Search

With the chiral unitary approach, we evaluate the hidden strange $B_{c}$-like molecular states of $b\bar{c}s\bar{s}$ systems $\bar{B}_{s}\bar{D}_{s}$, $\bar{B}_{s}^{*}\bar{D}_{s}$, $\bar{B}_{s}\bar{D}_{s}^{*}$, and $\bar{B}_{s}^{*}\bar{D}_{s}^{*}$ coupled to the non-strange channels. The $S$-wave scattering amplitudes are calculated based on the vector meson exchange, four pseudoscalar mesons contact interactions, and four vector mesons contact interactions obtained from the extended local hidden gauge approach. We find six states below the threshold of the most relevant channel. The binding energies of these states are around $1-10$ MeV and the widths are around $0.2-0.7$ MeV. Our research is a supplement to the mass spectra of $B_{c}$-like states, which may be useful for the experimental search in the future., Comment: 15 pages, 8 figures

The BESIII Collaboration claimed that a new $a_{0}(1817)$ resonance was found in the recent results of the $D_{s}^{+} \rightarrow K_{S}^{0}K^{+}π^{0}$ decay. For this decay process, we perform a unitary amplitude to analyze the contributions of the states $a_{0}(980)^{+}$ and $a_{0}(1710)^{+}$ with the final state interactions. Considering the Cabibbo-favored external and internal $W$-emission mechanisms at the quark level, and the contributions of the resonances $a_{0}(980)^{+}$, $a_{0}(1710)^{+}$ in the $S$-wave and $\bar{K}^{*}(892)^{0}$, ${K}^{*}(892)^{+}$ in the $P$-wave, the recent experimental data of the $K_{S}^{0}K^{+}$ invariant mass spectrum from the BESIII Collaboration can be described well. In our results, the states $a_{0}(980)$ and $a_{0}(1710)$ are dynamically generated from the final state interactions of $K\bar{K}$ and $K^{*}\bar{K}^{*}$, respectively, which support the molecular nature for them. Moreover, some obtained branching fractions are in agreement with the experimental measurements.

The decay process $Ξ_{b}^{-} \rightarrow pK^{-}K^{-}$ is studied with the final state interaction approach by considering the contributions from the $S$-wave meson-baryon interactions, and also the intermediate state $Λ(1520)$ in the $D$-wave. The low-lying resonances $Λ(1405)$ and $Λ(1670)$ have significant contributions, which are both dynamically generated from the $S$-wave final state interactions with isospin $I=0$. Furthermore, the $Λ(1520)$ state also has important contributions from $D$-wave. With these resonances contributions, the experimental data of the lower $pK^{-}$ invariant mass distributions are well described. We also discuss the contribution of another resonance in the $S$-wave with isospoin $I=1$, which cannot be ignored. Moreover, some of the branching fractions obtained for the corresponding decay channels are consistent with the experimental measurements., 18 pages, 6 figures, 3 tables, published in Phys. Rev. D

The stairs cleaning robot is a household type of cleaning robot, which is to solve the problem that ordinary household cleaning robots cannot efficiently deal with. Due to the complexity of structure of the stairs, it is difficult to rely on the ordinary cleaning robot to climb up stairs and clean up each step. This device is specifically designated to use for the complex surface combination of the stairs and perform to clean by each step. The design includes planetary gears to empower robot with the function of climbing stairs, and freely adjustable cleaning mechanism is used to be able to achieve automatically reciprocal motion, which allows stairs to be cleaned.

We investigate the scalar resonances in the processes of $D^{0} \rightarrow ��^{0}��^{0}��^{0}, ��^{0}��^{0}��, ��^{0}����$ decays based on the chiral unitary approach for the final state interaction. We start from singly Cabibbo-suppressed production diagrams which provide a primary quark pair to hadronize two pseudoscalar mesons in $D^{0}$ decays. The resonances $f_{0}(500)$, $f_{0}(980)$ and $a_{0}(980)$ are dynamically produced from the final state interactions of the meson pairs. In our results, the experimental data for the $��^{0}��$ invariant mass spectrum of the $D^{0} \rightarrow ��^{0}����$ decay can be described well. We also make the predictions for the $��^{0}��^{0}$ invariant mass spectrum of the $D^{0} \rightarrow ��^{0}��^{0}��^{0}$, where the $f_{0}(980)$ can be found, and for the $��^{0}��^{0}$, $��^{0}��$ invariant mass spectrum of the $D^{0} \rightarrow ��^{0}��^{0}��$, where the $f_{0}(500)$, $f_{0}(980)$ and $a_{0}(980)$ appear. Furthermore, the branching ratios of each decay channel are predicted. We expect more accurate measurements of these decays to better understand the nature of the states $f_{0}(500)$, $f_{0}(980)$ and $a_{0}(980)$.

