1,619 research outputs found
Spectroscopy of the All-Charm Tetraquark
We use a non-relativistic model to study the mass spectroscopy of a
tetraquark composed by quarks in the
diquark-antidiquark picture. By numerically solving the Schr\"{o}dinger
equation with a Cornell-inspired potential, we separate the four-body problem
into three two-body problems. Spin-dependent terms (spin-spin, spin-orbit and
tensor) are used to describe the splitting structure of the spectrum
and are also extended to the interaction between diquarks. Recent experimental
data on charmonium states are used to fix the parameters of the model and a
satisfactory description of the spectrum is obtained. We find that the
spin-dependent interaction is sizable in the diquark-antidiquark system,
despite of the heavy diquark mass, and that the diquark has a finite size if
treated in analogy to the systems. We find that the lowest -wave
tetraquarks might be below their thresholds of spontaneous
dissociation into low-lying charmonium pairs, while orbital and radial
excitations would be mostly above the corresponding charmonium pair threshold.
These states could be investigated in the forthcoming experiments at LHCb and
Belle II.Comment: Presented at the XVII International Conference on Hadron Spectroscopy
and Structure - Hadron2017, 25-29 September, 2017, University of Salamanca,
Salamanca, Spai
The Vertex in QCD Sum Rules
The form factor is evaluated in a QCD sum rule calculation for
both and off-shell mesons. We study the double Borel sum rule for
the three point function of two pseudoscalar and one vector meson current. We
find that the momentum dependence of the form factors is different if the
or the meson is off-shell, but they lead to the same coupling constant
in the vertex.Comment: 11 pages, Latex, 4 eps figure
Evolution of non-stationary pulses in a cold magnetized quark-gluon plasma
We study weakly nonlinear wave perturbations propagating in a cold
nonrelativistic and magnetized ideal quark-gluon plasma. We show that such
perturbations can be described by the Ostrovsky equation. The derivation of
this equation is presented for the baryon density perturbations. Then we show
that the generalized nonlinear Schr{\"o}dinger (NLS) equation can be derived
from the Ostrovsky equation for the description of quasi-harmonic wave trains.
This equation is modulationally stable for the wave number and
unstable for , where is the wave number where the group velocity
has a maximum. We study numerically the dynamics of initial wave packets with
the different carrier wave numbers and demonstrate that depending on the
initial parameters they can evolve either into the NLS envelope solitons or
into dispersive wave trains
On the energy dependence of the D^+/D^- production asymmetry
In this paper we discuss the origin of the asymmetry present in D meson
production and its energy dependence. In particular, we have applied the meson
cloud model to calculate the asymmetries in D^-/D^+ meson production in high
energy p-p collisions and find a good agreement with recent LHCb data. Although
small, this non-vanishing asymmetry may shed light on the role played by the
charm meson cloud of the proton.Comment: 8 pages, 8 figures. arXiv admin note: text overlap with
arXiv:hep-ph/000927
Tetraquark Production in Double Parton Scattering
We develop a model to study tetraquark production in hadronic collisions. We
focus on double parton scattering and formulate a version of the color
evaporation model for the production of the and of the
tetraquark, a state composed by the quarks. We find that
the production cross section grows rapidly with the collision energy
and make predictions for the forthcoming higher energy data of the LHC.Comment: 13 pages, 3 figures. Corrections in the text and reference
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