Using a data sample collected with the BESIII detector operating at the BEPCII storage ring, we observe a new neutral state Z_{c}(3900)^{0} with a significance of 10.4σ. The mass and width are ...measured to be 3894.8±2.3±3.2 MeV/c^{2} and 29.6±8.2±8.2 MeV, respectively, where the first error is statistical and the second systematic. The Born cross section for e^{+}e^{-}→π^{0}π^{0}J/ψ and the fraction of it attributable to π^{0}Z_{c}(3900)^{0}→π^{0}π^{0}J/ψ in the range E_{c.m.}=4.19-4.42 GeV are also determined. We interpret this state as the neutral partner of the four-quark candidate Z_{c}(3900)^{±}.
Though immensely successful, the standard model of particle physics does not offer any explanation as to why our Universe contains so much more matter than antimatter. A key to a dynamically ...generated matter-antimatter asymmetry is the existence of processes that violate the combined charge conjugation and parity (CP) symmetry
. As such, precision tests of CP symmetry may be used to search for physics beyond the standard model. However, hadrons decay through an interplay of strong and weak processes, quantified in terms of relative phases between the amplitudes. Although previous experiments constructed CP observables that depend on both strong and weak phases, we present an approach where sequential two-body decays of entangled multi-strange baryon-antibaryon pairs provide a separation between these phases. Our method, exploiting spin entanglement between the double-strange Ξ
baryon and its antiparticle
Formula: see text, has enabled a direct determination of the weak-phase difference, (ξ
- ξ
) = (1.2 ± 3.4 ± 0.8) × 10
rad. Furthermore, three independent CP observables can be constructed from our measured parameters. The precision in the estimated parameters for a given data sample size is several orders of magnitude greater than achieved with previous methods
. Finally, we provide an independent measurement of the recently debated Λ decay parameter α
(refs.
). The Formula: see text asymmetry is in agreement with and compatible in precision to the most precise previous measurement
.
We study the e^{+}e^{-}→γωJ/ψ process using 11.6 fb^{-1} e^{+}e^{-} annihilation data taken at center-of-mass energies from sqrts=4.008 GeV to 4.600 GeV with the BESIII detector at the BEPCII ...storage ring. The X(3872) resonance is observed for the first time in the ωJ/ψ system with a significance of more than 5σ. The relative decay ratio of X(3872)→ωJ/ψ and π^{+}π^{-}J/ψ is measured to be R=1.6_{-0.3}^{+0.4}±0.2, where the first uncertainty is statistical and the second systematic (the same hereafter). The sqrts-dependent cross section of e^{+}e^{-}→γX(3872) is also measured and investigated, and it can be described by a single Breit-Wigner resonance, referred to as the Y(4200), with a mass of 4200.6_{-13.3}^{+7.9}±3.0 MeV/c^{2} and a width of 115_{-26}^{+38}±12 MeV. In addition, to describe the ωJ/ψ mass distribution above 3.9 GeV/c^{2}, we need at least one additional Breit-Wigner resonance, labeled as X(3915), in the fit. The mass and width of the X(3915) are determined. The resonant parameters of the X(3915) agree with those of the Y(3940) in B→KωJ/ψ and of the X(3915) in γγ→ωJ/ψ observed by the Belle and BABAR experiments within errors.
Previous mass screening studies have shown that IgA antibodies against Epstein–Barr Virus (EBV) can facilitate early detection of nasopharyngeal carcinoma (NPC), but the impact of EBV-antibody ...screening for NPC-specific mortality remains unknown.
A prospective, cluster randomized, controlled trial for NPC screening (PRO-NPC-001) was conducted in 3 selected towns of Zhongshan City and 13 selected towns of Sihui City in southern China beginning in 2008. Serum samples of the screening group were tested for two previously selected anti-EBV antibodies. Subjects with serological medium risk were subsequently retested annually for 3 years, and those with serological high risk were referred to otorhinolaryngologists for diagnostic check-up. An interim analysis was carried out to evaluate the primary end points of the NPC-specific mortality and the early diagnostic rate, and the secondary end point of the NPC incidence, through linkage with the database of Zhongshan City.
Among 70 296 total subjects, 29 413 screened participants (41.8% of the total subjects) in the screening group and 50 636 in the control group, 153 (43.3 per 100 000 person-year), 62 (55.3 per 100 000 person-year) and 99 (33.1 per 100 000 person-year) NPC cases were identified. The early diagnostic rates of NPC were significantly higher in the participants (79.0%, P < 0.0001) and the screening group (45.9%, P < 0.0001) compared with the control group (20.6%). Although no differences were found between NPC-specific mortality of the screening group and the control group relative risk (RR)= 0.82, 95% confidence interval (CI) 0.37–1.79, lower NPC-specific mortality was noticed among participants from the screening group versus the control group (RR = 0.22, 95% CI 0.09–0.49).
