2,226 research outputs found
Probing the quark-gluon interaction with hadrons
We present a unified picture of mesons and baryons in the
Dyson-Schwinger/Bethe-Salpeter approach, wherein the quark-gluon and
quark-(anti)quark interaction follow from a systematic truncation of the QCD
effective action and includes all its tensor structures.
The masses of some of the ground state mesons and baryons are found to be in
reasonable agreement with the expectations of a `quark-core calculation',
suggesting a partial insensitivity to the details of the quark-gluon
interaction. However, discrepancies remain in the meson sector, and for excited
baryons, that suggest higher order corrections are relevant and should be
investigated following the methods outlined herein.Comment: 6 pages, 5 figures, 3 tables. Version to appear in PL
Shannon Entropy as Characterization Tool in Acoustics
We introduce Shannon's information entropy to characterize the avoided
crossing appearing in the resonant Zener-like phenomenon in ultrasonic
superlattices made of two different fluidlike meta- materials. We show that
Shannon's entropy gives a correct physical insight of the localization effects
taking place and manifest the informational exchange of the involved acoustic
states in the narrow region of parameters where the avoided crossing occurs.
Results for ultrasonic structures consisting of alternating layers of
methyl-metacrylate and water cavities, in which the acoustic Zener effect were
recently demonstrated, are also reported.Comment: 4 pages, 5 figures. Submitted to Phys. Rev. Let
Hamiltonian Formulation of Palatini f(R) theories a la Brans-Dicke
We study the Hamiltonian formulation of f(R) theories of gravity both in
metric and in Palatini formalism using their classical equivalence with
Brans-Dicke theories with a non-trivial potential. The Palatini case, which
corresponds to the w=-3/2 Brans-Dicke theory, requires special attention
because of new constraints associated with the scalar field, which is
non-dynamical. We derive, compare, and discuss the constraints and evolution
equations for the ww=-3/2 and w\neq -3/2 cases. Based on the properties of the
constraint and evolution equations, we find that, contrary to certain claims in
the literature, the Cauchy problem for the w=-3/2 case is well-formulated and
there is no reason to believe that it is not well-posed in general.Comment: 17 pages, no figure
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