37,094 research outputs found

    Rolling in the Modulated Reheating Scenario

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    In the modulated reheating scenario, the field that drives inflation has a spatially varying decay rate, and the resulting inhomogeneous reheating process generates adiabatic perturbations. We examine the statistical properties of the density perturbations generated in this scenario. Unlike earlier analyses, we include the dynamics of the field that determines the inflaton decay rate. We show that the dynamics of this modulus field can significantly alter the amplitude of the power spectrum and the bispectrum, even if the modulus field has a simple potential and its effective mass is smaller than the Hubble rate. In some cases, the evolution of the modulus amplifies the non-Gaussianity of the perturbations to levels that are excluded by recent observations of the cosmic microwave background. Therefore, a proper treatment of the modulus dynamics is required to accurately calculate the statistical properties of the perturbations generated by modulated reheating.Comment: 27 pages, 11 figures: minor changes made to match version in JCA

    The spectrum of the growth rate of the tunnel number is infinite

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    In a previous paper Kobayashi and Rieck defined the growth rate of the tunnel number of a knot KK, a knot invariant that measures the asymptotic behavior of the tunnel number under iterated connected sum of KK. We denote the growth rate by \mbox{gr}_t(K). In this paper we construct, for any ϵ>0\epsilon > 0, a hyperbolic knots KS3K \subset S^{3} for which 1 - \epsilon < \mbox{gr}_t(K) < 1. This is the first proof that the spectrum of the growth rate of the tunnel number is infinite

    Equivalence principle in the new general relativity

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    We study the problem of whether the active gravitational mass of an isolated system is equal to the total energy in the tetrad theory of gravitation. The superpotential is derived using the gravitational Lagrangian which is invariant under parity operation, and applied to an exact spherically symmetric solution. Its associated energy is found equal to the gravitational mass. The field equation in vacuum is also solved at far distances under the assumption of spherical symmetry. Using the most general expression for parallel vector fields with spherical symmetry, we find that the equality between the gravitational mass and the energy is always true if the parameters of the theory a1a_1, a2a_2 and a3a_3 satisfy the condition, (a1+a2)(a14a3/9)0(a_1+ a_2) (a_1-4a_3/9)\neq0. In the two special cases where either (a1+a2)(a_1+a_2) or (a14a3/9)(a_1-4a_3/9) is vanishing, however, this equality is not satisfied for the solutions when some components of the parallel vector fields tend to zero as 1/r1/\sqrt{r} for large rr.Comment: 18 pages, LaTeX, published in Prog. Theor. Phys. 96 No.5 (1996

    Fano Resonance in a Quantum Wire with a Side-coupled Quantum Dot

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    We report a transport experiment on the Fano effect in a quantum connecting wire (QW) with a side-coupled quantum dot (QD). The Fano resonance occurs between the QD and the "T-shaped" junction in the wire, and the transport detects anti-resonance or forward scattered part of the wavefunction. While in this geometry it is more difficult to tune the shape of the resonance than in the previously reported Aharonov-Bohm-ring type interferometer, the resonance purely consists of the coherent part of transport. By utilizing this advantage, we have qualitatively explained the temperature dependence of the Fano effect by including the thermal broadening and the decoherence. We have also proven that this geometry can be a useful interferometer to measure the phase evolution of electrons at a QD.Comment: REVTEX, 6 pages including 5 figures, final versio

    Method and apparatus for measuring distance

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    The invention employs a continuous wave radar technique and apparatus which can be used as a distance measuring system in the presence of background clutter by utilizing small passive transponders. A first continuous electromagnetic wave signal S sub 1 at a first frequency f sub 1 is transmitted from a first location. A transponder carried by a target object positioned at a second (remote) location receives the transmitted signal, phase-coherently divides the f sub 1 frequency and its phase, and re-transmits the transmitted signal as a second continuous electromagnetic wave signal S sub 2 at a lower frequency f sub 2 which is a subharmonic of f sub 1. The re-transmitted signal is received at the first location where a measurement of the phase difference is made between the signals S sub 1 and S sub 2, such measuremnt being indicative of the distance between the first and second locations

