In this work, we investigate the decay and production properties of the strange double-charm pentaquark P ccs with strangeness S = -1. Building upon our previous work predicting its JP = 1=2-molecular configuration, we employ three-point QCD sum rules to calculate its strong decay widths and estimate its production branching ratio via Xi+bc baryon decays. The total strong decay width to the EccK & strns; and 5cc pi final-state channels is determined as 85 + 19 MeV. Furthermore, using a rescattering mechanism, we analyze the b-* D*- s Xi++cc-* D-P ccs process and estimate the production branching ratio to be Br(Xi+bc-* D-Pmss ) = (4.3+2.0-1.5 ) & times; 10-6. The relatively narrow width and detectable branching ratio suggest the possibility searching for this pentaquark state in the future.

We revisit the light tetraquark states with quantum numbers J^PC=1^++ using QCD sum rules, focusing on a complete set of derivative-free diquark-antidiquark interpolating currents. By calculating the operator product expansion up to dimension-eight condensates, we extract the ground-state mass of the hidden-strange usu̅s̅ tetraquark from both Laplace sum rules (LSR) and finite-energy sum rules (FESR). Our combined analysis yields M_usu̅s̅ = 1.45±0.11 GeV, which agrees well with the mass of the a_1(1420) resonance and supports its tetraquark interpretation. Furthermore, we perform Gaussian sum rule (GSR) analyses to probe radial excitations, adopting a two-resonance narrow-width model. The GSR fit reveals a heavier state with mass m_2 = 1.86±0.12 GeV and a relative coupling r = 0.15±0.03 for the lighter state, indicating that the a_1(1930) is a promising candidate for a compact 1^++ tetraquark. We also discuss the dominant decay modes of these tetraquark candidates, emphasizing hidden-strange channels such as K^*K and f_0(980)π, which can be tested in future experiments.

We investigate the heavy quarkonium hybrid mesons with exotic quantum numbers = 2+- via QCD sum rule method. We construct the currents with three Lorentz indices and calculate the correlation functions up to dimension six at the leading order of . The states with = 2+- are extracted by constructing the corresponding projection operators. The obtained results indicate that the masses of 2+- and hybrid states are about 4.49 GeV and 10.48 GeV, respectively. We suggest to search for hybrid meson with = 2+- in / 0,1,2 and 0,1,2 final states.

We investigate the heavy quarkonium hybrid mesons with exotic quantum numbers JPC=2+− via QCD sum rule method. We construct the currents with three Lorentz indices and calculate the correlation functions up to dimension six at the leading order of αs. The states with JPC=2+− are extracted by constructing the corresponding projection operators. The obtained results indicate that the masses of 2+− c¯Gc and b¯Gb hybrid states are about 4.49 GeV and 10.48 GeV, respectively. We suggest to search for c¯Gc hybrid meson with JPC=2+− in J/ψf0,1,2 and χc0,1,2ω final states.

We investigate the three-body DDK system with quantum numbers I(J^P) = 1/2(0^-) within a coupled-channel framework that incorporates both DDK and D^*D^*K configurations. The D^(*)D^(*) interactions are described using the one-boson-exchange model constrained by the heavy-quark symmetry and fitted to the pole positions of X(3872), T_cc^+, and Z_c(3900). The D^(*)K interaction is from the chiral effective theory, motivated by the molecular interpretation of D_s0^*(2317), and is further constrained by lattice-QCD results for the DK scattering lengths. The resulting three-body problem is solved using the Gaussian expansion method, while the complex scaling method is employed to search for possible resonant states. We find that coupled-channel effects from D^*D^*K are negligible, and the DDK system supports a deeply bound state across a wide range of parameters. Depending on the long-range behavior of the DK interaction, an additional shallow state may emerge near the particle-dimer (D-DK) threshold. The deeply bound state exhibits a compact three-body structure, whereas the shallow state displays characteristic features of a three-body halo configuration. No clear resonance poles are identified within the explored parameter region. Similar results are obtained for the D^*D^*K system. These findings may provide new insight into few-body dynamics in systems involving charmed mesons and kaons.

