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An amplitude analysis of the Cabibbo-favored decay D+ -> K-pi+pi+pi 0 is performed, using 7.93 fb-1 of e+e- collision data collected with the BESIII detector at the center-of-mass energy of 3.773 GeV. The branching fractions of the intermediate processes are measured, with the dominant contribution D+-> K<overline>& lowast;8920 rho 770+\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {D}<^>{+}\to {\overline{K}}<^>{\ast }{(892)}<^>0\rho {(770)}<^>{+} $$\end{document} observed to have a branching fraction of (4.35 +/- 0.07stat.+/- 0.17syst.)%. With the detection efficiency derived from the amplitude analysis, the absolute branching fraction of D+-> K-pi+pi+pi 0 is measured to be (6.35 +/- 0.04stat.+/- 0.07syst.)%.

Charged-particle trajectories are usually reconstructed with the LHCb detector using combined information from the tracking devices placed upstream and downstream of the 4 T m dipole magnet. Trajectories reconstructed using only information from the tracker downstream of the dipole magnet, which are referred to as T tracks, have not been used for physics analysis to date. The challenges of the reconstruction of long-lived particles with T tracks for physics use are discussed and solutions are proposed. The feasibility and the tracking performance are studied using samples of long-lived Lambda and K-S(0) hadrons decaying between 6.0 and 7.6 m downstream of the proton-proton collision point, thereby traversing most of the magnetic field region and providing maximal sensitivity to magnetic and electric dipole moments. The reconstruction can be expanded upstream to about 2.5 m for use in direct searches of exotic long-lived particles. The data used in this analysis have been recorded between 2015 and 2018 and correspond to an integrated luminosity of 6 fb(-1). The results obtained demonstrate the possibility to further extend the decay volume and the physics reach of the LHCb experiment.

The process e(+) e(-) -> 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)(3686) process is found for the first time with a statistical significance of 6.3 sigma, and the cross sections at each center-ofmass energy are measured. The ratio of cross sections of e(+) e(-) -> K-S(0) K-S(0)psi(3686) relative to e(+) e(-) -> K+ K-psi(3686) is determined to be sigma(e(+) e(-) -> K-S(0) K-S(0)psi(3686))/sigma(e(+)e(-) -> K+ K- psi(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(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 0.8 sigma.

We measure the Born cross section for the reaction 𝑒+⁢𝑒−→𝜂⁢ℎ𝑐 from √𝑠 =4.129 to 4.600 GeV using datasets collected by the BESIII detector running at the BEPCII collider. A resonant structure in the cross-section line shape near 4.200 GeV is observed with a statistical significance of 7⁢𝜎. The parameters of this resonance are measured to be 𝑀=4188.8±4.7±8.0  MeV/𝑐2 and Γ=49±16±19  MeV, where the first uncertainties are statistical and the second systematic.

Studies are performed of the Cabibbo-favored decay Lambda(+)(c) -> Lambda(KSK+)-K-0 and the singly Cabibbosuppressed decay Lambda(+)(c) -> Lambda K-S(0)pi(+), based on a sample of e(+)e(-) collision data, corresponding to an integrated luminosity of 4.5 fb(-1), accumulated at center-of-mass energies between 4599.53 MeV and 4698.82 MeV with the BESIII detector. The decay Lambda(+)(c) -> Lambda K-S(0)pi(+) is observed for the first time. The branching fractions of Lambda(+)(c) -> Lambda(KSK+)-K-0 and Lambda(+)(c) -> Lambda K-S(0)pi(+) are measured to be (3.04 +/- 0.30 +/- 0.16) x 10(-3) and o1.73 +/- 0.27 +/- 0.10) x 10(-3), respectively, where the first uncertainties are statistical and the second are systematic. These results correspond to the most precise measurement of these quantities for both decays. Evidence of a K*(+) contribution in the Lambda(+)(c) -> Lambda K-S(0)pi(+) decay is found with a statistical significance of 4.71 sigma. The branching fraction of Lambda(+)(c) -> Lambda K*+ is calculated under three possible interference scenarios, with the significance increasing to 5.03 sigma when interference is taken into account.

