Amplitude analysis of Ds+→π+π−π+D_s^{+} \rightarrow \pi^{+} \pi^{-} \pi^{+}

Utilizing the data set corresponding to an integrated luminosity of $3.19$ fb$^{-1}$ collected by the BESIII detector at a center-of-mass energy of 4.178 GeV, we perform an amplitude analysis of the $D_s^+\to\pi^+\pi^-\pi^+$ decay. The sample contains 13,797 candidates with a signal purity of $\sim$80%. The amplitude and phase of the contributing $\pi\pi$ ${\cal S}$ wave are measured based on a quasi-model-independent approach, along with the amplitudes and phases of the ${\cal P}$ and ${\cal D}$ waves parametrized by Breit-Wigner models. The fit fractions of different intermediate decay channels are also reported.Comment: 14 pages, 6 figure

Bioinspired bactericidal surfaces with polymer nanocone arrays

Infections resulting from bacterial biofilm formation on the surface of medical devices are challenging to treat and can cause significant patient morbidity. Recently, it has become apparent that regulation of surface nanotopography can render surfaces bactericidal. In this study, poly(ethylene terephthalate) nanocone arrays are generated through a polystyrene nanosphere-mask colloidal lithographic process. It is shown that modification of the mask diameter leads to a direct modification of centre-to-centre spacing between nanocones. By altering the oxygen plasma etching time it is possible to modify the height, tip width and base diameter of the individual nanocone features. The bactericidal activity of the nanocone arrays was investigated against Escherichia coli and Klebsiella pneumoniae. It is shown that surfaces with the most densely populated nanocone arrays (center-to-center spacing of 200 nm), higher aspect ratios (>3) and tip widths <20 nm kill the highest percentage of bacteria (∼30%)

Measurement of the absolute branching fractions of J/ψ→γη and η decay modes

Based on a data sample of (1.0087±0.0044)×1010 J/ψ events collected by the BESIII detector at the BEPCII accelerator, the absolute branching fraction (BF) of the decay J/ψ→γη is measured with high precision using events in which the radiative photon converts to e+e-. Using the measured absolute BF of J/ψ→γη, the absolute BFs of four dominant η decay modes are measured for the first time. The results are B(J/ψ→γη)=(1.067±0.005±0.023)×10-3, B(η→γγ)=(39.86±0.04±0.99)%, B(η→π0π0π0)=(31.96±0.07±0.84)%, B(η→π+π-π0)=(23.04±0.03±0.54)%, and B(η→π+π-γ)=(4.38±0.02±0.10)%, where the first and second uncertainties are statistical and systematic, respectively. The results are consistent with the world average values within two standard deviation

Measurements of the center-of-mass energies of e+e-collisions at BESIII

During the 2016-17 and 2018-19 running periods, the BESIII experiment collected 7.5 fb -1 of e+e- collision data at center-of-mass energies ranging from 4.13 to 4.44 GeV. These data samples are primarily used for the study of excited charmonium and charmoniumlike states. By analyzing the di-muon process e+e-, we measure the center-of-mass energies of the data samples with a precision of 0.6 MeV. Through a run-by-run study, we find that the center-of-mass energies were stable throughout most of the data-collection period

Measurements of Born cross sections of e+e−→Ds*+DsJ−+c.c.

The Born cross sections are measured for the first time for the processes e+e-→Ds∗+Ds0∗(2317)-+c.c. and e+e-→Ds∗+Ds1(2460)-+c.c. at the center-of-mass energy s=4.600 GeV, 4.612 GeV, 4.626 GeV, 4.640 GeV, 4.660 GeV, 4.68 GeV, and 4.700 GeV, and for e+e-→Ds∗+Ds1(2536)-+c.c. at s=4.660 GeV, 4.680 GeV, and 4.700 GeV, using data samples collected with the BESIII detector at the BEPCII collider. No structures are observed in cross-section distributions for any of the processes