22,921 research outputs found
The recoil correction and spin-orbit force for the possible and states
In the framework of the one-boson exchange model, we have calculated the
effective potentials between two heavy mesons and from the t- and u-channel -, -, -, - and
-meson exchanges. We keep the recoil corrections to the and systems up to , which
turns out to be important for the very loosely bound molecular states. Our
numerical results show that the momentum-related corrections are favorable to
the formation of the molecular states in the , in the
and systems.Comment: 12 pages, 9 figures. arXiv admin note: substantial text overlap with
arXiv:1403.404
Hidden-Charm Tetraquarks and Charged Zc States
Experimentally several charged axial-vector hidden-charm states were
reported. Within the framework of the color-magnetic interaction, we have
systematically considered the mass spectrum of the hidden-charm and
hidden-bottom tetraquark states. It is impossible to accommodate all the three
charged states , and within the axial vector
tetraquark spectrum simultaneously. Not all these three states are tetraquark
candidates. Moreover, the eigenvector of the chromomagnetic interaction
contains valuable information of the decay pattern of the tetraquark states.
The dominant decay mode of the lowest axial vector tetraquark state is while its and modes are strongly suppressed,
which is in contrast with the fact that the dominant decay mode of
and is and respectively. We emphasize
that all the available experimental information indicates that is a
very promising candidate of the lowest axial vector hidden-charm tetraquark
state
The meson-exchange model for the interaction
In the present work, we apply the one-boson-exchange potential (OBEP) model
to investigate the possibility of Y(2175) and as bound states of
and respectively.
We consider the effective potential from the pseudoscalar -exchange and
-exchange, the scalar -exchange, and the vector
-exchange and -exchange. The and meson exchange
potential is repulsive force for the state and attractive for .
The results depend very sensitively on the cutoff parameter of the
-exchange () and least sensitively on that of the
-exchange (). Our result suggests the possible
interpretation of Y(2175) and as the bound states of
and respectively
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Effects of natural soiling and weathering on cool roof energy savings for dormitory buildings in Chinese cities with hot summers
Roofs with high-reflectance (solar reflectance) coating, commonly known as cool roofs, can stay cool in the sun, thereby reducing building energy consumption and mitigating the urban heat island. However, chemical-physical degradation and biological growth can decrease their solar reflectance and the ability to save energy. In this study, the solar spectral reflectance of 12 different roofing products with an initial albedo of 0.56β0.90 was measured before exposure and once every three months over 32 months. Specimens were exposed on the roofs of dormitory buildings in Xiamen and Chengdu, each major urban areas with hot summers. The albedos of high and medium-lightness coatings stabilized in the ranges 0.45β0.62 and 0.36β0.59 in both cities, respectively. This study yielded albedo loss exceeded those reported in the latest Chinese standard by 0.08β0.15. Finally, DesignBuilder (EnergyPlus) simulations estimate that a new cool roof with albedo 0.78 on a six-story dormitory building will yield annual site energy savings (heating and cooling) for the top floor, which are 8.01 kWh/m2 (24.2%) and 9.12 kWh/m2 (26.3%) per unit floor area in Xiamen and Chengdu, respectively; while an aged cool roof with albedo 0.45 and 0.56 will yield the annual savings by 5.12 kWh/m2 (15.4%) and 2.47 kWh/m2 (10.5%) in these two cities
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