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The recently released data on differential cross sections for γn→K0Σ0 from the A2 and BGOOD Collaborations are used to examine the theoretical model constructed in our previous work [Phys. Rev. D 105, 094017 (2022)] for γn→K+Σ−, and it is found that the model predictions are able to qualitatively reproduce the A2 data but fail to describe the BGOOD data. Then, a combined analysis of the γn→K0Σ0 and γn→K+Σ− reactions is performed to revise the theoretical model. Due to the inconsistency problem, the A2 and BGOOD data are included in fits separately. In the case of including the A2 data, both the data for γn→K0Σ0 and γn→K+Σ− can be fairly well described, and the contributions from the N(1710)1/2+, N(1880)1/2+, N(1900)3/2+, and Δ(1920)3/2+ resonances are found to dominate the reactions in the lower energy region. While in the case of including the BGOOD data, although most of the data for the γn→K+Σ− reaction can be described with the exception of some noticeable discrepancies on beam asymmetries at lower energies, the BGOOD data for γn→K0Σ0 can be only qualitatively described, and the contributions from the N(1710)1/2+, N(1900)3/2+, and Δ(1910)1/2+ resonances are found to dominate the reactions in the lower energy region. In both cases, the t-channel K*(892) exchange is found to play a crucial role at forward angles in the higher energy region. Further precise measurements of data for γn→K0Σ0 are called on to disentangle the discrepancies between the datasets from the A2 and BGOOD Collaborations.

The recently released data on differential cross sections for $γn \to K^0Σ^0$ from the A2 and BGOOD Collaborations are used to examine the theoretical model constructed in our previous work [Phys. Rev. D \textbf{105}, 094017 (2022)] for $γn \to K^+Σ^-$, and it is found that the model predictions are able to qualitatively reproduce the A2 data but fail to describe the BGOOD data. Then, a combined analysis of the $γn \to K^0Σ^0$ and $γn \to K^+Σ^-$ reactions is performed to revise the theoretical model. Due to the inconsistency problem, the A2 and BGOOD data are included in fits separately. In the case of including the A2 data, both the data for $γn \to K^0Σ^0$ and $γn \to K^+Σ^-$ can be fairly well described, and the contributions from the $N(1710)1/2^+$, $N(1880)1/2^+$, $N(1900)3/2^+$, and $Δ(1920)3/2^+$ resonances are found to dominate the reactions in the lower energy region. While in the case of including the BGOOD data, although most of the data for the $γn \to K^+ Σ^-$ reaction can be described with the exception of some noticeable discrepancies on beam asymmetries at lower energies, the BGOOD data for $γn \to K^0Σ^0$ can be only qualitatively described, and the contributions from the $N(1710)1/2^+$, $N(1900)3/2^+$, and $Δ(1910)1/2^+$ resonances are found to dominate the reactions in the lower energy region. In both cases, the $t$-channel $K^\ast(892)$ exchange is found to play a crucial role at forward angles in the higher energy region. Further precise measurements of data for $γn \to K^0Σ^0$ are called on to disentangle the discrepancies between the data sets from the A2 and BGOOD Collaborations., 14 pages,17 figures; Accepted for publication in Physical Review D

Recently, the Belle Collaboration has measured the Λc+→ηΛπ+ decay and reported the ηΛ and Λπ+ invariant mass distributions, which show the clear signals of the resonances Λ(1670) and Σ(1385), respectively. Based on our previous works [Eur. Phys. J. C 76, 496 (2016) and Phys. Rev. D 95, 074024 (2017)], we reanalyze this process by considering the S-wave ηΛ and ηπ+ final state interactions within the chiral unitary approach, which dynamically generate the Λ(1670) and a0(980), respectively. Our results are in agreement with the Belle measurements of the ηΛ and π+Λ invariant mass distributions. In addition, the π+η invariant mass distribution is also calculated and a cusp structure of a0(980) is clearly shown around the KK¯ mass threshold.

