Observation of χc1\chi_{c1} decays into vector meson pairs ϕϕ\phi\phi, ωω\omega\omega, and ωϕ\omega\phi

Decays of $\chi_{c1}$ to vector meson pairs $\phi\phi$, $\omega\omega$ and $\omega\phi$ are observed for the first time using $(106\pm4)\times 10^6$ \psip events accumulated at the BESIII detector at the BEPCII $e^+e^-$ collider. The branching fractions are measured to be $(4.4\pm 0.3\pm 0.5)\times 10^{-4}$, $(6.0\pm 0.3\pm 0.7)\times 10^{-4}$, and $(2.2\pm 0.6\pm 0.2)\times 10^{-5}$, for $\chi_{c1}\to \phi\phi$, $\omega\omega$, and $\omega\phi$, respectively. The observation of $\chi_{c1}$ decays into a pair of vector mesons $\phi\phi$, $\omega\omega$ and $\omega\phi$ indicates that the hadron helicity selection rule is significantly violated in $\chi_{cJ}$ decays. In addition, the measurement of $\chi_{cJ}\to \omega\phi$ gives the rate of doubly OZI-suppressed decay. Branching fractions for $\chi_{c0}$ and $\chi_{c2}$ decays into other vector meson pairs are also measured with improved precision.Comment: 4 pages, 2 figure

Amplitude analysis and branching fraction measurement of the decay Ds+→π+π0π0D_{s}^{+} \to \pi^{+}\pi^{0}\pi^{0}

Using a data set corresponding to an integrated luminosity of 6.32~$\rm fb^{-1}$ recorded by the BESIII detector at center-of-mass energies between 4.178 and 4.226~GeV, an amplitude analysis of the decay $D_{s}^{+} \to \pi^{+}\pi^{0}\pi^{0}$ is performed, and the relative fractions and phases of different intermediate processes are determined. The absolute branching fraction of the decay $D_{s}^{+} \to \pi^{+}\pi^{0}\pi^{0}$ is measured to be $(0.50\pm 0.04_{\text{stat}}\pm 0.02_{\text{syst}})\%$. The absolute branching fraction of the intermediate process $D_{s}^{+} \to f_0(980)\pi^{+}, f_0(980)\to\pi^{0}\pi^{0}$ is determined to be $(0.21\pm 0.03_{\text{stat}}\pm 0.03_{\text{syst}})\%$

Precision measurements of branching fractions for ψ′→π0Jψ \psi'\to\pi^0 J\psi and ηJψ\eta J\psi

We present a precision study of the \psip\to\pi^0 J/\psi and $\eta J/\psi$ decay modes. The measurements are obtained using $106\times10^6$ $\psi'$ events accumulated with the BESIII detector at the BEPCII \ee collider operating at a center-of-mass energy corresponding to the \psip mass. We obtain \mathcal{B}(\psip\to\pi^0 J/\psi)=(1.26\pm0.02{\rm (stat.)}\pm0.03{\rm (syst.)})\times 10^{-3} and \mathcal{B}(\psip\to\eta J/\psi)=(33.75\pm0.17{\rm (stat.)}\pm0.86{\rm (syst.)})\times 10^{-3}. The branching fraction ratio R=\frac{\mathcal{B}(\psip\to\pi^0 J/\psi)}{\mathcal{B}(\psip\to\eta J/\psi)} is determined to be $(3.74\pm0.06 {\rm(stat.)}\pm0.04 {\rm(syst.)})\times 10^{-2}$. The precision of these measurements of \mathcal{B}(\psip\to\pi^{0} J/\psi) and $R$ represent a significant improvement over previously published values.Comment: four figures, 12 page

Amplitude analysis and branching fraction measurement of Ds+→K−K+π+π0

The first amplitude analysis of the decay Ds+→K-K+π+π0 is presented using the data samples, corresponding to an integrated luminosity of 6.32 fb-1, collected with the BESIII detector at e+e- center-of-mass energies between 4.178 and 4.226 GeV. More than 3000 events selected with a purity of 97.5% are used to perform the amplitude analysis, and nine components are found necessary to describe the data. Relative fractions and phases of the intermediate decays are determined. With the detection efficiency estimated by the results of the amplitude analysis, the branching fraction of Ds+→K-K+π+π0 decay is measured to be (5.42±0.10stat±0.17syst)

Observation of D+→KS0a0(980)+D^{+}\to K_{S}^{0}a_{0}(980)^{+} in the amplitude analysis of D+→KS0π+ηD^{+} \to K_{S}^{0}\pi^+\eta

