62,847 research outputs found

    Empirical pricing kernels obtained from the UK index options market

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    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 5D5D Cosmological Models From Equation of State of Dark Energy

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    We consider a class of five-dimensional cosmological solutions which contains two arbitrary function μ(t)\mu(t) and ν(t)\nu(t). We found that the arbitrary function μ(t)\mu(t) contained in the solutions can be rewritten in terms of the redshift zz as a new arbitrary function f(z)f(z). We further showed that this new arbitrary function f(z)f(z) could be solved out for four known parameterized equations of state of dark energy. Then the 5D5D 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

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    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

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    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

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    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?

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    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 (MpsrM_{\rm psr}), mass of the planet (MplM_{\rm pl}) and orbital radius of the planet (rplr_{\rm pl}). Five aspects are considered: derived relation between MpsrM_{\rm psr} and rplr_{\rm pl}, movement of the pulsar around the center of mass, ratio of MpsrM_{\rm psr} and MplM_{\rm pl}, 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 (10−4∼10−1M⊙10^{-4}\sim10^{-1}M_{\odot}) with a quark planet (10−8∼10−3M⊙10^{-8}\sim10^{-3}M_{\odot}) 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

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    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 μ\mu and ν\nu 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

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    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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