Motivated by the latest BESIII measurements on Λ_c^+→ nπ^+η, we perform a systematic theoretical study of this decay. We take into account contributions from the N(1535) state dynamically generated by S-wave pseudoscalar meson-octet baryon interactions, the a_0(980) resonance originating from the S-wave pseudoscalar meson-pseudoscalar meson interactions, together with the intermediate states N(1440) and a_2(1320). Our results indicate that a_0(980) provides a significant contribution to this process. The inclusion of a_2(1320) hardly improves the fitting quality, while the nucleon resonances play a crucial role in describing the experimental behavior of the π^+η invariant mass spectrum in both low and high energy regions. Restricted by insufficient experimental statistics and a coarse bin size of 33 MeV, the precise contribution fraction of a_0(980) cannot be reliably extracted. We propose future higher-precision and higher-statistics experimental measurements of Λ_c^+→ nπ^+η, which can help reveal the intrinsic nature of a_0(980) and quantify the roles of different excited nucleon states in this decay.

Motivated by the observations of Tcs & strns;0(2900)0 and Tcs & strns;0(2900)++, we propose to search for Tcs & strns;0(2900)0 in the cleaner process B--> K-D0K0. In the D*K* molecular picture, our estimates suggest that Tcs & strns;0(2900)0 should contribute significantly to the D0K0 invariant mass distribution in B--> K-D0K0, as reported by the Belle II Collaboration. The corresponding fit fraction is estimated to be (9.72 +/- 3.92)% or (7.09 +/- 5.88)% in different fitting schemes. Further precise measurements of this process at Belle II and LHCb could be helpful for clarifying the nature of Tcs & strns;0(2900).

The Jiangmen Underground Neutrino Observatory (JUNO) collaboration has completed the construction of the 20,000-ton liquid scintillator detector and the associated muon veto detector system. To meet the physics objectives, the materials used in the detector must exhibit low radioactive contamination. The single-event rate in the fiducial volume (R < 17.2 m) of the scintillator is required to be approximately 7 Hz for energies above 0.7 MeV, resulting in an accidental coincidence background of about 1 event per day for reactor neutrino physics analyses. Since the beginning of the construction phase, we have screened the natural radioactivity content of thousands of materials, to select those that meet the design background budget. The radioactive impurity concentrations of the materials ultimately used in the JUNO detector are summarized in this paper. The construction of the entire detector and the subsequent filling of the liquid scintillator were completed in August 2025. From the initial data, the total count rate of natural radioactivity within the detector's fiducial volume has met the requirements and is sufficient to support the reactor antineutrino analysis.

Abstract We investigate the Λ c + → ηπ + Λ decay measured by the Belle and BESIII Collaborations, focusing on the possible role of the Σ(1380) state with spin-parity J P = 1/2 - . In our theoretical framework, the Λ(1670) and a0(980) are dynamically generated from meson-baryon and meson-meson final-state interactions, respectively, and the corresponding line shapes of these two states used here are applicable to all relevant hadronic reactions. Furthermore, the contributions from the intermediate Σ(1385) resonance and the possible Σ(1380) state are included explicitly. By comparing the invariant mass and angular distributions obtained with and without the Σ(1380) state, we demonstrate that this state plays an important role in improving the description of the experimental data. We also identify the kinematic regions most sensitive to the possible Σ(1380) contribution. Future high-precision measurements of this process will be instrumental for testing the existence of the Σ state with J P = 1/2 - .

