17 research outputs found
Gauge and Lorentz transformation placed on the same foundation
In this note we show that a "dynamical" interaction for arbitrary spin can be
constructed in a straightforward way if gauge and Lorentz transformations are
placed on the same foundation. As Lorentz transformations act on space-time
coordinates, gauge transformations are applied to the gauge field. Placing
these two transformations on the same ground means that all quantized field
like spin-1/2 and spin-3/2 spinors are functions not only of the coordinates
but also of the gauge field components. This change of perspective solves a
couple of problems occuring for higher spin fields like the loss of causality,
bad high-energy properties and the deviation of the gyromagnetic ratio from its
constant value g=2 for any spin, as caused by applying the minimal coupling.
Starting with a "dynamical" interaction, a non-minimal coupling can be derived
which is consistent with causality, the expectation for the gyromagnetic ratio,
and well-behaved for high energies. As a consequence, on this stage the
(elektromagnetic) gauge field has to be considered as classical field.
Therefore, standard quantum field theory cannot be applied. Despite this
inconvenience, such a common ground is consistent with an old dream of
physicists almost a century ago. Our approach, therefore, indicates a
straightforward way to realize this dream.Comment: 12 pages, no figures, published version. arXiv admin note:
substantial text overlap with arXiv:0908.376
Probing scalar particle and unparticle couplings in e+ e- -> t tbar with transversely polarized beams
In searching for indications of new physics scalar particle and unparticle
couplings in e^+ e^- \to t\bar t, we consider the role of transversely
polarized initial beams at e^+ e^- colliders. By using a general relativistic
spin density matrix formalism for describing the particles spin states, we find
analytical expressions for the squared amplitude of the process with t or \bar
t polarization measured, including the anomalous coupling contributions. Thanks
to the transversely polarized initial beams these contributions are first order
anomalous coupling corrections to the Standard Model (SM) contributions. We
present and analyse the main features of the SM and anomalous coupling
contributions. We show how differences between SM and anomalous coupling
contributions provide means to search for anomalous coupling manifestations at
future e^+ e^- linear colliders.Comment: 28 pages in LaTeX, including 7 encapsulated PostScript figures,
published versio
"Dynamical" non-minimal higher-spin interaction and gyromagnetic ratio
The field-dependent invariant representation
(the "dynamical" representation) of the Poincaré algebra
is considered as a dynamical principle in order to get a
corresponding "dynamical" electromagnetic coupling for higher
spins (). If in lower-spin (s=0,1/2) cases the
"dynamical" coupling is taken to coincide with the minimal
electromagnetic coupling, the higher-spin coupling is inevitably
non-minimal, containing a term linear in the field
strength tensor . This non-minimal coupling leads to g=2
Origin of Poor Cyclability in Li2NInSiO4 from First-Principles Calculations: Layer Exfoliation and Unstable Cycled Structure
Good cyclability is essential for the potential application of cathode materials. Here, we investigate the structural stability of two-dimensional (2D) Li-layered and three-dimensional (3D) structured polymorphs of Li 2FeSiO4 and Li2MnSiO4 using the density functional theory calculations. We find that all 2D Li-layered polymorphs of both materials are unstable upon full delithiation owing to layer exfoliation, which can lead to an amorphous structure. However, in contrast to the fact that the amorphization of Li2FeSiO4 can be prevented by the formation of the 3D cycled structure that is energetically stable, the 3D cycled structure of Li2MnSiO4 is found to be unstable during delithiationlithiation cycling. As a result, Li 2MnSiO4 easily undergoes amorphization and shows a poor cyclability.close2