BEL Center - Joint pheno+GW meetings - 2025-26 season

12 Dec 2025, 10:00 → 12 Dec 2026, 16:00 Europe/Zurich

Tournay-Solvay Castle

Alberto MARIOTTI (Vrije Universiteit Brussel), Benoît Tuybens (Nikhef), Daniel Mayerson (KU Leuven), Gauthier Durieux (CP3 - UCLouvain), Michel Tytgat

Venue location: https://maps.app.goo.gl/32Nt1sWMMsh8w5Hf9 (the parc is only open from 10am to 4.30pm between Dec and Feb).

There will be shared office space and meeting rooms to discuss and work outside presentation times.

Friday 12 December

10:00 → 16:00 Joint meeting

10:30 Coffee

11:00 Synergic cosmology across the spectrum

Speaker: Prof. Stefano Camera (Torino U.)

12:30 Lunch

14:00 Quantum Scattering Amplitudes for Gravitational Waves

Speaker: Rafael Aoude

Friday 30 January

10:00 → 13:30 Joint meeting: Pheno morning (Note the special venue!)

10:30 Coffee

11:00 Effective Field Theory for Thermal Phase transitions

I will present recent progress in applying effective field theory (EFT) to the precise computation of thermal phase transition parameters and the associated gravitational wave spectra. I will also briefly comment on byproducts of this work, including new methods for two-loop renormalization in EFT that avoid gauge-breaking counterterms and infrared rearrangement.

Speaker: Mikael Chala (Universidad de Granada)

12:00 Lunch

13:30 → 17:00 Joint meeting: Gravitational wave afternoon (Note the special venue!)

13:30 Introduction to LISA, its data analysis challenges, and modelling of extreme mass ratio inspirals

Speakers: Bert Depoorter (KU Leuven), Robrecht Keijzer (KU Leuven)

14:45 The LISA mission and its distributed data processing center

Speaker: Antoine Petiteau (APC)

16:00 Listening to the millihertz universe: LISA data analysis and the challenge of extreme mass ratio inspirals

The Laser Interferometer Space Antenna (LISA) will open a new window onto the gravitational wave Universe by observing millihertz signals from massive black hole mergers, compact galactic binaries, and extreme mass ratio inspirals (EMRIs). Extracting these signals from a data stream shaped by instrumental noise and astrophysical confusion requires advanced data analysis strategies. In this talk, I will outline the main challenges of LISA data analysis. I will then focus on EMRIs: long lived, highly structured signals produced when stellar mass compact objects spiral into massive black holes. These sources encode precise information about spacetime geometry and black hole astrophysics, yet their detection and characterization demand accurate waveform models and scalable search algorithms. I will discuss recent progress in EMRI modeling and how emerging data analysis pipelines aim to unlock their unique scientific potential.

Speaker: Lorenzo Speri (ESA)

Friday 27 February

10:00 → 17:00 Joint meeting

10:00 Baryogenesis from electroweak textures

The matter-antimatter asymmetry of the Universe represents one of the main open questions in particle physics and cosmology. In this talk, we will present a novel realization of cold baryogenesis (a mechanism involving the formation and decay of topological defects associated with the gauge group of the Standard Model known as SU(2) textures) that relies on the out-of-equilibrium dynamics during a strong first order electroweak phase transition. By performing extensive lattice simulations of the Higgs doublet and gauge field dynamics, we evaluate the related Chern-Simons number production as well as the rate of baryon number violation, as a function of the parameters of the phase transition and the shape of the Higgs potential. We finally provide an estimate for the total baryon asymmetry generated this way.

Speaker: Dr Simone Blasi (DESY)

11:30 Quantum Observables and Their Sensitivity to Fundamental Interactions at Polarized Lepton Colliders

High-energy colliders probe fundamental interactions through direct searches and precision measurements. Yet conventional observables, such as total cross sections and asymmetries do not fully exploit the intrinsically quantum nature of multi-particle final states. A density matrix based description of scattering processes provides access to genuinely quantum observables, offering complementary sensitivity to the underlying dynamics.