The most recent data on beam asymmetries Σ and beam-target asymmetries E from the CLAS Collaboration, together with the previous data on differential cross sections and beam asymmetries from the CLAS and LEPS Collaborations, for the γn→K+Σ− reaction are studied based on an effective Lagrangian approach in the tree-level Born approximation. The t-channel K and K*(892) exchanges, the u-channel Σ exchange, the interaction current, and the exchanges of N, Δ, and their excited states in the s channel are considered in constructing the reaction amplitudes to describe the available experimental data. The reaction mechanisms of γn→K+Σ− are analyzed, and the associated resonances’ parameters are extracted. The numerical results show that the Δ exchange and the N(1710)1/2+, N(1880)1/2+, N(1900)3/2+, and Δ(1920)3/2+ resonance exchanges in the s channel dominate the γn→K+Σ− reaction in the lower energy region, and the t-channel K*(892) exchange plays a crucial role at forward angles in the higher energy region.

In our previous work [Phys. Rev. D 101, 074025 (2020)], the photoproduction γp→K+Σ0(1385) has been investigated within an effective Lagrangian approach. There, the reaction amplitudes were constructed by considering the t-channel K and K*(892) exchanges, s-channel N contribution, u-channel Λ exchange, generalized contact term, and a minimum number of s-channel N and Δ resonance diagrams. It was found that the inclusion of one of the N(1895)1/2−, Δ(1900)1/2−, and Δ(1930)5/2− resonances is essential to reproduce the available differential and total cross-section data for γp→K+Σ0(1385). In the present work, we employ the same model to study the photoproduction γn→K+Σ−(1385), with the purpose being to understand the reaction mechanism and, in particular, to figure out which one of the N(1895)1/2−, Δ(1900)1/2−, and Δ(1930)5/2− resonances is really capable for a simultaneous description of the data for both K+Σ0(1385) and K+Σ−(1385) photoproduction reactions. The results show that the available data on differential and total cross sections and photobeam asymmetries for γn→K+Σ−(1385) can be reproduced only with the inclusion of the Δ(1930)5/2− resonance rather than the other two. The generalized contact term and the t-channel K exchange are found to dominate the background contributions. The resonance Δ(1930)5/2− provides the most important contributions in the whole energy region considered, and it is responsible for the bump structure exhibited in the total cross sections.

The most recent data on beam asymmetries, $Σ$, and beam-target asymmetries, $E$, from the CLAS Collaboration, together with the previous data on differential cross sections and beam asymmetries from the CLAS and LEPS Collaborations, for the $γn \to K^+Σ^-$ reaction are studied based on an effective Lagrangian approach in the tree-level Born approximation. The $t$-channel $K$ and $K^\ast(892)$ exchanges, the $u$-channel $Σ$ exchange, the interaction current, and the exchanges of $N$, $Δ$, and their excited states in the $s$ channel are considered in constructing the reaction amplitudes to describe the available experimental data. The reaction mechanisms of $γn \to K^+Σ^-$ are analyzed, and the associated resonances' parameters are extracted. The numerical results show that the $Δ$ exchange and the $N(1710)1/2^+$, $N(1880)1/2^+$, $N(1900)3/2^+$, and $Δ(1920)3/2^+$ resonance exchanges in the $s$-channel dominate the $γn \to K^+Σ^-$ reaction in the lower energy region, and the $t$-channel $K^\ast(892)$ exchange plays a crucial role at forward angles in the higher energy region., To be published in Physical Review D; 11 pages, 5 figures

