Xmas Theoretical Physics Workshop @Athens 2023

21 Dec 2023, 09:00 → 22 Dec 2023, 16:30 Europe/Athens

Amphitheater Alkis Argyriadis (Central Building of the National and Kapodistrian University of Athens)

Διημερίδα Θεωρητικής Φυσικής - 21 και 22 Δεκεμβρίου 2023

The primary goal of the annual Christmas workshop in Theoretical Physics held at the National and Kapodistrian University of Athens, is to bring together established and young researchers, in order to present their recent research results and to stimulate scientific interaction.

Invited Speakers

• Glenn Barnich (Université libre de Bruxelles)
• Karl Landsteiner (Autonomous University of Madrid)
• Vasilis Niarchos (University of Crete)
• Josef Prandler (University of Vienna)
• John Rizos (University of Ioannina)
• Augusto Sagnotti (Scuola Normale Superiore)
• Georgios Styliaris (Max Planck Institute of Quantum Optics, Garching)

Attendance:

The speakers will be in-person at the Amphitheater Alkis Argyriadis and the talks with be broadcasted live through Webex using the link.

SCAM CAUTION
We kindly suggest that you arrange the accommodation by yourself as we have been aware of several scam emails and phishing attempts sent to participants!

Registration opening July 10, 2023

Call for talks deadline Sept 30, 2023

Registration deadline Nov 30, 2023

Organizers
Ioannis Dalianis (UCY), Georgios Itsios (Humboldt University), Ioannis Papadimitriou (NKUA), Konstantinos Sfetsos (NKUA), Konstantinos Siampos (NKUA) and Vassilis Spanos (NKUA)

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This is the 8th annual Xmas Theoretical Physics Workshop to be held in Athens. For past meetings see 2014, 2015, 2016, 2017, 2018, 2019 & 2022

Poster 2023 Panoramic Athens.pdf

Thursday 21 December

09:00 → 09:30 Reception

09:30 → 09:45 Welcome address

Xmas 2023.pdf

09:45 → 10:30 Non supersymmetric strings and the (in)stabilities of their vacua

Speaker: Augusto Sagnotti

Athens_23_red.pdf

10:30 → 11:15 Pseudospectra of Holographic Quasinormal Modes

Quasinormal modes and frequencies are the eigenvectors and eigenvalues of a non-Hermitian differential operator. They are of crucial importance in the physics of black holes. The analysis of quasinormal modes in asymptotically Anti-de Sitter geometries plays also a key role in the study of strongly coupled quantum many-body systems via gauge/gravity duality. In contrast to normal Sturm-Liouville operators, the eigenvalues of non-Hermitian (and non-normal) operators generally exhibit instability under small perturbations. After a brief review of quasinormal modes I will discuss the stability analysis of quasinormal frequencies for asymptotically planar AdS black holes based on pseudospectrum analysis. Specifically, we concentrate on the pseudospectra of scalar and transverse gauge fields, shedding light on their relevance within the framework of gauge/gravity duality.

Speaker: Karl Landsteiner (Unknown)

Xmas_Athens.pdf

11:15 → 11:45 Coffee break

11:45 → 12:30 On non-supersymmetric string models

Speaker: John Rizos (Nuclear Physics Laboratory)

talk_XMAS-ATHENS2023_rizos.pdf

12:30 → 13:00 Two dimensional black holes and matrix quantum mechanics

Speaker: Olga Papadoulaki

Papadoulaki_Xmas.pdf

13:00 → 14:30 Lunch break

14:30 → 15:00 Natural Alignment Beyond the Standard Model

Speaker: Apostolos Pilaftsis (University of Manchester)

PILAFTSIS_Athens_2023.pdf

15:00 → 15:30 Probing the deep string spectrum

Speaker: Chrysoula Markou

Chrysoula_Xmas.pdf

15:30 → 16:00 PTA gravitational waves and James Webb early galaxies: from Primordial Black Holes to Axion Clusters

Recent observations have granted to us two unique insights into the early universe: the presence of a low-frequency stochastic gravitational wave background detected by the NANOGrav and Pulsar Timing Array (PTA) experiments and the emergence of unusually massive galaxy candidates at high redshifts reported by the James Webb Space Telescope (JWST). In this talk, I will consider the possibility that both observations have a common origin. First, I will scrutinize primordial black holes (PBHs) in the mass range between 10^6 and 10^13 solar masses. While superheavy PBHs act as seeds of accelerated galaxy formation capable of explaining the JWST extreme galaxies, they can also form binary mergers that source gravitational waves which can be potentially identified as the PTA signal. The analysis is performed taking into account the constraints on the relevant region of the PBH parameter space including the novel bound imposed by the so-called Ultraviolet Luminosity Function (UV LF) of galaxies observed by the Hubble Space Telescope. Then, I will discuss minicluster seeds in the initial axion density field due to the decay of the axion string network in the post-inflationary scenario. For axions heavier than 10^(-25) eV , the resulting clusters have a significant impact on large-scale structure, which is also strictly constrained by the UV LF.

Speaker: Sokratis Trifinopoulos

Athens.pdf

16:00 → 16:30 Stochastic dynamics from quantum field theory

The partition function of a scalar field theory can be computed order by order in the interaction potential within perturbative quantum field theory. We will show that when there exists a separation of scales, the statistics of the long/slow field-modes obey a Fokker-Planck equation exhibiting nonstandard probability drift and diffusion due to short/fast dynamics. Our main application will be scalar physics on de Sitter space (where the Hubble radius provides the required scale separation) but the results extend to any open system with this property.

Speaker: Spyros Sypsas

Sypsas.pdf

Friday 22 December

09:30 → 10:15 Lessons from discrete light-cone quantization for gravitational physics on null hypersurfaces

Speaker: Glenn Barnich

LightconeAthens.pdf

10:15 → 11:00 Quantum systems as manipulators of information: Entanglement, complexity, and phases of matter

Speaker: Georgios Styliaris

styliaris_xmas23_athens.pdf

11:00 → 11:30 Coffee break

11:30 → 12:15 New Light on Light Dark Sectors

Speaker: Josef Prandler

2023Athens.pdf

12:15 → 13:00 Bootstrability with improved truncation methods

Speaker: Vasilis Niarchos

2023_Athens_v1.pdf

13:00 → 14:30 Lunch break

14:30 → 15:00 Entangled Universe

Speaker: Nikolaos Tetradis

Tetradis Xmas Workshop.pdf

15:00 → 15:30 Gauge Invariance at Large Charge

Speaker: Pantelis Panopoulos

Athens talk 22:12:23.pdf

15:30 → 16:00 Corrections to electroweak vacuum decay in metric-affine gravity

Speaker: Ioannis Gialamas

XMAS_2023_Gialamas.pdf

16:00 → 16:30 Anisotropic scale-separated AdS flux vacua

Speaker: George Tringas

Tringas.pdf