G. Papini

Neutrino optics and oscillations in gravitational fields

We study the propagation of neutrinos in gravitational fields using wave functions that are exact to first order in the metric deviation. For illustrative purposes, the geometrical background is represented by the Lense-Thirring metric. We derive explicit expressions for neutrino deflection, helicity transitions, flavor oscillations, and oscillation Hamiltonian.

Schwarzschild field with maximal acceleration corrections

Abstract We consider a model in which accelerated particles experience line-elements with maximal acceleration corrections. When applied to the Schwarzschild metric, the effective field experienced by accelerated test particles contains corrections that vanish in the limit ℏ→0, but otherwise affect the behaviour of matter greatly. A new effect appears in the form of a spherical shell, external to the Schwarzschild sphere, impenetrable to classical particles.

Weyl-dirac theory with torsion

SummaryDirac’s unified theory of gravitation and electromagnetism is extended to include torsion. The conformal invariance of the resultant theory seems to imply charge quantization for source fields. The electromagnetic-field equations in vacuum bear a strong resemblance to those of the Ginzburg-Landau formulation of superconductivity. In the general theory, which involves a cosmological constant, the conformal invariance is spontaneously broken if the ratio of the scalar curvature and the cosmological constant is negative.RiassuntoSi estende la teoria unificata di Dirac della gravitazione e dell’elettromagnetismo a comprendere la torsione. L’invarianza conforme della teoria risultante sembra implicare quantizzazione di carica per campi sorgente. Le equazioni del campo elettromagnetico nel vuoto mostrano una forte somiglianza con quelle della formulazione di Ginzburg e Landau della superconduttività. Nella teoria generale, che comprende una costante cosmologica, l’invarianza conforme è spontaneamente violata se il rapporto tra la curvatura scalare e la costante cosmologica è negativo.РезюмеПроводится обобщение единой теории Дирака гравитации и електромагнетизма, чтобы включить кручение. Конформная инвариантность результирующей теории, по-видимому, подразумевает квантование заряда для полей источникоб. Уравнения электромагнитного поля в вакууме очень похожи на уравнения сверхпроводимости в формулировке Гинзбурга-Ландау. В общей теории, которая включает космологическую константу, конформная инвариантность нарушается спонтанно, если отношение скалярной кривизны и космологической константы является отрицательным.

Spin-2 particles in gravitational fields

We give a solution of the wave equation for massless, or massive spin-2 particles propagating in a gravitational background. The solution is covariant, gauge-invariant and exact to first order in the background gravitational field. The background contribution is confined to a phase factor from which geometrical and physical optics can be derived. The phase also describes Mashhoons spin-rotation coupling and, in general, the spin-gravity interaction.

Maximal acceleration and the time-energy uncertainty relation

SummaryIn 1981, Caianiello showed that maximal acceleration arises when quantum considerations, namely the position-momentum uncertainty relations, are incorporated into the geometry of a particle in eight-dimensional phase space. The time-energy uncertainty relation was later used by Caianiello in an alternative derivation of maximal acceleration. The alternative derivation, given in 1984, was subsequently criticized by Sharma and Srirankanathan. This criticism is shown here to be unfounded. Caianiello’s 1984 derivation is also analyzed. It is found that, while maximal acceleration follows from an equation due to Landau and Lifshitz, this equation cannot be treated as a consequence of the time-energy uncertainty relation.RiassuntoNel 1981 Caianiello ha mostrato che l’accelerazione massimale compare quando le considerazioni quantistiche, cioè le relazioni di incertezza posizione-momento, sono incorporate nella geometria di una particella nello spazio di fase a otto dimensioni. La relazione d’incertezza tempo-energia è stata usata successivamente da Caianiello in una derivazione alternativa di accelerazione massimale. La derivazione alternativa, data nel 1984, è stata poi criticata da Sharma e Srirankanathan. Qui si mostra che tale critica è infondata. Si analizza anche la derivazione del 1984 di Caianiello. Si trova che, mentre l’accelerazione massimale segue da un’equazione dovuta a Landau e Lifshitz, questa equazione non può essere trattata come una conseguenza della relazione d’incertezza tempo-energia.РезюмеВ 1981 г. Каянелло показвл, что возникает максимальное ускорение, когда квантовое рассмотрение, а именно соотношения неопределенностей между координатами и импульсами, включается в геометрию частицы в восьмимерном фазовом пространстве. Соотношение неопределенностей между временем и энергией использовалось позднее Каянелло в альтернативном выводе максимального ускорения. Этот альтернативный вывод, проведенный в 1984 г., был подвергнут критике в работе Шарма и Шриранканатана. В этой работе показывается, что эта критика необоснована, Также анализируется вывод Каянелло, проведенный в 1984 г. Получено, что хотя максимальное ускорение следует из уравнения Ландау и Лифшица, это уравнение не может может рассматриваться как следствие соотношения неопределенностей между временем и энергией.

Parity and time reversal in the spin-rotation interaction

Department of Physics, University of Regina, Regina, Saskatchewan, Canada S4S 0A2and International Institute for Advanced Scientific Studies, 84019 Vietri sul Mare (Sa), Italy~Received 6 November 2001; published 14 March 2002!A recently reported discrepancy between experimental and theoretical values of the muon’s g22 factor isinterpreted as due to small violations of the conservation of P and T in the spin-rotation coupling. Theexperiments place an upper limit on these violations and on the weight change of spinning gyroscopes.DOI: 10.1103/PhysRevD.65.077901 PACS number~s!: 11.30.Er, 04.20.Cv, 04.80.2y, 13.40.Em

MAXIMAL ACCELERATION CORRECTIONS TO THE LAMB SHIFT OF HYDROGEN, DEUTERIUM AND HE+

Abstract The maximal acceleration corrections to the Lamb shift of one-electron atoms are calculated in a nonrelativistic approximation. They are compatible with experimental results, are in particularly good agreement with the 2 S 2 P Lamb shift in hydrogen and reduce by ∼ 50% the experiment-theory discrepancy for the 2 S 2 P shift in He + .

Can Gravity Distinguish between Dirac and Majorana Neutrinos

We show that spin-gravity interaction can distinguish between Dirac and Majorana neutrino wave packets propagating in a Lense-Thirring background. Using time-independent perturbation theory and the gravitational phase to generate a perturbation Hamiltonian with spin-gravity coupling, we show that the associated matrix element for the Majorana neutrino differs significantly from its Dirac counterpart. This difference can be demonstrated through significant gravitational corrections to the neutrino oscillation length for a two-flavor system, as shown explicitly for SN 1987A.

A dynamical symmetry breaking model in Weyl space

The dynamical process following the breaking of Weyl geometry to Riemannian geometry is considered by studying the motion of de Sitter bubbles in a Weyl vacuum. The bubbles are given in terms of an exact, spherically symmetric thin shell solution to the Einstein equations in a Weyl–Dirac theory with a time-dependent scalar field of the form β=f(t)/r. The dynamical solutions obtained lead to a number of possible applications. An important feature of the thin shell model is the manner in which β provides a connection between the interior and exterior geometries since information about the exterior geometry is contained in the boundary conditions for β.

Maximal acceleration of thin shells in Weyl space

Abstract It is shown that maximal acceleration, which arises in various theories when aspects of quantum mechanics are taken into account, also arises in a geometric causal approach to quantum mechanics in which a particle is represented by a bubble in Weyl space. This result supports the hypothesis that quantum effects can be given a spacetime description.