A gauge-invariant model is constructed for the $γp \to K^+Λ(1690)$ reaction within a tree-level effective Lagrangian approach with the purpose to understand the underlying production mechanisms and to study the resonance contributions in this reaction. In addition to the $t$-channel $K$ and $K^\ast$ exchanges, the $s$-channel nucleon exchange, and the interaction current, the $s$-channel nucleon resonance exchanges are also included in constructing the reaction amplitudes to describe the data. It is found that the contributions from the $s$-channel $N(2570)5/2^-$ exchange are required to describe the most recently measured total cross-section data for $γp \to K^+Λ(1690)$ from the CLAS Collaboration. Further analysis shows that the interaction current dominates the $γp \to K^+Λ(1690)$ reaction near the threshold as a result of gauge invariance. The $t$-channel $K$ exchange contributes significantly, while the contributions from the $t$-channel $K^\ast$ exchange as well as the $s$-channel nucleon exchange turn out to be negligible. The contributions from the $s$-channel $N(2570)5/2^-$ exchange are found to be responsible for the bump structure shown in the CLAS total cross-section data above the center-of-mass energy $W \approx 2.7$ GeV. The predictions of the differential cross sections for $γp \to K^+Λ(1690)$ are shown and discussed, which can provide theoretical guidances for the future experiments., To be published in Chinese Physics C

Recently, the Belle Collaboration has measured the $Λ_c^+ \to ηΛπ^+$ decay and reported the $ηΛ$ and $Λπ^+ $ invariant mass distributions, which show the clear signals of the resonances $Λ(1670)$ and $Σ(1385)$, respectively. Based on our previous works [Eur. Phys. J. C 76 (2016) 496 and Phys. Rev. D 95 (2017) 074024], we re-analyze this process by considering the $S$-wave $ηΛ$ and $ηπ^+$ final state interactions within the chiral unitary approach, which dynamically generate the $Λ(1670)$ and $a_0(980)$, respectively. Our results are in good agreement with the Belle measurements, which supports the molecular nature of the $Λ(1670)$ and $a_0(980)$. In addition, the $ηπ^+$ invariant mass distributions are also computed and a cusp structure of $a_0(980)$ is cleary shown around the $K\bar{K}$ mass threshold., 8 pages, 9 figures

In our previous work [Phys. Rev. D $\bf{101}$, 074025 (2020)], the photoproduction $��p \to K^+ ��^0(1385)$ has been investigated within an effective Lagrangian approach. There, the reaction amplitudes were constructed by considering the $t$-channel $K$ and $K^\ast(892)$ exchanges, $s$-channel $N$ contribution, $u$-channel $��$ exchange, generalized contact term, and a minimum number of $s$-channel $N$ and $��$ resonance diagrams. It was found that the inclusion of one of the $N(1895){1/2}^-$, $��(1900){1/2}^-$, and $��(1930){5/2}^-$ resonances is essential to reproduce the available differential and total cross-section data for $��p \to K^+ ��^0(1385)$. In the present work, we employ the same model to study the photoproduction $��n \to K^+ ��^-(1385)$, with the purpose being to understand the reaction mechanism and, in particular, to figure out which one of the $N(1895){1/2}^-$, $��(1900){1/2}^-$, and $��(1930){5/2}^-$ resonances is really capable for a simultaneous description of the data for both $K^+ ��^0(1385)$ and $K^+ ��^-(1385)$ photoproduction reactions. The results show that the available data on differential and total cross sections and photo-beam asymmetries for $��n \to K^+ ��^-(1385)$ can be reproduced only with the inclusion of the $��(1930){5/2}^-$ resonance rather than the other two. The generalized contact term and the $t$-channel $K$ exchange are found to dominate the background contributions. The resonance $��(1930){5/2}^-$ provides the most important contributions in the whole energy region considered, and it is responsible for the bump structure exhibited in the total cross sections., 7 pages, 7 figures. Accepted for publication in PRD

The data on differential cross sections and photon-beam asymmetries for the γp→K+Λ(1520) reaction have been analyzed within a tree-level effective Lagrangian approach. In addition to the t-channel K and K* exchanges, the u-channel Λ exchange, the s-channel nucleon exchange, and the interaction current, a minimal number of nucleon resonances in the s channel are introduced in constructing the reaction amplitudes to describe the data. The results show that the experimental data can be well reproduced by including either the N(2060)5/2− or the N(2120)3/2− resonance. In both cases, the contact term and the K exchange are found to make significant contributions, while the contributions from the K* and Λ exchanges are negligible in the former case and considerable in the latter case. Measurements of the data on target asymmetries are called on to further pin down the resonance contents and to clarify the roles of the K* and Λ exchanges in this reaction.