Chirality lies at the heart of low-energy QCD, governing the symmetry structure that shapes hadron masses and strong interaction dynamics. Among the most compelling open questions tied to chiral dynamics and spontaneous chiral symmetry breaking is the longstanding Λ polarization puzzle, in which Λ hyperons produced in unpolarized hadronic collisions exhibit a surprisingly large transverse polarization that remains theoretically unexplained. This whitepaper presents the proposal for the Hyperon-Nucleon Spectrometer (H-NS) at the High-Intensity heavy-ion Accelerator Facility (HIAF). Leveraging the high energy and high intensity of HIAF's proton and heavy-ion beams, the H-NS experiment will perform systematic studies of hyperon polarization phenomena and their underlying mechanisms in proton-proton (pp), proton-nucleus (pA), and nucleus-nucleus (AA) collisions in the fixed target mode. A wide-range beam energy scan, including proton beams from 3 GeV up to 9.3 GeV (HIAF) and up to 32 GeV (upgraded HIAF), will be conducted to examine the dependence of polarization on collision energy. The spectrometer is designed with specialized detectors capable of high-precision reconstruction of final-state baryon polarizations. Among its many interesting and important measurements, H-NS will simultaneously measure hyperon and proton spin observables to explore the polarization mechanism in hadronic interactions and the spin structure of baryons. Furthermore, the use of pA and AA collisions will enable detailed investigations of cold and hot nuclear matter effects on spin polarization. Its physics program and detector development will significantly benefit the future Electron-ion Collider in China.

Motivated by recent BESIII measurements of the singly Cabibbo-suppressed processes Λ^+_c → ΛK^+ π^0 and Λ^+_c → ΛK_S^0 π^+, we investigate the process Λ^+_c → ΛK^0 π^+ by taking into account the contribution from the low-lying excited baryon Σ^*(1/2^-), dynamically generated via the S-wave pseudoscalar meson-octet baryon interaction, as well as from the intermediate resonances K^*(892) and N(1535). Our model successfully reproduces the BESIII π^+K^0 invariant mass distribution, and predicts a distinct cusp structure around 1.43 GeV in the π^+Λ invariant mass distribution, which is associated with the predicted Σ^*(1/2^-). Future high-precise measurements of this process at BESIII, Belle II, and the proposed Super Tau-Charm Facility experiments will be crucial for testing the existence of Σ^*(1/2^-) and advancing our understanding of the light baryon spectrum.

Motivated by recent BESIII measurements of the singly Cabibbo-suppressed processes Lambda c+->Lambda K+pi 0 and Lambda c+->Lambda KS0 pi+ , we investigate the process Lambda c+->Lambda K0 pi+ by taking into account the contribution from the low-lying excited baryon Sigma*(1/2-), dynamically generated via the S-wave pseudoscalar meson-octet baryon interaction, as well as from the intermediate resonances K*(892) and N (1535). Our model successfully reproduces the BESIII pi+K0 invariant mass distribution, and predicts a distinct cusp structure around 1.43 GeV in the pi+Lambda invariant mass distribution, which is associated with the predicted Sigma*(1/2-). Future high-precise measurements of this process at BESIII, Belle II, and the proposed Super Tau-Charm Facility experiments will be crucial for testing the existence of Sigma*(1/2-) and advancing our understanding of the light baryon spectrum.

The Cabibbo-favored decay Λ_c^+ → n K̅^0π^+ offers a unique window to explore unresolved puzzles in the low-energy baryon spectroscopy and the isospin dynamics of the K̅N system. Recent experimental results present a, for now, contradiction: LHCb and Belle analyses of Λ_c^+ → p K^-π^+ suggest the pK^- (I=0) component dominates, while the BESIII hints at significant contributions from both isospin 0 and 1 in the nK̅^0 system of Λ_c^+ → n K_S^0 π^+. Furthermore, the measured branching fraction of Λ_c^+ → n K_S^0 π^+ exceeds SU(3) symmetry predictions by a factor of 3-4, signaling strong contributions from low-lying resonances. In this work, we provide a theoretical analysis of Λ_c^+ → n K̅^0π^+ within the coupled-channel chiral unitary approach, where the N(1535) and Λ(1670) can be dynamically generated. Our calculations show a narrow peak from N(1535) in the π^+ n invariant mass spectrum and a distinct dip from Λ(1670) in the K̅^0 n spectrum. The dip structure is qualitatively consistent with the Λ(1670) manifestation in K̅N →K̅N scattering, supporting its molecular interpretation. This study not only connects the experimental observations but also highlights Λ_c^+ → n K̅^0π^+ as a crucial process to disentangle the nature of N(1535) and Λ(1670). Future precise measurements of this decay channel by the BESIII, Belle II, LHCb, and the proposed Super Tau-Charm Factory are strongly encouraged.