The CP-even fractions (F+) of the decays D-0 -> pi(+) pi(-) pi(0) and D-0 -> K+ K- pi(0) are measured with a quantum-correlated psi(3770) -> D (D) over bar data sample collected by the BESIII experiment corresponding to an integrated luminosity of 7.93 fb(-1). The results are F+pi(+) pi(-) pi(0) = 0.9406 +/- 0.0055 +/- 0.0033 and F-+(K+ K- pi 0) = 0.631 +/- 0.014 +/- 0.011, where the first uncertainties are statistical and the second systematic. These measurements are consistent with the previous determinations, and the uncertainties for F+pi(+) pi(-) pi(0) and F-+(K+ K- pi 0) are reduced by factors of 2.6 and 2.6, respectively. The reported results provide important inputs for the precise measurement of the angle gamma of the Cabibbo-Kobayashi-Maskawa matrix and indirect CP violation in charm mixing.

The beta decay of the lightest charmed baryon.+ c provides unique insights into the fundamental mechanism of strong and electro-weak interactions, serving as a testbed for investigating non-perturbative quantum chromodynamics and constraining the Cabibbo-Kobayashi-Maskawa (CKM) matrix parameters. This article presents the first observation of the Cabibbosuppressed decay Lambda(+) (c) -> ne(+)v(e), utilizing 4.5 fb(-1) of electron-positron annihilation data collected with the BESIII detector. A novel Graph Neural Network based technique effectively separates signals from dominant backgrounds, notably Lambda(+) (c) -> Lambda e(+)v(e), achieving a statistical significance exceeding 10s. The absolute branching fraction ismeasured to be (3.57 +/- 0.34(stat.)+/- 0.14(syst).) x 10(-3). For the first time, the CKM matrix element |V-cd| is extracted via a charmed baryon decay as 0:208 +/- 0:011(exp): +/- 0:007(LQCD) +/- 0:001 tau(+)(Lambda) (c). This work highlights a new approach to further understand fundamental interactions in the charmed baryon sector, and showcases the power ofmodernmachine learning techniques in experimental high-energy physics.

We present a measurement of the branching fraction and time-dependent charge-parity (CP) decay-rate asymmetries in B-0 -> J/psi pi(0) decays. The data sample was collected with the Belle II detector at the SuperKEKB asymmetric e(+)e(-) collider in 2019-2022 and contains (387 +/- 6) x 10(6) B (B) over bar meson pairs from Upsilon(4S) decays. We reconstruct 392 +/- 24 signal decays and fit the CP parameters from the distribution of the proper-decay-time difference of the two B mesons. We measure the branching fraction to be (B-0 -> J/psi pi(0)) = (2.00 +/- 0.12 +/- 0.09) x 10(-5) and the direct and mixing-induced CP asymmetries to be C-CP = 0.13 +/- 0.12 +/- 0.03 and S-CP = -0.88 +/- 0.17 +/- 0.03, respectively, where the first uncertainties are statistical and the second are systematic. We observe mixing-induced CP violation with a significance of 5.0 standard deviations for the first time in this mode.

Based on 6.1 fb(-1) of ethorne- 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 Lambda(+)(c) -> Lambda pi(+)eta is performed, and branching fractions and decay asymmetry parameters of intermediate processes are determined. The process Lambda(+)(c) -> Lambda a(0)(980)(+) is observed for the first time, and evidence for the pentaquark candidate Sigma(1380)(+) decaying into Lambda pi(+) is found with statistical significance larger than 3 sigma with mass and width fixed to theoretical predictions. The branching fraction product B[ Lambda(+)(c) -> Lambda a(0) (980)(+)]B[a(0)(980)(+) -> pi(+)eta] 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(Lambda(+)(c) -> Lambda pi(+)eta). Finally, we precisely obtain the absolute branching fraction B(Lambda(+)(c) -> Lambda pi(+)eta) = (1.94 +/- 0.07(stat) +/- 0.11(syst))%.