X-Ray Diffuse Scattering Study on Ionic-Pair Displacement Correlations in Relaxor Lead Magnesium Niobate

Ionic-pair equal-time displacement correlations in relaxor lead magnesium niobate, $Pb(Mg_{1/3}Nb_{2/3})O_{3}$, have been investigated at room temperature in terms of an x-ray diffuse scattering technique. Functions of the distinct correlations have been determined quantitatively. The results show the significantly strong rhombohedral-polar correlations regarding Pb-O, Mg/Nb-O, and O-O' pairs. Their spatial distribution forms an ellipse or a sphere with the radii of 30-80$\AA$. This observation of local structure in the system proves precursory presence of the polar microregions in the paraelectric state which leads to the dielectric dispersion.Comment: 11 pages, 3 figure

Measurement of the absolute branching fraction for Λc+→Λμ+νμ

We report the first measurement of the absolute branching fraction for Λc+→Λμ+νμ. This measurement is based on a sample of e+e− annihilation data produced at a center-of-mass energy s=4.6 GeV, collected with the BESIII detector at the BEPCII storage rings. The sample corresponds to an integrated luminosity of 567 pb−1. The branching fraction is determined to be B(Λc+→Λμ+νμ)=(3.49±0.46(stat)±0.27(syst))%. In addition, we calculate the ratio B(Λc+→Λμ+νμ)/B(Λc+→Λe+νe) to be 0.96±0.16(stat)±0.04(syst)

Evidence for the singly Cabibbo suppressed decay Lambda_c+ --> p eta and search for Lambda_c+ --> p pi0

We study the singly Cabibbo suppressed decays Lambda_c+ --> p eta and Lambda_c+ → pπ0 using Lambda+Lambda_c- pairs produced by e+e- collisions at a center-of-mass energy of sqrt(s) =4.6 GeV. The data sample was collected by the BESIII detector at the BEPCII collider and corresponds to an integrated luminosity of 567 pb-1. We find the first evidence for the decay Lambda_c+ --> p eta with a statistical significance of 4.2 sigma and measure its branching fraction to be B( Lambda_c+ --> p eta)=(1.24±0.28(stat)±0.10(syst))10-3. No significant Lambda_c+ --> p pi0 signal is observed. We set an upper limit on its branching fraction B( Lambda_c+ --> p pi0)<2.7x10-4 at the 90% confidence level

Precise Measurement of the e+e- →π+π-J /ψ Cross Section at Center-of-Mass Energies from 3.77 to 4.60 GeV

The cross section for the process e+e-→π+π-J/ψ is measured precisely at center-of-mass energies from 3.77 to 4.60 GeV using 9 fb-1 of data collected with the BESIII detector operating at the BEPCII storage ring. Two resonant structures are observed in a fit to the cross section. The first resonance has a mass of (4222.0±3.1±1.4) MeV/c2 and a width of (44.1±4.3±2.0) MeV, while the second one has a mass of (4320.0±10.4±7.0) MeV/c2 and a width of (101.4-19.7+25.3±10.2) MeV, where the first errors are statistical and second ones are systematic. The first resonance agrees with the Y(4260) resonance reported by previous experiments. The precision of its resonant parameters is improved significantly. The second resonance is observed in e+e-→π+π-J/ψ for the first time. The statistical significance of this resonance is estimated to be larger than 7.6σ. The mass and width of the second resonance agree with the Y(4360) resonance reported by the BABAR and Belle experiments within errors. Finally, the Y(4008) resonance previously observed by the Belle experiment is not confirmed in the description of the BESIII data

Measurement of cross sections of the interactions e + e − → ϕϕω and e + e − → ϕϕϕ at center-of-mass energies from 4.008 to 4.600 GeV

Using data samples collected with the BESIII detector at the BEPCII collider at six center-of-mass energies between 4.008 and 4.600 GeV, we observe the processes e+e− → φφω and e+e− → φφφ. The Born cross sections are measured and the ratio of the cross sections σ (e+e− → φφω)/σ (e+e− → φφφ) is estimated to be 1.75±0.22±0.19 averaged over six energy points, where the first uncertainty is statistical and the second is systematic. The results represent first measurements of these interactions