The Experts below are selected from a list of 230613 Experts worldwide ranked by ideXlab platform

Johannes Courtial - One of the best experts on this subject based on the ideXlab platform.

  • lorentz transformation and galileo transformation windows
    Proceedings of SPIE, 2014
    Co-Authors: Stephen Oxburgh, Norman Gray, M. Hendry, Johannes Courtial
    Abstract:

    We define Lorentz-transformation windows as windows that change the direction of transmitted Light Rays like a Lorentz transformation. Similarly, Galileo-transformation windows change the direction of transmitted Light Rays like a Galileo transformation. This Light-Ray-direction change distorts the scene seen through such a window in the same way in which the scene would be distorted in a photo taken with a camera moving through the scene. Lorentz-transformation windows can also undo the distortion of the scene when moving at relativistic velocity relative to it. For small angles between the direction of the Light Rays and the direction of the velocity, Galileo-transformation windows can be realised with relatively simple telescope windows, which consist of arRays of identical micro-telescopes.

  • generalized laws of refraction that can lead to wave optically forbidden Light Ray fields
    Journal of The Optical Society of America A-optics Image Science and Vision, 2012
    Co-Authors: Johannes Courtial, Tomas Tyc
    Abstract:

    The recent demonstration of a metamaterial phase hologram so thin that it can be classified as an interface in the effective-medium approximation [Science 334, 333 (2011)] has dramatically increased interest in generalized laws of refraction. Based on the fact that scalar wave optics allows only certain Light-Ray fields, we divide generalized laws of refraction into two categories. When applied to a planar cross section through any allowed Light-Ray field, the laws in the first category always result in a cross section through an allowed Light-Ray field again, whereas the laws in the second category can result in a cross section through a forbidden Light-Ray field.

  • tim a Ray tracing program for metatoy research and its dissemination
    Computer Physics Communications, 2012
    Co-Authors: Dean Lambert, Alasdair C Hamilton, George W A Constable, Harsh Snehanshu, Sharvil Talati, Johannes Courtial
    Abstract:

    TIM (The Interactive METATOY) is a Ray-tracing program specifically tailored towards our research in METATOYs, which are optical components that appear to be able to create wave-optically forbidden Light-Ray fields. For this reason, TIM possesses features not found in other Ray-tracing programs. TIM can either be used interactively or by modifying the openly available source code; in both cases, it can easily be run as an applet embedded in a web page. Here we describe the basic structure of TIMʼs source code and how to extend it, and we give examples of how we have used TIM in our own research.

  • experimental demonstration of Ray optical refraction with confocal lenslet arRays
    Optics Letters, 2010
    Co-Authors: Johannes Courtial, Blair C Kirkpatrick, Eric Logean, Toralf Scharf
    Abstract:

    We observe imaging through windows comprising pairs of confocal lenslet arRays that have different focal lengths but that are otherwise identical. Image space is stretched in the longitudinal direction only. Such windows are examples of METATOYs, optical components that can change Light-Ray direction in ways that appear wave-optically forbidden.

  • fermat s principle and the formal equivalence of local Light Ray rotation and refraction at the interface between homogeneous media with a complex refractive index ratio
    Optics Letters, 2009
    Co-Authors: Bhuvanesh Sundar, Alasdair C Hamilton, Johannes Courtial
    Abstract:

    We derive a formal description of local Light-Ray rotation in terms of complex refractive indices. We show that Fermat's principle holds, and we derive an extended Snell's law. The change in the angle of a Light Ray with respect to the normal of a refractive index interface is described by the modulus of the refractive index ratio; the rotation around the interface normal is described by the argument of the refractive index ratio.

V M Braun - One of the best experts on this subject based on the ideXlab platform.

  • three loop evolution equation for flavor nonsinglet operators in off forward kinematics
    Journal of High Energy Physics, 2017
    Co-Authors: V M Braun, A N Manashov, S Moch, M Strohmaier
    Abstract:

    Using the approach based on conformal symmetry we calculate the three-loop (NNLO) contribution to the evolution equation for flavor-nonsinglet leading twist operators in the MS scheme. The explicit expression for the three-loop kernel is derived for the corresponding Light-Ray operator in coordinate space. The expansion in local operators is performed and explicit results are given for the matrix of the anomalous dimensions for the operators up to seven covariant derivatives. The results are directly applicable to the renormalization of the pion Light-cone distribution amplitude and flavor-nonsinglet generalized parton distributions.

  • three loop evolution equation for flavor nonsinglet operators in off forward kinematics
    arXiv: High Energy Physics - Phenomenology, 2017
    Co-Authors: V M Braun, A N Manashov, S Moch, M Strohmaier
    Abstract:

    Using the approach based on conformal symmetry we calculate the three-loop (NNLO) contribution to the evolution equation for flavor-nonsinglet leading twist operators in the $\overline{\text{MS}}$ scheme. The explicit expression for the three-loop kernel is derived for the corresponding Light-Ray operator in coordinate space. The expansion in local operators is performed and explicit results are given for the matrix of the anomalous dimensions for the operators up to seven covariant derivatives. The results are directly applicable to the renormalization of the pion Light-cone distribution amplitude and flavor-nonsinglet generalized parton distributions.

