Talk 1 - Ching-Hua Li: Test tau - e universality at LHCb

Abstract: The SM includes three lepton families: electrons, muons, and tau leptons, each associated with a corresponding neutrino type. A key feature of the SM is the universality of the electroweak gauge coupling among the three known fermion families, known as lepton flavor universality (called LFU). Any significant observation of a deviation from this universality, occurring in SM only when the phase space or amplitude becomes dependent on lepton mass, would indicate new physics beyond the SM. The test of LFU is aimed at measuring such deviations in the extent of lepton flavor symmetry breaking relative to SM predictions. This talk will present my study using the branching fraction ratio between the semileptonic decays B -> D* e nu and B -> D* tau nu with tau -> e nu nu, to test LFU in LHCb.

Talk 2 - Sarah Ferraiuolo : Probing Cosmology with Gravitational-Wave and Euclid data

Talk 3 - Raphael BERTRAND: Optimisation of embedded neural networks for the energy reconstruction of the liquid argon calorimeter cells of ATLAS

Abstract: The Large Hadron Collider (LHC) collides protons at nearly the speed of light, producing new particles observed by the ATLAS detector. In 2026, the LHC will undergo a major upgrade to the High-Luminosity LHC (HL-LHC), increasing luminosity by a factor of 5–7 and delivering up to 200 simultaneous collisions. To cope with the resulting data rates, ATLAS will replace the readout electronics of the Liquid Argon Calorimeter (LAr) as part of its Phase-II upgrade. The new LASP board, equipped with two FPGAs, will perform real-time energy reconstruction for 384 channels each, covering about 180,000 calorimeter cells in total.
At high pileup, overlapping electronic pulses challenge the current Optimal Filtering (OF) algorithm used to compute the energy. Neural network (NN)–based alternatives are being explored to surpass OF while respecting FPGA constraints: <125 ns latency and limited resource usage. After earlier studies of recurrent and convolutional architectures, a dense-layer design is proposed, reducing both latency and resource consumption.
Bayesian hyperparameter optimisation is used to adapt the network size, balancing energy resolution with FPGA feasibility. The results show how to achieve optimal performance within hardware limits. In addition, deep evidential regression is employed to estimate uncertainties by fitting predicted energies to probability distributions, enabling quantification of both data noise and model imprecision with minimal overhead.
The talk will compare network architectures and present the Bayesian optimization results, as well as demonstrate uncertainty estimation with evidential regression

Abstract: The observation of the Higgs boson by the ATLAS and CMS collaborations at CERN in 2012 is without a doubt one of the most significant milestones in the history of particle physics. It confirmed our understanding of the origin of particle masses, and proved the theoretical soundness of the Standard Model of particle physics. This discovery happened more than 13 years ago; is the Higgs boson now "old news"? Not at all! In this seminar, I will explain why the Higgs boson's relationship with fermions is fundamental to our understanding of nature and how studying its interactions with charm and beauty quarks can shed light on the flavor puzzle of the Standard Model. I will also go over exciting recent, ongoing, and future experimental developments at the LHC and beyond.

Zoom: https://univ-amu-fr.zoom.us/j/96864416838?pwd=K8T5LWaJXROnA0R0SpmjRRiHLure4m.1

Résumé: Que ce soit à la surface de la Terre ou dans ses profondeurs, dans les abysses océaniques ou dans l’atmosphère, la radioactivité est présente partout et la vie aussi. Quel rôle a pu jouer la radioactivité naturelle dans l’émergence et l’évolution de cette vie depuis plusieurs milliards d’années ? Explorer cette question requiert de caractériser et de comprendre la radioactivité des différents compartiments du système Terre (atmosphère, océan, surfaces continentales, terre solide).  A travers quelques activités de recherche pluridisciplinaires sur les volcans actifs, les sources minérales et en laboratoire souterrain ou plus récemment sur l’atmosphère et les fonds océaniques, nous illustrerons combien la radioactivité naturelle demeure encore mal connue ainsi que son impact sur le vivant. Ces exemples illustreront toute la richesse et le potentiel des interactions entre biologie, géosciences et physique nucléaire.  

Abstract: The direct search for dark matter has made remarkable progress over the past 15 years, driven in large part by the success of dual-phase xenon time projection chambers. Ever larger experiments have achieved unprecedented sensitivity only by pushing radioactive backgrounds to unprecedented low levels. One of the most persistent obstacles is posed by radioactive noble gases dissolved in the xenon - especially radon, whose decay products can mimic the signals of dark matter.

In this talk, I will introduce the XENONnT experiment and explain which methods were applied to suppress the radon background to a world-leading level of less than 1 microBq/kg. I will give an overview of current techniques for detecting and removing radon, and discuss how these methods pave the way toward even lower backgrounds in the next-generation XLZD experiment.

Abstract: LHCb’s historical approach to training and documentation has had a very organic evolution. While this had advantages, the increasingly scattered documentation has often left users unsure where to find resources and which ones are up to date. This seminar will explore the changing approaches to training and documentation LHCb has been taking in the last year as well as looking towards the future: what has been working, how things can be improved further, etc. We will also investigate how the new dedicated team within LHCb has been trying to help improve maintenance, discoverability and longevity. Finally, we will consider things to bear in mind when approaching your own projects’ documentation or your own training sessions for large physics collaborations.

Abstract: After the successful first upgrade of the LHCb detector, which started operation at the begining of the LHCb Run 3 in 2022, the LHCb collaboration is planning for a second upgrade of the detector for the Run 5 of the LHC, in 2036, to operate with 10 times higher luminosity than the current detector. I will present the project, the technical challenges associated to running a flavour experiment in this difficult environment, and the ongoing developments for them.