In our previous work [Phys. Rev. C 101, 014003 (2020)], the photoproduction reaction $��p \to K^{\ast +} ��$ has been investigated within an effective Lagrangian approach. There, the reaction amplitudes were constructed by including the $t$-channel $K$, $K^\ast$, and $��$ exchanges, the $u$-channel $��$, $��$, and $��^\ast$ exchanges, the $s$-channel $N$, $N(2000)5/2^+$, and $N(2060)5/2^-$ exchanges, and the interaction current. It has been shown that the data on both the differential cross sections and the spin density matrix elements were simultaneously and satisfactorily described. In this paper, we study the photoproduction reaction $��n \to K^{\ast 0} ��$ based on the same reaction mechanism as that of $��p \to K^{\ast +} ��$ with the purpose of getting a unified description of the data for both $��p \to K^{\ast +} ��$ and $��n \to K^{\ast 0} ��$ within a same model. All hadronic coupling constants, form factor cutoffs, and the resonance masses and widths in the present calculations remain the same as in our previous work for $��p \to K^{\ast +} ��$. The available differential cross-section data for $��n \to K^{\ast 0} ��$ are well reproduced. Further analysis shows that the cross sections of $��n \to K^{\ast 0} ��$ are dominated by the contributions of the $t$-channel $K$ exchange, while the $s$-channel $N(2000)5/2^+$ and $N(2060)5/2^-$ exchanges provide considerable contributions as well., to be published in Chinese Physics C

The photoproduction reaction of $��p \to ��^\prime p$ is investigated based on an effective Lagrangian approach in the tree-level approximation, with the purpose being to understand the reaction mechanisms and to extract the resonance contents and the associated resonance parameters in this reaction. Apart from the $t$-channel $��$ and $��$ exchanges, $s$- and $u$-channel nucleon exchanges, and generalized contact term, the exchanges of a minimum number of nucleon resonances in the $s$ channel are taken into account in constructing the reaction amplitudes to describe the experimental data. It is found that a satisfactory description of the available data on both differential cross sections and photon beam asymmetries can be obtained by including in the $s$ channel the exchanges of the $N(1875)3/2^-$ and $N(2040)3/2^+$ resonances. The reaction mechanisms of $��p \to ��^\prime p$ are discussed and a prediction for the target nucleon asymmetries is presented., 10 pages, 5 figures. Version published in PRD. arXiv admin note: text overlap with arXiv:2002.04213

The data on differential cross sections and photon-beam asymmetries for the $��p \to K^+��(1520)$ reaction have been analyzed within a tree-level effective Lagrangian approach. In addition to the $t$-channel $K$ and $K^\ast$ exchanges, the $u$-channel $��$ exchange, the $s$-channel nucleon exchange, and the interaction current, a minimal number of nucleon resonances in the $s$ channel are introduced in constructing the reaction amplitudes to describe the data. The results show that the experimental data can be well reproduced by including either the $N(2060)5/2^-$ or the $N(2120)3/2^-$ resonance. In both cases, the contact term and the $K$ exchange are found to make significant contributions, while the contributions from the $K^\ast$ and $��$ exchanges are negligible in the former case and considerable in the latter case. Measurements of the data on target asymmetries are called on to further pin down the resonance contents and to clarify the roles of the $K^\ast$ and $��$ exchanges in this reaction., 12 pages, 8 figures; version published in Phys. Rev. D

