An amplitude analysis of the singly Cabibbo-suppressed decay D^0 → K^+ K^- π^0 π^0 is performed, for the first time, to determine the relative magnitudes and phases of different intermediate processes. The analysis uses e^+e^- collision data collected with the BESIII detector at the center-of-mass energy 3.773 GeV corresponding to an integrated luminosity of 20.3 fb^-1. The absolute branching fraction of D^0 → K^+ K^- π^0 π^0 is measured to be . The dominant intermediate process is D^0 → K^*(892)^+K^*(892)^-, with a branching fraction of (2.79 ± 0.13_stat.± 0.11_syst.) × 10^-3. Amplitude analysis reveals that the D^0 → K^*(892)^+K^*(892)^- decay is S-wave dominant. The longitudinal polarization fraction of D^0 → K^*(892)^+ K^*(892)^- is measured to be 0.468±0.046_stat.±0.011_syst..

Based on (10087±44)×10^6 J/ψ events collected with the BESIII detector, the J/ψ^0_SK^0_Sπ^0 and J/ψ^0π^0η processes are studied. The X(2370) is observed in both the K^0_SK^0_Sπ^0 and π^0π^0η invariant mass spectra, with statistical significances greater than 14σ and 20σ, respectively. By combining measurements from these processes with those from the previously reported J/ψ^0_SK^0_Sη^' process, the mass and width of the X(2370) are determined to be 2359^+13_-14 MeV/c^2 and 170^+44_-29 MeV, respectively. In addition, the decay X(2370)→ a_0(980)^0π^0 with a_0(980)^0→ π^0η is observed with a statistical significance exceeding 9σ. The properties of the X(2370)—decay pattern similarities to that of η_c, are consistent with those of a pseudoscalar glueball.

A partial wave analysis of the process ψ(2S)_c1, χ_c1^+π^-η^' is performed using (2712.4±14.3)×10^6 ψ(2S) events collected with the BESIII detector. An isovector state with exotic quantum numbers J^PC=1^-+, denoted as π_1(1600), is observed for the first time in the charmonium decay of χ_c1_1^±(1600)π^∓, π_1^±(1600)^±η^' with a statistical significance over 21σ. Its mass and width are determined to be 1828 ± 8 ( stat)^+11_-33( syst) MeV/c^2 and 638 ± 26 ( stat)^+35_-86( syst) MeV, respectively, using a relativistic Breit-Wigner function with a mass-dependent width. The corresponding product of branching fractions is determined to be ℬ[χ_c1_1(1600)^±π^∓] ×ℬ[π_1(1600)^±^±η^'] = ( 4.30 ± 0.14 ( stat)^+1.04_-1.03( syst) ) × 10^-4.

Using a direct scan of 26 energy points near the J/ψ resonance, we perform the first measurement of the relative phase ϕ_γ, 3g between the strong and electromagnetic amplitudes in J/ψ→K̅^0 K^*(892)^0+c.c. and J/ψ→ K^+ K^*(892)^-+c.c.. Unexpectedly, the phase in the neutral channel is found to be ∼ 150^∘, deviating from orthogonality (90^∘) by 4.2σ and from a relative real amplitude (0^∘ or 180^∘) by 10.0σ or 1.6σ, respectively. In contrast, the charged channel phase is consistent with ∼ 180^∘ within 1σ, exhibiting model-dependent behavior. The corresponding branching fractions are consistent with the world averages but achieve better than twofold improvement in precision. The ratios between the branching fractions of J/ψ→K̅^0 K^*(892)^0+c.c. and J/ψ→ K^+ K^*(892)^-+c.c. are also measured. After subtracting the electromagnetic contribution, the corresponding strong amplitude ratios obey isospin symmetry within 1.8σ. A search for direct CP violation yields asymmetries consistent with zero.