The Jiangmen Underground Neutrino Observatory (JUNO) is a 20-kton liquid scintillator-based, low-radioactivity, multi-purpose neutrino detector located 693 meters (1800 m.w.e.) underground in the Guangdong province, China. To detect scintillation light produced in the target, the detector is equipped with 17,612 20-inch photomultipliers (PMTs), forming the Large PMT system (LPMT). In addition, 25,600 3-inch photomultipliers (the Small Photomultiplier System or SPMT) are deployed in the gaps between the LPMTs. This paper presents the design and performance of the underwater front-end electronics developed for the SPMT system. It details the individual electronics boards and their key components, the inter-board interfaces, the system-level design, and the firmware architecture that supports data acquisition and control. It also outlines mechanical and thermal integration, board validation procedures, and system performance metrics. The readout chain includes digitization of 128 PMT channels per unit, synchronized time-stamping, charge measurement, event packaging, and bandwidth management. Comprehensive validation confirms the system's readiness to meet JUNO's stringent physics goals. The underwater electronics achieve noise levels as low as 0.04 photoelectrons with minimal crosstalk (below 0.4

We investigate the Λ_c^+ → ηπ^+ Λ decay measured by the Belle and BESIII Collaborations, focusing on the possible role of the Σ(1380) state with spin-parity J^P=1/2^-. In our theoretical framework, the Λ(1670) and a_0(980) are dynamically generated from meson-baryon and meson-meson final-state interactions, respectively, and the corresponding line shapes of these two states used here are applicable to all relevant hadronic reactions. Furthermore, the contributions from the intermediate Σ(1385) resonance and the possible Σ(1380) state are included explicitly. By comparing the invariant mass and angular distributions obtained with and without the Σ(1380) state, we demonstrate that this state plays an important role in improving the description of the experimental data. We also identify the kinematic regions most sensitive to the possible Σ(1380) contribution. Future high-precision measurements of this process will be instrumental for testing the existence of the Σ state with J^P=1/2^-.

We study the J/ψ→ Λπ reaction by looking at the π^+ Λ mass distribution at low energies, in search of signals for the low lying Σ^+ states. Apart from a clear signal of the Σ(1385) (3/2^+) state, we find a smaller peak for the predicted Σ(1430) (1/2^-), which has already been confirmed by the Belle Collaboration. A first analysis, considering only the πΛ interaction, shows that the low energy part of the spectrum is better reproduced including contributions from the Σ(1430) and the predicted Σ(1380)(1/2^-) state that has been claimed before from analyses of different experiments. However, when we consider the π interaction the need for the Σ(1380) disappears.

The Jiangmen Underground Neutrino Observatory (JUNO) is a 20-kiloton liquid scintillator neutrino detector, located 650 meters (1800 m.w.e.) underground in Jiangmen, Guangdong, China. JUNO is primarily designed for reactor neutrino measurements and has been taking data since 2025. With the largest mass of its kind and an excellent energy resolution, JUNO is a leading observatory for high-precision measurements of MeV neutrinos. The standard global trigger system serves as the primary trigger for JUNO. We present a newly developed multi-messenger trigger system that extends the capabilities of the global trigger by providing a lower energy threshold and an independent monitoring capability. During the 2025 operation, it achieved an effective energy threshold of approximately 110 +/- 10 keV, providing a lower threshold configuration suitable for low-energy event analysis. The system shows the potential to further reduce the threshold to well below 100 keV. Based on the multi-messenger trigger system, an astrophysical monitor has been developed to receive and process external alerts from other messengers, such as gravitational-wave observations. A Transient Neutrino Burst Monitor is integrated to detect short-time-scale neutrino burst events and enables real-time monitoring of transient astrophysical phenomena. The system is sensitive to neutrino bursts from core-collapse supernovae within a distance of about 250 kpc.

