10,270 research outputs found
Unification of SU(2)xU(1) Using a Generalized Covariant Derivative and U(3)
A generalization of the Yang-Mills covariant derivative, that uses both
vector and scalar fields and transforms as a 4-vector contracted with Dirac
matrices, is used to simplify and unify the Glashow-Weinberg-Salam model. Since
SU(3) assigns the wrong hypercharge to the Higgs boson, it is necessary to use
a special representation of U(3) to obtain all the correct quantum numbers. A
surplus gauge scalar boson emerges in the process, but it uncouples from all
other particles.Comment: 12 pages, no figures. To be published in Int. J. Mod. Phys.
The split-operator technique for the study of spinorial wavepacket dynamics
The split-operator technique for wave packet propagation in quantum systems
is expanded here to the case of propagating wave functions describing
Schr\"odinger particles, namely, charge carriers in semiconductor
nanostructures within the effective mass approximation, in the presence of
Zeeman effect, as well as of Rashba and Dresselhaus spin-orbit interactions. We
also demonstrate that simple modifications to the expanded technique allow us
to calculate the time evolution of wave packets describing Dirac particles,
which are relevant for the study of transport properties in graphene.Comment: 19 pages, 4 figure
Theoretical investigation of electron-hole complexes in anisotropic two-dimensional materials
Trions and biexcitons in anisotropic two-dimensional materials are
investigated within an effective mass theory. Explicit results are obtained for
phosphorene and arsenene, materials that share features such as a direct
quasi-particle gap and anisotropic conduction and valence bands. Trions are
predicted to have remarkably high binding energies and an elongated
electron-hole structure with a preference for alignment along the armchair
direction, where the effective masses are lower. We find that biexciton binding
energies are also notably large, especially for monolayer phosphorene, where
they are found to be twice as large as those for typical monolayer transition
metal dichalcogenides.Comment: 3 figures, 5 pages + Supplementary Material, accepted for publication
in Phys. Rev.
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