46 research outputs found
Holographic Hadro-Quarkonium
We consider the recently suggested model for some resonances near the open
charm threshold as bound states of charmonium inside excited light mesons. It
is argued in the soft-wall holographic model of QCD that such states of heavy
quarkonium necessarily exist at sufficiently large spin of the light meson. The
bound state is provided by the dilaton exchange through the 5D bulk. We also
argue that the decay of such bound systems into mesons with open heavy flavors
due to splitting of the heavy quarkonium can be treated as semiclassical
tunneling and is suppressed. This behavior is in agreement with the known
relative suppression of the decay of the discussed charmonium-like resonances
into channels with D mesons.Comment: 11 pages, 1 figur
Pionic transitions from X(3872) to chi_{cJ}
We consider transitions from the resonance X(3872) to the chi_{cJ} states of
charmonium with emission of one or two pions as a means of studying the
structure of the X resonance. We find that the relative rates for these
transitions to the final states with different J significantly depend on
whether the initial state is a pure charmonium state or a four-quark/molecular
state.Comment: 12 page
Possible new resonance at the threshold in annihilation
We argue that the recent CLEO-c data on annihilation into pairs of
charmed mesons at c.m. energy around 4.0 GeV are not well described by a single
resonance , but can be better understood if there is an additional
narrow resonance with mass within few MeV from the threshold.Comment: 9 pages, 1 figur
Hadro-Charmonium
We argue that relatively compact charmonium states, , ,
, can very likely be bound inside light hadronic matter, in particular
inside higher resonances made from light quarks and/or gluons. The charmonium
state in such binding essentially retains its properties, so that the bound
system decays into light mesons and the particular charmonium resonance. Thus
such bound states of a new type, which we call hadro-charmonium, may explain
the properties of some of the recently observed resonant peaks, in particular
of Y(4.26), Y(4.32-4.36), Y(4.66), and Z(4.43). We discuss further possible
implications of the suggested picture for the observed states and existence of
other states of hadro-charmonium and hadro-bottomonium.Comment: 4 pages, RevTe
Understanding the newly observed Y(4008) by Belle
Very recently a new enhancement around 4.05 GeV was observed by Belle
experiment. In this short note, we discuss some possible assignments for this
enhancement, i.e. and molecular state. In these two
assignments, Y(4008) can decay into with comparable
branching ratio with that of . Thus one suggests
high energy experimentalists to look for Y(4008) in channel.
Furthermore one proposes further experiments to search missing channel
, and especially and
, which will be helpful to distinguish and
molecular state assignments for this new enhancement.Comment: 4 pages, 5 figures. Typos correcte
No Sommerfeld resummation factor in e+e- -> ppbar ?
The Sommerfeld rescattering formula is compared to the e+e- -> ppbar BaBar
data at threshold and above. While there is the expected Coulomb enhancement at
threshold, two unexpected outcomes have been found: |G^p (4M_p^2)|= 1, like for
a pointlike fermion, and moreover data show that the resummation factor in the
Sommerfeld formula is not needed. Other e+e- -> baryon-antibaryon cross
sections show a similar behavior near threshold.Comment: 9 pages, 6 figure
Mass spectrum of the axial-vector hidden charmed and hidden bottom tetraquark states
In this article, we perform a systematic study of the mass spectrum of the
axial-vector hidden charmed and hidden bottom tetraquark states using the QCD
sum rules, and identify the as an axial-vector tetraquark state
tentatively.Comment: 24 pages, 38 figures, slight revisio
The Dipion Mass Spectrum In e+e- Annihilation and tau Decay: A Dynamical (rho0, omega, phi) Mixing Approach
We readdress the problem of finding a simultaneous description of the pion
form factor data in e+e- annihilations and in tau decays. For this purpose, we
work in the framework of the Hidden Local Symmetry (HLS) Lagrangian and modify
the vector meson mass term by including the pion and kaon loop contributions.
This leads us to define the physical rho, omega and phi fields as linear
combinations of their ideal partners, with coefficients being meromorphic
functions of s, the square of the 4--momentum flowing into the vector meson
lines. This allows us to define a dynamical, i.e. s-dependent, vector meson
mixing scheme. The model is overconstrained by extending the framework in order
to include the description of all meson radiative (V P gamma and P gamma gamma
couplings) and leptonic (Ve+e- couplings) decays and also the isospin breaking
(omega/ phi --> pi+ pi-) decay modes. The model provides a simultaneous,
consistent and good description of the e+e- and tau dipion spectra. The
expression for pion form factor in the latter case is derived from those in the
former case by switching off the isospin breaking effects specific to e+e- and
switching on those for tau decays. Besides, the model also provides a good
account of all decay modes of the form V P gamma, Pgamma gamma as well as the
isospin breaking decay modes. It leads us to propose new reference values for
the rho^0 --> e+ e- and omega --> pi+ pi- partial widths which are part of our
description of the pion form factor. Other topics (phi --> K anti K, the rho
meson mass and width parameters) are briefly discussed. Therefore, we confirm
the 3.3 sigma discrepancy between the theoretical estimate of a_mu based on
e+e- and its direct BNL measurement.Comment: 71 pages, 8 figures. Accepted by EPJ C. Version 3: correct minor
typos, minor changes spread out into the text. Extension of Sections 12.2 and
12.3.5 and introduction of the new Appendix