We present a global analysis of neutrino oscillation data, including high-precision measurements of the neutrino mixing angle θ13 at reactor experiments, which have confirmed previous indications in favor of θ13>0. Recent data presented at this Conference are also included. We focus on the correlations between θ13 and the mixing angle θ23, as well as between θ13 and the neutrino CP-violation phase δ . We find interesting indications for θ23<π/4 and possible hints for δ∼π, with no significant difference between normal and inverted mass hierarchy.

Large-scale extragalactic magnetic fields may induce conversions between very-high-energy photons and axionlike particles (ALPs), thereby shielding the photons from absorption on the extragalactic background light. However, in simplified “cell” models, used so far to represent extragalactic magnetic fields, this mechanism would be strongly suppressed by current astrophysical bounds. Here we consider a recent model of extragalactic magnetic fields obtained from large-scale cosmological simulations. Such simulated magnetic fields would have large enhancement in the filaments of matter. As a result, photon-ALP conversions would produce a significant spectral hardening for cosmic TeV photons. This effect would be probed with the upcoming Cherenkov Telescope Array detector. This possible detection would give a unique chance to perform a tomography of the magnetized cosmic web with ALPs.

We perform a global analysis of neutrino oscillation data, including high-precision measurements of the neutrino mixing angle theta_13 at reactor experiments, which have confirmed previous indications in favor of theta_13> 0. Recent data presented at the Neutrino 2012 conference are also included. We focus on the correlations between theta_13 and the mixing angle theta_23, as well as between theta_13 and the neutrino CP-violation phase . We find interesting indications for theta_23 < =pi/44 and possible hints for delta~pi, with no significant difference between normal and inverted mass hierarchy

A fraction of active galactic nuclei producing very high-energy (VHE) rays are located in galaxy clusters. The magnetic field present in the intracluster medium would lead to conversions of VHE photons into axionlike particles (ALPs), which are a generic prediction of several extensions of the Standard Model. ALPs produced in this way would traverse cosmological distances unaffected by the extragalactic background light at variance with VHE photons which undergo a substantial absorption. Eventually, a nontrivial fraction of ALPs would reconvert into VHE photons in the magnetic field of the Milky Way. This mechanism produces a significant hardening of the VHE spectrum of active galactic nuclei in galaxy clusters. As a specific example we consider the energy spectra of two observed VHE -ray sources located in galaxy clusters, namely 1ES 0414+009 at redshift z=0.287 and Mkn 501 at z=0.034. We find that the hardening in the observed spectra becomes relevant at E>=1 TeV. The detection of this signature would allow one to indirectly probe the existence of ultralight ALPs with mass ma<=10^8 eV and photon-ALP coupling ga<=10^10 GeV^-1 with the presently operating imaging atmospheric Cherenkov telescopes like H.E.S.S., MAGIC, VERITAS and CANGAROO-III and even more likely with the planned detectors like Cherenkov Telescope Array, High Altitude Water Cherenkov Experiment and Hundred*i Square-km Cosmic ORigin Explorer. An independent laboratory check of ultralight ALPs invoked in this mechanism can be performed with the planned upgrade of the photon regeneration experiment Any Light Particle Search at Deutsches Elektronen-Synchrotron and with the next generation solar axion detector

Breve review sullo stato della fisica del neutrino

Background radiation fields pervade the Universe, and above a certain energy any γ-ray flux emitted by an extragalactic source should be attenuated due to e+e- pair production. The opacity could be alleviated if photons oscillated into hypothetical axion-like particles (ALPs) in ambient magnetic fields, leading to a γ-ray excess especially at high optical depths that could be detected with imaging air Cherenkov telescopes (IACTs). Here, we introduce a method to search for such a signal in γ-ray data and to estimate sensitivities for future observations. Different magnetic fields close to the γ-ray source are taken into account in which photons can convert into ALPs that then propagate unimpeded over cosmological distances until they re-convert in the magnetic field of the Milky Way. Specifically, we consider the coherent field at parsec scales in a blazar jet as well as the turbulent field inside a galaxy cluster. For the latter, we explicitly derive the transversal components of a magnetic field with gaussian turbulence which are responsible for the photon-ALP mixing. To illustrate the method, we apply it to a mock IACT array with characteristics similar to the Cherekov Telescope Array and investigate the dependence of the sensitivity to detect a γ-ray excess on the magnetic-field parameters.

Universe should be opaque to photons with energy TeV due scattering on the extragalactic background light during their propagation. However, a surprisingly high degree of transparency of the universe has been observed. In order to explain this fact, the conversion between photons and hypothetical axion-like particles in the turbulent extragalactic magnetic field has been invoked. We have derived new equations to calculate the mean survival probability of the photons. We have also found that the photon transfer functions on different lines of sight could have relevant deviations with respect to the mean value, producing both an enhancement or a suppression in the observable photon flux.

The standard three-neutrino (3ν) oscillation framework is being increasingly refined by results coming from different sets of experiments, using neutrinos from solar, atmospheric, accelerator and reactor sources. At present, each of the known oscillation parameters [the two squared mass gaps [δm2;Δm2] and the three mixing angles [θ12; θ13; θ23] is dominantly determined by a single class of experiments. Conversely, the unknown parameters (the mass hierarchy, the θ23 octant and the CP-violating phase δ) can currently be constrained only through a combined analysis of various (eventually all) classes of experiments. In the light of recent new results coming from reactor and accelerator experiments, and of their interplay with solar and atmospheric data, we update the estimated Nσ ranges of the known 3ν parameters and revisit the status of the unknown ones. Concerning the hierarchy, no significant difference emerges between normal and inverted mass ordering. A slight overall preference is found for θ23 in the first octant and for nonzero CP violation with sin δ < 0; however, for both parameters, such preference exceeds 1σ only for normal hierarchy. We also discuss the correlations and stability of the oscillation parameters within different combinations of data sets