Project
The goal of the project is to contribute crucial steps forward in the theoretical understanding of the main open problems in astroparticle physics, also profiting of the decisive experimental results expected from observational astrophysics, precision cosmology and particle accelerators. These scientific goals and their relevance to the advancement of knowledge are outlined below. The activities are organized in terms of four Work Packages, carried out by the 8 Research Units in a collaborative and synergic approach.
WP1 – DARK MATTER
Particle dark matter offers a unique connection between cosmology, astrophysics and elementary particle physics. The project will profit from the complementary expertise of the Research Units members in all these fields, to deeply investigate dark matter as a new, yet undiscovered, elementary particle. It has become clear that to detect a true particle-dark matter signal requires refined techniques, able to combine information coming from different sources. Our envisaged strategy is therefore to exploit all possible information obtainable with an integrated multi-wavelength (from radio to gamma-rays), multi-messenger (electromagnetic/charged cosmic-rays, neutrinos), multi-technique (direct/indirect detection) and cross-field (astro/particle) endeavor.
A relevant direction is to study cross-correlations of different signals, in order to look for crucial differences in the response of background and dark matter signal sources, and to exploit these differences to define new search strategies. For electromagnetic signals, that trace the dark matter distribution in cosmic structures, the project develops multi-wavelength angular cross-correlation studies. For charged-cosmic-rays signals, at high energies the project investigates the relevance of anisotropies, while at low energies it develops advanced modeling of transport both in the Galaxy and in the heliosphere based on stochastic techniques. Crucial is also to rethink the modeling of the astrophysical environment, to reach an assessment of the relevant sources of backgrounds.
For direct detection, the main direction is toward redefining predictions for annual and diurnal modulation signatures, in the light of the recent results on dark matter distribution at the galactic scale obtained in high-resolution numerical simulations, and investigating the ability of multi-target detectors to grab the dark matter particle properties.
While all these studies will be mostly directed to deeply investigate dark matter at the GeV to TeV mass scale, many investigations (like e.g. multiwavelength studies and their implications) will be relevant also for dark matter in terms of lighter particles, like for warm dark matter candidates.
WP2 – NEUTRINO PHYSICS
The discovery of a nonzero mixing angle between the first and third generations has opened the door to CP-violation exploration and mass-hierarchy determination via flavor oscillations. The project investigates the implications for neutrinos from different sources (artificial, terrestrial, astrophysical, cosmological), as well as in neutrinoless double-beta decay. Searches toward the determination of the nature (Dirac or Majorana) of massive neutrinos will be of highest priority.
Even within the “standard” scenario with three neutrinos families, assessing the neutrino absolute masses, hierarchy, nature and CP-violating properties represent top priorities in fundamental physics, with deep and diverse theoretical implications according to the possible outcomes of such searches. Furthermore, potential emerging indications in favor of light sterile neutrinos (in oscillation phenomena) or heavy sterile neutrinos (in some dark matter or New Physics scenarios) are going to be explored by laboratory experiments, astrophysical observations and precision cosmology. The project investigates scenarios compatible with such intervening data and refines the calculation of cosmological observables sensitive to absolute neutrino masses, to the number of active/sterile neutrinos, and to their distributions and oscillations in the early Universe.
From expected developments in observational astrophysics, neutrinos as probes of known or hypothetical sources, both at low energies (Earth, Sun, supernovae) and high energies (cosmogenic, from dark matter annihilation/decay) are posed under deep investigation.
WP3 – COSMOLOGICAL ASPECTS
The presence in the Research Units of complementary expertise in both theoretical/observational cosmology and particle physics offers a unique opportunity to use cosmology as a particle physics laboratory.
The first goal of the project is to derive crucial responses from the wealth of cosmological data coming from Planck and other cosmological missions. This is achieved by devising, testing, implementing and validating accurate data processing methods, with specific attention to a careful extraction of the cosmological information. In this framework, the projects plans to: develop new and powerful data analysis methods that fully handle the increasing amount of information contained in cosmological data; assess the impact of uncertainties and foregrounds contaminations to CMB data; develop accurate predictions for new theoretical scenarios and compare them with available and intervening data; provide the most accurate and updated forecasts for the next experiments and, whenever possible, identify the best experimental configurations.
The outcome and implications of the previous point is then used to extract information on dark matter particles, neutrinos and dark energy. This is obtained by realizing global analyses of cosmological observables: CMB, SNIa, LSS, baryonic acoustic oscillations, cosmic shear. In this WP the focus is on obtaining information having direct impact on New Physics: neutrino absolute mass scale; additional light particles and their mass and interactions (like e.g. sterile neutrinos able to explain dark radiation); dark matter abundance and distribution on large and small scales, relevant for understanding the type of dark matter particle required to explain the observed Universe; hints for dynamical dark energy and its impact on New Physics at the fundamental level.
Implications of cosmological data can also be directed to assess the status of the minimal cosmological scenario and to understand if extensions are required. The ΛCDM model is tested with improved theoretical methods which are currently under development and that allow to evaluate the dynamical role of inhomogeneity on the expansion rate of the Universe, to include non-linear scales in the analysis of large scale structure and to test structure formation using cluster mass profiles. If hints of a CDM crisis at small scales will persist, alternative scenarios will be necessary and the projects intends to move along the following paths, with their implications for fundamental physics: dark matter is not a cold weakly interacting massive particle; dark energy is not a cosmological constant; gravity is not described by General Relativity. The guiding principles are: motivation in terms of New Physics and possibility of identification through clear observational signatures.
Results from the previous points are also exploited to acquire insight on the connection between neutrino physics and generation of the baryon asymmetry of the Universe, via the leptogenesis mechanism. Analyses of both the production of a baryon/lepton asymmetry and accurate predictions of the baryon density of the Universe in standard and non-standard particle physics and cosmological scenarios are put under deep scrutiny.
WP4 – PARTICLE PHYSICS ASPECTS
WP4 is where the intimate connection between cosmological/astrophysical analyses is coordinated with particle physics. Goal of WP4 is in fact to identify a path toward the development of particle physics frameworks beyond the Standard Model able to solve the astroparticle physics puzzles studied in WP1-WP3 and to attempt, if possible, to find common solutions.
In connection with WP1, the main objective is to identify successful New Physics models able to accommodate dark matter candidates. The project concentrates from one side on supersymmetry (especially non-minimal extensions) and on generic New Physics models on the other side. The interplay between particle physics (through the realization of specific predictions for the LHC searches) and astrophysical dark matter searches (realized in WP1) has two main goals: assess what New Physics models are able to solve the dark matter problem; identify crucial observables to test New Physics with astrophysical data.
In connection with WP2 and WP3, the objective is the construction of successful theoretical models for neutrino masses and mixings and the identification of their links to leptogenesis. Emphasis is posed both on TeV-scale New Physics and on supersymmetric theories endowed with grand unification.