We perform for the first time an amplitude analysis of the decay $D^{+}\to K_{S}^{0}\pi^+\eta$ and report the observation of the decay $D^{+}\to K_{S}^{0}a_{0}(980)^{+}$ using 2.93 fb$^{-1}$ of $e^+e^-$ collision data taken at a center-of-mass energy of 3.773 GeV with the BESIII detector. As the only W-annihilation free decay among $D$ to $a_{0}(980)$-pseudoscalar, $D^{+}\to K_{S}^{0}a_{0}(980)^{+}$ is the ideal decay to extract the contributions of the external and internal $W$-emission amplitudes involving $a_{0}(980)$ and study the final-state interactions. The absolute branching fraction of $D^{+}\to K_{S}^{0}\pi^+\eta$ is measured to be $(1.27\pm0.04_{\rm stat.}\pm0.03_{\rm syst.})\%$. The product branching fractions of $D^{+}\to K_{S}^{0}a_{0}(980)^{+}$ with $a_{0}(980)^{+}\to \pi^+\eta$ and $D^{+}\to \pi^+ K_0^*(1430)^0$ with $K_0^*(1430)^0\to K_{S}^{0}\eta$ are measured to be $(1.33\pm0.05_{\rm stat.}\pm0.04_{\rm syst.})\%$ and $(0.14\pm0.03_{\rm stat.}\pm0.01_{\rm syst.})\%$, respectively

Study of the doubly Cabibbo-suppressed decays Ds+→K+K+π−D^+_s\to K^+K^+\pi^- and Ds+→K+K+π−π0D^+_s\to K^+K^+\pi^-\pi^0

Based on 7.33 fb$^{-1}$ of $e^+e^-$ collision data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, the experimental studies of the doubly Cabibbo-suppressed decays $D^+_s\to K^+K^+\pi^-$ and $D^+_s\to K^+K^+\pi^-\pi^0$ are reported. We determine the absolute branching fraction of $D^+_s\to K^+K^+\pi^-$ to be (${1.23^{+0.28}_{-0.25}}({\rm stat})\pm0.06({\rm syst})$) $\times 10^{-4}$. No significant signal of $D^+_s\to K^+K^+\pi^-\pi^0$ is observed and the upper limit on its decay branching fraction at 90\% confidence level is set to be $1.7\times10^{-4}$.Comment: 10 pages, 4 figures, 4 table

Search for the lepton number violating decay Σ−→pe−e− and the rare inclusive decay Σ−→Σ+X

Using a data sample of (1310.6±7.0)×106 J/ψ events taken with the BESIII detector at the center-of-mass energy of 3.097 GeV, we search for the first time for the lepton number violating decay ς-→pe-e- and the rare inclusive decay ς-→ς+X, where X denotes any possible particle combination. The ς- candidates are tagged in J/ψ→ς¯(1385)+ς- decays. No signal candidates are found, and the upper limits on the branching fractions at the 90% confidence level are determined to be B(ς-→pe-e-)<6.7×10-5 and B(ς-→ς+X)<1.2×10-4

Measurement of the doubly Cabibbo-suppressed decay D+→K+π+π−π0 with semileptonic tags

We propose a new semileptonic tag method to study the doubly Cabibbo-suppressed D decay in ψ(3770)→DD¯ reaction. Utilizing the dataset corresponding to an integrated luminosity of 2.93 fb-1 at a center-of-mass energy of 3.773 GeV collected by the BESIII detector, we determine the branching fraction for D+→K+π+π-π0 to be (1.03±0.12stat±0.06syst)×10-3, in which the contributions from narrow intermediate resonances, D+→K+η, D+→K+ω, and D+→K+φ have been excluded. Combining the world average of the branching fraction of D+→K-π+π+π0, we determine B(D+→K+π+π-π0)/B(D+→K-π+π+π0)=(1.65±0.21)%, corresponding to (5.73±0.73)tan4θc, where θc is the Cabibbo mixing angle. These results are consistent with our previous measurement with hadronic tags but are significantly larger than other doubly Cabibbo-suppressed decays in the charm sector

Precise Measurement of the e^{+}e^{-}→D_{s}^{*+}D_{s}^{*-} Cross Sections at Center-of-Mass Energies from Threshold to 4.95 GeV

The process e^{+}e^{-}→D_{s}^{*+}D_{s}^{*-} is studied with a semi-inclusive method using data samples at center-of-mass energies from threshold to 4.95 GeV collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross sections of the process are measured for the first time with high precision in this energy region. Two resonance structures are observed in the energy-dependent cross sections around 4.2 and 4.4 GeV. By fitting the cross sections with a coherent sum of three Breit-Wigner amplitudes and one phase-space amplitude, the two significant structures are assigned masses of (4186.8±8.7±30) and (4414.6±3.4±6.1)  MeV/c^{2}, widths of (55±15±53) and (122.5±7.5±8.1)  MeV, where the first errors are statistical and the second ones are systematic. The inclusion of a third Breit-Wigner amplitude is necessary to describe a structure around 4.79 GeV