Shape quantum phase transitions are an important topic in nuclear structure. In this paper, we investigate the finite-N shape quantum phase transition in the SU3-IBM. In this newly proposed framework, a sphere-like γ -soft spectrum is identified to address the long-standing puzzle of apparently spherical nuclei, and it represents a distinct γ -soft rotational mode. In this paper, the shape phase transition along the new γ -soft line is examined first, and the neighboring case on the prolate side is then analyzed. Some diagnostic observables are examined. We show that double shape phase transitions occur along a single parameter path. The new γ -softness is demonstrated to be a shape phase, and the shape phase transition from the new γ -soft phase to the prolate shape is identified. Experimental indications are also identified, and ^108 Pd may be a candidate critical nucleus.

Silicon carbide detectors exhibit good detection performance and have been studied for various detection applications. However, in some applications, the presence of metal is undesirable, such as low-penetration particle detection, UV light detection, and medical dosimetry. A graphene-optimized 4H-SiC detector has been fabricated not only meet the aforementioned detection requirements but also shorten the signal rise time. Its electrical properties, rise time, and the charge collection performance of alpha particles are reported. The effective doping concentration of the lightly doped 4H-SiC epitaxial layer is about 4.5 x 10(13)cm(-3), approaching the limit of the lowest doping level by the silicon carbide (SiC) epitaxial growth technique. The rise time of the grapheneoptimized ring electrode (RE) detector is reduced by 24% at 200 V compared to the RE detector. The charge collection efficiency (CCE) of graphene-optimized 4H-SiC p-i-n is 99.22%. When the graphene has been irradiated using 80-MeV proton beam with fluence of 2.1 x 10(11)n(eq)/cm(2), the irradiation has no significant impact on the rise time and uniformity of the rise time for the graphene-optimized 4H-SiC detectors. This study proves that graphene has a certain radiation resistance. Graphene-optimized 4H-SiC detectors can not only reduce the signal rise time but also improve the uniformity of signal rise time and the stability of charge collection. This research may expand the application of graphene-based 4H-SiC detectors in fields such as low-penetration particles' detection, high-energy particles' detection, low-energy heavy-ion detection, medical dosimetry, and transient current technique (TCT) measurement.

Accurately identifying radioactive nuclides is essential for environmental monitoring and nuclear security.This study aims to develop a deep learning-based methodology within tomographic gamma scanning (TGS) to distinguish 137 Cs 110mand Ag, as their misidentifi cation poses signifi cant safety risks in nuclear waste management. A bidirectional long short-term memory (Bi-LSTM) network was employed as the baseline classifi er, withhyperparameter optimization performed to enhance discrimination capability. A Monte Carlo model was constructedaccording to actual nuclear waste drum dimensions, incorporating detector response and environmental radioactivebackground contributions. The Bi-LSTM model was trained and evaluated using simulated spectroscopic data undervarying 137Cs/ 110m ⁰ᵐAg activity ratios. The optimized Bi-LSTM model achieved an average identifi cation accuracy exceeding 97

Shape quantum phase transition is an important and hot topic in nuclear structure. In this paper, we begin to study the finite-N shape quantum phase transition in the SU3-IBM. In this new proposed model, new spherical-like γ-soft spectra was found to resolve the spherical nucleus puzzle, which is a new γ-soft rotational mode. In this paper, the shape phase transition along the new γ-soft line is first discussed, and then the neighbouring case at the prolate side is also studied. Some key quantities are discussed. We find that double shape phase transitions occur along a single parameter path. The new γ-softness is really a shape phase and the shape phase transition from the new γ-soft phase to the prolate shape is found. The experimental supports are also found and108Pd may be the critical nucleus.

The spontaneous conversion of muonium to antimuonium is an interesting charged lepton flavor violation phenomenon that offers a sensitive probe for potential new physics and serves as a tool to constrain the parameter space beyond the Standard Model. The Muonium-to-Antimuonium Conversion Experiment (MACE) was designed to utilize a high-intensity muon beam, a Michel electron magnetic spectrometer, a positron transport system, and a positron detection system to either discover or constrain this rare process with a conversion probability of 𝒪(10^-13) . This article presents an overview of the theoretical framework and a detailed description of the experimental design for muonium-to-antimuonium conversion.

