482,289 research outputs found
Decay width of process in a chiral constituent quark model
The width of three-body single-pion decay process is
calculated by using the wave function obtained from our chiral SU(3)
constituent quark model calculation. The effect of the dynamical structure on
the width of is taken into account in both the single
channel and coupled two-channel approximations. Our numerical
result shows that in the coupled-channel approximation, namely, the
hidden-color configuration being considered, the obtained partial decay width
of is about several hundred , while in the single
channel it is just about . We, therefore,
conclude that the partial width in the single-pion decay process of is
much smaller than the widths in its double-pion decay processes. Our prediction
may provide a criterion for judging different interpretations of the
structure, as different pictures for the may result quite different
partial decay width.Comment: 6 pages, 1 figure, and 1 table, typos correcte
Haldane, Large-D and Intermediate-D States in an S=2 Quantum Spin Chain with On-Site and XXZ Anisotropies
Using mainly numerical methods, we investigate the ground-state phase diagram
of the S=2 quantum spin chain described by , where
denotes the anisotropy parameter of the nearest-neighbor interactions and
the on-site anisotropy parameter. We restrict ourselves to the case with
and for simplicity. Each of the phase boundary lines
is determined by the level spectroscopy or the phenomenological renormalization
analysis of numerical results of exact-diagonalization calculations. The
resulting phase diagram on the - plane consists of four phases; the
XY 1 phase, the Haldane/large- phase, the intermediate- phase and the
N\'eel phase. The remarkable natures of the phase diagram are: (1) the Haldane
state and the large- state belong to the same phase; (2) there exists the
intermediate- phase which was predicted by Oshikawa in 1992; (3) the shape
of the phase diagram on the - plane is different from that believed
so far. We note that this is the first report of the observation of the
intermediate- phase
Electroproduction of the d* dibaryon
The unpolarized cross section for the electroproduction of the isoscalar
di-delta dibaryon is calculated for deuteron target using a
simple picture of elastic electron-baryon scattering from the and the components of the deuteron. The calculated
differential cross section at the electron lab energy of 1 GeV has the value of
about 0.24 (0.05) nb/sr at the lab angle of 10 (30) for the
Bonn B potential when the dibaryon mass is taken to be 2.1 GeV. The cross
section decreases rapidly with increasing dibaryon mass. A large calculated
width of 40 MeV for combined with a small
experimental upper bound of 0.08 MeV for the decay width appears to have
excluded any low-mass model containing a significant admixture of the
configuration.Comment: 11 journal-style pages, 8 figure
On the role of confinement on solidification in pure materials and binary alloys
We use a phase-field model to study the effect of confinement on dendritic
growth, in a pure material solidifying in an undercooled melt, and in the
directional solidification of a dilute binary alloy. Specifically, we observe
the effect of varying the vertical domain extent () on tip selection,
by quantifying the dendrite tip velocity and curvature as a function of
, and other process parameters. As decreases, we find that the
operating state of the dendrite tips becomes significantly affected by the
presence of finite boundaries. For particular boundary conditions, we observe a
switching of the growth state from 3-D to 2-D at very small , in both
the pure material and alloy. We demonstrate that results from the alloy model
compare favorably with those from an experimental study investigating this
effect.Comment: 13 pages, 9 figures, 3 table
Reassessment of the Collins Mechanism for Single-spin Asymmetries and the behaviour of Delta d(x) at large x.
It is shown that the Collins mechanism explanation of the transverse
single-spin asymmetries in p^{\uparrow} p -> \pi X leads to a transversely
polarized d quark density Delta_T d(x) which violates the Soffer bound when one
uses several standard forms for the longitudinally polarized d quark density
Delta d(x) obtained from polarized deep inelastic scattering. Imposition of the
Soffer bound with these Delta d(x) yields results in hopeless disagreement with
the data. Remarkably, imposition of the Soffer bound, but using
parametrizations of Delta d(x) that respect the PQCD condition Delta q(x) /
q(x) -> 1 as x -> 1, leads to an excellent fit to most of the data. The
implications for the polarized DIS neutron longitudinal asymmetry A_1^n at
large x are dramatic.Comment: 13 pages, 11 figures, 1 table and 4 figures changed. Revised version
to appear in Phys. Rev.
Woolsack 1963 volume 1 number 1
Table of Contents:
Excessive Juvenile Detention by Richard L. Vaughn Judge of the Juvenile Court of San Diego County
Bambic ALSA President
Common Law Ramble by W.J. Miller Barrister-at-law
General Hickman : Some points about studying law
Editorial
Student Bar President’s corner by Jon Gudmunds
Phi Delta Phi
Phi Alpha Delta
Congressman UTT : Limited Test Ban Treaty
Tobacco on Trial : Guilty? by Milan L. Brandon, M. D.
Congressman Van Deerlin : Congressional Conflict of Interest Problem
Trusts and the Estate Owner by Paul L. Crosby Life Underwriter N.Y. Life Insurance Co.
Meet the Facultyhttps://digital.sandiego.edu/woolsack/1000/thumbnail.jp
Growth Index of DGP Model and Current Growth Rate Data
Recently, some efforts focus on differentiating dark energy and modified
gravity with the growth function . In the literature, it is useful
to parameterize the growth rate
with the growth index . In this note, we consider the general DGP model
with any . We confront the growth index of DGP model with currently
available growth rate data and find that the DGP model is still consistent with
it. This implies that more and better growth rate data are required to
distinguish between dark energy and modified gravity.Comment: 12 pages, 1 table, 2 figures, Latex2e; v2: discussions added, Phys.
Lett. B in press; v3: published versio
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