arXiv subjects
Publications and source records attributed to S. Esposito.
An account is given of some topical unpublished work by Ettore Majorana, revealing his very deep intuitions and skilfulness in Theoretical Physics. The relevance of the quite unknown results obtained by him is pointed out as well.
We give, for the first time, the English translation of a manuscript by Ettore Majorana, which probably corresponds to the text for a seminar delivered at the University of Naples in 1938, where he lectured on Theoretical Physics. Some passages reveal a physical interpretation of the Quantum Mechanics which anticipates of several years the Feynman approach in terms of path integrals, independently of the underlying mathematical formulation.
Quantitative bounds on Lorentz symmetry violation in the neutrino sector have been obtained by analyzing existing laboratory data on neutron $β$ decay and pion leptonic decays. In particular some parameters appearing in the energy-momentum dispersion relations for $ν_e$ and $ν_μ$ have been constrained in two typical cases arising in many models accounting for Lorentz violation.
We report on theoretical courses by Fermi and Majorana, giving evidence of the first appearance and further development of Quantum Mechanics teaching in Italy. On the basis of original documents, we make a comparison between Fermi's and Majorana's approaches. A detailed analysis is carried out of Fermi's course on Theoretical Physics attended by Majorana in 1927-28. Three (previously unknown) programs on advanced Physics courses submitted by Majorana to the University of Rome between 1933 and 1936 and the course he held in Naples in 1938 complete our analysis: Fermi's phenomenological approach resounded in Majorana, who however combined it with a deeper theoretical approach, closer to the modern way of presenting Quantum Mechanics.
In 1927, just after he obtained a full professorship, Enrico Fermi delivered his first course on Theoretical Physics at the Institute of Physics in Rome. The following year Edoardo Amaldi, Emilio Segre' and Ettore Majorana became students of that course. The lectures given in 1927-28, whose content may be easily reconstructed, probably had a deep impact in forming such young students, who participated actively in the Physics researches carried on in Rome soon after. In this perspective, the case of Ettore Majorana is certainly the most important one: as a lecturer, in 1933-36 he planned to give three advanced Physics courses in Rome, before obtaining his full professorship in Theoretical Physics "for high and well-deserved repute" in 1937. From the analysis of the lectures he delivered in Naples in 1938, we can conclude that, in part, Majorana referred to the Fermi lectures he followed as a student, but he also introduced some advanced (for that time) topics, rendering his course a very modern one. Much of these frontier topics were already cited in the programmes of the mentioned three courses he presented few years earlier.
We comment on a recent paper announcing the discovery of a previously unknown publication of Ettore Majorana on the Thomas-Fermi atomic model. In pointing out that such a publication was not written by Majorana, we correct some misunderstandings and clarify the historical and scientific relevance of the "forgotten publication".
We give, for the first time, the critical complete text of a manuscript by Ettore Majorana, conserved in the same file of the lecture notes for his course on Theoretical Physics at the University of Naples. He probably refers to a seminar delivered in that University. Some passages reveal a physical interpretation of the Quantum Mechanics which anticipates of several years the Feynman approach in terms of path integrals, independently of the underlying mathematical formulation.
We analyze in some detail the course of Theoretical Physics held by Ettore Majorana at the University of Naples in 1938, just before his mysterious disappearance. In particular we give an account of the recently retrieved "Moreno Paper", where the lecture notes are reported. Six of these lectures are not present in the collection of the original manuscripts deposited at the Domus Galilaeana in Pisa, consisting of only ten lectures.
We analyze in some detail the course of Theoretical Physics held by Ettore Majorana at the University of Naples in 1938, just before his mysterious disappearance. In particular we present the recently discovered "Moreno Paper", where all the lecture notes are reported. Six of these lectures are not present in the collection of the original manuscripts conserved at the Domus Galilaeana in Pisa, consisting of only ten lectures.
We give a straightforward generalization of the Ginzburg-Landau theory for superconductors where the scalar phase field is replaced by an antisymmetric Kalb-Ramond field. We predict that at very low temperatures, where quantum phase effects are expected to play a significant role, the presence of vortices destroys superconductivity.
We give an account of the appearance and first developments of the statistical model of atoms proposed by Thomas and Fermi, focusing on the main results achieved by Fermi and his group in Rome. Particular attention is addressed to the unknown contribution to this subject by Majorana, anticipating some important results reached later by leading physicists.
After a quick historical account of the introduction of the group-theoretical description of Quantum Mechanics in terms of symmetries, as proposed by Weyl, we examine some unpublished papers by Ettore Majorana. Remarkable results achieved by him in frontier research topics as well as in physics teaching point out that the Italian physicist can be well considered as a follower of Weyl in his reformulation of Quantum Mechanics.
We study some implications on standard matter oscillations of solar neutrinos induced by a background of extremely low energy thermal neutrinos trapped inside the Sun by means of coherent refractive interactions. Possible experimental tests are envisaged and current data on solar neutrinos detected at Earth are briefly discussed.
We study the direct interaction of an antisymmetric Kalb-Ramond field with a scalar particle derived from a gauge principle. The method outlined in this paper to define a covariant derivative is applied to a simple model leading to a linear coupling between the fields. Although no conserved Noether charge exists, a conserved topological current comes out from the antisymmetry properties of the Kalb-Ramond field. Some interesting features of this current are pointed out.
We review the purely leptonic neutrino emission processes, contributing to the energy loss rate of the stellar plasma. We perform a complete analysis up to the first order in the electromagnetic coupling constant. In particular the radiative electromagnetic corrections, at order $α$, to the process $e^+ e^- -> ν\barν$ at finite density and temperature have been computed. This process gives one of the main contributions to the cooling of stellar interior in the late stages of star evolution. As a result of the analysis we find that the corrections affect the energy loss rate, computed at tree level, by a factor $(-4 ÷1) %$ in the temperature and density region where the pair annihilation is the most efficient cooling mechanism.
We study the tunneling through an arbitrary number of finite rectangular opaque barriers and generalize earlier results by showing that the total tunneling phase time depends neither on the barrier thickness nor on the inter-barrier separation. We also predict two novel peculiar features of the system considered, namely the independence of the transit time (for non resonant tunneling) and the resonant frequency on the number of barriers crossed, which can be directly tested in photonic experiments. A thorough analysis of the role played by inter-barrier multiple reflections and a physical interpretation of the results obtained is reported, showing that multibarrier tunneling is a highly non-local phenomenon.
We consider radiative electromagnetic corrections, at order α, to the process $e^+ e^- \to ν\barν$ at finite density and temperature. This process represents one of the main contributions to the cooling of stellar environments in the late stages of star evolution. We find that these corrections affect the energy loss rate by a factor $(-4 ÷1) %$ with respect to the tree level estimate, in the temperature and density ranges where the neutrino pair production via e^+ e^- annihilation is the most efficient cooling mechanism.
Higher-dimensional theories have the remarkable feature of predicting a time (and hence redshift) dependence of the `fundamental' four dimensional constants on cosmological timescales. In this paper we update the bounds on a possible variation of the fine structure constant alpha at the time of BBN (z =10^10) and CMB (z=10^3). Using the recently-released high-resolution CMB anisotropy data and the latest estimates of primordial abundances of 4He and D, we do not find evidence for a varying alpha at more than one-sigma level at either epoch.