833 research outputs found
Illustrative Model for Parity Doubling of Energy Levels
A one-dimensional quantum mechanical model possessing mass gap, a gapless
excitation, and an approximate parity doubling of energy levels is constructed
basing on heuristic QCD-inspired arguments. The model may serve for
illustrative purposes in considering the related dynamical phenomena in
particle and nuclear physics.Comment: 8 pages, 1 figur
Relation between quark and gluon condensates from QCD sum rules
A new relation between -meson mass, weak -meson decay constant,
quark and gluon condensates is derived from the QCD sum rules. As a byproduct
an explanation for the dominance of -decay for the -meson
is proposed.Comment: 7 pages, submitted to Phys. Lett.
Towards understanding broad degeneracy in non-strange mesons
The spectroscopic regularities of modern empirical data on the non-strange
mesons up to 2.4 GeV can be summarized as a systematic clustering of states
near certain values of energy. It is getting evident that some unknown
X-symmetry triggers the phenomenon. We review the experimental status of this
symmetry and recent theoretical attempts put forward for explanation of broad
degeneracy.Comment: Brief review, 16 pages, 1 figur
A multiquark approach to excited hadrons and Regge trajectories
We propose a novel approach to construction of hadron spectroscopy. The case
of light nonstrange mesons is considered. By assumption, all such mesons above
1 GeV appear due to creation of constituent quark-antiquark pairs inside the pi
or rho (omega) mesons. These spin-singlet or triplet pairs dictate the quantum
numbers of formed resonance. The resulting classification of light mesons turns
out to be in a better agreement with the experimental observations than the
standard quark model classification. It is argued that the total energy of
quark components should be proportional to the hadron mass squared rather than
the linear mass. As a byproduct a certain relation expressing the constituent
quark mass via the gluon and quark condensate is put forward. We show that our
approach leads to an effective mass counting scheme for meson spectrum and
results in the linear Regge and radial Regge trajectories by construction. An
experimental observation of these trajectories might thus serve as an evidence
not for string but for multiquark structure of highly excited hadrons.Comment: 15 pages. arXiv admin note: substantial text overlap with
arXiv:1705.0189
A five-dimensional effective model for excited light mesons
In the usual holographic approach to QCD, the meson spectrum is generated due
to a non-trivial 5-dimensional background. We propose an alternative
5-dimensional scenario in which the spectrum emerges due to coupling to a
scalar field whose condensation is supposed to be dual to the formation of
gluon condensate and mimics the scale anomaly in QCD. The spectrum of model has
finite number of discrete states plus continuum and reveals a Regge-like
behavior in the strong coupling regime.Comment: 4 pages, to appear in the proceedings of MENU201
Note on relation between bottom-up holographic models and large-Nc QCD
We discuss a derivation of the quadratic in fields part of action of
bottom-up holographic models from some general properties of the large-Nc limit
in QCD.Comment: 12 pages, some mistakes in formulae are correcte
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