  • conformal symmetry of the lange neubert evolution equation
    Physics Letters B, 2014
    Co-Authors: V M Braun, A N Manashov
    Abstract:

    The Lange–Neubert evolution equation describes the scale dependence of the wave function of a meson built of an infinitely heavy quark and Light antiquark at Light-like separations, which is the hydrogen atom problem of QCD. It has numerous applications to the studies of B -meson decays. We show that the kernel of this equation can be written in a remarkably compact form, as a logarithm of the generator of special conformal transformation in the Light-Ray direction. This representation allows one to study solutions of this equation in a very simple and mathematically consistent manner. Generalizing this result, we show that all heavy–Light evolution kernels that appear in the renormalization of higher-twist B -meson distribution amplitudes can be written in the same form.

A N Manashov - One of the best experts on this subject based on the ideXlab platform.

  • three loop evolution equation for flavor nonsinglet operators in off forward kinematics
    Journal of High Energy Physics, 2017
    Co-Authors: V M Braun, A N Manashov, S Moch, M Strohmaier
    Abstract:

    Using the approach based on conformal symmetry we calculate the three-loop (NNLO) contribution to the evolution equation for flavor-nonsinglet leading twist operators in the MS scheme. The explicit expression for the three-loop kernel is derived for the corresponding Light-Ray operator in coordinate space. The expansion in local operators is performed and explicit results are given for the matrix of the anomalous dimensions for the operators up to seven covariant derivatives. The results are directly applicable to the renormalization of the pion Light-cone distribution amplitude and flavor-nonsinglet generalized parton distributions.

  • three loop evolution equation for flavor nonsinglet operators in off forward kinematics
    arXiv: High Energy Physics - Phenomenology, 2017
    Co-Authors: V M Braun, A N Manashov, S Moch, M Strohmaier
    Abstract:

    Using the approach based on conformal symmetry we calculate the three-loop (NNLO) contribution to the evolution equation for flavor-nonsinglet leading twist operators in the $\overline{\text{MS}}$ scheme. The explicit expression for the three-loop kernel is derived for the corresponding Light-Ray operator in coordinate space. The expansion in local operators is performed and explicit results are given for the matrix of the anomalous dimensions for the operators up to seven covariant derivatives. The results are directly applicable to the renormalization of the pion Light-cone distribution amplitude and flavor-nonsinglet generalized parton distributions.

  • conformal symmetry of the lange neubert evolution equation
    Physics Letters B, 2014
    Co-Authors: V M Braun, A N Manashov
    Abstract:

    The Lange–Neubert evolution equation describes the scale dependence of the wave function of a meson built of an infinitely heavy quark and Light antiquark at Light-like separations, which is the hydrogen atom problem of QCD. It has numerous applications to the studies of B -meson decays. We show that the kernel of this equation can be written in a remarkably compact form, as a logarithm of the generator of special conformal transformation in the Light-Ray direction. This representation allows one to study solutions of this equation in a very simple and mathematically consistent manner. Generalizing this result, we show that all heavy–Light evolution kernels that appear in the renormalization of higher-twist B -meson distribution amplitudes can be written in the same form.

Hideyoshi Arakida - One of the best experts on this subject based on the ideXlab platform.

  • General Relativistic Aberration Equation and Measurable Angle of Light Ray in Kerr–de Sitter Spacetime
    'MDPI AG', 2021
    Co-Authors: Hideyoshi Arakida
    Abstract:

    As an extension of our previous paper, instead of the total deflection angle α, we will mainly focus on the discussion of measurable angle of the Light Ray ψP at the position of observer P in Kerr–de Sitter spacetime, which includes the cosmological constant Λ. We will investigate the contribution of the radial and transverse motion of the observer which are connected with radial velocity vr and transverse velocity bvϕ (b is the impact parameter) as well as the spin parameter a of the central object which induces the gravito-magnetic field or frame dragging and the cosmological constant Λ. The general relativistic aberration equation is employed to take into account the influence of motion of the observer on the measurable angle ψP. The measurable angle ψP derived in this paper can be applicable to the observer placed within the curved and finite-distance region in the spacetime. The equation of Light trajectory will be obtained in such a sense that the background is de Sitter spacetime instead of Minkowski one. As an example, supposing the cosmological gravitational lensing effect, we assume that the lens object is the typical galaxy and the observer is in motion with respect to the lensing object at a recession velocity vr=bvϕ=vH=H0D (where H0 is a Hubble constant and D means the distance between the observer and the lens object). The static terms O(Λbm,Λba) are basically comparable with the second order deflection term O(m2), and they are almost one order smaller that the Kerr deflection −4ma/b2. The velocity-dependent terms O(Λbmvr,Λbavr) for radial motion and O(Λb2mvϕ,Λb2avϕ) for transverse motion are at most two orders of magnitude smaller than the second order deflection O(m2). We also find that even when the radial and transverse velocity have the same sign, asymptotic behavior as ϕ approaches 0 is different from each other, and each diverges to opposite infinity

