36,214 research outputs found
Probing the Galaxy I. The galactic structure towards the galactic pole
Observations of (B-V) colour distributions towards the galactic poles are
compared with those obtained from synthetic colour-magnitude diagrams to
determine the major constituents in the disc and spheroid. The disc is
described with four stellar sub-populations: the young, intermediate, old, and
thick disc populations, which have respectively scale heights of 100 pc, 250
pc, 0.5 kpc, and 1.0 kpc. The spheroid is described with stellar contributions
from the bulge and halo. The bulge is not well constrained with the data
analyzed in this study. A non-flattened power-law describes the observed
distributions at fainter magnitudes better than a deprojected R^{1/4}-law.
Details about the age, metallicity, and normalizations are listed in Table 1.
The star counts and the colour distributions from the stars in the intermediate
fields towards the galactic anti-centre are well described with the stellar
populations mentioned above. Arguments are given that the actual solar offset
is about 15 pc north from the galactic plane.Comment: 11 pages TeX, 4 separate pages with additional figures, accepted for
publication in A&
Spinon-Holon binding in model
Using a phenomenological model, we discuss the consequences of spinon-holon
binding in the U(1) slave-boson approach to model. Within a small
( hole concentration) expansion, we show that spinon-holon binding produces
a pseudo-gap normal state with a segmented Fermi surface and the
superconducting state is formed by opening an "additional" d-wave gap on the
segmented Fermi surface. The d-wave gap merge with the pseudo-gap smoothly as
temperature . The quasi-particles in the superconducting state are
coupled to external electromagnetic field with a coupling constant of order
where , depending on the strength of the
effective spinon-holon binding potential.Comment: 9 pages, 3 figure
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