IgA antibodies against EBV can identify high-risk population and was effective in screening for early asymptomatic NPC. Although the mortality reduction was not significant in the primary end point, we noted encouraging evidence of a mortality reduction in screening participants in this interim analysis.
NCT00941538.
We report the first measurement of the absolute branching fraction for Λ_{c}^{+}→Λe^{+}ν_{e}. This measurement is based on 567 pb^{-1} of e^{+}e^{-} annihilation data produced at sqrts=4.599 GeV, ...which is just above the Λ_{c}^{+}Λover ¯_{c}^{-} threshold. The data were collected with the BESIII detector at the BEPCII storage rings. The branching fraction is determined to be B(Λ_{c}^{+}→Λe^{+}ν_{e})=3.63±0.38(stat)±0.20(syst)%, representing a significant improvement in precision over the current indirect determination. As the branching fraction for Λ_{c}^{+}→Λe^{+}ν_{e} is the benchmark for those of other Λ_{c}^{+} semileptonic channels, our result provides a unique test of different theoretical models, which is the most stringent to date.
In present study, the Inconel 718 alloys fabricated by selective laser melting (SLM) were subjected to traditional homogenization plus double aging heat treatment (HT1), and a novel heat treatment ...(HT2). The effect of heat treatment on the anisotropic microstructure and the small punch creep (SPC) property of Inconel 718 samples was investigated. The experimental results show that the general high-angle grain boundaries with stress concentration, and the equiaxed and columnar grains are observed in the HT1 samples. Compared with the traditional solution treatment at 1065 °C for the HT1 samples, a higher solution performed at 1150 °C can efficiently eliminate the stress concentration and lead to the transformation of columnar grains to equiaxed grains in the HT2 samples by introducing complete recrystallization. The recrystallization is accompanied by the formation of annealing twins with high proportion Σ3n (n = 1, 2, 3) twin boundaries. The larger γ″ phases, less grain boundaries perpendicular to the load direction and smaller Laves phases in the HT1-Z (Z represents parallel to the building direction) sample result in a longer creep life. Microcracks distributed along the general high-angle grain boundaries rather than twin boundaries promote the final intergranular fracture. The anisotropy in creep rupture time of SLMed Inconel 718 alloy can be obviously alleviated by applying higher temperature solution treatment.
In this study, Inconel 718 alloy cylindrical rods with their axes normal or parallel to the building directions were fabricated by selective laser melting (SLM), then homogenized and double aged. ...Creep tests of the heat-treated samples were conducted under a constant stress of 650 MPa at 650 °C. The microstructures of the as-built, heat-treated and post-creep horizontal and vertical samples were characterized using scanning and transmission electron microscopy and electron backscatter diffraction. The experimental results showed that both equiaxed grains and columnar dendrites exist in the horizontal and vertical samples before and after creep. The average grain sizes remained nearly unchanged during creep. The larger grain size and reduced regions of transverse grain boundaries, as well as the promoted precipitation of the γ″ phases at the creep test condition contributed to the longer creep rupture life (~120 h) of the vertical sample. Stress concentration occurring especially at the transverse grain boundaries led to the final failure by intergranular fracture for the two building orientational samples. The anisotropy of creep behavior of the SLMed Inconel 718 alloy could not be eliminated by the present heat treatment schedule.
This study aimed to genotype the variants in FABP4, FASN, SCD, SREBP1 and TCAP genes, and to analyze their associations with intramuscular fat (IMF) content, carcass traits and body size in Chinese ...Qinchuan cattle (QC). The association studies showed that the FABP4 c.220A > G polymorphism was significantly associated with ultrasound longissimus muscle depth (ULMD) and IMF, the FASN g.16024A > G polymorphism was significantly associated with ULMD and some body size traits, the SREBP1 84 bp indel was significantly associated with back fat thickness, ULMD and some body size traits. The frequencies of well-characterized A allele in FABP4 c.220A > G in Korean cattle (KOR) and Japanese Black cattle (JB), T allele in SCD g.8586C > T in KOR, SS genotype in SREBP1 84 bp indel in KOR and JB, DELDEL genotype in TCAP g.592-597CTGCAGinsdel in KOR were significantly higher than in Chinese cattle breeds. Thus, the associated four polymorphisms were expected to be genetic selection markers for meat quality, carcass traits and body size of QC.
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