A measurement of the CKM angle γ is performed by applying a novel, unbinned, model-independent approach to datasets of electron-positron collisions collected by the BESIII experiment and proton-proton collisions by the LHCb experiment, corresponding to integrated luminosities of 8 fb^-1 and 9 fb^-1, respectively. The CP-violating phase γ is determined from B^±→ D(→ K_ S^0 h^'+h^'-) h^± decays in LHCb data, where h^(') is either a pion or kaon, while the corresponding strong-phase parameters are measured using doubly tagged D→ K_ S/L^0 h^'+ h^'- decays in the quantum-correlated DD system present in BESIII data. A joint fit to both datasets, which allows for a simultaneous determination of the associated CP-violating observables and strong-phase parameters, yields γ= (71.3± 5.0)^∘. The result is the most precise to date and consistent with previous measurements and world averages.

Pulsar wind nebulae (PWNe) are major cosmic ray accelerators, yet the mechanisms transporting high-energy particles into the interstellar medium remain elusive. Building on the LHAASO discovery of an ultra-high-energy (UHE) γ-ray source near the bow-shock PWN powered by the pulsar PSR J1740+1000, we present a joint Einstein Probe (EP) and LHAASO study of this system. EP observations reveal an extended X-ray tail far exceeding the structure previously seen by XMM-Newton. Updated LHAASO observations show that the γ-ray emission is elongated, with its major axis aligned with the extended X-ray tail revealed by EP. This is the first detection of an X-ray pulsar tail associated with a spatially coincident extended UHE γ-ray emission. The X-ray and γ-ray spectrum can be well explained with a single population of relativistic electrons via synchrotron and inverse Compton radiation, respectively, removing the need for particle re-acceleration during propagation. The results unambiguously show that electrons/positrons above 100 TeV are escaping from the PWN. Instead of the immediate, isotropic diffusion into ambient interstellar medium that is typically assumed, these particles are transported anisotropically over at least ∼10 pc, either guided by the background magnetic field or carried by an advective outflow.

We present a comprehensive analysis of the recently discovered TeV gamma-ray source, LHAASO J2238+5900. Based on data collected from the LHAASO, our fitting results suggest that the source is significantly extended with an angular extension of 0.54° ±0.01° and is spatially coincident with the pulsar PSR J2238+5903. Its spectrum is characterized by a power-law with a cutoff at 41.0±3.5 TeV. Additionally, the source exhibits a significant signal of 7.9σabove 100 TeV, implying that it is a PeVatron candidate. While the gamma-ray emission is consistent with a pulsar wind nebula (PWN) scenario, the relatively large extension size also allows for a halo interpretation, potentially caused by electron-positron pairs escaping from the PWN.

Using e^+e^- annihilation data collected at 26 center-of-mass energy points between 3000.00 and 3119.88 MeV with the BESIII detector, corresponding to a total integrated luminosity of about 440.7 pb^-1, we study the cross section lineshape of e^+e^-→ K_S^0 K^+π^-+c.c.. The relative phases and magnitudes between J/ψ strong and electromagnetic decay amplitudes are measured to be (123.7±5.3)^∘;4.31±0.22 or (-123.1±5.2)^∘;4.38±0.22, with corresponding branching fractions ℬ(J/ψ→ K_S^0 K^+π^-+c.c.)=(5.17±0.20) or (5.36±0.20)×10^-3. Based on a partial wave analysis, the cross sections of e^+e^-→K̅^0 K^*(892)^0+c.c. and e^+e^-→ K^+ K^*(892)^-+c.c. are obtained. For these subprocesses, the relative phases and magnitudes are determined as (155.2±15.5)^∘;3.67±0.27 or (-154.1±15.5)^∘;3.71±0.25 and (180.1±31.8)^∘;25.06±2.51, respectively. The large relative phases deviate from the orthogonality relation expected from experiment and from the assumption of purely real amplitudes by more than 3σ. The measured branching fractions ℬ(J/ψ→K̅^0 K^*(892)^0)+c.c.=(4.18±0.18) or (4.31±0.19)×10^-3, ℬ(J/ψ→ K^+ K^*(892)^-+c.c.)=(7.09±0.28)×10^-3 are all consistent with the world average values, but achieve better than a twofold improvement in precision. The ratios between the branching fractions of J/ψ→K̅^0 K^*(892)^0+c.c. and J/ψ→K̅^+ K^*(892)^-+c.c. are ℛ_K^*K̅=0.589±0.012 or 0.612±0.013. After subtracting the electromagnetic contribution, the corresponding strong amplitude ratios are ℛ^3g_K^*K̅=0.884±0.050 or 0.909±0.044, which deviate 2.3 or 2.1σ from the unity. No evidence for direct CP violation is observed.

