We model the transport of cosmic ray nuclei in the Galaxy by means of a new numerical code. Differently from previous numerical models we account for a generic spatial distribution of the diffusion coefficient. We found that in the case of radially u
niform diffusion, the main secondary/primary ratios (B/C, N/O and sub-Fe/Fe) and the modulated antiproton spectrum match consistently the available observations. Convection and re-acceleration do not seem to be required in the energy range we consider: $1 < E < 10^3$ GeV/nucleon. We generalize these results accounting for radial dependence of the diffusion coefficient, which is assumed to trace that of the cosmic ray sources. While this does not affect the prediction of secondary/primary ratios, the simulated longitude profile of the diffuse $gamma$-ray emission is significantly different from the uniform case and may agree with EGRET measurements without invoking ad hoc assumptions on the galactic gas density distribution.
Theoretical estimates for the half life of neutrinoless double beta decay in candidate nuclei are affected by both particle and nuclear physics uncertainties, which may complicate the interpretation of decay signals or limits. We study such uncertain
ties and their degeneracies in the following context: three nuclei of great interest for large-scale experiments (76-Ge, 130-Te, 136-Xe), two representative particle physics mechanisms (light and heavy Majorana neutrino exchange), and a large set of nuclear matrix elements (NME), computed within the quasiparticle random phase approximation (QRPA). It turns out that the main theoretical uncertainties, associated with the effective axial coupling g_A and with the nucleon-nucleon potential, can be parametrized in terms of NME rescaling factors, up to small residuals. From this parametrization, the following QRPA features emerge: (1) the NME dependence on g_A is milder than quadratic; (2) in each of the two mechanisms, the relevant lepton number violating parameter is largely degenerate with the NME rescaling factors; and (3) the light and heavy neutrino exchange mechanisms are basically degenerate in the above three nuclei. We comment on the challenging theoretical and experimental improvements required to reduce such particle and nuclear physics uncertainties and their degeneracies.
The ARGO-YBJ experiment has been in stable data taking for 5 years at the YangBaJing Cosmic Ray Observatory (Tibet, P.R. China, 4300 m a.s.l., 606 g/cm$^2$). With a duty-cycle greater than 86% the detector collected about 5$times $10$^{11}$ events in
a wide energy range, from few hundreds GeV up to about 10 PeV. A number of open problems in cosmic ray physics has been faced exploiting different analyses. In this paper we summarize the latest results in cosmic ray physics and in gamma-ray astronomy.
Despite large progresses in building new detectors and in the analysis techniques, the key questions concerning the origin, acceleration and propagation of Galactic Cosmic Rays are still open. A number of new EAS arrays is in progress. The most ambit
ious and sensitive project between them is LHAASO, a new generation multi-component experiment to be installed at very high altitude in China (Daocheng, Sichuan province, 4400 m a.s.l.). The experiment will face the open problems through a combined study of photon- and charged particle-induced extensive air showers in the wide energy range 10$^{11}$ - 10$^{18}$ eV. In this paper the status of the experiment will be summarized, the science program presented and the outlook discussed in comparison with leading new projects.
We consider a simplifed model for self-induced flavor
We study a very general four dimensional Field Theory model describing the dynamics of a massless higher spin $N$ symmetric tensor field particle interacting with a geometrical background.This model is invariant under the action of an extended linear
diffeomorphism. We investigate the consistency of the equations of motion, and the highest spin degrees of freedom are extracted by means of a set of covariant constraints. Moreover the the highest spin equations of motions (and in general all the highest spin field 1-PI irreducible Green functions) are invariant under a chain of transformations induced by a set of $N-2$ Ward operators, while the auxiliary fields equations of motion spoil this symmetry. The first steps to a quantum extension of the model are discussed on the basis of the Algebraic Field Theory.Technical aspects are reported in Appendices; in particular one of them is devoted to illustrate the spin-$2$ case.
We discuss the question of gauge choice when analysing relativistic density perturbations at second order. We compare Newtonian and General Relativistic approaches. Some misconceptions in the recent literature are addressed. We show that the comoving
-synchronous gauge is the unique gauge in General Relativity that corresponds to the Lagrangian frame and is entirely appropriate to describe the matter overdensity at second order. The comoving-synchronous gauge is the simplest gauge in which to describe Lagrangian bias at second order.
We investigate the connection between Gravitys Rainbow and Horava-Lifshitz gravity, since both theories incorporate a modification in the UltraViolet regime which improves their quantum behavior at the cost of the Lorentz invariance loss. In particul
ar, extracting the Wheeler-De Witt equations of the two theories in the case of Friedmann-Lemaitre-Robertson-Walker and spherically symmetric geometries, we establish a correspondence that bridges them.
The Electron Cyclotron Resonance Ion Source (ECRIS) is nowadays the most effective device that can feed particle accelerators in a continuous and reliable way, providing high-current beams of low- and medium-charge-state ions and relatively intense c
urrents for highly charged ions. The ECRIS is an important tool for research with ion beams (in surface, atomic, and nuclear science) while, on the other hand, it implies plasma under extreme conditions and thus constitutes an object of scientific interest in itself. The fundamental aspect of the coupling between the electromagnetic wave and the plasma is hereinafter treated together with some variations to the classical ECR heating mechanism, with particular attention being paid to the frequency tuning effect and two-frequency heating. Considerations of electron and ion dynamics will be presented together with some recent observations connecting the beam shape with the frequency of the electromagnetic wave feeding the cavity. The future challenges of higher-charge states, high-charge breeding efficiency, and high absolute ionization efficiency also call for the exploration of new heating schemes and synergy between experiments and modelling. Some results concerning the investigation of innovative mechanisms of plasma ignition based on upper hybrid resonance will be described.
This chapter describes the basic principles, design features and characteristics of microwave discharge ion sources. A suitable source for the production of intense beams for high-power accelerators must satisfy the requirements of high brightness, s
tability and reliability. The 2.45 GHz off-resonance microwave discharge sources are ideal devices to generate the required beams, as they produce multimilliampere beams of protons, deuterons and singly charged ions. A description of different technical designs will be given, analysing their performance, with particular attention being paid to the quality of the beam, especially in terms of its emittance.