The landmark detection of neutrinos from SN1987A marked the dawn of neutrino astrophysics. The neutrino burst provided essential insights into fundamental properties of neutrinos, and served as key probes of stellar evolution and supernova dynamics. The recent advancement in coherent elastic neutrino-nucleus scattering enables the detection of core-collapse supernova burst neutrinos using tonne-scale liquid xenon detectors originally designed for dark matter direct detection. Leveraging this capability, we developed and deployed an online supernova monitoring system for the PandaX-4T experiment. This system features a GPS module with millisecond-level timing precision, a low false-alarm rate, and high sensitivity to galactic core-collapse supernova explosion events. The methodology is robust, directly scalable, and planned for implementation in the next-generation PandaX-20T experiment.

Scalar-mediated interactions may exist among neutrinos, dark matter particles, or between the two. Double β-decay experiments provide a powerful tool to probe such exotic interactions. Using ^{136}Xe double β-decay data from PandaX-4T, we perform the first direct spectral search in the energy range of 20 to 2800 keV, setting the most stringent limits to date on scalar-mediated neutrino self-interactions for mediator masses below 2  MeV/c^{2}. These results place significant constraints on models invoking such interactions to alleviate the Hubble tension. Assuming the same scalar also mediates dark matter self-interactions, constraints on the dark matter-scalar interactions can be placed in conjunction with cosmological constraints.

We report a precise measurement of Po-216 half-life using the PandaX-4T liquid-xenon time-projection chamber (TPC). Rn-220, emanating from a Th-228 calibration source, is injected to the detector and undergoes successive alpha decays, first to Po-216 and then to Pb-212. The PandaX-4T detector measures the five-dimensional (5D) information of each decay, including time, energy, and three-dimensional position. Therefore, we can identify the Rn-220 and Po-216 decay events and pair them exactly to extract the lifetime of each Po-216. With a large data set and high-precision Rn-220 - Po-216 pairing technique, we measure the Po-216 half-life to be 143.7 +/- 0.5 ms, which is the most precise result to date and agrees with previously published values. The leading precision of this measurement demonstrates the power of the 5D calorimeter and the potential of exact parent-daughter pairing in the xenon TPC.

We investigate the mass and strong decay properties of the Ω(2012) resonance using QCD sum rules, assuming it to be an S-wave Ξ(1530)K molecular pentaquark state with IJ^P = 03/2^-. A unified interpolating current is constructed, and the two-point and three-point correlation functions are calculated up to dimension-10 condensates in the OPE series. The negative-parity contribution is isolated by employing parity-projected sum rules. The two-body strong decays to Ξ^0 K^- and Ξ^- K^0 are studied via their three-point correlation functions. Our analysis yields a mass of 2.00 ± 0.15 GeV and a total two-body decay width of Γ= 3.97^+8.31_-1.92 MeV for the Ξ(1530)K molecular state. The ratios of branching fractions are obtained as ℛ^Ξ^- K^0_Ξ^0 K^- = 0.85 and ℛ^ΞπK_ΞK = 0.61. These results are compatible well with the experimental data for the Ω(2012) and support its interpretation as a Ξ(1530)K molecular pentaquark state.

The recent observation of a family of fully-charm tetraquark states by the LHCb, ATLAS and CMS Collaborations suggests the possible existence of fully-heavy dibaryons. In this work, we investigate the Ω_cccΩ_ccc and Ω_bbbΩ_bbb dibaryons in both the ^1S_0 and ^5S_2 channels using the method of QCD sum rules. We employ the iterative dispersion relation (IDR) method to efficiently compute the massive five-loop banana diagrams that appear in these systems, and properly address the tricky small-circle divergence problem in the nonperturbative terms. Our analyses reveal that for both charm and bottom systems, the scalar dibaryon lies lower than its tensor counterpart. The mass of the scalar Ω_cccΩ_ccc dibaryon is found to be slightly above the 2Ω_ccc mass threshold, while the Ω_bbbΩ_bbb systems may form bound states.

