6,745 research outputs found
The Role of CP violation in D0 anti-D0 Mixing
In current searches for D0 anti-D0 mixing, the time evolution of
``wrong-sign'' decays is used to distinguish between a potential mixing signal
and the dominant background from doubly-Cabibbo-suppressed decays. A term
proportional to in the expression for the time evolution is often
neglected in theoretical discussions and experimental analyses of these
processes. We emphasize that, in general, this term does not vanish even in the
case of CP invariance. Furthermore, CP invariance is likely to be violated if
the rate of D0 anti-D0 mixing is close to the experimental bound. The
consequence of either of these two facts is that the strongest existing
measured bound is not applicable for constraining New Physics.Comment: 14 pages, uuencoded gzip-compressed postscript (84 kB
Scale Dependent Dimension of Luminous Matter in the Universe
We present a geometrical model of the distribution of luminous matter in the
universe, derived from a very simple reaction-diffusion model of turbulent
phenomena. The apparent dimension of luminous matter, , depends linearly
on the logarithm of the scale under which the universe is viewed: , where is a correlation length.
Comparison with data from the SARS red-shift catalogue, and the LEDA database
provides a good fit with a correlation length Mpc. The
geometrical interpretation is clear: At small distances, the universe is
zero-dimensional and point-like. At distances of the order of 1 Mpc the
dimension is unity, indicating a filamentary, string-like structure; when
viewed at larger scales it gradually becomes 2-dimensional wall-like, and
finally, at and beyond the correlation length, it becomes uniform.Comment: 6 pages, 2 figure
Surface Brightness Gradients Produced by the Ring Waves of Star Formation
We compute surface brightness profiles of galactic disks for outwardly
propagating waves of star formation with a view to investigate the stellar
populations in ring galaxies. We consider two mechanisms which can create
outwardly propagating star forming rings in a purely gaseous disk --- a
self-induced wave and a density wave. We show that the surface brightness
profiles produced by both scenarios of ring formation are similar and are
strongly sensitive to the velocity of the wave. The results of our computations
are compared with the observational quantities sensitive to the young and old
stellar populations in the ring galaxies A0035-335 (the Cartwheel galaxy) and
VIIZw466. The best fit to the observed radial H_alpha surface brightness
distribution in the Cartwheel galaxy is obtained for a wave velocity of about
90 km/s. The red continuum brightness of the ring can be fully explained by the
evolving stars present in the trailing part of the wave. However the red
continuum brightness in regions internal to the ring indicates that the wave of
star formation propagates in a pre-existing stellar disk in the Cartwheel. The
H_alpha and K-band surface brightness profiles in VIIZw466 match the values
expected from stellar populations produced by a wave of star formation
propagating in a purely gaseous disk very well. We conclude that VIIZw466 is
probably experiencing the first event of star formation in the disk.Comment: Uses aas2pp4.sty and epsfig.sty, 15 pages To appear in Astrophysical
Journal, March 10, 199
Modification of Kawai model about the mixing of the pseudoscalar mesons
The Kawai model describing the glueball-quarkonia mixing is modified. The
mixing of , and is re-investigated based on
the modified Kawai model. The glueball-quarkonia content of the three states is
determined from a fit to the data of the electromagnetic decays involving
, . Some predictions about the electromagnetic decays
involving are presented.Comment: revtex 8 page
Lower bounds for several online variants of bin packing
We consider several previously studied online variants of bin packing and
prove new and improved lower bounds on the asymptotic competitive ratios for
them. For that, we use a method of fully adaptive constructions. In particular,
we improve the lower bound for the asymptotic competitive ratio of online
square packing significantly, raising it from roughly 1.68 to above 1.75.Comment: WAOA 201
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