18,701 research outputs found
Electromagnetic Form Factors of Nucleons with QCD Constraints Sytematic Study of the Space and Time-like Regions
Elastic electromagnetic form factors of nucleons are investigated both for
the time-like and the space-like momentums under the condition that the QCD
constraints are satisfied asymptotically. The unsubtracted dispersion relation
with the superconvergence conditions are used as a realization of the QCD
conditions. The experimental data are analyzed by using the dispersion formula
and it is shown that the calculated form factors reproduce the experimental
data reasonably well.Comment: 14 page
Thermal noise in half infinite mirrors with non-uniform loss: a slab of excess loss in a half infinite mirror
We calculate the thermal noise in half-infinite mirrors containing a layer of
arbitrary thickness and depth made of excessively lossy material but with the
same elastic material properties as the substrate. For the special case of a
thin lossy layer on the surface of the mirror, the excess noise scales as the
ratio of the coating loss to the substrate loss and as the ratio of the coating
thickness to the laser beam spot size. Assuming a silica substrate with a loss
function of 3x10-8 the coating loss must be less than 3x10-5 for a 6 cm spot
size and a 7 micrometers thick coating to avoid increasing the spectral density
of displacement noise by more than 10%. A similar number is obtained for
sapphire test masses.Comment: Passed LSC (internal) review. Submitted to Phys. Rev. D. (5/2001)
Replacement: Minor typo in Eq. 17 correcte
Near-Solar-Circle Method for Determination of the Galactic Constants
We propose a method to determine the galactic constants R_0 (distance to the
Galactic Center) and V_0 (rotation velocity of the Sun) from measurements of
distances, radial velocities and proper motions of objects near the solar
circle. This is a modification of the solar-circle method to a more practical
observational method. We apply the method to determine R_0 using data from the
literature with known distances and radial velocities, and obtain R_0 = 7.54
+/- 0.77 kpc.Comment: 5 pages, 4 figures, accepted for PASJ (Vol. 63 No. 5
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