6,855 research outputs found
Dynamics of electromagnetic waves in Kerr geometry
Here we are interested to study the spin-1 particle i.e., electro-magnetic
wave in curved space-time, say around black hole. After separating the
equations into radial and angular parts, writing them according to the black
hole geometry, say, Kerr black hole we solve them analytically. Finally we
produce complete solution of the spin-1 particles around a rotating black hole
namely in Kerr geometry. Obviously there is coupling between spin of the
electro-magnetic wave and that of black hole when particles propagate in that
space-time. So the solution will be depending on that coupling strength. This
solution may be useful to study different other problems where the analytical
results are needed. Also the results may be useful in some astrophysical
contexts.Comment: 15 Latex pages, 4 Figures; Accepted for publication in Classical and
Quantum Gravit
Stochastically driven instability in rotating shear flows
Origin of hydrodynamic turbulence in rotating shear flows is investigated. The particular emphasis is on flows whose angular velocities decrease but specific angular momenta increase with increasing radial coordinate. Such flows are Rayleigh stable, but must be turbulent in order to explain observed data. Such a mismatch between the linear theory and observations/experiments is more severe when any hydromagnetic/magnetohydrodynamic instability and the corresponding turbulence therein is ruled out. The present work explores the effect of stochastic noise on such hydrodynamic flows. We focus on a small section of such a flow which is essentially a plane shear flow supplemented by the Coriolis effect. This also mimics a small section of an astrophysical accretion disk. It is found that such stochastically driven flows exhibit large temporal and spatial correlations of perturbation velocities, and hence large energy dissipations, that presumably generate instability. A range of angular velocity profiles (for the steady flow), starting with the constant angular momentum to that of the constant circular velocity are explored. It is shown that the growth and roughness exponents calculated from the contour (envelope) of the perturbed flows are all identical, revealing a unique universality class for the stochastically forced hydrodynamics of rotating shear flows. This work, to the best of our knowledge, is the first attempt to understand origin of instability and turbulence in the three-dimensional Rayleigh stable rotating shear flows by introducing additive stochastic noise to the underlying linearized governing equations. This has important implications in resolving the turbulence problem in astrophysical hydrodynamic flows such as accretion disks
Interplay of IR-Improved DGLAP-CS Theory and NLO Parton Shower MC Precision
We present the interplay between the new IR-improved DGLAP-CS theory and the
precision of NLO parton shower/ME matched MC`s as it is realized by the new MC
Herwiri1.031 in interface to MC@NLO. We discuss phenomenological implications
using comparisons with recent LHC data on single heavy gauge boson production.Comment: 8 pages, 4 figures; presented by BFLW at ICHEP 201
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