236 research outputs found
Masses of light tetraquarks and scalar mesons in the relativistic quark model
Masses of the ground state light tetraquarks are dynamically calculated in
the framework of the relativistic diquark-antidiquark picture. The internal
structure of the diquark is taken into account by calculating the form factor
of the diquark-gluon interaction in terms of the overlap integral of the
diquark wave functions. It is found that scalar mesons with masses below 1 GeV:
f_0(600) (\sigma), K^*_0(800) (\kappa), f_0(980) and a_0(980) agree well with
the light tetraquark interpretation.Comment: 9 pages, Report-no adde
Weak decays of the B_c meson to charmonium and D mesons in the relativistic quark model
Semileptonic and nonleptonic decays of the B_c meson to charmonium and D
mesons are studied in the framework of the relativistic quark model. The decay
form factors are explicitly expressed through the overlap integrals of the
meson wave functions in the whole accessible kinematical range. The
relativistic meson wave functions are used for the calculation of the decay
rates. The obtained results are compared with the predictions of other
approaches.Comment: 27 pages, 17 figures, 1 figure and 1 reference added, version to
appear in Phys. Rev.
Pion condensation of quark matter in the static Einstein universe
In the framework of an extended Nambu--Jona-Lasinio model we are studying
pion condensation in quark matter with an asymmetric isospin composition in a
gravitational field of the static Einstein universe at finite temperature and
chemical potential. This particular choice of the gravitational field
configuration enables us to investigate phase transitions of the system with
exact consideration of the role of this field in the formation of quark and
pion condensates and to point out its influence on the phase portraits. We
demonstrate the effect of oscillations of the thermodynamic quantities as
functions of the curvature and also refer to a certain similarity between the
behavior of these quantities as functions of curvature and finite temperature.
Finally, the role of quantum fluctuations for spontaneous symmetry breaking in
the case of a finite volume of the universe is shortly discussed.Comment: RevTex4; 15 pages, 10 figure
Study of decays
We investigate the production of the novel -wave mesons and
, identified as and , in heavy
meson decays, respectively. With the heavy quark limit, we give our modelling
wave functions for the scalar meson . Based on the assumptions of
color transparency and factorization theorem, we estimate the branching ratios
of decays in terms of the obtained wave functions. Some
remarks on productions are also presented.Comment: 16 pages, 2 figures, Revtex4, to be published in Phys. Rev.
Matrix theory of gravitation
A new classical theory of gravitation within the framework of general
relativity is presented. It is based on a matrix formulation of
four-dimensional Riemann-spaces and uses no artificial fields or adjustable
parameters. The geometrical stress-energy tensor is derived from a matrix-trace
Lagrangian, which is not equivalent to the curvature scalar R. To enable a
direct comparison with the Einstein-theory a tetrad formalism is utilized,
which shows similarities to teleparallel gravitation theories, but uses complex
tetrads. Matrix theory might solve a 27-year-old, fundamental problem of those
theories (sec. 4.1). For the standard test cases (PPN scheme,
Schwarzschild-solution) no differences to the Einstein-theory are found.
However, the matrix theory exhibits novel, interesting vacuum solutions.Comment: 24 page
The semileptonic B->pi decay in a Constituent Quark-Meson model
We evaluate the form factors describing the exclusive decay B-> pi l nu by
using a Constituent Quark-Meson model based on an effective quark-meson
Lagrangian (CQM). The model allows for an expansion in the pion momenta and we
consider terms up to the first order in the pion field derivatives. We compute
the leading terms in the soft pion limit and consider corrections to this
limit.Comment: 6 pages, 3 figures, LaTeX (uses aps, epsf, revtex), formula 26
corrected, discussion enlarged, references updated and other minor change
Propagation and Structure of Planar Streamer Fronts
Streamers often constitute the first stage of dielectric breakdown in strong
electric fields: a nonlinear ionization wave transforms a non-ionized medium
into a weakly ionized nonequilibrium plasma. New understanding of this old
phenomenon can be gained through modern concepts of (interfacial) pattern
formation. As a first step towards an effective interface description, we
determine the front width, solve the selection problem for planar fronts and
calculate their properties. Our results are in good agreement with many
features of recent three-dimensional numerical simulations.
