DOI 10.1393/ncc/i2009-10489-1 Colloquia: IFAE 2009 IL NUOVO CIMENTO Vol. 32 C, N. 3-4 Maggio-Agosto 2009 Neutrino and astroparticle physics V. Antonelli( 1 ) and F. S. Cafagna( 2 ) ( 1 ) Dipartimento di Fisica, Universit` a di Milano and INFN, Sezione di Milano via Celoria 16, 20133 Milano, Italy ( 2 ) INFN, Sezione di Bari - via Amendola 173, 70126 Bari, Italy (ricevuto il 19 Settembre 2009; pubblicato online il 27 Novembre 2009) Summary. — We report on the neutrinos and astroparticle session of this workshop and discuss the present status and future perspectives of this research field. PACS 95.85.Ry – Neutrino, muon, pion, and other elementary particles; cosmic rays. PACS 98.70.Rz – γ-ray sources; γ-ray bursts. PACS 95.55.Vj – Neutrino, muon, pion, and other elementary particle detectors; cosmic ray detectors. PACS 95.55.Ym – Gravitational radiation detectors; mass spectrometers; and other instrumentation and techniques. 1. – Introduction Summarize a session having such a widespread range of arguments is difficult. Neu- trinos and astroparticle physics are argument as waste as the flux and energy ranges of the cosmic rays themselves. In this section we tried to have a paramount view of the arguments, sketching, where it was possible, an ideal line connecting all the contributions. For sake of simplicity, in this report, we decided to group the two arguments trying to outline the connection. 2. – Present and future of neutrino physics The structure of the “quasi bi-maximal” PMNS matrix, describing neutrino mixing, is very different from the almost diagonal CKM matrix of the quark case. The PMNS matrix can be decomposed in the product of 3 matrices, each of which has to do with the mixing between a different couple of neutrino mass eigenstates: U PMNS = ⎛ ⎝ 1 0 0 0 c 23 s 23 0 −s 23 c 23 ⎞ ⎠ ⎛ ⎝ c 13 0 s 13 e −iδ 0 1 0 −s 13 e iδ 0 c 13 ⎞ ⎠ ⎛ ⎝ c 12 s 12 0 −s 12 c 12 0 0 0 1 ⎞ ⎠ , where c ij , s ij denote the cosine and sine of the mixing angle θ ij and δ is the Dirac CP -violating phase. The mixing parameters appearing in the first and the last factors of this matrix product can be derived by the atmospheric neutrinos and the accelerator c  Societ` a Italiana di Fisica 291 brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Scientific Open-access Literature Archive and Repository