2,530 research outputs found
Analysis of the tensor-tensor type scalar tetraquark states with QCD sum rules
In this article, we study the ground states and the first radial excited
states of the tensor-tensor type scalar hidden-charm tetraquark states with the
QCD sum rules. We separate the ground state contributions from the first radial
excited state contributions unambiguously, and obtain the QCD sum rules for the
ground states and the first radial excited states, respectively. Then we search
for the Borel parameters and continuum threshold parameters according to four
criteria and obtain the masses of the tensor-tensor type scalar hidden-charm
tetraquark states, which can be confronted to the experimental data in the
future.Comment: 12 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1607.0484
The decay width of the as an axialvector tetraquark state in solid quark-hadron duality
In this article, we tentatively assign the to be the
diquark-antidiquark type axialvector tetraquark state, study the hadronic
coupling constants , , with the QCD sum rules in details. We take into account both the
connected and disconnected Feynman diagrams in carrying out the operator
product expansion, as the connected Feynman diagrams alone cannot do the work.
Special attentions are paid to matching the hadron side of the correlation
functions with the QCD side of the correlation functions to obtain solid
duality, the routine can be applied to study other hadronic couplings directly.
We study the two-body strong decays ,
, , and obtain the total
width of the . The numerical results support assigning the
to be the diquark-antidiquark type axialvector tetraquark
state, and assigning the to be the meson-meson type axialvector
molecular state.Comment: 16 pages, 3 figure
Symmetry Dictionary on Charge and Spin Nonlinear Responses for All Magnetic Point Groups with Nontrivial Topological Nature
Recently, charge or spin nonlinear transport with nontrivial topological
properties in crystal materials has attracted much attention. In this paper, we
perform a comprehensive symmetry analysis for all 122 magnetic point groups
(MPGs) and provide a useful dictionary for charge and spin nonlinear transport
from Berry curvature dipole, Berry connection polarization and Drude term with
nontrivial topological nature. The results are obtained by making a full
symmetry investigation on matrix representations of six nonlinear response
tensors. We further identify every MPG that can accommodate two or three of the
nonlinear tensors. The present work gives a solid theoretical basis for overall
understanding the second-order nonlinear responses in realistic materials.Comment: 5 pages, 2 figure
Utility-maximization Resource Allocation for Device-to-Device Communication Underlaying Cellular Networks
Device-to-device(D2D) underlaying communication brings great benefits to the
cellular networks from the improvement of coverage and spectral efficiency at
the expense of complicated transceiver design. With frequency spectrum sharing
mode, the D2D user generates interference to the existing cellular networks
either in downlink or uplink. Thus the resource allocation for D2D pairs should
be designed properly in order to reduce possible interference, in particular
for uplink. In this paper, we introduce a novel bandwidth allocation scheme to
maximize the utilities of both D2D users and cellular users. Since the
allocation problem is strongly NP-hard, we apply a relaxation to the
association indicators. We propose a low-complexity distributed algorithm and
prove the convergence in a static environment. The numerical result shows that
the proposed scheme can significant improve the performance in terms of
utilities.The performance of D2D communications depends on D2D user locations,
the number of D2D users and QoS(Quality of Service) parameters
Possible pentaquark candidates: new excited states
In this article, we study the axialvector-diquark-scalar-diquark-antiquark
type charmed pentaquark states with with the QCD sum
rules by carrying out the operator product expansion up to the vacuum
condensates of dimension in a consistent way. In calculations, we separate
the contributions of the negative parity and positive parity pentaquark states
unambiguously, and choose three sets input parameters to study the masses and
pole residues of the charmed pentaquark states and
in details. Then we estimate the masses of the charmed pentaquark states
, , and with
to be according to the
breaking effects, which is compatible with the ,
, , .Comment: 24 pages, 28 figure
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