In our previous work [Phys. Rev. C {\bf 96}, 035206 (2017)], the high-precision differential cross-section data for $��p \to K^{*+}��$ reported by the CLAS Collaboration has been analyzed within an effective Lagrangian approach. It was found that apart from the $t$-channel $K$, $K^*$, and $��$ exchanges, the $u$-channel $��$, $��$, and $��^*$ exchanges, the $s$-channel $N$ exchange, and the interaction current, one needs to introduce at least two nucleon resonances in the $s$ channel in constructing the reaction amplitudes to describe the cross-section data. One of the needed resonances is $N(2060)5/2^-$, and the other one could be one of the $N(2000)5/2^+$, $N(2040)3/2^+$, $N(2100)1/2^+$, $N(2120)3/2^-$, and $N(2190)7/2^-$ resonances. In this paper, we further include in our analysis the data on spin density matrix elements for $K^*$ meson reported recently by the CLAS Collaboration, with the purpose being to impose further constraints on extracting the resonance contents and to gain a better understanding of the reaction mechanism. It turns out that with the new data on spin density matrix elements taken into account, only the set with the $N(2060)5/2^-$ and $N(2000)5/2^+$ resonances among those five possible solutions extracted from the analysis of the differential cross-section data can satisfactorily describe the data on both the differential cross sections and the spin density matrix elements. Further analysis shows that this reaction is dominated by the $t$-channel $K$ exchange and $s$-channel $N(2060)5/2^-$ and $N(2000)5/2^+$ exchanges., 9 figures, 11 pages

This paper proposes a newly developed single-delta bridge-cell, modular multilevel cascade converter (SDBC-MMCC)-based distribution-level static synchronous compensator (DSTATCOM) for single-phase load compensation in three-phase, three-wire electric power distribution systems. Each main circuit arm of the DSTATCOM uses a modular multilevel cascade converter based on full-H-bridge (FHB) cells. The three main DSTATCOM arms are delta-connected to allow phase-independent operations for phase balancing and unity power factor correction of the single-phase load in three-phase, three-wire electric power distribution systems. By using the symmetrical components method, a feedforward compensation algorithm was employed for the DSTATCOM. A simulation of the DSTATCOM was performed for functioning verification. Finally, a hardware test system was built by using a multi-DSP-based control system. The test results verified the effectiveness of the proposed SDBC-MMCC-based DSTATCOM in single-phase load compensation.

This paper proposes a combination control scheme for direct compensation current and dc-link voltage balance in a multilevel cascade static synchronous compensator (STATCOM). A cascade full H-bridge (FHB) based-converter with modular structure is employed as the main circuit of the STATCOM, which is suitable for high-power and high-voltage applications. For achieving reactive power compensation and power factor correction (PFC), a direct compensation current control is applied to provide or absorb reactive power. For maintaining the dc-link voltage balance between FHB cells in the converter, a voltage balance control is developed. A phase-shift pulse width modulation (PS-PWM) is applied as the modulation scheme of the FHB converter for fast compensation response. Finally, the STATCOM is constructed and simulated with MatLab/Simulink program. Simulation results verify that the proposed STATCOM not only maintains the dc-link voltages balance between FHB cells, but also regulates the needed reactive power currents with a fast response time during the system compensations.

A shunt compensator is developed in the paper for power flow balancing in a three-phase distribution-level microgrid with single-phase distributed generation units and loads. The symmetrical components decomposition of the three-phase currents in the microgrid is performed to derive a compensation scheme for the compensator. With the on-line compensation of the compensator, the power source offers balanced power flow. A three-phase, delta-connected, distribution-level static synchronous compensator (DSTATCOM) using multilevel cascade full H-bridge (FHB) converter is developed as the compensator. Computer simulation verifies the transient and steady-state compensation effects of the developed compensator.

