3,277 research outputs found
Lattice study on two-color QCD with six flavors of dynamical quarks
We study the dynamics of SU(2) gauge theory with NF=6 Dirac fermions by means
of lattice simulation to investigate if they are appropriate to realization of
electroweak symmetry breaking. The discrete analogue of beta function for the
running coupling constant defined under the Schroedinger functional boundary
condition are computed on the lattices up to linear size of L/a=24 and preclude
the existence of infrared fixed point below 7.6. Gluonic observables such as
heavy quark potential, string tension, Polyakov loop suggest that the target
system is in the confining phase even in the massless quark limit.Comment: 7 pages, 9 figures, Proceedings of The 30th International Symposium
on Lattice Field Theory, June 24-29, 2012, Cairns, Australi
Warped Compactification with a Four-Brane
Warped compactification of the six-dimensional bulk with a negative
cosmological constant is realized with a 4-brane along with an abelian gauge
theory. No fine tuning of couplings are needed to obtain the vanishing
cosmological constant in four dimensions, as is the case for the bulk with a
positive cosmological constant.Comment: 6 pages, late
Improvement in the performance of the X-ray source based on parametric X-ray radiation using a wedge-shaped target crystal
The properties of parametric X-ray radiation (PXR) emitted from a wedge-shaped Si(111) crystal plate were experimentally investigated using the PXR generator at the Laboratory for Electron Beam Research and Application (LEBRA) of Nihon University. The wedge surface was imposed on a symmetric-cut Si(111) plate and has an asymmetric cut-surface with respect to the (111) crystal planes. As a result of the experiment, it was found that the PXR intensity improved can be obtained suppressing the degradation of the X-ray performance using a wedgeshaped
target. With this improvement, phase-contrast images without absorption contrast could be obtained from DEI images taken with the exposure of severalten seconds. The reduction of the exposure time made it possible to carry out a computed tomography (CT) experiment by DEI within a practical machine time, and phase-contrast tomograms of a biological sample were obtained at the PXR energy of 17.5 keV
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