The recent observation of a family of fully charm tetraquark states by the LHCb, ATLAS, and CMS Collaborations suggests the possible existence of fully heavy dibaryons. In this work, we investigate the S2cccS2ccc and S2bbbS2bbb dibaryons in both the 1S0 and 5S2 channels using the method of QCD sum rules. We employ the iterative dispersion relation (IDR) method to efficiently compute the massive five-loop banana diagrams that appear in these systems, and properly address the tricky small-circle divergence problem in the nonperturbative terms. Our analyses reveal that for both charm and bottom systems, the scalar dibaryon lies lower than its tensor counterpart. In the MS scheme, the mass of the scalar S2cccS2ccc dibaryon is found to be slightly above the 2S2ccc mass threshold, while the S2bbbS2bbb systems may form bound states. However, they are predicted to be much heavier in the on-shell scheme.

We report a new measurement of the solar proton–proton (pp) neutrino flux via neutrino–electron elastic scattering using the PandaX-4T Run 2 data set collected between 2024 and 2026, corresponding to an exposure of 1.9 tonne·yr. Before Run 2 data taking, the detector underwent a series of upgrades to improve its response and background conditions. Time variations of radioactive noble-gas impurities are constrained using the physics data themselves, complemented by measurements from the gas-assay system. The analysis introduced improvements in the data processing chain, detector response characterization, and background models. A blind spectral analysis was then performed on the electronic-recoil data across a wide energy range from 20 to 1000 keV. In combination with the Run 0 data published earlier, the fitted pp flux is (8.5 ± 3.5)× 10^10 cm^-2s^-1, consistent with the prediction of the Standard Solar Model. With a statistical significance of 2.2σ above background, this marks the first positive indication of solar pp neutrino–electron scattering below an electronic-recoil energy of 165 keV.

Abstract We present a comprehensive next-to-leading order (NLO) QCD sum rule analysis for light hybrid mesons with J PC = 1 −− , incorporating condensates up to dimension-8 and NLO corrections to the perturbative, gluon condensate, and four-quark condensate contributions. These corrections are found to be substantial and reveal the necessity of contributions beyond leading order. Employing both Laplace (LSR) and Gaussian (GSR) sum rules, our analysis predicts a mass in the conservative range of 2.1 – 2.4 GeV for the light 1 −− hybrid. These predictions are significantly lower than previous leading-order (LO) estimates (around 2.9 GeV) and bridge the gap between QCD sum rules and other approaches. Our findings establish the ϕ(2170) resonance as a prime candidate for the light vector hybrid meson.

We study the three-body systems DNN and D*NN within a hadronic molecular framework by combining a realistic nucleon-nucleon interaction with a D(*)N potential constrained by heavy-quark symmetry. The three-body Schr & ouml;dinger equation is solved with the Gaussian expansion method, and the analytic structure of the spectrum is investigated using the complex scaling method. We find that the DNN system supports a robust and compact bound state in the I(JP) = 12 (1-) channel over a broad range of cutoff values, even when the corresponding DN subsystem is weakly bound or unbound. For D*NN, the spin-1 nature of the heavy meson and the associated spin-dependent forces generate a clear spin hierarchy: deeply bound states appear in both 0- and 2- channels, while the 1- channel exhibits a characteristic twobranch pattern with a strongly bound compact branch and a more weakly bound, spatially extended branch. The root-mean-square radii indicate pronounced spatial compression compared with the deuteron scale, highlighting the cooperative roles of realistic NN correlations, the D(*)N interactions, and heavy-quark symmetry in forming compact heavy-flavor few-body bound states. No three-body resonances under complex scaling are found in the explored parameter space. Our results provide quantitative benchmarks for future experimental searches for such charmed-meson-nuclear bound states.