Based on 6.1  fb^{-1} of e^{+}e^{-} annihilation data collected at center-of-mass energies from 4.600 to 4.843 GeV with the BESIII detector at the BEPCII collider, a partial wave analysis of Λ_{c}^{+}→Λπ^{+}η is performed, and branching fractions and decay asymmetry parameters of intermediate processes are determined. The process Λ_{c}^{+}→Λa_{0}(980)^{+} is observed for the first time, and evidence for the pentaquark candidate Σ(1380)^{+} decaying into Λπ^{+} is found with statistical significance larger than 3σ with mass and width fixed to theoretical predictions. The branching fraction product B[Λ_{c}^{+}→Λa_{0}(980)^{+}]B[a_{0}(980)^{+}→π^{+}η] is determined to be (1.05±0.16_{stat}±0.05_{syst}±0.07_{ext})%, which is larger than theoretical calculations by 1-2 orders of magnitude. Here the third (external) systematic is from B(Λ_{c}^{+}→Λπ^{+}η). Finally, we precisely obtain the absolute branching fraction B(Λ_{c}^{+}→Λπ^{+}η)=(1.94±0.07_{stat}±0.11_{syst})%.

The concept of ''SU(3) analysis'' is proposed for the B(E2) anomaly based on various mechanisms reported recently. The B(E2) anomaly is analyzed in the SU(3) symmetry limit. According to the results of the analysis, the SU(3) third-order interaction can generate the level-crossing phenomenon for any mechanism, which is vital for the emergence of the B(E2) anomaly. Thus, this anomaly is found to be related with the SU(3) symmetry. The B(E2) anomaly in is also analyzed.

The process e^+e^-→K_S^0K_S^0ψ (3686) is studied by analyzing e+e− collision data samples collected at eight center-of-mass energies ranging from 4.682 to 4.951 GeV with the BESIII detector operating at the BEPCII collider, corresponding to an integrated luminosity of 4.1 fb−1. Observation of the e^+e^-→K_S^0K_S^0ψ (3686) process is found for the first time with a statistical significance of 6.3σ, and the cross sections at each center-of-mass energy are measured. The ratio of cross sections of e^+e^-→K_S^0K_S^0ψ (3686) relative to e+e− → K+K−ψ(3686) is determined to be σ(e^+e^-→K_S^0K_S^0ψ (3686))/σ(e^+e^-→K^+K^-ψ (3686))=0.45± 0.25 , which is consistent with the prediction based on isospin symmetry. The uncertainty includes both statistical and systematic contributions. Additionally, the K_S^0ψ (3686) invariant mass distribution is found to be consistent with three-body phase space. The significance of a contribution beyond three-body phase space is only 0.8σ.

Using 7.9fb−1 of e+e− collision data collected at s=3.773 GeV with the BESIII detector at the BEPCII collider, we search for the massless dark photon with the flavor-changing neutral current processes D0→ωγ′ and D0→γγ′ for the first time. No significant signals are observed, and the upper limits at the 90% confidence level on the massless dark photon branching fraction are set to be 1.1×10−5 and 2.0×10−6 for D0→ωγ′ and D0→γγ′, respectively. These results provide the most stringent constraint on the new physics energy scale associated with cuγ′ coupling in the world, with the new physics energy scale related parameter |C|2+|C5|2<8.2×10−17 GeV−2 at the 90% confidence level. Published by the American Physical Society 2025

Due to high spatial resolution, low material budget and good particle identification (PID) performance, drift chamber is an important choice for CEPC trackers. In order to improve the PID capability of drift chambers, an innovative cluster counting method (dN/dx) is proposed. Unlike the dE/dx method by measuring the energy loss directly, the dN/dx method measures the number of primary ionizations along the trajectories of particles as they pass through the drift chamber. In this study, a test system with a detector prototype and fast readout electronics was set up and tested with an electron beam. Derivative-based reconstruction algorithm was adopted for the peak finding and clusterization in the signal waveforms. The test results show that the mean noise is about 0.9 mV, and the rise time of most peaks is less than 3 ns, which indicates that the system has low noise and high bandwidth, and can be used to accurately measure the ionization signals. The preliminary test results have basically validated the feasibility of the dN/dx method.

Based on a sample of (2712.4 ± 14.3) × 106 ψ(3686) events collected with the BESIII detector, a partial wave analysis of the decay ψ (3686)→ΛΣ^0π^0 + c.c. is performed to investigate Λ* and Σ* resonances in the π^0Σ^0 and π0Λ invariant mass distributions. Significant contributions are found from the Λ(1405), Λ(1520), Λ(1600), Λ(1670), Λ(1690), Λ(1800), Λ(1890), Λ(2325), Σ(1385), Σ(1660), Σ(1670), Σ(1750), and Σ(1910). The masses, widths, and production branching fractions for each component are determined. In addition, the branching fraction of ψ (3686)→ΛΣ^0π^0 + c.c. is measured to be (1.544 ± 0.013 ± 0.071) × 10−4 for the first time, where the first uncertainty is statistical and the second systematic.

