Search for the decay J/ψ→γ+invisibleJ/\psi\to\gamma + \rm {invisible}

We search for $J/\psi$ radiative decays into a weakly interacting neutral particle, namely an invisible particle, using the $J/\psi$ produced through the process $\psi(3686)\to\pi^+\pi^-J/\psi$ in a data sample of $(448.1\pm2.9)\times 10^6$ $\psi(3686)$ decays collected by the BESIII detector at BEPCII. No significant signal is observed. Using a modified frequentist method, upper limits on the branching fractions are set under different assumptions of invisible particle masses up to 1.2 $\mathrm{\ Ge\kern -0.1em V}/c^2$. The upper limit corresponding to an invisible particle with zero mass is 7.0$\times 10^{-7}$ at the 90\% confidence level

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

Search for New Hadronic Decays of hch_c and Observation of hc→K+K−π+π−π0h_c\rightarrow K^{+}K^{-}\pi^{+}\pi^{-}\pi^{0}

Ten hadronic final states of the $h_c$ decays are investigated via the process $\psi(3686)\rightarrow \pi^0 h_c$, using a data sample of $(448.1 \pm 2.9) \times 10^6$ $\psi(3686)$ events collected with the BESIII detector. The decay channel $h_c\rightarrow K^{+}K^{-}\pi^{+}\pi^{-}\pi^{0}$ is observed for the first time with a significance of $6.0 \sigma$. The corresponding branching fraction is determined to be $\mathcal{B}(h_c\rightarrow K^{+}K^{-}\pi^{+}\pi^{-}\pi^{0}) =(3.3 \pm 0.6 \pm 0.6)\times 10^{-3}$ (the first uncertainty is statistical and the second systematical). Evidence for the decays $h_c\rightarrow \pi^{+} \pi^{-} \pi^{0} \eta$ and $h_c\rightarrow K^{0}_{S}K^{\pm}\pi^{\mp}\pi^{+}\pi^{-}$ is found with a significance of $3.6 \sigma$ and $3.8 \sigma$, respectively. The corresponding branching fractions (and upper limits) are obtained to be $\mathcal{B}(h_c\rightarrow \pi^{+} \pi^{-} \pi^{0} \eta ) =(7.2 \pm 1.8 \pm 1.3)\times 10^{-3}$ $(< 1.8 \times 10^{-2})$ and $\mathcal{B}(h_c\rightarrow K^{0}_{S}K^{\pm}\pi^{\mp}\pi^{+}\pi^{-}) =(2.8 \pm 0.9 \pm 0.5)\times 10^{-3}$ $(<4.7\times 10^{-3})$. Upper limits on the branching fractions for the final states $h_c \rightarrow K^{+}K^{-}\pi^{0}$, $K^{+}K^{-}\eta$, $K^{+}K^{-}\pi^{+}\pi^{-}\eta$, $2(K^{+}K^{-})\pi^{0}$, $K^{+}K^{-}\pi^{0}\eta$, $K^{0}_{S}K^{\pm}\pi^{\mp}$, and $p\bar{p}\pi^{0}\pi^{0}$ are determined at a confidence level of 90\%.Comment: 10 pages, 2 figure

Determination of the absolute branching fractions of D0→K−e+νe and D+→K¯0e+νe

Using 2.93 fb-1 of e+e- collision data collected with the BESIII detector at a center-of-mass energy of 3.773 GeV, we measure the absolute branching fractions of the decays D0→K-e+νe and D+→K̄0e+νe to be (3.567±0.031stat±0.025syst)% and (8.68±0.14stat±0.16syst)%, respectively. Starting with the process e+e-→DD¯, a new reconstruction method is employed to select events that contain candidates for both D→K̄e+νe and D¯→Ke-ν¯e decays. The branching fractions reported in this work are consistent within uncertainties with previous BESIII measurements that selected events containing D→K̄e+νe and hadronic D¯ decays. Combining our results with the lifetimes of the D0 and D+ mesons and the previous BESIII measurements leads to a ratio of the two decay partial widths of Γ¯D0→K-e+νeΓ¯D+→K̄0e+νe=1.039±0.021. This ratio supports isospin symmetry in the D0→K-e+νe and D+→K̄0e+νe decays within 1.9σ

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-)&lt;6.7×10-5 and B(ς-→ς+X)&lt;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