Using a low background data sample of 9.7×10^{5} J/ψ→γη^{'}, η^{'}→γπ^{+}π^{-} events, which are 2 orders of magnitude larger than those from the previous experiments, recorded with the BESIII ...detector at BEPCII, the decay dynamics of η^{'}→γπ^{+}π^{-} are studied with both model-dependent and model-independent approaches. The contributions of ω and the ρ(770)-ω interference are observed for the first time in the decays η^{'}→γπ^{+}π^{-} in both approaches. Additionally, a contribution from the box anomaly or the ρ(1450) resonance is required in the model-dependent approach, while the process specific part of the decay amplitude is determined in the model-independent approach.
The singly Cabibbo-suppressed decay Lambda(+)(c) -> n pi(+) e is observed for the first time with a statistical significance of 7.3 sigma by using 3.9 fb(-1) of e(+)e(-) collision data collected ...at center-of-mass energies between 4.612 and 4.699 GeV with the BESIII detector at BEPCII. The branching fraction of Lambda(+)(c) -> n pi(+) is measured to be (6.6 +/- 1.2(stat) 0.4(syst)) x 10(-4). By taking the upper limit of branching fractions of Lambda(+)(c) -> n pi(+) from the Belle experiment, the ratio of branching fractions between Lambda(+)(c) -> n pi(+) and Lambda(+)(c) -> p pi(0) is calculated to be larger than 7.2 at the 90% confidence level, which disagrees with most predictions of the available phenomenological models. In addition, the branching fractions of the Cabibbo-favored decays Lambda(+)(c) -> Lambda pi(+) and Lambda(+)(c)-> Sigma(0)(pi+) are measured to be (1.31 +/- 0.08(stat) +/- 0.05(syst)) x 10(-2) and (1.22 +/- 0.08(stat) +/- 0.07(syst)) x 10(-2), respectively, which are consistent with previous results.
Using data samples collected with the BESIII detector operating at the BEPCII storage ring, we measure the cross sections of the e + e − → π + π − D + D − process at center-of-mass energies from ...4.190 to 4.946 GeV with a partial reconstruction method. Resonance structures are seen and the cross section line shape can be described by the coherent sum of either two Breit-Wigner functions or a Breit-Wigner function and a phase space term. The mass and width of the resonance at about 4.4 GeV are determined to be (4371.6±2.5±9.2) MeV/c 2 and (167±4±29) MeV, respectively, which are in agreement with those of the ψ(4360) or Y(4390) state. The spin-3D-wave charmonium state X(3842) is searched for through the e + e − → π + π − X(3842) → π + π − D + D − process, and evidence with a significance of 4.2σ is found in the data samples with center-of-mass energies from 4.6 to 4.7 GeV.
We aimed to conduct a meta-analysis to evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS) in patients with post-stroke depression (PSD). Six relevant electronic databases ...(PubMed, CENTRAL, Embase, Web of Science, CINAHL, and PsycINFO) were searched. Randomized controlled trials (RCTs) that compared rTMS with control condition for PSD were included. The mean change in depression symptom scores was defined as the primary efficacy outcome. Secondary outcomes included the remission rate of depression, stroke recovery, and cognitive function recovery. In total, 7 RCTs with 351 participants were included. At post-treatment, rTMS was significantly more effective than the control condition, with a standardized mean difference (SMD) of -1.15 (95%CI: -1.62 to -0.69; P<0.001, I2=71%) and remission with an odds ratio (OR) of 3.46 (95%CI: 1.68 to 7.12; P<0.001; I2=11%). As for stroke recovery, rTMS was also better than the control condition (SMD=-0.67, 95%CI: -1.02 to -0.32; P<0.001). However, no significant difference was found for cognitive function recovery between the two groups (SMD=4.07, 95%CI: -1.41 to 9.55; P=0.15). To explore the potential moderators for the primary outcome, a series of subgroup and sensitivity analyses were performed. The results implied that rTMS may be more effective in Asian samples than in North American samples (P=0.03). In conclusion, from the current evidence in this study, rTMS could be an effective treatment for patients with PSD. Further clinical studies with larger sample sizes and clearer subgroup definitions are needed to confirm these outcomes.
