62,847 research outputs found
Empirical pricing kernels obtained from the UK index options market
Empirical pricing kernels for the UK equity market are derived as the ratio between risk-neutral densities, inferred from FTSE 100 index options, and historical real-world densities, estimated from time series of the index. The kernels thus obtained are almost compatible with a risk averse representative agent, unlike similar estimates for the US market
Reconstruction of Cosmological Models From Equation of State of Dark Energy
We consider a class of five-dimensional cosmological solutions which contains
two arbitrary function and . We found that the arbitrary
function contained in the solutions can be rewritten in terms of the
redshift as a new arbitrary function . We further showed that this
new arbitrary function could be solved out for four known parameterized
equations of state of dark energy. Then the models can be reconstructed
and the evolution of the density and deceleration parameters of the universe
can be determined.Comment: 10 pages, 4 eps figures, ws-ijmpd.cls styl
Massive Overlap Fermions on Anisotropic Lattices
We formulate the massive overlap fermions on anisotropic lattices.
We find that the dispersion relation for the overlap fermion resembles the
continuum form in the low-momentum region once the bare parameters are properly
tuned. The quark self-energy and the quark field renormalization constants are
calculated to one-loop in bare lattice perturbation theory.
We argue that massive domain wall quarks might be helpful in lattice QCD
studies on heavy-light hadron spectroscopy.Comment: 21 pages, 5 figures, one reference added compared with v.
Control of fast electron propagation in foam target by high-Z doping
The influence of high-Z dopant (Bromine) in low-Z foam (polystyrene) target
on laser-driven fast electron propagation is studied by the 3D hybrid
particle-in-cell (PIC)/fluid code HEETS.It is found that the fast electrons are
better confined in doped targets due to the increasing resistivity of the
target, which induces a stronger resistive magnetic field which acts to
collimate the fast electron propagation.The energy deposition of fast electrons
into the background target is increased slightly in the doped target, which is
beneficial for applications requiring long distance propagation of fast
electrons, such as fast ignition
Radiation and Potential Barriers of a 5D Black String Solution
By using a massless scalar field we examine the effect of an extra dimension
on black hole radiation. Because the equations are coupled, we find that the
structure of the fifth dimension (as for membrane and induced-matter theory)
affects the nature of the radiation observed in four-dimensional spacetime. In
the case of the Schwarzschild-de Sitter solution embedded in a Randall-Sundrum
brane model, the extension of the black hole along the fifth dimension looks
like a black string. Then it is shown that, on the brane, the potential barrier
surrounding the black hole has a quantized as well as a continuous spectrum. In
principle, Hawking radiation may thus provide a probe for higher dimensions.Comment: 9 pages, 3 figures, accepted for publication on MPL
PSR B1828-11: a precession pulsar torqued by a quark planet?
The pulsar PSR B1828-11 has long-term, highly periodic and correlated
variations in both pulse shape and the rate of slow-down. This phenomenon may
provide evidence for precession of the pulsar as suggested previously within
the framework of free precession as well as forced one. On a presumption of
forced precession, we propose a quark planet model to this precession henomenon
instead, in which the pulsar is torqued by a quark planet. We construct this
model by constraining mass of the pulsar (), mass of the planet
() and orbital radius of the planet (). Five aspects
are considered: derived relation between and ,
movement of the pulsar around the center of mass, ratio of and
, gravitational wave radiation timescale of the planetary system,
and death-line criterion. We also calculate the range of precession period
derivative and gravitational wave strength (at earth) permitted by the model.
Under reasonable parameters, the observed phenomenon can be understood by a
pulsar () with a quark planet
() orbiting it. According to the calculations
presented, the pulsar would be a quark star because of its low mass, which
might eject a lump of quark matter (to become a planet around) during its
birth.Comment: 6 pages, 3 figures, accepted by MNRAS (Letters
Correspondence Between DGP Brane Cosmology and 5D Ricci-flat Cosmology
We discuss the correspondence between the DGP brane cosmology and 5D
Ricci-flat cosmology by letting their metrics equal each other. By this
correspondence, a specific geometrical property of the arbitrary integral
constant I in DGP metric is given and it is related to the curvature of 5D
bulk. At the same time, the relation of arbitrary functions and in
a class of Ricci-flat solutions is obtained from DGP brane metric.Comment: 8 pages, 1 figure, accepted by MPLA, added referenc
Pitch perception of focus and surprise in Mandarin Chinese: Evidence for parallel encoding via additive division of pitch range
This study addressed the question of how multiple layers of meanings can be simultaneously encoded with F0 in speech by assessing pitch perception thresholds of focus and surprise in Mandarin Chinese. We synthetically increased the pitch height of one syllable in a sentence up to 12 semitones from its neutral baseline in one-semitone steps, and asked listeners to judge the strength of focus and surprise conveyed by the manipulated utterances. Results showed that for the perception of focus, at least 4 semitones above the baseline were needed while for surprise, at least 7 semitones above were needed. Despite the threshold difference, there was a downward overlap of surprise with focus, i.e., the range of 7-12 semitones above the baseline signalled both focus and surprise. These results suggest that the pitch perception threshold for focus in Mandarin may be higher than that in non-tonal languages due to the use of F0 for lexical contrast in Mandarin. They also reveal, more intriguingly, an encoding mechanism of additive division of pitch range. That is, a higher-level function such as surprise is encoded by using additional pitch ranges beyond that used by lower-level functions such as focus and lexical tone, without harming the encoding of the lower-level functions
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