A measurement of the CKM angle γ and related strong-phase parameters is performed using a novel, model-independent approach in B^±→ D(→ K^0_ S h^'+h^'-) h^± decays, where h^(')≡ π, K. The analysis uses a joint data sample of electron-positron collisions collected by the BESIII experiment at the Beijing Electron-Positron Collider II during 2010–2011 and 2021–2022, corresponding to an integrated luminosity of 8 fb^-1, and proton-proton collisions collected by the LHCb experiment at the Large Hadron Collider during 2011–2018, corresponding to an integrated luminosity of 9 fb^-1. The two datasets are analyzed simultaneously by applying per-event weights based on the amplitude variation over the D-decay phase space to enhance the sensitivity to CP-violating observables. The CKM angle γ is determined to be γ= (71.3± 5.0)^∘, which constitutes the most precise single measurement to date.

Microquasars, binary systems featuring relativistic jets, have emerged as sources for particle acceleration beyond PeV energies. We present a study of the broadband γ-ray emission from one of the most prominent Galactic microquasars GRS 1915+105 based on data accumulated by LHAASO and Fermi-LAT over 4 and 17 years, respectively. A joint analysis of LHAASO-WCDA and LHAASO-KM2A data reveals extended γ-ray emission whose centroid appears significantly shifted, by 0.13°, from the binary system and its jets. The spectral energy distribution is well described by a curved spectrum with progressive steepening that can be described by a log-parabola function with no evidence for a sharp cutoff, consistent with parent particles reaching multi-PeV energies and an extreme acceleration efficiency approaching the limit set by the available potential drop across the source. Several features, most notably the shift of the emission and single-power-law spectrum down to GeV band, favor radiation by cosmic rays accelerated in the source interacting with the dense ambient medium. Our spectral modeling implies that at least a few percent of the jet mechanical power is transferred to protons, whose maximum energy reaches beyond 5 PeV. These results strengthen the case for microquasars as exceptionally efficient accelerators in our Galaxy.

The quest for the origin of cosmic ray (CRs) is a fundamental issue in astrophysics. Shocks of supernova remnants (SNRs) have been considered as the dominant contributors to Galactic CRs below the spectral knee near ∼ 3 petaelectronvolt (PeV). Whether SNRs are efficient accelerators of particles beyond PeV energies has long been debated. Here we report observations of very-high-energy γ-ray emission up to hundreds of TeV from two middle age shell-type SNRs, G150.3+4.5 and γ-Cygni, with the Large High Altitude Air Shower Observatory (LHAASO). Two (or three) distinct morphological/spectral components with convex spectral shapes are observed in both sources, with the low-energy one being more extended than the high-energy one.

We search for possible charmonium(-like) states decaying into the pp̅ final state by studying the Born cross sections of the e^+e^-→ pp̅ reaction, and we determine the proton electromagnetic form factors by analyzing the proton angular distribution. The measurement is performed using a sample of e^+e^- collision data collected at 47 center-of-mass energies from 3.510 to 4.946 GeV, corresponding to an integrated luminosity of 26 fb^-1, recorded by the BESIII detector collected at the BEPCII collider. The decay ψ(3770)→ pp̅ is observed with a significance of 6.6σ including systematic uncertainties. Furthermore, a structure near 4.2 GeV is observed with significances of 4.6σ or 4.8σ for the ψ(4160) or Y(4230) hypotheses including systematic uncertainties, respectively; these interpretations cannot presently be distinguished. In addition, the moduli of the form factor ratios |G_E/G_M| and of the magnetic form factors |G_M| are extracted by analyzing the proton polar angle distribution with higher precision at large time-like squared momentum transfer. These results provide important experimental insights into both the decay mechanisms of charmonium(-like) states in the open charm region and the internal structure of proton.

