The goal of the present research program is to undertake a vast and diversified activity in “Astroparticle Physics”, a recent field of particle physics involving those phenomenological and theoretical aspects of nuclear and subnuclear physics which are relevant for astrophysics and cosmology. This field is in a state of rapid evolution, both for the increased ability in observing phenomena of interest for particle physics and astrophysics, and for the enormous impact on fundamental questions. In particular, almost all the modern indications for new physics and for emerging “new paradigms” (e.g., dark matter and dark energy, neutrino masses, bariogenesis, inflationary models, ultra high energy cosmic rays) find their natural place in the field of astroparticle physics. The fundamental objective is thus to contribute in a qualified and significant way to the scientific development – both theoretical and phenomenological – of this important research field.

In this variegated field there is a widely recognized need for a deeper exchange of knowledge and ideas, for a better organized management of the research activity, and for a more effective participation of young researchers and students. The above considerations justify the attempt to form a more solid collaboration among research units that, though belonging to different institutions, have already been engaged for several years in this branch of physics, so as to increase their scientific potential within a common and well formulated research project. It is worth stressing that a large part of the research topics are common to all units, and that a specific collaboration already exists between some of them. It is also worth mentioning that the impressive research activity of the various research units in the last few years is testified by a large number of (often highly cited) publications in leading refereed journals, by many invited talks in major conferences in Italy and abroad, and by the organization of several workshops and schools in astroparticle physics. This deeply-rooted activity provides a solid scientific basis for the research project in astroparticle physics.

In the other sections of this document, we describe the main guidelines of the activity currently carried out in the various units belonging to this project. Here we simply identify and describe four main topics (A, B, C, D) of major scientific and cultural interest for our project.

A) NEUTRINOS IN PHYSICS, ASTROPHYSICS AND COSMOLOGY

This field, which is of great interest for all the units, has concerned a large fraction of the total scientific productions from the various groups in the last few years. Results of high relevance have been achieved in the analysis of flavour oscillations and of absolute mass constraints of neutrinos produced in terrestrial or astrophysical environments. This is an extremely wide research field, strongly linked with the other three research topics, and involving many unsolved theoretical problems, as well as many experiments in progress or proposed. Undoubtedly, neutrino physics and astrophysics, both standard (masses and mixings) and nonstandard (new states, new interactions) will continue to be a rich research field in the next years. The following research topics can be sketched:

• Solar neutrino physics, stellar astrophysics, and related cross sections
• Physics of atmospheric and (long-baseline) accelerator neutrinos
• Interpretation of observations of reactor antineutrinos and geoneutrinos
• Properties of neutrinos of astrophysical origin (supernovae, nucleosynthesis)
• Theoretical aspects of neutrino oscillations in vacuum and matter
• Global phenomenological analyses of neutrino oscillations
• Absolute neutrino masses: laboratory and cosmological constraints
• Theoretical models for neutrino (and other fermion) mass matrices
• Open problems: Mass hierarchy, mixing 1-3, CP phase
• New physics: sterile neutrinos, magnetic moments, nonstandard interactions

B) NUCLEAR AND SUBNUCLEAR PHYSICS IN THE EARLY UNIVERSE

Within our project, the study of the behaviour of matter and space-time in the extreme conditions characterizing the early universe has concerned a wide spectrum of important theoretical researches, ranging from string and brane cosmology to the study of hadronic matter in complex and high-density environments, from the cosmological implications of supersymmetry to CP violation effects, from inflationary models to the primordial generation of nuclei, magnetic fields, and possible topological defects. The early universe is – and will continue to be – a privileged laboratory to test the most advanced physical theories of matter and space-time, especially considering the probable observational improvements that can be expected in this field. The main topics are:

• String, brane, and extra-dimension cosmology
• Extended theories of gravitation and cosmology
• Time variation of fundamental parameters
• Supersymmetry and its cosmological implications
• CP violation, baryogenesis and leptogenesis
• Magnetic fields, topological defects, and phase transitions in the early universe
• Big bang nucleosynthesis and related cross sections
• Compact quark stars, hadronic physics of astrophysical interest


C) DARK MATTER, DARK ENERGY AND AND COSMIC STRUCTURES

The problems set by the existence of dark matter and dark energy are so important that they have reached the general public. In this field, several units have achieved very relevant results in the theory and phenomenology of the particle candidates of dark matter (neutralinos, WIMPs, baryonic mirror matter), in the dynamical characterization of the possible scalar fields associated to dark energy, and in their links with the formation of large scale structures. In this field, the mere existence of two gigantic unsolved problems (dark matter and dark energy) guarantees, by itself, the importance of this research topic in the next future. Main topics of this sector:

• Dark matter: supersymmetric and mirror models
• Direct and indirect signatures of particle dark matter
• Search of dark matter through gravitational lensing
• Dark matter and its (de)coupling with dark energy
• Dark energy: scalar field potentials and their physics
• Linear and nonlinear dark energy dynamics
• Cosmic background radiation (CMBR)
• Galaxy formation and particle physics
• Cosmic structures and field theory models
• Deep galaxy samples and cosmic components


D) ASTROPHYSICAL SOURCES OF RADIATION

The astrophysical phenomena associated to extremely high energy are generally poorly understood. Among them, particular interest has been devoted to supernovae, to compact quark stars, to gamma ray bursts (origin, relation with supernovae) and to ultra high energy cosmic rays (origin, propagation, detection). Also in this case, the increasing theoretical interest and the new observations which will become possible in the next decade guarantee a high level of scientific interest for this research topic. Main topics:

• Nuclear reactions and stars evolution
• Supernovae and particle physics
• Ultra high energy cosmic rays: origin and propagation
• Ultra high energy cosmic rays: detection and interpretation
• Gamma ray bursts: theoretical and phenomenological aspects
• Gamma ray bursts and their relation with supernovae


Among the above topics, several are of common interest for various research groups. Within the proposed project, we intend to strengthen and widen the existing collaborations among research units, as well as between them and other institutions in Italy and abroad, and with some experimental groups. For such reason, particular attention will be paid to the mobility of all researchers, to the support of young students through grants and fellowships, to the education and exchange of ideas through national and international schools, workshops, and conferences. These synergies will allow the strengthening of a scientific activity which, as documented in the following, is already of very high quality and impact within the international scientific community.