A bstract Based on 7.33 fb − 1 of e + e − collision data collected by the BESIII detector operating at the BEPCII collider at center-of-mass energies from 4.128 to 4.226 GeV, a search for the Majorana neutrino ν m is conducted in the lepton-number-violating decays of $$ {D}_{\textrm{s}}^{+} $$ D s + → h − h 0 e + e + . Here, h − represents a K − or π − , and h 0 represents a π 0 , $$ {K}_S^0 $$ K S 0 or ϕ . No significant signal is observed, and the upper limits of their branching fractions at the 90% confidence level are determined to be $$ \mathcal{B} $$ B ( $$ {D}_{\textrm{s}}^{+} $$ D s + → ϕπ − e + e + ) < 6 . 9 × 10 − 5 , $$ \mathcal{B} $$ B ( $$ {D}_{\textrm{s}}^{+} $$ D s + → ϕK − e + e + ) < 9 . 9 × 10 − 5 , $$ \mathcal{B} $$ B ( $$ {D}_{\textrm{s}}^{+} $$ D s + → $$ {K}_S^0 $$ K S 0 π − e + e + ) < 1 . 3 × 10 − 5 , $$ \mathcal{B} $$ B ( $$ {D}_{\textrm{s}}^{+} $$ D s + → $$ {K}_S^0 $$ K S 0 K − e + e + ) < 2 . 9 × 10 − 5 , $$ \mathcal{B} $$ B ( $$ {D}_{\textrm{s}}^{+} $$ D s + → π − π 0 e + e + ) < 2 . 9 × 10 − 5 and $$ \mathcal{B} $$ B ( $$ {D}_{\textrm{s}}^{+} $$ D s + → K − π 0 e + e + ) < 3 . 4 × 10 − 5 . The Majorana neutrino is searched for with different mass assumptions within the range [0 . 20 , 0 . 80] GeV /c 2 in the decay of $$ {D}_{\textrm{s}}^{+} $$ D s + → ϕe + ν m with ν m → π − e + , and the upper limits of the branching fractions at the 90% confidence level are at the level of 10 − 5 –10 − 2 , depending on the mass of the Majorana neutrino.

Abstract Based on a data sample of (10087 ± 44) × 106 J/ψ events taken with the BESIII detector, we search for the flavor-changing neutral current charmonium decay J/ψ → D 0 μ + μ − + c.c. . No significant signal above the background is observed, and the upper limit on its branching fraction is set to be ℬ(J/ψ → D 0 μ + μ − + c.c.) < 1.1 × 10 −7 at the 90% confidence level. This marks the first search for a flavor-changing neutral current charmonium decay involving muons in the final state.

A bstract By analyzing e + e − collision data with an integrated luminosity of 7.9 fb − 1 collected with the BESIII detector at the center-of-mass energy of 3.773 GeV, the branching fraction of D + → τ + ν τ is determined as $$ \mathcal{B} $$ B = (9.9 ± 1.1 stat ± 0.5 syst ) × 10 − 4 . Using the most precise result $$ \mathcal{B} $$ B ( D + → μ + ν μ ) = (3.981 ± 0.079 stat ± 0.040 syst ) × 10 − 4 [1], we determine R τ/μ = Γ( D + → τ + ν τ )/Γ( D + → μ + ν μ ) = 2.49 ± 0.31, achieving a factor of two improvement in precision compared to the previous BESIII result. This measurement is in agreement with the standard model prediction of lepton flavor universality within one standard deviation.

B(E2) anomaly is becoming a hot topic in the field of nuclear structure. Since the B(E2) anomaly was experimentally found, understanding the mechanism of its production has become an important problem. Theoretical studies have found that the SU3-IBM and other extended IBM theories can give explanations, but different mechanisms were found. In this paper, the concept “SU(3) analysis” for B(E2) anomaly is proposed, and some new conclusions are obtained. The SU(3) third-order interaction [L× Q × L]^(0) and level-crossing are both vital for the emergence of the B(E2) anomaly. This technique can help us to better understand the realistic reason of the B(E2) anomaly.

