[en] It is argued that the dominant contribution to the neutrino masses can be provided by those interactions which incorporate a full quark-lepton correspondence and whose characteristic mass scale furnishes the lightest oasis in the so-called 'energy desert'. In particular the possibility that the suppression of the neutrino mass sepctrum has its origin beyond the single-generation level is discussed. Thus, using the minimal U'(1) horizontal symmetry, it is possible to correlate the structure of the Majorana mass matrix with the various Dirac mass matrices of the theory. (author)

[en] The interaction of the S=1/2 fermion field with the 2(2S+1)- component massless field is considered. New interpretation of the bispinors corresponding to the S=1 particles is proposed. The equation analogous to the Dirac oscillator is obtained. 13 refs

[en] We built a *-product on the phase space of an elementary massless particle with zero spin and we study explicitely relations between this *-product and the corresponding unitary irreducible representation of the Poincare group

[en] In this paper, the non-BPS amplitudes ($Z<2m$) are considered. Utilizing on-shell methods, the three point amplitudes of two equal-mass particles and one massless particle were constructed, where the two massive particles are non-BPS states. We verify the result by matching the $Z=0$ and BPS limit with $\mathcal{N}=2$ supersymmetry. As an application we derive the non-BPS coupling for $\mathcal{N}=4$ super-Maxwell and supergravity.

[en] Localizability of a quantum mechanical system is described by a suitable Euclidean system of covariance (ESC). It turns out to be a characteristic feature of relativistic massless particles with non-zero (definite) helicity not to possess localized states for bounded regions. Nevertheless, for physical reasons, a massless particle is expected to be concentratable in bounded regions. We show that ESC, admitting a dilational covariance, describe physical sytems which are concentratable in any non-void ball, and give a complete description of these ESC for a massless particle. The description occurs in terms of countable convex combinations of extremal points. (orig.)

[en] A brief review of the status of the neutrino masses and mixing is presented, with emphasis on Italian contributions to this field of research.

[en] We review the progress in the calculation of the 2 → 2 scattering process at next-to-next-to-leading order

[en] A method that may underlie an attempt at proving the previously proposed new identity for Green's functions is described for N = 1 supersymmetric massless electrodynamics regularized by higher derivatives. With the aid of this method, it is shown that some contributions to the identity in question do indeed vanish.

[en] We construct localized oscillating finite energy solutions of the massless wave equation which move like massive relativistic particles with energy E = γω and momentum p-vector = γk-vector where ω is the frequency of the oscillating lump and k-vector its wave vector. It is a construction of a single massive ''quantum particle'' from ''light''. (author). 11 refs

[en] Transversal position operators for a massless particle are discussed. The relationships are studied between the two-component position operator constructed according to Angelopoulos, Bayen, Flato and the two-component position operator introduced in the infinite momentum frame. The equivalency of the two position operators is shown. (Z.J.)