The single‐phase rectifier‐inverter is the main circuit of the single‐phase UPS. Traditionally, the half‐bridge with split capacitor topology and the three‐arm topology are employed for pursuing low cost and high efficiency. This paper presents a three‐arm topology replacing one transistor‐arm with one diode‐arm to further reduce the cost as compared to three‐arm topology. The diode‐arm is placed on the rectifier side and the PFC function is achieved through the rectifier arm (REC‐arm) which provides the common path for the rectifier and inverter. To control the inverter voltage with only the inverter arm (INV‐arm), the feedforward control method is adopted for the INV‐arm to reduce the interaction with the rectifier through the REC‐arm. Modeling of the proposed rectifier‐inverter with the diode‐arm and controller design of the rectifier and inverter portions are provided in this paper. A 500VA UPS is built. The effectiveness of the proposed method is confirmed with some experimental results.

A grid-connected photovoltaic (PV) power supply system with on-line voltage regulation capability is presented. It employs the three-arm rectifier-inverter topology with PV modules connected directly on the dc-link. The common-arm is with line-frequency switching and synchronous to the input voltage, aiming for a lower switching loss and decoupling the control of rectifier and inverter portions. As a result, the rectifier and inverter portions can be controlled independently with the rectifier-arm and inverter-arm, respectively. For maximum power point tracking (MPFF) of the PV modules and balancing the power among utility, PV, and the load, a variable dc-link voltage is adopted and controlled by the rectifier-arm based on the MPPT control algorithm. The inverter-arm then regulates the load voltage with good regulation and low distortion. Due to large variation of the dc-link voltage, a feedforward plus feedback control technique with variable gain is developed to keep constant bandwidth of the current loop at any operation condition. Therefore, the performance of the rectifier and inverter portions can be ensured. A system containing a 2 kVA converter and a 1.2 kW PV module is set up, and some experimental results are provided for demonstrating the effectiveness of the proposed method.

This paper focuses on the transient stability analysis and enhancement evaluation of an actual cogeneration plant. The cogeneration system is constructed in the ElectroMagnetic Transient Program (EMTP) environment for analyses. Simulation results show that the needed CCT curves for successful grid-disconnection operation are much lower than calculated CCT curves without executing grid-disconnection operation. Therefore, three schemes including installations of power factor correction capacitor, static var compensator (SVC) and static synchronous compensator (STATCOM) for enhancement of grid-disconnection operation are studied, respectively. Simulation results are given and discussed.

A delta-connected static synchronous compensator (STATCOM) is proposed for real-time load compensation of unbalanced load. The structure of the STATCOM is a multilevel cascaded full H-bridge inverter which is suitable for high-voltage, high-power applications. First, use of the symmetrical components method derives the control algorithm of the STATCOM. The STATCOM is then built in the Matlab/Simulink environment. Finally, simulation results indicate that the proposed delta-connected STATCOM is effective for real-time load compensation of unbalanced loads.

In this paper, a delta-connected DSTATCOM with cascaded H-bridge multilevel inverter is proposed for real-time load power factor correction in power distribution systems. First, a feed forward compensation scheme is developed for the DSTATCOM for fast response requirement. Then, the DSTATCOM is built and simulated with Matlab/Simulink program. Accordingly, a hardware prototype is constructed by using DSP-based control system. Finally, experimental results verify the function of the DSTATCOM.

This paper proposes a distribution level static synchronous compensator (DSTATCOM) for fast load compensation of unbalanced loads in electric power distribution systems. For fast response requirement, a new feedforward compensation scheme is derived and employed in the paper. First, the compensation scheme of the DSTATCOM is derived with the symmetrical components method. Then, computer simulation with the program Matlab/Simulink preliminarily verifies the effectiveness of the proposed DSTATCOM. Accordingly, a hardware prototype is built with a floating-point DSP TMS320C6711-based system. Use of a current-regulated PWM (CRPWM) inverter as the power stage of the DSTATCOM generates needed compensation currents for real-time load compensation. Finally, experimental results confirm the effectiveness of the proposed DSTATCOM.