 and 3+1 space-time dimensions. In the s
econd part of the talk we discuss on-going work aimed at understanding the
entanglement properties of free field theories in AdS\, including analyti
c results in 1+1 dimensions and numerical analyses in 2+1 and 3+1 dimensio
ns.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/53/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jan Plefka (Humboldt U.\, Berlin)
DTSTART:20251202T100000Z
DTEND:20251202T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/54
DESCRIPTION:Title: High-precision gravitational wave physics from worldline quantum field t
heory\nby Jan Plefka (Humboldt U.\, Berlin) as part of NKUA HEP Semina
rs\n\n\nAbstract\nThe gravitational two-body problem has been fundamental
to physics since Newton's time. With the advent of gravitational wave astr
onomy and the anticipated third generation of gravitational wave detectors
in the 2030s\, there is an increasing need for high-precision predictions
from Einstein's theory of gravity regarding the encounters of black holes
and neutron stars in our universe.\nFascinatingly\, perturbative quantum
field theory methods—developed for high-precision predictions of element
ary particle scattering at the LHC—have proven remarkably efficient for
this classical physics problem. This unexpected connection has led to insp
iring synergies between collider and gravitational wave physics.\n\nIn my
talk\, I will present our approach using a worldline quantum field theory
inspired by string theory\, which has emerged as the most efficient tool f
or quantifying the scattering of spinning black holes. We have achieved hi
ghest-precision perturbative results for the scattering angle\, radiated e
nergy\, and momentum recoil of such black hole encounters at the fifth ord
er in Newton's gravitational coupling G\, assuming a mass hierarchy betwee
n the two bodies. This four-loop calculation has moreover revealed a new c
lass of mathematical functions related to Calabi-Yau manifolds\, previousl
y studied only in mathematics and string theory compactifications\, here a
ppearing for the first time in a physics context.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/54/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ioannis Tsiares (IPhT\, Saclay and LPENS\, Paris)
DTSTART:20260224T100000Z
DTEND:20260224T110000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/55
DESCRIPTION:Title: Analytic Conformal Bootstrap in two-dimensions and AdS$_3$ gravity\n
by Ioannis Tsiares (IPhT\, Saclay and LPENS\, Paris) as part of NKUA HEP S
eminars\n\n\nAbstract\nΤα τοπικά δεδομένα (local data) ι
σχυρά αλληλεπιδρώντων Σύμμορφων Θεωριώ
ν Πεδίου (CFTs) περιορίζονται αυστηρά -- και
σε ορισμένες περιπτώσεις καθορίζονται
πλήρως -- από βασικές συνθήκες όπως η μον
αδιακότητα (unitarity) και η τοπικότητα (locality)
. Αυτό το πλαίσιο έχει γίνει γνωστό ως το
``Conformal Bootstrap''. Σε δύο χωροχρονικές διαστά
σεις\, το bootstrap είναι κατά μία έννοια πιο
ισχυρό λόγω της παρουσίας της άπειρης δι
άστασης άλγεβρας Virasoro. Θα συζητήσουμε πρ
όσφατα αποτελέσματα στο Virasoro analytic bootstrap
και τη σύνδεσή τους\, μέσω AdS/CFT\, με το πρό
βλημα της τρισδιάστατης βαρύτητας σε AdS.
Πιο συγκεκριμένα\, θα παρουσιάσω πρόσφατ
η πρόοδο προς την αναλυτική κατανόηση τω
ν λεγόμενων Virasoro crossing kernels — απαραίτητα
δομικά στοιχεία της crossing equation— και το πώ
ς αυτή η δομή συνδέεται με την κβαντική β
αρύτητα στον AdS$_3$ μέσω της λεγόμενης ``Viras
oro TQFT''.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/55/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Masahide Yamaguchi (Institute for Basic Science (IBS) and Tokyo In
stitute of Technology (TIT))
DTSTART:20260615T090000Z
DTEND:20260615T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/56
DESCRIPTION:Title: Cosmological first-order phase transitions: tunneling at finite temperat
ure\nby Masahide Yamaguchi (Institute for Basic Science (IBS) and Toky
o Institute of Technology (TIT)) as part of NKUA HEP Seminars\n\n\nAbstrac
t\nCosmological phase transitions\, especially first order phase transitio
ns\, have attracted renewed interest as potential sources of gravitational
waves. Accurately predicting the resulting gravitational wave signal requ
ires a reliable estimate of the transition rate\, which is governed by a s
addle-point configuration known as the bounce solution. The seminal work o
f Coleman\, Glaser\, and Martin established that at zero temperature\, any
nontrivial bounce solution to the equations of motion that minimizes the
Euclidean action is O(D)-symmetric in D-dimensional spacetime. At finite t
emperature\, however\, it has not been proven that an O(D-1)-symmetric bou
nce solution in the spatial directions indeed yields the minimal Euclidean
action\, despite this assumption being widely used in the literature. In
this talk\, we extend the Coleman–Glaser–Martin analysis to finite tem
perature. We rigorously prove that for a broad class of scalar potentials\
, any saddle-point configuration with the least action is necessarily O(D-
1)-symmetric and monotonic in the spatial directions. This result provides
a firm mathematical foundation for the symmetry properties widely assumed
in studies of thermal vacuum decay and cosmological phase transitions.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/56/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dimitris Chatzis (Swansea University)
DTSTART:20260512T090000Z
DTEND:20260512T100000Z
DTSTAMP:20260422T213051Z
UID:NKUA-HEP/57
DESCRIPTION:by Dimitris Chatzis (Swansea University) as part of NKUA HEP S
eminars\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/57/
END:VEVENT
END:VCALENDAR