117,333 research outputs found
Generalized generating functional for mixed-representation Green’s functions: Coherent-state path integral representation
No full textDynamical generation of flavor vacuum and Lorentz invariance
No full textIn this paper we review dynamical generation of field mixing after chiral symmetry breaking. We also study the explicit form of Lorentz boosts transformations of flavor states in a two-flavor scalar model with field mixing. We find that Lorentz symmetry is spontaneously broken on flavor vacuum because of its dynamically generated condensate structure
Chiral symmetry-breaking schemes and dynamical generation of masses and field mixing
No full textIn this paper we review dynamical generation of field mixing after chiral symmetry breaking. We also study the explicit form of discrete transformations of flavor states in a two-flavor scalar model with field mixing. We find that CPT symmetry is spontaneously broken on flavor vacuum because of its dynamically generated condensate structure
Flavor neutrinos as unstable particles
No full textIn this paper we review flavor-energy uncertainty relations for neutrino oscillations in quantum field theory, putting in evidence the analogy with the case of unstable particles. Our study reveals that flavor neutrinos are intrinsically characterized by an energy distribution with a non-vanishing width. In the ultrarelativistic limit, the energy width is bounded from below by the inverse of the oscillation length, which plays the same role as the half-life for unstable particles
Equivalence principle violation at finite temperature in scalar-tensor gravity
No full textWe analyze possible violations of the equivalence principle in scalar-tensor gravity at finite temperature T. We first present an approach where the equivalence principle violation is achieved within the framework of quantum field theory. Then, we rely on an alternative approach first proposed by Gasperini, which leads to the same outcome obtained in the framework of quantum field theory (one-loop corrections) at finite T. Finally, we exhibit the application of the above formalism both to a generic diagonal metric, cast in spherical coordinates, and to the Brans-Dicke theory. In the last case, we show that it is possible to put a significant constraint on the free parameter of the theory by means of experimental bounds on the equivalence principle
Non-relativistic neutrinos and the weak equivalence principle apparent violation
No full textWe study the non-relativistic limit of Dirac equation for mixed neutrinos. We demonstrate that such a procedure inevitably leads to a redefinition of the inertial mass. This happens because, in contrast to the case when mixing is absent, the antiparticle sector contribution cannot be neglected for neutrinos with definite flavor. We then show that, when a gravitational interaction is switched on, in the weak-field approximation the mass parameter which couples to gravity (gravitational mass) does not undergo the same reformulation as the inertial mass, thus leading to an apparent breakdown of the weak equivalence principle
Tests of macrorealism in meson oscillation physics
No full textMacrorealism formalizes the seemingly intuitive notion that, in contrast with the principles of quantum mechanics, a physical system can be in a definite state at any given time and moreover its dynamical evolution is independent of the measurements performed on it. In this study, we carry out a comparative analysis between three-time Leggett-Garg-type inequalities and the conditions of no-signaling-in-time and arrow-of-time for macrorealism within the context of meson oscillations. Our findings indicate that, under given initial conditions, no violations of Leggett-Garg inequalities are observed. However, no-signaling-in-time conditions are found to be violated, thereby revealing the impossibility of applying a macrorealistic description to the physics of meson oscillations
Leggett-Garg inequalities in the quantum field theory of neutrino oscillations
No full textWe investigate Leggett-Garg inequalities for neutrino oscillations in the quantum field theoretical setting. We derive an exact flavor-mass uncertainty relation and prove that this uncertainty product yields an upper bound to the violation of the inequalities. The relation between temporal nonclassicality and quantum uncertainty real-izes the Luders upper bound to the violation of the Leggett-Garg inequalities in quantum field theory, analogous to the Tsirelson upper bound to the violation of the Bell inequalities. By studying the problem both in the exact field-theoretical setting and in the limiting quantum mechanical approximation, we show that on average the inequalities are violated more often and more strongly in quantum field theory than in quantum mechanics
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