13,727 research outputs found
Non-Relativistic Limit of Dirac Equations in Gravitational Field and Quantum Effects of Gravity
Based on unified theory of electromagnetic interactions and gravitational
interactions, the non-relativistic limit of the equation of motion of a charged
Dirac particle in gravitational field is studied. From the Schrodinger equation
obtained from this non-relativistic limit, we could see that the classical
Newtonian gravitational potential appears as a part of the potential in the
Schrodinger equation, which can explain the gravitational phase effects found
in COW experiments. And because of this Newtonian gravitational potential, a
quantum particle in earth's gravitational field may form a gravitationally
bound quantized state, which had already been detected in experiments. Three
different kinds of phase effects related to gravitational interactions are
discussed in this paper, and these phase effects should be observable in some
astrophysical processes. Besides, there exists direct coupling between
gravitomagnetic field and quantum spin, radiation caused by this coupling can
be used to directly determine the gravitomagnetic field on the surface of a
star.Comment: 12 pages, no figur
Precursor problem and holographic mutual information
The recent proposal of Almheiri et al.http://arxiv.org/abs/1411.7041,
together with the Ryu-Takayanagi formula, implies the entanglement wedge
hypothesis for certain choices of boundary subregions. This fact is derived in
the pure AdS space. A similar conclusion holds in the presence of quantum
corrections, but in a more restricted domain of applicability. We also comment
on http://arxiv.org/abs/1601.05416 and some similarities and differences with
this workComment: 13 pages, 1 figur
Superconductivity Near a Quantum Critical Point in Ba(Fe,Co)2As2
We will examine the possible link between spin fluctuations and the
superconducting mechanism in the iron-based high temperature superconductor
Ba(Fe,Co)2As2 based on NMR and high pressure transport measurements.Comment: Invited paper to m2s-IX (2009
The effects of decision flexibility in the hierarchical investment decision process
Large institutional investors allocate their funds over a number of classes (e.g. equity, fixed income and real estate), various geographical regions and different industries. In practice, these allocation decisions are usually made in a hierarchical (top-down), consecutive way. At the higher decision level, the allocation is made on basis of benchmark portfolios (indexes). Such indexes are then set as targets for the lower levels. For example, at the top level the allocation decision is made on the basis of asset class benchmark indexes, on the second level the decisions are made on the basis of sector benchmark indexes, etc. Obviously, the lower levels have considerable flexibility to deviate from these targets. That is the reason why targets often come with limits on the maximally allowed deviation (or "tracking error") from these targets. The potential consequences of deviations from the benchmark portfolios have received very little attention in the literature. In this paper, we discuss and illustrate this influence. The lower level tracking errors with respect to the benchmark indexes propagate to the top level. As a result the risk-return characteristics of the actual aggregate portfolio will be different from those of the initial benchmark-based portfolio. We illustrate this effect for a two level process to allocate funds over individual US stocks and sectors. We show that the benchmark allocation approaches used in practice yield inferior solutions when compared to a non-hierarchical approach where full information about individual lower level investment opportunities is available. Our results reveal that even small deviations from the benchmark portfolios can cause large shifts in the top-level risk-return space. This implies that the incorporation of lower level information in the initial top-level decision process will lead to a different (possibly better) allocation.decision flexibility;multi-level decision process;porfolio management;tracking error analysis
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