  • Application of time transfer function to McVittie spacetime: gravitational time delay and secular increase in astronomical unit
    General Relativity and Gravitation, 2011
    Co-Authors: Hideyoshi Arakida
    Abstract:

    We attempt to calculate the gravitational time delay in a time-dependent gravitational field, especially in McVittie spacetime, which can be considered as the spacetime around a gravitating body such as the Sun, embedded in the FLRW (Friedmann–Lemaître–Robertson–Walker) cosmological background metric. To this end, we adopt the time transfer function method proposed by Le Poncin-Lafitte et al. (Class Quantum Gravity 21:4463, 2004 ) and Teyssandier and Le Poncin-Lafitte (Class Quantum Gravity 25:145020, 2008 ), which is originally related to Synge’s world function Ω( x _ A , x _ B ) and enables to circumvent the integration of the null geodesic equation. We re-examine the global cosmological effect on Light propagation in the solar system. The round-trip time of a Light Ray/signal is given by the functions of not only the spacial coordinates but also the emission time or reception time of Light Ray/signal, which characterize the time-dependency of solutions. We also apply the obtained results to the secular increase in the astronomical unit, reported by Krasinsky and Brumberg (Celest Mech Dyn Astron 90:267, 2004 ), and we show that the leading order terms of the time-dependent component due to cosmological expansion is 9 orders of magnitude smaller than the observed value of d AU/ dt , i.e., 15 ± 4 (m/century). Therefore, it is not possible to explain the secular increase in the astronomical unit in terms of cosmological expansion.

  • application of time transfer function to mcvittie spacetime gravitational time delay and secular increase in astronomical unit
    arXiv: General Relativity and Quantum Cosmology, 2011
    Co-Authors: Hideyoshi Arakida
    Abstract:

    We attempt to calculate the gravitational time delay in a time-dependent gravitational field, especially in McVittie spacetime, which can be considered as the spacetime around a gravitating body such as the Sun, embedded in the FLRW (Friedmann-Lema\^itre-Robertson-Walker) cosmological background metric. To this end, we adopt the time transfer function method proposed by Le Poncin-Lafitte {\it et al.} (Class. Quant. Grav. 21:4463, 2004) and Teyssandier and Le Poncin-Lafitte (Class. Quant. Grav. 25:145020, 2008), which is originally related to Synge's world function $\Omega(x_A, x_B)$ and enables to circumvent the integration of the null geodesic equation. We re-examine the global cosmological effect on Light propagation in the solar system. The round-trip time of a Light Ray/signal is given by the functions of not only the spacial coordinates but also the emission time or reception time of Light Ray/signal, which characterize the time-dependency of solutions. We also apply the obtained results to the secular increase in the astronomical unit, reported by Krasinsky and Brumberg (Celest. Mech. Dyn. Astron. 90:267, 2004), and we show that the leading order terms of the time-dependent component due to cosmological expansion is 9 orders of magnitude smaller than the observed value of $d{\rm AU}/dt$, i.e., $15 \pm 4$ ~[m/century]. Therefore, it is not possible to explain the secular increase in the astronomical unit in terms of cosmological expansion.

M Strohmaier - One of the best experts on this subject based on the ideXlab platform.

  • three loop evolution equation for flavor nonsinglet operators in off forward kinematics
    Journal of High Energy Physics, 2017
    Co-Authors: V M Braun, A N Manashov, S Moch, M Strohmaier
    Abstract:

    Using the approach based on conformal symmetry we calculate the three-loop (NNLO) contribution to the evolution equation for flavor-nonsinglet leading twist operators in the MS scheme. The explicit expression for the three-loop kernel is derived for the corresponding Light-Ray operator in coordinate space. The expansion in local operators is performed and explicit results are given for the matrix of the anomalous dimensions for the operators up to seven covariant derivatives. The results are directly applicable to the renormalization of the pion Light-cone distribution amplitude and flavor-nonsinglet generalized parton distributions.

  • three loop evolution equation for flavor nonsinglet operators in off forward kinematics
    arXiv: High Energy Physics - Phenomenology, 2017
    Co-Authors: V M Braun, A N Manashov, S Moch, M Strohmaier
    Abstract:

    Using the approach based on conformal symmetry we calculate the three-loop (NNLO) contribution to the evolution equation for flavor-nonsinglet leading twist operators in the $\overline{\text{MS}}$ scheme. The explicit expression for the three-loop kernel is derived for the corresponding Light-Ray operator in coordinate space. The expansion in local operators is performed and explicit results are given for the matrix of the anomalous dimensions for the operators up to seven covariant derivatives. The results are directly applicable to the renormalization of the pion Light-cone distribution amplitude and flavor-nonsinglet generalized parton distributions.