Using e^+e^- collision data collected with the BESIII detector at the BEPCII collider corresponding to a total integrated luminosity of 44 fb^-1, we present the first measurement of the Born cross sections for the process e^+e^-→ K_S^0^+Σ^-+c.c. at 56 center-of-mass energies from 3.510 to 4.951 GeV. By fitting the dressed cross sections of e^+e^-→ K_S^0^+Σ^-+c.c. with the assumption of a power-law function plus a charmonium(-like) resonance, i.e. ψ(3770), ψ(4040), ψ(4160), Y(4230), Y(4360), ψ(4415), Y(4500), Y(4660), and Y(4710), no significant signal of any charmonium(-like) state decaying into the K_S^0^+Σ^-+c.c. is observed. Upper limits on the product of the electronic width and branching fraction at the 90% confidence level are given for each resonance. Combining this result with the previous measurement of the isospin-symmetric process e^+e^-→ K^-^+ Σ^0 + c.c., the ratio of the Born cross sections, R=σ^B(e^+e^-→ K_S^0^+Σ^-+c.c.)/σ^B(e^+e^-→ K^-^+Σ^0+c.c.), is found to be approximately 1.

Based on the antisolvent-induced crystallization method of (3-glycine, we successfully achieved the controlled preparation of (3-glycine crystals ranging from submicron to centimeter scale using antisolvent methods. Importantly, we developed one-step in situ inducing strategy to form (3-glycine composite films. Based on the solubility differences of polymers in water and antisolvents, (3-glycine/polymer films were classified into three categories with distinct properties. In particular, (3-glycine/PCL films demonstrated high effective piezoelectric coefficient (10.3 pm/V) and superior stability in crystal form. The piezoelectric nanogenerator (PENG) fabricated using (3-glycine/PCL films exhibited excellent electrical output performance under mechanical pressure. Furthermore, under ultrasound stimulation, the PENG generated outputs of about 620 and 274 mV in vitro and in vivo, respectively. The device also exhibited good biocompatibility, indicating promising applications in implantable electrical stimulation therapeutic devices.

Based on a novel method for producing antineutrons via J/ψ decays, we report a study of n̅p inelastic scattering into final states containing kaons. The analysis uses (10087±44)× 10^6 J/ψ events collected at the BESIII detector operating at the BEPCII storage ring. Antineutrons are produced via J/ψ→ p π^-n̅ decays and tagged by the detected protons and pions, resulting in antineutron momenta ranging from 0 to 1174 MeV/c, while target protons are provided by the hydrogen in the beam-pipe material. The cross sections of the reactions n̅p → K^+K^-π^+ and n̅p → K^+K^-π^+π^0 are measured to be 0.53^+0.15_-0.12± 0.08 mb and 1.09^+0.36_-0.30± 0.31 mb respectively, where the first uncertainties are statistical and the second systematic. Due to limited statistics, the intermediate states in these processes are not investigated. The observation of clean antineutron-proton scattering events indicates the potential of this approach for future investigations of antineutron-proton interactions.

The Large High Altitude Air Shower Observatory (LHAASO) monitors sources within its field of view for up to 7 hr daily, achieving a duty cycle exceeding 98% and an annual point-source sensitivity of 1.5% Crab units (CU) in the very-high-energy (VHE) band. This unbiased sky-survey mode facilitates systematic monitoring and investigation of outburst phenomena. In this paper, we present results from an unprecedented 3 yr monitoring campaign (2021 March–2024 March) of Markarian 421 (Mrk 421) using LHAASO, spanning energies from 0.4 to 20 TeV. We find that the blazar stayed in a quiescent state in 2021 and became active starting in 2022 with a total of 23 VHE outburst events identified, where the highest observed daily significance reaches 20 σ with a flux equivalent to approximately 3.3 CU. LHAASO’s continuous monitoring suggests the flaring occupancy of Mrk 421 to be around 14%. During long-term monitoring, multiwavelength (MWL) variability and correlation analyses are conducted using complementary data from the Fermi Large Area Telescope, Monitor of All-sky X-ray Image Gas Slit Camera, the Neil Gehrels Swift Observatory X-Ray Telescope, and the Zwicky Transient Facility. A significant correlation (>3 σ ) is observed between the X-ray and VHE bands with no detectable time lag, while the correlation between the GeV and TeV bands is weaker. The energy spectrum of the TeV emission during the quiescent state is different from that in the active state, implying the existence of two modes of energy dissipation in the blazar jet. Using simultaneous MWL data, we also analyzed both the long-term and outburst-period spectral energy distributions, and discussed the possible origin of the outburst events.

