Encontrados 7 documentos, a visualizar página 1 de 1
Dispersion and uncertainty in multislit matter wave diffraction
Glionna, G.; Blin, A. H.; Hiller, B.; Nemes, M. C.; Sampaio, Marcos; Piza, A. F. R. de ToledoWe show that single and multislit experiments involving matter waves may be constructed to assess dispersively generated correlations between the position and momentum of a single free particle. These correlations give rise to position dependent phases which develop dynamically as a result of dispersion and may play an important role in the interference patterns. To the extent that initial transverse coherence ...
Thouless theorem for one and two degrees of freedom
Magalhães,A.R. Bosco de; Fonseca,C.H. d'Àvila; Nemes,M.C.We perform an accessible demonstration of Thouless theorem for systems of one and two degrees of freedom, using only elementary quantum mechanics. This theorem is specially useful to ¯nd the vacuum of a transformed set of bosonic operators. A further motivation comes from experiments involving few trapped ions or ¯elds in cavity quantum electrodynamics, usually modelled by few linearly interacting oscillators.
The role of hidden ambiguities in the linear sigma model with fermions
Hiller, Brigitte; Mota, A. L.; Nemes, M. C.; Osipov, Alexander A.; Sampaio, MarcosThe UL(3)×UR(3) linear sigma model (LSM) with quark degrees of freedom is used to show that radiative corrections generate undetermined finite contributions. Their origin is related to surface terms which are differences between divergent integrals with the same degree of divergence. The technique used to detect these ambiguities is an implicit regularization on basic divergent integrals that do not depend on e...
Mass scales and their relations in symmetric quantum field theory
Gobira,S. R.; Nemes,M. C.We illustrate the importance of mass scales and their relation in the specific case of the linear sigma model within the context of its one loop Ward identities. In the calculation it becomes apparent the delicate and essential connection between divergent and finite parts of amplitudes. The examples show how to use mass scales identities which are absolutely necessary to manipulate graphs involving several mas...
Ambiguities and symmetry relations in the perturbative solution of Quantum Elec...
Gobira,S. R.; Battistel,O. A.; Nemes,M. C.We show that ambiguities and symmetry violations arising in one loop calculations can always be avoided provided the regularization scheme employed satisfies three consistency conditions. Our calculations are effected by assuming only implicitly the presence of a regulator in the integrand. We demonstrate in this way that there is a set of three relations involving divergent integrals of the same degree of dive...
Testing a new strategy to treat divergent amplitudes in QED
Scarpelli,A. P. Baêta; Battistel,O. A.; Nemes,M. C.We analyse a new strategy to manipulate and calculate divergent amplitudes in the context of Quantum Electrodynamics. We compare our results with results of Dimensional Regularization and (one parameter) Pauli-Villars regularization prescriptions and conclude that the present technique allows for an unambiguous determination of the physical content of the divergent amplitude. The results obtained for QED can be...
Finite Temperature Effects in the NonintegrableSU(3) Lipkin Model
Terra, M. O.; Nemes, M. C.; Providência, C. da; Providência, J. daIn the present work we use nonrelativistic many body physics techniques to generalize the classical limit of quantum systems in such a way as to incorporate statistical mixtures. Finite temperature effects are thus incorporated in a natural way. We give a detailed account of the thermodynamics of theSU(3) Lipkin model and then derive the classical thermal (chaotic) dynamics of the system. The most remarkable fe...
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