In the present long paper, you find the physics of the model and the
interfacial approach further explained. As a first ingredient of this approach,
we here analyze planar fronts, their profile and velocity. We encounter a
selection problem, recall some knowledge about such problems and apply it to
planar streamer fronts. We make analytical predictions on the selected front
profile and velocity and confirm them numerically.
(abbreviated abstract)Comment: 23 pages, revtex, 14 ps file
Dynamical stability of infinite homogeneous self-gravitating systems: application of the Nyquist method
We complete classical investigations concerning the dynamical stability of an
infinite homogeneous gaseous medium described by the Euler-Poisson system or an
infinite homogeneous stellar system described by the Vlasov-Poisson system
(Jeans problem). To determine the stability of an infinite homogeneous stellar
system with respect to a perturbation of wavenumber k, we apply the Nyquist
method. We first consider the case of single-humped distributions and show
that, for infinite homogeneous systems, the onset of instability is the same in
a stellar system and in the corresponding barotropic gas, contrary to the case
of inhomogeneous systems. We show that this result is true for any symmetric
single-humped velocity distribution, not only for the Maxwellian. If we
specialize on isothermal and polytropic distributions, analytical expressions
for the growth rate, damping rate and pulsation period of the perturbation can
be given. Then, we consider the Vlasov stability of symmetric and asymmetric
double-humped distributions (two-stream stellar systems) and determine the
stability diagrams depending on the degree of asymmetry. We compare these
results with the Euler stability of two self-gravitating gaseous streams.
Finally, we determine the corresponding stability diagrams in the case of
plasmas and compare the results with self-gravitating systems
Experimental Tests of Factorization in Charmless Non-Leptonic Two-Body B Decays
Using a theoretical framework based on the next-to-leading order QCD-improved
effective Hamiltonian and a factorization Ansatz for the hadronic matrix
elements of the four-quark operators, we reassess branching fractions in
two-body non-leptonic decays , involving the lowest lying
light pseudoscalar and vector mesons in the standard model. Using
the sensitivity of the decay rates on the effective number of colors, , as
a criterion of theoretical predictivity, we classify all the current-current
(tree) and penguin transitions in five different classes. The recently measured
charmless two-body decays and charge conjugates) are
dominated by the -stable QCD penguins (class-IV transitions) and their
estimates are consistent with data. The measured charmless and transition ,
on the other hand, belong to the penguin (class-V) and tree (class-III)
transitions. The class-V penguin transitions are in general more difficult to
predict. We propose a number of tests of the factorization framework in terms
of the ratios of branching ratios for some selected decays
involving light hadrons and , which depend only moderately on the
form factors. We also propose a set of measurements to determine the effective
coefficients of the current-current and QCD penguin operators. The potential
impact of decays on the CKM phenomenology is emphasized by
analyzing a number of decay rates in the factorization framework.Comment: 64 pages (LaTex) including 13 figures, requires epsfig.sty; submitted
to Phys. Rev.
Jovian Magnetospheric Injections Observed by the Hubble Space Telescope and Juno
peer reviewedWe compare Hubble Space Telescope observations of Jupiter's FUV auroras with contemporaneous conjugate Juno in situ observations in the equatorial middle magnetosphere of Jupiter. We show that bright patches on and equatorward of the main emission are associated with hot plasma injections driven by ongoing active magnetospheric convection. During the interval that Juno crossed the magnetic field lines threading the complex of auroral patches, a series of energetic particle injection signatures were observed, and immediately prior, the plasma data exhibited flux tube interchange events indicating ongoing convection. This presents the first direct evidence that auroral morphology previously termed “strong injections” is indeed a manifestation of magnetospheric injections, and that this morphology indicates that Jupiter's magnetosphere is undergoing an interval of active iogenic plasma outflow
- …