The processes of K^-p → π^0 π^0 Σ^0 and K^- p → π^0 Λ(1405) are studied within the effective Lagrangian approach. In addition to the “background" contribution from the u-channel nucleon pole term, contribution from the Σ(1660) resonance with spin-parity J^P=1/2^+ is also considered. For the K^-p → π^0 π^0 Σ^0 reaction, we perform a calculation for the total and differential cross sections by considering the contribution from the Σ(1660) intermediate resonance decaying into π^0 Λ(1405) with Λ(1405) decaying into π^0 Σ^0. With our model parameters, the available experimental data on both the K^-p → π^0 π^0 Σ^0 and K^- p → π^0 Λ(1405) reactions can be fairly well reproduced. It is shown that we really need the contribution from the Σ(1660) resonance, and that these experimental measurements could be used to determine some properties of the Σ(1660) resonance.

The Cabibbo-favored decay A+ c-* nK & strns;0tc+ offers a unique window to explore unresolved puzzles in the low-energy baryon spectroscopy and the isospin dynamics of the K & strns;N system. Recent experimental results present a, for now, contradiction: LHCb and Belle analyses of A+ c-* pK-tc+suggest the pK-(I = 0) component dominates, while the Beijing Spectrometer III (BESIII) hints at significant contributions from both isospin 0 and 1 in the nK & strns;0 system of A+ c-* nK0Stc+. Furthermore, the measured branching fraction of A+ c-* nK0Stc+exceeds SU(3) symmetry predictions by a factor of 3-4, signaling strong contributions from low-lying resonances. In this work, we provide a theoretical analysis of A & thorn;c-* nK & strns;0tc+ within the coupled-channel chiral unitary approach, where the N(1535) and A(1670) can be dynamically generated. Our calculations show a narrow peak from N(1535) in the tc+n invariant mass spectrum and a distinct dip from A(1670) in the K & strns;0n spectrum. The dip structure is qualitatively consistent with the A(1670) manifestation in K & strns;N-* K & strns;N scattering, supporting its molecular interpretation. This study not only connects the experimental observations but also highlights A+ c-* nK & strns;0tc+ as a crucial process to disentangle the nature of N(1535) and A(1670). Future precise measurements of this decay channel by the BESIII, Belle II, LHCb, and the proposed Super Tau-Charm Facility are strongly encouraged.

The processes of K (-) p -> pi (0) pi (0)Sigma(0) and K (-) p -> pi (0) boolean AND are studied within the effective Lagrangian approach. In addition to the "background" contribution from the u-channel nucleon pole term, the contribution from the resonance with spin-parityJ(P)=1=2(+) is also considered. For the K (-) p -> pi (0) pi (0)Sigma(0) reaction, we perform a calculation for the total and differential cross sections by considering the contribution from the intermediate resonance decaying into pi (0)boolean AND with decaying into pi (0)Sigma(0) . With our model parameters, the available experimental data on both the K (-) p -> pi (0) pi (0)Sigma(0) and K (-) p -> pi (0) boolean AND (1405) reactions can be fairly well reproduced. It is shown that the contribution from the resonance is necessary, and that these experimental measurements could be used to determine some properties of the Sigma (1660) resonance.

Over 25,600 3-inch photomultiplier tubes (PMTs) have been instrumented for the central detector of the Jiangmen Underground Neutrino Observatory. Each PMT is equipped with a high-voltage divider and a frontend cable with waterproof sealing. Groups of sixteen PMTs are connected to the underwater frontend readout electronics via specialized multi-channel waterproof connectors. This paper outlines the design and mass production processes for the high-voltage divider, the cable and connector, as well as the waterproof potting of the PMT bases. The results of the acceptance tests of all the integrated PMTs are also presented.

We present a theoretical analysis of the process A+ c -* p K & strns;0tc0 within the chiral unitary approach, with particular emphasis on the dynamically generated N(1535) resonance. In addition to N(1535), our model incorporates contributions from other intermediate resonances including N(1650), K*(892), K*0(1430), N(1440), and E(1750). The calculated invariant mass distributions and Dalitz plot are in good agreement with the recent Belle measurements. Our analysis highlights the crucial role of N(1535) state in this decay channel and supports its interpretation as a dynamically generated state arising from coupled-channel meson-baryon interactions.