Based on (2712.4 ± 14.3) × 106 ψ(3686) events collected at the BESIII detector operating at the BEPCII collider, we present the first observation of the decay ψ (3686)→K^-Λ (1520)Ξ^+ + c.c.. The product branching fraction ℬ[ψ (3686)→K^-Λ (1520)Ξ^++c.c.]×ℬ[Λ (1520)→ pK^-] is measured to be (9.47 ± 0.75 ± 0.97) × 10−7, where the first uncertainty is statistical and the second systematic.

We perform the first amplitude analysis of D_{s}^{+}→π^{+}π^{+}π^{-}π^{0} decays based on data samples of electron-positron collisions recorded with the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV, corresponding to an integrated luminosity of 7.33  fb^{-1}. We report the observation of D_{s}^{+}→f_{0}(980)ρ(770)^{+} with a statistical significance greater than 10σ and determine the branching fractions B(D_{s}^{+}→π^{+}π^{+}π^{-}π^{0}|_{non-η})=(2.04±0.08_{stat}±0.05_{syst})% and B(D_{s}^{+}→ηπ^{+})=(1.56±0.09_{stat}±0.04_{syst})%. Moreover, we measure the relative branching fraction between ϕ→π^{+}π^{-}π^{0} and ϕ→K^{+}K^{-} to be [B(ϕ(1020)→π^{+}π^{-}π^{0})/B(ϕ(1020)→K^{+}K^{-})]=0.230±0.014_{stat}±0.010_{syst}., which deviates from the world average value by more than 4σ.

Abstract The process e + e − → K S 0 K S 0 ψ 3686 $$ {e}^{+}{e}^{-}\to {K}_S^0{K}_S^0\psi (3686) $$ is studied by analyzing e + e − collision data samples collected at eight center-of-mass energies ranging from 4.682 to 4.951 GeV with the BESIII detector operating at the BEPCII collider, corresponding to an integrated luminosity of 4.1 fb −1. Observation of the e + e − → K S 0 K S 0 ψ 3686 $$ {e}^{+}{e}^{-}\to {K}_S^0{K}_S^0\psi (3686) $$ process is found for the first time with a statistical significance of 6.3σ, and the cross sections at each center-of-mass energy are measured. The ratio of cross sections of e + e − → K S 0 K S 0 ψ 3686 $$ {e}^{+}{e}^{-}\to {K}_S^0{K}_S^0\psi (3686) $$ relative to e + e − → K + K − ψ(3686) is determined to be σ e + e − → K S 0 K S 0 ψ 3686 σ e + e − → K + K − ψ 3686 = 0.45 ± 0.25 $$ \frac{\sigma \left({e}^{+}{e}^{-}\to {K}_S^0{K}_S^0\psi (3686)\right)}{\sigma \left({e}^{+}{e}^{-}\to {K}^{+}{K}^{-}\psi (3686)\right)}=0.45\pm 0.25 $$ , which is consistent with the prediction based on isospin symmetry. The uncertainty includes both statistical and systematic contributions. Additionally, the K S 0 ψ 3686 $$ {K}_S^0\psi (3686) $$ invariant mass distribution is found to be consistent with three-body phase space. The significance of a contribution beyond three-body phase space is only 0.8σ.

Using 20.3  fb^{-1} of e^{+}e^{-} collision data collected at a center-of-mass energy of E_{c.m.}=3.773  GeV with the BESIII detector operating at the BEPCII collider, we determine the branching fraction of the leptonic decay D^{+}→μ^{+}ν_{μ} to be (4.034±0.080_{stat}±0.040_{syst})×10^{-4}. Interpreting our measurement with knowledge of the Fermi coupling constant G_{F}, the masses of the D^{+} and μ^{+} as well as the lifetime of the D^{+}, we determine f_{D^{+}}|V_{cd}|=(48.02±0.48_{stat}±0.24_{syst}±0.12_{input}±0.15_{EM})  MeV after taking into account necessary radiative corrections. This result is a factor of 2.3 more precise than the previous best measurement. Using the value of the magnitude of the c→d Cabibbo-Kobayashi-Maskawa matrix element |V_{cd}| given by the global standard model fit, we obtain the D^{+} decay constant f_{D^{+}}=(213.5±2.1_{stat}±1.1_{syst}±0.8_{input}±0.7_{EM})  MeV. Alternatively, using the value of f_{D^{+}} from a precise lattice quantum chromodynamics calculation, we extract |V_{cd}|=0.2265±0.0023_{stat}±0.0011_{syst}±0.0009_{input}±0.0007_{EM}.