34,798 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
Charm mass corrections to the bottomonium mass spectrum
The one-loop corrections to the bottomonium mass spectrum due to the finite
charm mass are evaluated in the framework of the relativistic quark model. The
obtained corrections are compared with the results of perturbative QCD.Comment: 6 pages, references added, version to be published in Phys. Rev.
Masses of heavy tetraquarks in the relativistic quark model
The masses of heavy tetraquarks with hidden charm and bottom are calculated
in the framework of the relativistic quark model. The tetraquark is considered
as the bound state of a heavy-light diquark and antidiquark. The light quark in
a heavy-light diquark is treated completely relativistically. The internal
structure of the diquark is taken into account by calculating the diquark-gluon
form factor in terms of the diquark wave functions. New experimental data on
charmonium-like states above open charm threshold are discussed. The obtained
results indicate that the X(3872) can be the tetraquark state with hidden
charm. The masses of ground state tetraquarks with hidden bottom are found to
be below the open bottom threshold.Comment: 10 pages, 1 figure, minor changes, version to be published in
Phys.Lett.
Radiative M1-decays of heavy-light mesons in the relativistic quark model
Radiative magnetic dipole decays of heavy-light vector mesons into
pseudoscalar mesons V -> P\gamma are considered within the relativistic quark
model. The light quark is treated completely relativistically, while for the
heavy quark the 1/m_Q expansion is used. It is found that relativistic effects
result in a significant reduction of decay rates. Comparison with previous
predictions and recent experimental data is presented.Comment: 11 pages, 2 figures, few comments added, version to appear in Phys.
Lett.
Excited heavy tetraquarks with hidden charm
The masses of the excited heavy tetraquarks with hidden charm are calculated
within the relativistic diquark-antidiquark picture. The dynamics of the light
quark in a heavy-light diquark is treated completely relativistically. The
diquark structure is taken into account by calculating the diquark-gluon form
factor. New experimental data on charmonium-like states above open charm
threshold are discussed. The obtained results indicate that X(3872), Y(4260),
Y(4360), Z(4248), Z(4433) and Y(4660) could be tetraquark states with hidden
charm.Comment: 11 page
Relativistic description of the charmonium mass spectrum
The charmonium mass spectrum is considered in the framework of the
constituent quark model with the relativistic treatment of the c quark. The
obtained masses are in good agreement with the existing experimental data
including the mass of eta_c(2S).Comment: 5 page
The two definitions of the index difference
Given two metrics of positive scalar curvature metrics on a closed spin
manifold, there is a secondary index invariant in real -theory. There exist
two definitions of this invariant, one of homotopical flavour, the other one
defined by a index problem of Atiyah-Patodi-Singer type. We give a complete and
detailed proof of the folklore result that both constructions yield the same
answer. Moreover, we generalize this to the case of two families of positive
scalar curvature metrics, parametrized by a compact space. In essence, we prove
a generalization of the classical "spectral-flow-index theorem" to the case of
families of real operators.Comment: Revised versio
An alternative construction of B-M and B-T unitals in Desarguesian planes
We present a new construction of non-classical unitals from a classical
unital in . The resulting non-classical unitals are B-M unitals.
The idea is to find a non-standard model of with the
following three properties: 1. points of are those of ; 2.
lines of are certain lines and conics of ; 3. the points in
form a non-classical B-M unital in .
Our construction also works for the B-T unital, provided that conics are
replaced by certain algebraic curves of higher degree.Comment: Keywords: unital, desarguesian plane 11 pages; ISSN: 0012-365
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