263,756 research outputs found
(2317) meson production at RHIC
Production of (2317) mesons in relativistic heavy ion collisions at
RHIC is studied. Using the quark coalescence model, we first determine the
initial number of (2317) mesons produced during hadronization of
created quark-gluon plasma. The predicted (2317) abundance depends
sensitively on the quark structure of the (2317) meson. An
order-of-magnitude larger yield is obtained for a conventional two-quark than
for an exotic four-quark (2317) meson. To include the hadronic effect
on the (2317) meson yield, we have evaluated the absorption cross
sections of the (2317) meson by pion, rho, anti-kaon, and vector
anti-kaon in a phenomenological hadronic model. Taking into consideration the
absorption and production of (2317) mesons during the hadronic stage of
heavy ion collisions via a kinetic model, we find that the final yield of
(2317) mesons remains sensitive to its initial number produced from the
quark-gluon plasma, providing thus the possibility of studying the quark
structure of the (2317) meson and its production mechanism in
relativistic heavy ion collisions.Comment: 12 pages, 6 figure
Helium star evolutionary channel to super-Chandrasekhar mass type Ia supernovae
Recent discovery of several overluminous type Ia supernovae (SNe Ia)
indicates that the explosive masses of white dwarfs may significantly exceed
the canonical Chandrasekhar mass limit. Rapid differential rotation may support
these massive white dwarfs. Based on the single-degenerate scenario, and
assuming that the white dwarfs would differentially rotate when the accretion
rate , employing Eggleton's
stellar evolution code we have performed the numerical calculations for
1000 binary systems consisting of a He star and a CO white dwarf (WD). We
present the initial parameters in the orbital period - helium star mass plane
(for WD masses of and , respectively), which
lead to super-Chandrasekhar mass SNe Ia. Our results indicate that, for an
initial massive WD of , a large number of SNe Ia may result from
super-Chandrasekhar mass WDs, and the highest mass of the WD at the moment of
SNe Ia explosion is 1.81 , but very massive () WDs
cannot be formed. However, when the initial mass of WDs is , the
explosive masses of SNe Ia are nearly uniform, which is consistent with the
rareness of super-Chandrasekhar mass SNe Ia in observations.Comment: 6 pages, 7 figures, accepted for publication in Astronomy and
Astrophysic
Bound states of the Klein-Gordon equation for vector and scalar general Hulthen-type potentials in D-dimension
We solve the Klein-Gordon equation in any -dimension for the scalar and
vector general Hulth\'{e}n-type potentials with any by using an
approximation scheme for the centrifugal potential. Nikiforov-Uvarov method is
used in the calculations. We obtain the bound state energy eigenvalues and the
corresponding eigenfunctions of spin-zero particles in terms of Jacobi
polynomials. The eigenfunctions are physical and the energy eigenvalues are in
good agreement with those results obtained by other methods for D=1 and 3
dimensions. Our results are valid for value when and for any
value when and D=1 or 3. The % -wave () binding energies for
a particle of rest mass are calculated for the three lower-lying
states using pure vector and pure scalar potentials.Comment: 25 page
A meshless, integration-free, and boundary-only RBF technique
Based on the radial basis function (RBF), non-singular general solution and
dual reciprocity method (DRM), this paper presents an inherently meshless,
integration-free, boundary-only RBF collocation techniques for numerical
solution of various partial differential equation systems. The basic ideas
behind this methodology are very mathematically simple. In this study, the RBFs
are employed to approximate the inhomogeneous terms via the DRM, while
non-singular general solution leads to a boundary-only RBF formulation for
homogenous solution. The present scheme is named as the boundary knot method
(BKM) to differentiate it from the other numerical techniques. In particular,
due to the use of nonsingular general solutions rather than singular
fundamental solutions, the BKM is different from the method of fundamental
solution in that the former does no require the artificial boundary and results
in the symmetric system equations under certain conditions. The efficiency and
utility of this new technique are validated through a number of typical
numerical examples. Completeness concern of the BKM due to the only use of
non-singular part of complete fundamental solution is also discussed
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