1,721,585 research outputs found
Neutrinos, mixed bosons, quantum reference frames and entanglement
No full textWe discuss the relevance of quantum reference frames in the description of mixed particle states. We show that the notion of a rest frame for mixed particles, which is classically ill-defined, can be introduced in the context of quantum frames. We discuss the possible implications, displaying a new form of frame-dependent entanglement that characterizes reactions involving mixed particles, and suggest a possible route to extract observables related to such an entanglement
Neutrino capture on tritium as a probe of flavor vacuum condensate and dark matter
Full text linkWe show that the study of neutrino capture on tritium, for non-relativistic neutrinos, can allow to distinguish among the various neutrino models, eventually prove the quantum field theory condensation effects and permit to test the hypothesis according to which the flavor vacuum energy gives a contribution to the dark matter of the universe. Indeed, we show that the capture rate depends on the neutrino model considered, and that it brings an imprint of the flavor vacuum condensate. Experiments like PTOLEMY, designed to reveal the cosmic neutrino background, then can give an indication of the existence of the dark matter component induced by neutrino mixing
Boson mixing and flavor vacuum in the expanding Universe: A possible candidate for the dark energy
Full text linkWe analyze the boson mixing in curved spacetime and compute the expectation value of the energy-momentum tensor of bosons on the flavor vacuum in spatially flat Friedmann-Lemaître-Robertson-Walker metrics. We show that the energy-momentum tensor of the flavor vacuum behaves as the effective energy-momentum tensor of a perfect fluid. Assuming a fixed de Sitter background, we show that the equation of state can assume values in the interval [−1,1], and, in the flat space-time limit has a value −1, which is the one of the dark energy. The results here presented show that vacuum of mixed bosons like neutrino super-partners, can represent a possible component of the dark energy of the Universe
Fermion condensates induced by axial interactions and cosmological implications
No full textWe reveal the presence of a new source of axial current due to the condensed vacuum generated by the spin-spin interaction. To show this, we consider a quartic Dirac Lagrangian containing a spin-spin interaction term, possibly originating from torsion in Einstein-Cartan-like theories. We use a mean field approach to analyze the quantized theory. We show that the diagonalization of the field Hamiltonian defines a new vacuum state, energetically favored with respect to the free vacuum. Such a vacuum, which is a condensate of particle-antiparticle pairs, is characterized by a nontrivial expectation value of the axial current operator. The new source of axial current, here obtained, can have effects both at the atomic level and at the astrophysical-cosmological level depending on the origin of the spin-spin interaction term. The condensate spontaneously breaks Lorentz symmetry, therefore it implies the possibility of CPT violation in the early universe. Furthermore the condensate induces a new source term in the gravitational field equations and may affect the dark sector of the Universe at cosmological level
A background independent notion of causality
No full textWe develop a notion of causal order on a generic manifold as independent of the underlying differential and topological structure. We show that sufficiently regular causal orders can be recovered from a distinguished algebra of sets, which plays a role analogous to that of topologies and sigma algebras. We then discuss how a natural notion of measure can be associated to the algebra of causal sets
Inquinamento e salute: il caso della contrada Martucci
No full textThe research highlights groundwater pollution spread over a certain area of Apulia which is of greatest importance for its agricultural activitie
L'associazione beclometasone-salbutamolo nelle sindromi broncospastiche sostenute da sequele di T.B.C. polmonare
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