Past Events

Abstract: The Extended Baryon Oscillation Spectroscopic Survey (eBOSS) concluded observations of the cosmic distance scale and the growth of structure in February, 2019.  The three dimensional clustering in all samples from the Sloan Digital Sky Survey (SDSS) was used to make 15 distinct, high precision measurements of Baryon Acoustic Oscillations (BAO) to an effective redshift z<2.4 and six measurements of redshift space distortions (RSD) to z<1.5.  With this redshift coverage and sensitivity, the SDSS experiment is unparalleled in its ability…

Abstract: The prime energy producer in the sun is the fusion of hydrogen to form helium. However, there is more than one way for this fusion to take place: for stars the size of the sun or smaller, the proton-proton (pp) chain reactions dominate (~99%), while in heavier stars, the carbon-nitrogen-oxygen (CNO) cycle is expected to play a more important role. Not only these fusion reactions would not have been possible without the emission of neutrinos, neutrinos are the only…

Abstract: A search for new physics with XENON1T revealed an excess of electronic recoil events in the (1 – 7) keV region, favoring signal over background with significances of 3.5 sigma for solar axions/ALPs, 3.2 sigma for an enhanced neutrino magnetic moment, and 3.0 sigma global (4.0 local) for bosonic dark matter with a peak at 2.3 +- 0.2 keV (68% C.L.). Additionally, a previously undetected tritium component, favoured at 3.2 sigma over known backgrounds, can neither be confirmed nor…

Abstract:  A remarkable feature of the Standard Model (SM) is that each lepton flavour (electron, muon, tau) is equally likely to interact with a W boson. This is known as Lepton Flavour Universality. In a recent ATLAS measurement, a novel technique using events with top-quark pairs has been exploited to test the ratio of the probabilities for tau leptons and muons to be produced in W boson decays, R(τ/μ). In the SM, R(τ/μ) is expected to be unity, but a longstanding tension…

ABSTRACT: It is now well established that the dominant part of non-relativistic matter in the Universe is some substance which appears to be oblivious to any force but gravity. The nature of this dark matter remains a nagging puzzle, and several candidates remain in the running. For instance, dark matter might be a new particle, as light as an electron, which might weakly interact with standard particles. Or it could be partly made of primordial black holes as massive as many Suns,…

Abstract: The standard model of cosmology is built upon on a series of propositions on how the early, intermediate, and late epochs of the Universe behave. In particular, it predicts that dark energy and dark matter currently pervades the cosmos. Understanding the properties of the dark sector is plausibly the biggest challenge in theoretical physics. There is, however, a broad assumption in cosmology that the Universe on its earlier stages is fully understood and that discrepancies between the standard model…

Abstract: This seminar presents the search for the rare Higgs boson decay to a pair of muons performed by the CMS experiment at the LHC, based on the full Run 2 dataset. Events are categorized based on the characteristics of major Higgs boson production mechanisms and are analyzed using machine learning techniques, which significantly boosts the sensitivity of the search. A 3.0σ excess is observed in data, constituting the first evidence for the Higgs boson coupling to muons. http://physics.lbl.gov/rpm/index.php/events/ If you…

ABSTRACT Clustering of matter on large scales provides an important source of information on key cosmological parameters. To extract this information we need to understand the relation between the tracers we observe and the underlying matter field. The clustering strength of halos and galaxies on large scales is linearly biased compared to the matter clustering. This linear bias mainly depends on halo mass and redshifts, though selections based on other scalar halo properties (age, spin, concentration etc.) show additional bias…