Observation of η ′ → π + π − μ + μ Achasov, M. N.; Adlarson, P.; Ahmed, S. ...
Physical review. D,
04/2021, Letnik:
103, Številka:
7
Journal Article
Recenzirano
Odprti dostop
Using ( 1310.6 ± 7.0 ) × 106 J / ψ events acquired with the BESIII detector at the BEPCII storage rings, the decay η ′ → π+ π−μ+μ− is observed for the first time with a significance of 8 σ via the ...process J / ψ → γ η ′ . We measure the branching fraction of η ′ → π+ π−μ+μ− to be B ( η ′ → π+ π−μ+μ− ) = ( 1.97 ± 0.33 ( stat ) ± 0.19 ( syst ) ) × 10−5, where the first and second uncertainties are statistical and systematic, respectively.
beta decay of proton-rich nuclei plays an important role in exploring isospin mixing. The beta decay of P-26 at the proton drip line is studied using double-sided silicon strip detectors operating in ...conjunction with high-purity germanium detectors. The T = 2 isobaric analog state (IAS) at 13 055 keV and two new high-lying states at 13 380 and 11 912 keV in Si-26 are unambiguously identified through beta-delayed two-proton emission (beta 2p). Angular correlations of two protons emitted from Si-26 excited states populated by P-26 beta decay are measured, which suggests that the two protons are emitted mainly sequentially. We report the first observation of a strongly isospin-mixed doublet that deexcites mainly via two-proton decay. The isospin mixing matrix element between the Si-26 IAS and the nearby 13 380-keV state is determined to be 130(21) keV, and this result represents the strongest mixing, highest excitation energy, and largest level spacing of a doublet ever observed in beta-decay experiments.
Using data samples with a total integrated luminosity of 20.1 fb−1 collected by the BESIII detector operating at the BEPCII collider, the cross section of the process e+ e− → π+ π− ψ ( 3686 ) is ...measured at center-of-mass energies between 4.0076 and 4.6984 GeV. The measured cross section is consistent with previous results, and with much improved precision. A fit to the measured energy-dependent cross section, which includes three Breit-Wigner functions and a nonresonant contribution, confirms the existence of the charmonium-like states Y (4220), Y (4390), and Y (4660). This is the first observation of the Y (4660) at the BESIII experiment.
The cross sections of e^{+}e^{-}→π^{+}π^{-}h_{c} at center-of-mass energies from 3.896 to 4.600 GeV are measured using data samples collected with the BESIII detector operating at the Beijing ...Electron Positron Collider. The cross sections are found to be of the same order of magnitude as those of e^{+}e^{-}→π^{+}π^{-}J/ψ and e^{+}e^{-}→π^{+}π^{-}ψ(2S), but the line shape is inconsistent with the Y states observed in the latter two modes. Two structures are observed in the e^{+}e^{-}→π^{+}π^{-}h_{c} cross sections around 4.22 and 4.39 GeV/c^{2}, which we call Y(4220) and Y(4390), respectively. A fit with a coherent sum of two Breit-Wigner functions results in a mass of (4218.4_{-4.5}^{+5.5}±0.9) MeV/c^{2} and a width of (66.0_{-8.3}^{+12.3}±0.4) MeV for the Y(4220), and a mass of (4391.5_{-6.8}^{+6.3}±1.0) MeV/c^{2} and a width of (139.5_{-20.6}^{+16.2}±0.6) MeV for the Y(4390), where the first uncertainties are statistical and the second ones systematic. The statistical significance of Y(4220) and Y(4390) is 10σ over one structure assumption.
A search for the charged lepton flavor violating decay J/ψ → e± τ∓ with τ∓ → π∓ π0 ντ is performed with about 10 × 10 9 J/ψ events collected with the BESIII detector at the BEPCII. No significant ...signal is observed, and an upper limit is set on the branching fraction B (J/ψ → e± τ∓) < 7.5 × 10−8 at the 90% confidence level. This improves the previously published limit by two orders of magnitude.
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