Next Seminars
The B+ -> K+ nu nu decay is mediated by a flavor-changing neutral current, which makes this decay quite rare in the Standard Model, happening about 6 times every million B+ decays, according to the theory. Moreover, the presence of two undetected neutrinos in the final state and of only one visible charged track makes searching for this decay particularly challenging.
We perform an analysis using electron-positron collisions recorded by the Belle II experiment between the years 2019 and 2022, using the properties of the accompanying B meson in the event to suppress background from other decays of the signal B candidate and light-quark pair production. We determine the branching fraction of the decay to be 2.7 sigma above the Standard Model expectation, providing the first evidence for this decay with a significance of 3.6 standard deviations.
Euclid is an ESA mission aiming at studying the geometry and nature of the dark Universe. Over a span of six years, Euclid will meticulously survey nearly 15,000 square degrees of the extragalactic sky. Equipped with optical capabilities spanning from 530 to 920 nanometers and near-infrared imaging in Y, J, and H bands, as well as slitless spectroscopy ranging from 1206 to 1892 nanometers, Euclid will capture detailed data on distant galaxies between redshift of 0.84 and 2. Launched successfully on July 1, 2023, Euclid was placed in orbit around the second Lagrange point where both of its cutting-edge instruments, the VIS and the NISP, underwent meticulous commissioning and calibration over the initial six months of the mission. As the Euclid survey commenced in February 2024, this presentation will provide insights into the mission's status at Lagrange 2 and showcase the initial scientific images and results captured by both instruments.
5 last Seminars
Marie Curie, première femme lauréate du prix Nobel de physique, puis de chimie, première femme nommée professeur à la Sorbonne, a fait exploser de multiples plafonds de verre, quand ce n’étaient pas les murs de pierre de la société russe, puis française, puis internationale. Outre son activité de premier plan en physique, elle a pris de nombreuses initiatives novatrices moins connues comme ses actions envers l’enseignement des sciences aux enfants, la médecine, son implication dans Commission Internationale de Coopération Intellectuelle (CICI), ancêtre de l’UNESCO, la formation de radiologues sur le front de la Grande Guerre…
Cette conférence informelle s’adresse à tous, non-physiciens comme physiciens, curie-eux et curie-euses de l’histoire de notre science et de cette femme hors du commun.
The existence of nonbaryonic dark matter (DM) in the Universe is compelling, as suggested by astrophysical and cosmological observations. The most commonly assumed production mechanism for DM in the early universe corresponds to the weakly interacting massive particle (WIMP) paradigm, in which DM has mass and couplings at the electroweak scale. However, the current null experimental results and severe constraints on the natural parameter space are forcing us to search beyond the standard WIMP paradigm. In this talk, I will review alternative DM production mechanisms in the early universe, both thermal and non-thermal, like the FIMP and the SIMP paradigms. The possible impact of alternative non-standard cosmological scenarios will also be analyzed. Finally, experimental avenues for DM detection are discussed.
Document to collect questions:
https://docs.google.com/document/d/1_NEaFIEQfeKQCADn3IKZEznWSi6OYO5WGSslyQbe5-A/edit
Neutrino tagging is a new experimental method for accelerator based neutrino experiments. The method consists in exploiting the neutrino production mechanism, the $\pi^\pm\to\mu^\pm \nu_\mu$ decay, to kinematically reconstruct the neutrino properties from the decay incoming and outgoing charged particles. The reconstruction of these particles relies on the recent progress and on-going developments in silicon particle detector technology. The method is particularly suited to study neutrino interactions at short baseline experiments and neutrino oscillations at long baseline ones with mega-ton scale natural water Cherenkov detectors.
After introducing the method, its benefits, and the sensitivity to key observables it would offer, the seminar will discuss its implementation. The discussion will start with a presentation of the recent proof-of-principle of the tagging technique, performed using the CERN NA62 experiment as a miniature tagged neutrino experiment. Then, ideas on how to implement a full scale tagged experiment will be presented in particular regarding the beam line design and the silicon pixel technology.