The Dark Matter - LHC Endeavour to Unveil TeV New Physics

Abstract

After more than four decades of relentless tests of the Standard Model (SM) of particle physics, one can safely state that it correctly describes the fundamental interactions all the way up to the energy scale of 100 GeV. Yet, the observational evidences that neutrinos are massive and that a large amount of non-baryonic dark matter exists corroborate the theoretical demand for the presence of new non-SM physics at the TeV scale. Interestingly enough, the main theoretical motivation for new physics (NP) at the electroweak scale (i.e., the presence of an ultraviolet SM completion to enforce the stability of the electroweak breaking scale) nicely joins the need for some form of cold matter: indeed, most theoretically dictated extensions of the SM (low-energy supersymmetry, extra-dimensions, etc.) entail the existence of some new stable particle which can play the role of dark matter candidate. I'll discuss the interplay between the searches for TeV NP which are going on at the LHC and the searches for dark matter related to TeV NP both in direct and indirect DM probes. It is exciting that the coming decade has the potentiality to witness the simultaneous success of the high-energy (LHC) and astroparticle (DM) roads in our endeavour to unveil the presence of NP at the electroweak scale.

Giant planet accretion and dynamical evolution: considerations on systems around small-mass stars

Abstract

The classical model of giant planet formation envisions that multi-Earth mass solid cores formed from the accretion of planetesimals and that these cores then captured by gravity a massive atmosphere from the gas in the proto-planetary disk. A problem in this scenario is that the solid cores have to grow on a timescale shorter than the gas-dissipation timescale, which observations set to be a few My only. This is not easy, particularly in disks with small densities, such as those around low-mass stars. For this reason it is expected that giant planets cannot form around low-mass stars or they form very rarely. However, microlensing and radial velocity detections show that giant planets do exist around stars down to at least 0.2 solar masses. This conflict between models and observations suggests that the process of giant planet accretion needs to be revisited.

Abstract

In its all-sky survey, the ESA global astrometry mission Gaia, due to launch in two years' time, will perform high-precision astrometry and photometry for 1 billion stars down to V = 20 mag. The data collected in the Gaia catalogue, to be published by the end of the decade, will likely revolutionize our understanding of many aspects of stellar and Galactic astrophysics. One of the relevant areas in which the Gaia observations will have great impact is the astrophysics of planetary systems. I will start by addressing some of the complex technical problems related to and challenges inherent in correctly modelling the signals of planetary systems present in measurements collected with an observatory poised to carry out precision astrometry at the micro-arcsecond (μas) level. Then, I will discuss the potential of Gaia μas astrometry for important contributions to the astrophysics of planetary systems, particularly when seen in synergy with other indirect and direct methods for the detection and characterization of planetary systems.