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
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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.
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.
Investigation of the temperature effects on the water retention properties of compacted bentonite is of great importance in the context of geological disposal of high-level radioactive waste (HLW) ...based on the multi-barrier concept. Gaomiaozi (GMZ) bentonite, collected from the Inner Mongolia Autonomous Region of China, has been selected as a potential buffer/backfill material for the construction of Chinese HLW deep geological repository. In this study, soil water retention curves (SWRCs) of both confined and unconfined compacted GMZ01 bentonite specimens with an initial dry density of 1.70 g/cm³were investigated at temperatures 20, 40, 60 and 80 °C. Results indicate that the water content decreases as temperature rises, even though the temperature effects on the water retention capacity of compacted GMZ01 bentonite depend on constraint-conditions. The influence of constraint conditions is more significant at relatively low suctions. Under unconfined conditions, the temperature effect is insignificant. However, under confined conditions, the influence on the water retention capacity is found to be significantly suction dependent. The hysteresis behavior of unconfined compacted bentonite becomes less significant as temperature increases. Based on the corresponding results obtained, a modified model was developed for describing the SWRCs of confined compacted GMZ01 bentonite with consideration of temperature effects. It appears that the calculated SWRCs agree well with the experimental ones, indicating that the modified model can satisfactorily describe the effect of temperature on the water retention properties of confined compacted GMZ01 bentonite.
Based on 4.4 fb -1 of e + e - annihilation data collected at the center-of-mass energies between 4.60 and 4.70 GeV with the BESIII detector at the BEPCII collider, the pure W-boson-exchange decay Λ c ...+ → Ξ 0 K + is studied with a full angular analysis. The corresponding decay asymmetry is measured for the first time to be α Ξ 0 K + = 0.01 ± 0.16(stat) ± 0.03(syst). This result reflects the noninterference effect between the S- and P-wave amplitudes. The phase shift between S- and P-wave amplitudes has two solutions, which are δ p - δ s = -1.55 ± 0.25(stat) ± 0.05(syst) rad or 1.59 ± 0.25(stat) ± 0.05(syst) rad.
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