Using (2.71 ± 0.01) × 10^9 ψ(3686) events collected with the BESIII detector, a joint full angular distribution analysis is carried out for the process ψ(3686) → Ω^-(^-) ^+(→^+). The first simultaneous measurement of the weak decay parameters ϕ_Ω^- and ϕ_^+ for Ω^- → K^-Λ and ^+ → K^+ is performed, yielding the first result for the CP-sensitive observable, ϕ_ CP = (-0.004 ± 0.055 ± 0.017) rad, where the first and second uncertainties are statistical and systematic, respectively. This further enables the extraction of the weak and strong phase differences between the P- and D-wave amplitudes: (ξ_D - ξ_P) = (-0.15 ± 2.25 ± 0.69) rad and (δ_D - δ_P) = (-0.97 ± 0.88 ± 0.34) rad. Additionally, the polarization correlations between Ω^- and ^+ are measured.

We report a measurement of the Born cross section and the effective form factor for the e^+e^-→ pp̅ reaction at 47 center-of-mass energies between 3.510 and 4.946 GeV. The measurement is performed using the energy-scan technique and is based on data corresponding to an integrated luminosity of 26 fb^-1 collected with the BESIII detector at the BEPCII collider. For the first time, the moduli of the electromagnetic form factor ratio |G_E/G_M| and of the magnetic form factor |G_M| are determined with high precision by analyzing the distribution of the polar angle of the proton at a large timelike momentum transfer. These results provide essential insights into the nature of charmonium(-like) states above the open-charm threshold and the dynamics underlying the proton electromagnetic form factors.

Based on 8.5 fb^-1 of e^+e^- collision data collected at center-of-mass energies between 4.42 and 4.95 GeV with the BESIII detector at the BEPCII storage ring, we investigate the process e^+e^-→ π^+π^-D_s^+D_s^-. With no significant signal observed, upper limits on the Born cross sections of e^+e^-→ π^+π^-D_s^+D_s^- at each energy value are determined at the 90

Using a sample of (10087±44)×10^6 J/ψ events collected with the BESIII detector, we investigate the inelastic scattering processes Λ+p^0+p and +p→^0+p, exploiting hyperons from J/ψ decays as an effective beam and the beam-pipe materials as targets. The processes Λ+^9Be^0+p+^8Li and +^9Be→^0+p+^8Li are measured at a hyperon momentum of 1.074 GeV/c, with cross sections of (10.1±1.4_ stat±0.7_ syst) mb and (1.7±0.6_ stat±0.4_ syst) mb, respectively. Under the assumption of surface-dominated hyperon-nucleus scattering, these measurements are used to extract the corresponding proton-target cross sections. Independently, direct measurements using the hydrogen component of the beam-pipe oil yield (3.2±1.1_ stat±0.5_ syst) mb for Λ+p^0+p and (1.5±0.5_ stat±0.1_ syst) mb for +p→^0+p, consistent with the indirect determinations. The combined cross sections are (4.7±0.7) mb and (1.1±0.3) mb, respectively. The +p→^0+p signal constitutes the first evidence for anti-hyperon inelastic scattering with baryonic final states, with a significance of 3.1σ. The pronounced difference between the Λp and inelastic scattering cross sections provides new experimental constraints on hyperon-nucleon and anti-hyperon-nucleon interactions.