364 research outputs found
Possible Molecular States of System and Y(4140)
The interpretation of Y(4140) as a molecule is studied
dynamically in the one boson exchange approach, where , and
exchange are included. Ten allowed states with
low spin parity are considered, we find that the , ,
, and configurations are most
tightly bound. We suggest the most favorable quantum numbers are
for Y(4140) as a molecule, however,
and can not be excluded. We propose to search for the
and partners in the and final
states, which is an important test of the molecular hypothesis of Y(4140) and
the reasonability of our model. The molecule is
deeply bound, experimental search in the channel at Tevatron
and LHC is suggested.Comment: 13 pages,2 figure
Pion propagation in the linear sigma model at finite temperature
We construct effective one-loop vertices and propagators in the linear sigma
model at finite temperature, satisfying the chiral Ward identities and thus
respecting chiral symmetry, treating the pion momentum, pion mass and
temperature as small compared to the sigma mass. We use these objects to
compute the two-loop pion self-energy. We find that the perturbative behavior
of physical quantities, such as the temperature dependence of the pion mass, is
well defined in this kinematical regime in terms of the parameter
m_pi^2/4pi^2f_pi^2 and show that an expansion in terms of this reproduces the
dispersion curve obtained by means of chiral perturbation theory at leading
order. The temperature dependence of the pion mass is such that the first and
second order corrections in the above parameter have the same sign. We also
study pion damping both in the elastic and inelastic channels to this order and
compute the mean free path and mean collision time for a pion traveling in the
medium before forming a sigma resonance and find a very good agreement with the
result from chiral perturbation theory when using a value for the sigma mass of
600 MeV.Comment: 18 pages, 11 figures, uses RevTeX and epsfig. Expanded conclusions,
added references. To appear in Phys. Rev.
Scalar meson dynamics in Chiral Perturbation Theory
A comparison of the linear sigma model (LM) and Chiral Perturbation
Theory (ChPT) predictions for pion and kaon dynamics is presented. Lowest and
next-to-leading order terms in the ChPT amplitudes are reproduced if one
restricts to scalar resonance exchange. Some low energy constants of the order
ChPT Lagrangian are fixed in terms of scalar meson masses. Present values
of these low energy constants are compatible with the LM dynamics. We
conclude that more accurate values would be most useful either to falsify the
LM or to show its capability to shed some light on the controversial
scalar physics.Comment: 9 pages, REVTeX 4.0. Final version accepted for publicatio
Beyond CP violation: hadronic physics at BaBar
I report on recent studies of hadronic physics performed by the BaBar
Collaboration. Emphasis is given to the measurement of the properties of newly
discovered charmed hadrons and to the searches for light and heavy pentaquarks.Comment: 14 pages, 20 postscript figues, contributed to the Proceedings of the
First APS Topical Group Meeting on Hadron Physics, Fermilab, Batavia, IL
(October 24-26, 2004
B->rho pi decays, resonant and nonresonant contributions
We point out that a new contribution to B decays to three pions is relevant
in explaining recent data from the CLEO and BABAR collaborations, in particular
the results on quasi-two-body decays via a rho meson. We also discuss the
relevance of these contribution to the measurement of CP violations.Comment: 5 pages, 2 figures, few references and minor comments adde
Chiral Lagrangian for strange hadronic matter
A generalized Lagrangian for the description of hadronic matter based on the
linear -model is proposed. Besides the baryon
octet, the spin-0 and spin-1 nonets, a gluon condensate associated with broken
scale invariance is incorporated. The observed values for the vacuum masses of
the baryons and mesons are reproduced. In mean-field approximation, vector and
scalar interactions yield a saturating nuclear equation of state. We discuss
the difficulties and possibilities to construct a chiral invariant baryon-meson
interaction that leads to a realistic equation of state. It is found that a
coupling of the strange condensate to nucleons is needed to describe the
hyperon potentials correctly. The effective baryon masses and the appearance of
an abnormal phase of nearly massless nucleons at high densities are examined. A
nonlinear realization of chiral symmetry is considered, to retain a Yukawa-type
baryon-meson interaction and to establish a connection to the Walecka-model.Comment: Revtex, submitted to Phys. Rev.
Radiative open charm decay of the Y(3940), Z(3930), X(4160) resonances
We determine the radiative decay amplitudes for decay into and , or and of some of the charmonium like
states classified as X,Y,Z resonances, plus some other hidden charm states
which are dynamically generated from the interaction of vector mesons with
charm. The mass distributions as a function of the or
invariant mass show a peculiar behavior as a consequence of
the nature of these states. The experimental search of these
magnitudes can shed light on the nature of these states.Comment: 18 pages, 9 figure
Study of f_0(980) and f_0(1500) from B_s \to f_0(980)\pi, f_0(1500)\pi Decays
In this paper, we analyze the scalar mesons and from
the decays within Perturbative
QCD approach. From the leading order calculations, we find that (a) in the
allowed mixing angle ranges, the branching ratio of is about , which is smaller than
that of (the difference is a few times even one
order); (b) the decay is better to distinguish
between the lowest lying state or the first excited state for ,
because the branching ratios for two scenarios have about one-order difference
in most of the mixing angle ranges; and (c) the direct CP asymmetries of for two scenarios also exists great difference. In
scenario II, the variation range of the value according to the mixing angle is very small, except for
the values corresponding to the mixing angles being near or
, while the variation range of in scenario I is very large. Compared with the future data for
the decay , it is ease to determine the nature
of the scalar meson .Comment: 16 pages, 3 figures, Revte
Structure of the axial-vector meson and the strong coupling constant with the light-cone QCD sum rules
In this article, we take the point of view that the charmed axial-vector
meson is the conventional meson and calculate the
strong coupling constant in the framework of the light-cone
QCD sum rules approach. The numerical values of strong coupling constants
and are very large, and support the
hadronic dressing mechanism. Just like the scalar mesons and
, the scalar meson and axial-vector meson
may have small kernels of the typical
meson size, the strong couplings to the hadronic channels (or the virtual
mesons loops) may result in smaller masses than the conventional
mesons in the constituent quark models, and enrich the pure states
with other components.Comment: 17 pages, 7 figures, revised version. In the first version, I take
the value in numerical calculation, in the
revised version, I take a small value , the
value of the strong coupling constant is also change
Long distance expansion for the NJL model with SU(3) and U_A(1) breaking
This work is a follow up of recent investigations, where we study the
implications of a generalized heat kernel expansion, constructed to incorporate
non-perturbatively the effects of a non-commutative quark mass matrix in a
fully covariant way at each order of the expansion. As underlying Lagrangian we
use the Nambu -- Jona-Lasinio model of QCD, with and
breaking, the latter generated by the 't Hooft flavour determinant interaction.
The associated bosonized Lagrangian is derived in leading stationary phase
approximation (SPA) and up to second order in the generalized heat kernel
expansion. Its symmetry breaking pattern is shown to have a complex structure,
involving all powers of the mesonic fields allowed by symmetry. The considered
Lagrangian yields a reliable playground for the study of the implications of
symmetry and vacuum structure on the mesonic spectra, which we evaluate for the
scalar and pseudoscalar meson nonets and compare with other approaches and
experiment.Comment: LaTeX, 30 pages, added discussions and references, title change,
version to appear in Nucl. Phys.
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