Donnerstag, 9. Oktober 2025 17:30 Uhr Particle physics: today and tomorrow
Prof. Dr. Mark Thomson, CERN
Prof. Dr. Mark Thomson, CERN
Chilufya Mwewa Kapya, DESY Hamburg
Daniel Price, Monash University Take a molecular cloud, collapse it to form a star and the leftover material will form planets. Sounds easy, right? But even our own solar system is riddled with clues that forming stars and planets is a bit. more. complicated. It turns out that accreting gas to form any small object is hard. Accreting gas at the rate needed to form the Sun in a few hundred thousand years is even harder. None of this is new. What is new is the observational revolution of the last 10 years, showing us the insides of protoplanetary discs, bringing fresh clues as to how both stars and exoplanets form [seemingly, together]. This has dramatic implications for our understanding of how accretion works. I will argue that the typical pathway to form stars and planets is a violent mess, imprinted in subtle and not-so-subtle ways on disc observations and also in the leftovers from our solar system’s formation. The story is misaligned flow, accretion streamers, infall, warps and variability. If you don’t care about stars or planets but the story sounds familiar, it’s because it’s not so different for making black holes or galaxies either...
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Floriane Arrouas, Université de Toulouse, France Direct observation of Coherent Backward Scattering and Coherent Forward Scattering peaks in a shaken Bose gas Floriane Arrouas Université de Toulouse, France The quantum kicked rotor is a paradigmatic model of chaotic dynamics, where the classical unbounded diffusion in momentum is suppressed. This effect is called the dynamical localization, and is the equivalent in momentum space of Anderson localization, a very well-known phenomenon arising from quantum interference effects in the presence of spatial disorder. Both localization effects exhibit distinct peak signatures in reciprocal space. The Coherent BackScattering (CBS) peak is a marker of weak localization, and has been observed in numerous systems. The recently predicted Coherent Forward Scattering (CFS) peak[1] however, is a hallmark of strong (Anderson) localization, and has only been observed indirectly so far [2]. In this talk, I will present the recent experimental observation of the coherent forward scattering peak with ultracold atoms[3]. This peak is not only a key hallmark of non-ergodic behavior but also crucially encodes the system’s underlying symmetries. References: [1] T. Karpiuk, N. Cherroret, K. L. Lee, B. Grémaud, C. A. Müller, and C. Miniatura Phys. Rev. Lett. 109, 190601 (2012). [2] Hainaut, C., Manai, I., Clément, JF. et al. Nat Commun 9, 1382 (2018). [3] F. Arrouas, J. Hébraud, N. Ombredane, E. Flament, D. Ronco, N. Dupont, J. Billy, G. Lemarié, C. Miniatura, B. Georgeot, B. Peaudecerf and D. Guéry-Odelin, in preparation (2025).