To understand the nature of two poles for the $��(1405)$ state, we revisit the interactions of $\bar{K}N$ and $����$ with their coupled channels, where two-poles structure is found in the second Riemann sheet. We also dynamically generate two poles in the single channel interaction of $\bar{K}N$ and $����$, respectively. Moreover, we make a further study of two poles' properties by evaluating the couplings, the compositeness, the wave functions, and the radii for the interactions of four coupled channels, two coupled channels and the single channel. Our results show that the nature of two poles is unique. The higher-mass pole is a pure $\bar{K} N$ molecule, and the lower-mass one is a compositeness of mainly $����$ with tiny component $\bar{K} N$. From our results, one can conclude that the $��(1405)$ state would be overlapped with two different states of the same quantum number., Some tiny corrections have been made. Welcome for more comments

We investigate the $D_{s}^{+} \rightarrow K^{+} K^{-} ��^{+}$ decay theoretically with the final state interactions, which is based on the chiral unitary approach and takes into account the external and internal $W$-emission mechanisms at the quark level. Only considering three resonances contributions, the $f_0(980)$ in $S$-wave, the $\bar {K}^{*}(892)^{0}$ and $��(1020)$ in $P$-wave, one can make a good description of the recent experimental data from BESIII Collaboration, where the contribution from $S$-wave is found to be small. Besides, we also make a calculation of the corresponding branching fractions, which are consistent with the results of BESIII Collaboration and Particle Data Group., More discussions were made. Welcome for comments

In the present work, we investigate the decays of $B^{0}_{s} \rightarrow ����^{+}��^{-}$ and $B^{0} \rightarrow ����^{+}��^{-}$ with the final state interactions based on the chiral unitary approach. In the final state interactions of the $��^+��^-$ with its coupled channels, we study the effects of the $����$ channel in the two-body interactions for the reproduction of the $f_{0}(980)$ state. Our results for the $��^+��^-$ invariant mass distributions of the decay $B^{0}_{s} \rightarrow ����^{+}��^{-}$ describe the experimental data up to 1 GeV well, with the resonance contributions from the $f_{0}(980)$ and $��$. For the predicted invariant mass distributions of the $B^{0} \rightarrow ����^{+}��^{-}$ decay, we found that the contributions from the $f_{0}(500)$ are significant except for the ones from the $f_{0}(980)$ state. With some experimental branching ratios as input to determine the production vertex factors, we make some predictions for the branching ratios of the other final decay channels, including the vector mesons, in the $B^0_{(s)}$ decays, where some of them are consistent with the experimental ones within the uncertainties., More comments are added

The conductive mechanism is discussed in this paper. The calculation formula of Q and square resistance value is given to express the increase of RFID antennapsilas work efficiency. The influence factor of printing RFID antenna using conductive ink is given according to work feature and requirement of RFID antenna and lots of experiment data. These factors are conductive performance of metal granule in conductive ink, metal granule content in ink, solvent volatilization and design figure of antenna.

On the basis of discussion of RFID system work principle, the method of calculation of minimum action magnetic intensity and its impact factor are proposed. To the tag read-write angle, the relationship between tag read-write range and its loss detection is analyzed. The value of detection rate on conveyor belt is tested by experiment. Two methods of improving tag detection are discussed. They are named multi-tag and multi-reader. The tag detection of single-tag, two-tag and three-tag are also tested by experiment. The feature of multi-reader is analyzed. They provide a good way for design and applications of RFID system.

A novel manufacture technology in regard to EAS responder of conductive ink was introduced. According to its operating principle, running characteristics of recovery and puncturing responder were analyzed as well as a calculation for parasitic and tuning capacitance. In addition, a new match technology was provided for retrievable parasitic capacitance. Also, the capacitance structure of the response flat and the puncturing mechanism were studied connected with alarge number of data, which provided a manufacture method for the puncturing responder based on this excellent match.