    Superconductivity in an organic insulator at very high magnetic fields

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    We investigate by electrical transport the field-induced superconducting state (FISC) in the organic conductor λ\lambda-(BETS)2_2FeCl4_4. Below 4 K, antiferromagnetic-insulator, metallic, and eventually superconducting (FISC) ground states are observed with increasing in-plane magnetic field. The FISC state survives between 18 and 41 T, and can be interpreted in terms of the Jaccarino-Peter effect, where the external magnetic field {\em compensates} the exchange field of aligned Fe3+^{3+} ions. We further argue that the Fe3+^{3+} moments are essential to stabilize the resulting singlet, two-dimensional superconducting stateComment: 9 pages 3 figure

    Proton and neutron correlations in 10^{10}B

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    We investigate positive-parity states of 10^{10}B with the calculation of antisymmetrized molecular dynamics focusing on pnpn pair correlations. We discuss effects of the spin-orbit interaction on energy spectra and pnpn correlations of the JπT=11+0J^\pi T=1^+_10, =31+0=3^+_10, and 01+10^+_11 states. The 11+01^+_10 state has almost no energy gain of the spin-orbit interaction, whereas the 31+03^+_10 state gains the spin-orbit interaction energy largely to come down to the ground state. We interpret a part of the two-body spin-orbit interaction in the adopted effective interactions as a contribution of the genuine NNNNNN force, and find it to be essential for the level ordering of the 31+03^+_10 and 11+01^+_10 states in 10^{10}B. We also apply a 2α+pn2\alpha+pn model to discuss effects of the spin-orbit interaction on T=0T=0 and T=1T=1 pnpn pairs around the 2α\alpha core. In the spin-aligned JπT=3+0J^\pi T=3^+0 state, the spin-orbit interaction affects the (ST)=(10)(ST)=(10) pair attractively and keeps the pair close to the core, whereas, in the 1+01^+0 state, it gives a minor effect to the (ST)=(10)(ST)=(10) pair. In the 0+10^+1 state, the (ST)=(01)(ST)=(01) pair is somewhat dissociated by the spin-orbit interaction.Comment: 12 pages 9 figure

    Stability and Hermitian-Einstein metrics for vector bundles on framed manifolds

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    We adapt the notions of stability of holomorphic vector bundles in the sense of Mumford-Takemoto and Hermitian-Einstein metrics in holomorphic vector bundles for canonically polarized framed manifolds, i.e. compact complex manifolds X together with a smooth divisor D such that K_X \otimes [D] is ample. It turns out that the degree of a torsion-free coherent sheaf on X with respect to the polarization K_X \otimes [D] coincides with the degree with respect to the complete K\"ahler-Einstein metric g_{X \setminus D} on X \setminus D. For stable holomorphic vector bundles, we prove the existence of a Hermitian-Einstein metric with respect to g_{X \setminus D} and also the uniqueness in an adapted sense.Comment: 21 pages, International Journal of Mathematics (to appear

    Wolfenstein Parametrization Re-examined

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    The Wolfenstein parametrization of the 3×33\times 3 Kobayashi-Maskawa (KM) matrix VV is modified by keeping its unitarity up to the accuracy of O(λ6)O(\lambda^{6}). This modification can self-consistently lead to the off-diagonal asymmetry of VV: Vij2Vji2|V_{ij}|^{2}-|V_{ji}|^{2} = Zkϵijk Z\displaystyle\sum_{k}\epsilon^{~}_{ijk} with Z=A2λ6(12ρ)Z=\approx A^{2}\lambda^{6} (1-2\rho), which is comparable in magnitude with the Jarlskog parameter of CPCP violation JA2λ6ηJ\approx A^{2}\lambda^{6}\eta. We constrain the ranges of JJ and ZZ by using the current experimental data, and point out that the possibility of a symmetric KM matrix has almost been ruled out.Comment: 5 Latex pages including a figure; Two references are adde
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