We present a theoretical analysis of the process Λ_c^+ → pK̅^0 π^0 within the chiral unitary approach, with particular emphasis on the dynamically generated N(1535) resonance. In addition to N(1535), our model incorporates contributions from other intermediate resonances including N(1650), K^*(892), K_0^*(1430), N(1440), and Σ(1750). The calculated invariant mass distributions and Dalitz plot are in good agreement with the recent Belle measurements. Our analysis highlights the crucial role of N(1535) state in this decay channel and supports its interpretation as a dynamically generated state arising from coupled-channel meson-baryon interactions.

The Cabibbo-favored decay Λ c + → n K ¯ 0 π + offers a unique window to explore unresolved puzzles in the low-energy baryon spectroscopy and the isospin dynamics of the K ¯ N system. Recent experimental results present a, for now, contradiction: LHCb and Belle analyses of Λ c + → p K − π + suggest the p K − ( I = 0 ) component dominates, while the Beijing Spectrometer III (BESIII) hints at significant contributions from both isospin 0 and 1 in the n K ¯ 0 system of Λ c + → n K S 0 π + . Furthermore, the measured branching fraction of Λ c + → n K S 0 π + exceeds SU(3) symmetry predictions by a factor of 3–4, signaling strong contributions from low-lying resonances. In this work, we provide a theoretical analysis of Λ c + → n K ¯ 0 π + within the coupled-channel chiral unitary approach, where the N ( 1535 ) and Λ ( 1670 ) can be dynamically generated. Our calculations show a narrow peak from N ( 1535 ) in the π + n invariant mass spectrum and a distinct dip from Λ ( 1670 ) in the K ¯ 0 n spectrum. The dip structure is qualitatively consistent with the Λ ( 1670 ) manifestation in K ¯ N → K ¯ N scattering, supporting its molecular interpretation. This study not only connects the experimental observations but also highlights Λ c + → n K ¯ 0 π + as a crucial process to disentangle the nature of N ( 1535 ) and Λ ( 1670 ) . Future precise measurements of this decay channel by the BESIII, Belle II, LHCb, and the proposed Super Tau-Charm Facility are strongly encouraged.

We discuss the landscape of flavor physics at the Circular Electron-Positron Collider (CEPC), based on the nominal luminosity outlined in its Technical Design Report. The CEPC is designed to operate in multiple modes to address a variety of tasks. At the Z pole, the expected production of 4 Tera Z bosons will provide unique and highly precise measurements of Z boson couplings, while the substantial number of boosted heavy-flavored quarks and leptons produced in clean Z decays will facilitate investigations into their flavor physics with unprecedented precision. We investigate the prospects of measuring various physics benchmarks and discuss their implications for particle theories and phenomenological models. Our studies indicate that, with its highlighted advantages and anticipated excellent detector performance, the CEPC can explore beauty and tau physics in ways that are superior to or complementary with the Belle II and Large-Hadron-Collider-beauty experiments, potentially enabling the detection of new physics at energy scales of 10 TeV and above. This potential also extends to the observation of yet-to-be-discovered rare and exotic processes, as well as testing fundamental principles such as lepton flavor universality, lepton and baryon number conservation, etc., making the CEPC a vibrant platform for flavor physics research. The WW threshold scan, Higgs-factory operation and top-pair productions of the CEPC further enhance its merits in this regard, especially for measuring the Cabibbo-Kobayashi-Maskawa matrix elements, and Flavor-Changing-Neutral-Current physics of Higgs boson and top quarks. We outline the requirements for detector performance and considerations for future development to achieve the anticipated scientific goals. The role of machine learning for innovative detector design and advanced reconstruction algorithms is also stressed. The CEPC flavor physics program not only develops new capabilities for exploring flavor physics beyond existing projects but also enriches the physics opportunities of this machine. It should be remarked that, given the richness of the CEPC flavor physics, this manuscript is not meant to be a comprehensive survey, but rather an investigation of representative cases. Uncovering the full potential of flavor physics at the CEPC will require further dedicated explorations in the future.