The continuous spectrum of double beta decay (ββ) provides a sensitive probe to test the predictions of the standard model and to search for signatures of new physics beyond it. We present a comprehensive analysis of the ^{136}Xe ββ spectrum utilizing 39.1±0.7  kg·yr of ^{136}Xe exposure from the PandaX-4T experiment. The analysis yields the most precise measurement to date of the ^{136}Xe two-neutrino double beta decay (2νββ) half-life, (2.14±0.05)×10^{21}  years, the uncertainty of which is reduced by a factor of 2 compared to our previous result. We measure the parameter ξ_{31}^{2ν}, defined as the ratio between the subleading and leading components of the ^{136}Xe 2νββ nuclear matrix element, to be 0.59_{-0.38}^{+0.41}, which is consistent with theoretical predictions. We also search for Majoron-emitting modes of ^{136}Xe ββ, establishing the most stringent limit for the spectral index n=7.

We investigate isospin-breaking effects in double-charm molecular pentaquarks with the D^(*)Σ_c^(*) configuration, using the one-boson-exchange potential framework. In these systems, the isospin-breaking effects arise from two sources: the strong interaction, which manifests as the threshold difference of the D^(*)Σ_c^(*) components in the same isospin multiplet and the mass splittings of the exchanged isovector mesons (π and ρ); and the electromagnetic interaction between charged D^(*) and Σ_c^(*) components. We calculate the binding properties and the isospin mixing angle between the I=1/2 and I=3/2 states of the D^(*)Σ_c^(*) system. Our results show that the isospin-breaking effect contributes a significant correction of roughly 10%-30% to the binding energy. This effect is particularly pronounced in loosely bound molecular candidates, which are characterized by small binding energies and large root-mean-square radii. We therefore conclude that the explicit inclusion of isospin-breaking effects is essential for achieving the precision in theoretical calculations necessary to match rapidly advancing experimental programs. Our results are expected to provide valuable guidance for future high-precision experimental studies of deuteron-like molecular states.

This corrects the article DOI: 10.1103/rtnh-jn8s.

The observation of neutrinoless quadruple beta decay (0ν4β) in the absence of neutrinoless double beta decay (0ν2β) has been argued to provide a strong indication that neutrinos are Dirac particles. We report a search for 0ν4β decay of ^136Xe using a total ^136Xe exposure of 148.4 kg·yr, collected during the commissioning and the first science runs of the PandaX-4T experiment. No significant excess of events over the background is observed. A lower limit on the 0ν4β decay half-life of ^136Xe is set at 6.01 x 10^24 yr at the 90

In QCD sum rules for light-quark systems, infrared (IR) divergences can appear in the Wilson coefficients of certain condensates. These divergences manifest explicitly in the coordinate-space expressions of the light-quark propagators. We propose an improved method to eliminate these IR divergences at the propagator level and present a subtraction formula that implements this procedure. Compared to the existing methods that rely on the mixing between quark and gluon condensates of the same dimension to eliminate IR divergences, this method is more intuitive and easier to apply in practical QCD sum rule calculations.

Within the method of parity-projected QCD sum rules, we study the mass spectra of light hybrid baryons with I(JP) = 1/2(1/21), 3/2(1/21), 1/2(3/21), 3/2(3/21) by constructing the local qqqg interpolating currents. We calculate the correlation functions up to dimension eight condensates at the leading order of as. The stable QCD Lapalce sum rules can be established for the positive-parity N1/2+, Delta 3/2+, Delta 1/2+ and negative-parity N1/2-, N3/2-, Delta 1/2- channels to extract their mass spectra. The lowest-lying hybrid baryons are predicted to be the positive-parity N1/2+ state around 2.01 GeV. These hybrid baryons mainly decay into conventional baryon plus meson final states. We propose to search for the light hybrid baryons through the & upsih;/yi(3686) decays via the three-gluon emission mechanism in BESIII and BelleII experiments. Hopefully, our studies of the light hybrid baryons will be useful for understanding the excited baryon spectrum and the behavior of gluonic degrees of freedom in QCD.