In this talk, I will outline the general framework for defining and reconstructing quantum observables in collider experiments, focusing on spin density matrices and their measurable components. I will discuss how different classes of interactions; scalar, vector, and tensor mediators populate distinct structures in the density matrix, thereby motivating the need for multiple, carefully chosen observables. Attention will be given to quantum-information-theoretic quantities such as entanglement, Bell inequality violations, purity, and magic, and to how each probes different aspects of the quantum structure of scattering amplitudes.

As a concrete example, I will consider top-antitop production at future lepton colliders and present analytic results for the spin density matrix. I will demonstrate how beam polarization can be exploited to enhance sensitivity to specific operator structures and improve discrimination among possible interaction scenarios. These results illustrate how quantum observables, combined with polarized beams, provide a systematic framework for probing potential new physics beyond conventional collider analyses.

Speaker: Priyanka Lamba

12:45 Lunch

14:00 Geometric resonances for high-frequency gravitational-wave detection

Gravitational waves at kilohertz and higher frequencies provide a unique window onto the early Universe at energy scales far beyond those accessible through the cosmic microwave background, potentially probing physics well above the electroweak scale. Yet existing detector concepts fall many orders of magnitude short of the big-bang nucleosynthesis bound on a stochastic gravitational-wave background in this regime. In this talk, I will present a new interferometric concept that exploits geometric resonances arising from directional changes of light inside high-Q optical cavities. For suitable folded or looped geometries, gravitational-wave–induced phase shifts can accumulate coherently over many traversals, leading to narrowband resonances with a characteristic comb-like structure. This distinctive spectral signature provides a powerful handle to discriminate a stochastic background from instrumental noise, without relying on cross-correlation between detectors. I will explain the underlying physical mechanism, discuss possible realizations compatible with planned tunnel layouts such as the Einstein Telescope, and comment on projected sensitivities, open challenges, and connections to established interferometer designs.

Speaker: Jan Heisig

15:20 Bridging the microhertz gap in the gravitational-wave landscape

Over the past decade, LIGO/Virgo/KAGRA have given us abundant evidence for gravitational waves emitted by binary systems. But binaries can also absorb gravitational waves, leaving potentially detectable imprints on their orbits. In this talk, I will describe how this effect can be used to search for gravitational waves at frequencies that are inaccessible to all other current and future experiments — in particular, how laser-ranging measurements of the Moon and other satellites around the Earth will allow us to explore the “microhertz gap” between the frequencies probed by pulsar timing arrays and future space-based interferometers such as LISA. As examples of the discovery potential of this approach, I will show how it is able to place unique constraints on gravitational waves from cosmological phase transitions, and will discuss how it will shed light on the possible gravitational-wave background recently detected by pulsar timing arrays.

Speaker: Alex Jenkins

Friday 27 March

10:00 → 16:00 Joint meeting

10:00 Julien Lesgourgues

Speaker: Julien Lesgourgues (RWTH Aachen university)

11:30 Shockwave in EFTs

Speaker: Christophe Grojean (DESY (Hamburg) and Humboldt University (Berlin))

12:45 Lunch

Friday 24 April

10:00 → 16:30 Joint meeting

10:00 Raffaele D'Agnolo

Speaker: Raffaele D'Agnolo (CEA IPhT Saclay)

11:30 Marco Cirelli

Speaker: Marco Cirelli (CNRS LPTHE Jussieu)

12:45 Lunch

Friday 29 May

09:00 → 16:00 Joint meeting

10:00 Diego Blas

Speaker: Diego Blas (ICREA/IFAE)

11:30 Machine learning for high-energy physics

Speaker: Tilman Plehn (Heidelberg University)

12:45 Lunch

Friday 25 September

10:00 → 17:00 Joint meeting

10:00 Brando Bellazzini

Speaker: Brando Bellazzini (Université Paris-Saclay (FR))

11:30 Lorenzo Ubaldi

Speaker: Lorenzo Ubaldi

Friday 6 November

10:00 → 16:00 Joint meeting

Friday 27 November

10:00 → 16:00 Joint meeting