15,225 research outputs found
Drell-Hearn-Gerasimov Sum Rule for the Nucleon in the Large-N_c Limit
We show that the Drell-Hearn-Gerasimov sum rule for the nucleon is entirely
saturated by the \Delta resonance in the limit of a large number of colors, N_c
\to \infty. Corrections are at relative order 1/N_c^2.Comment: 6 pages, latex, no figure
Determination of flavor asymmetry for by the Drell-Yan process
Flavor asymmetries for the valence and sea quarks of the can
be obtained from Drell-Yan experiments using charged hyperon beams on proton
and deuteron targets. A large, measurable difference in sea quark asymmetries
is predicted between SU(3) and pseudoscalar meson models. The latter predict
that in , , whereas the former predict
. Estimates of valence quark asymmetries based on
quark models also show large deviations from SU(3) predictions, which should be
measurable.Comment: 15 pages, latex. Figures available from [email protected].
To be published in Phys. Lett.
A vicinal surface model for epitaxial growth with logarithmic free energy
We study a continuum model for solid films that arises from the modeling of
one-dimensional step flows on a vicinal surface in the
attachment-detachment-limited regime. The resulting nonlinear partial
differential equation, , gives the evolution
for the surface slope as a function of the local height in a monotone
step train. Subject to periodic boundary conditions and positive initial
conditions, we prove the existence, uniqueness and positivity of global strong
solutions to this PDE using two Lyapunov energy functions. The long time
behavior of converging to a constant that only depends on the initial data
is also investigated both analytically and numerically.Comment: 18 pages, 7 figure
Generalized Parton Distributions and Transversity in Nucleons and Nuclei
We present an exploratory study using generalized parton distributions of
several observables related to transverse degrees of freedom in hadronic
structure -- the nucleon transverse momentum, the transverse radius, or impact
parameter, and the momentum transfer, , dependence of the longitudinal
variable -- in both nucleons and nuclei.Comment: 6 pages, 3 figures, Talk presented at "Baryons 04", October
25th-30th, 2004, Palaiseau, Franc
Effect of assortative mixing in the second-order Kuramoto model
In this paper we analyze the second-order Kuramoto model presenting a
positive correlation between the heterogeneity of the connections and the
natural frequencies in scale-free networks. We numerically show that
discontinuous transitions emerge not just in disassortative but also in
assortative networks, in contrast with the first-order model. We also find that
the effect of assortativity on network synchronization can be compensated by
adjusting the phase damping. Our results show that it is possible to control
collective behavior of damped Kuramoto oscillators by tuning the network
structure or by adjusting the dissipation related to the phases movement.Comment: 7 pages, 6 figures. In press in Physical Review
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