Higher-order multipole amplitude measurement in ψ(2S)→γχc2\psi(2S)\to\gamma\chi_{c2}

Using $106\times10^6$ $\psi(2S)$ events collected with the BESIII detector at the BEPCII storage ring, the higher-order multipole amplitudes in the radiative transition $\psi(2S)\to\gamma\chi_{c2}\to\gamma\pi\pi/\gamma KK$ are measured. A fit to the $\chi_{c2}$ production and decay angular distributions yields $M2=0.046\pm0.010\pm0.013$ and $E3=0.015\pm0.008\pm0.018$, where the first errors are statistical and the second systematic. Here $M2$ denotes the normalized magnetic quadrupole amplitude and $E3$ the normalized electric octupole amplitude. This measurement shows evidence for the existence of the $M2$ signal with $4.4\sigma$ statistical significance and is consistent with the charm quark having no anomalous magnetic moment.Comment: 14 pages, 4 figure

Study of χcJ\chi_{cJ} radiative decays into a vector meson

The decays $\chi_{cJ}\to\gamma V$ ($V=\phi, \rho^0, \omega$) are studied with a sample of radiative \psip\to\gamma\chi_{cJ} events in a sample of (1.06\pm0.04)\times 10^{8} \psip events collected with the BESIII detector. The branching fractions are determined to be: ${\cal B}(\chi_{c1}\to \gamma\phi)=(25.8\pm 5.2\pm 2.3)\times 10^{-6}$, ${\cal B}(\chi_{c1}\to \gamma\rho^0)=(228\pm 13\pm 22)\times 10^{-6}$, and ${\cal B}(\chi_{c1}\to \gamma\omega)=(69.7\pm 7.2\pm 6.6)\times 10^{-6}$. The decay $\chi_{c1}\to \gamma\phi$ is observed for the first time. Upper limits at the 90% confidence level on the branching fractions for $\chi_{c0}$ and \chict decays into these final states are determined. In addition, the fractions of the transverse polarization component of the vector meson in $\chi_{c1}\to \gamma V$ decays are measured to be $0.29_{-0.12-0.09}^{+0.13+0.10}$ for $\chi_{c1}\to \gamma\phi$, $0.158\pm 0.034^{+0.015}_{-0.014}$ for $\chi_{c1}\to \gamma\rho^0$, and $0.247_{-0.087-0.026}^{+0.090+0.044}$ for $\chi_{c1}\to \gamma\omega$, respectively. The first errors are statistical and the second ones are systematic.Comment: 8 pages, 3 figure

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

First Observation of the Decays chi_{cJ} -> pi^0 pi^0 pi^0 pi^0

We present a study of the P-wave spin -triplet charmonium chi_{cJ} decays (J=0,1,2) into pi^0 pi^0 pi^0 pi^0. The analysis is based on 106 million \psiprime decays recorded with the BESIII detector at the BEPCII electron positron collider. The decay into the pi^0 pi^0 pi^0 pi^0 hadronic final state is observed for the first time. We measure the branching fractions B(chi_{c0} -> pi^0 pi^0 pi^0 pi^0)=(3.34 +- 0.06 +- 0.44)*10^{-3}, B(chi_{c1} -> pi^0 pi^0 pi^0 pi^0)=(0.57 +- 0.03 +- 0.08)*10^{-3}, and B(chi_{c2} -> pi^0 pi^0 pi^0 pi^0)=(1.21 +- 0.05 +- 0.16)*10^{-3}, where the uncertainties are statistical and systematical, respectively.Comment: 7 pages, 3 figure

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

Crystal Structures Reveal the Multi-Ligand Binding Mechanism of Staphylococcus aureus ClfB

Staphylococcus aureus (S. aureus) pathogenesis is a complex process involving a diverse array of extracellular and cell wall components. ClfB, an MSCRAMM (Microbial Surface Components Recognizing Adhesive Matrix Molecules) family surface protein, described as a fibrinogen-binding clumping factor, is a key determinant of S. aureus nasal colonization, but the molecular basis for ClfB-ligand recognition remains unknown. In this study, we solved the crystal structures of apo-ClfB and its complexes with fibrinogen α (Fg α) and cytokeratin 10 (CK10) peptides. Structural comparison revealed a conserved glycine-serine-rich (GSR) ClfB binding motif (GSSGXGXXG) within the ligands, which was also found in other human proteins such as Engrailed protein, TCF20 and Dermokine proteins. Interaction between Dermokine and ClfB was confirmed by subsequent binding assays. The crystal structure of ClfB complexed with a 15-residue peptide derived from Dermokine revealed the same peptide binding mode of ClfB as identified in the crystal structures of ClfB-Fg α and ClfB-CK10. The results presented here highlight the multi-ligand binding property of ClfB, which is very distinct from other characterized MSCRAMMs to-date. The adherence of multiple peptides carrying the GSR motif into the same pocket in ClfB is reminiscent of MHC molecules. Our results provide a template for the identification of other molecules targeted by S. aureus during its colonization and infection. We propose that other MSCRAMMs like ClfA and SdrG also possess multi-ligand binding properties

Search for CP and PP violating pseudoscalar decays into ππ\pi\pi

Using a sample of $(225.2\pm 2.8)\times 10^6$ $J/\psi$ events collected with the Beijing Spectrometer (BESIII) at the Beijing Electron-Positron Collider, CP and $P$ violating decays of $\eta$, $\eta'$ and \etac into $\pi^+\pi^-$ and $\pi^0 \pi^0$ are searched for in \jpsi radiative decays. No significant $\eta$, $\eta'$ or \etac signal is observed, and 90% confidence level upper limits of \BR(\eta \to \pi^+\pi^-)<3.9\times 10^{-4}, \BR(\eta' \to \pi^+\pi^-)<5.5\times 10^{-5}, \BR(\etac \to \pi^+\pi^-)<1.3\times 10^{-4}, \BR(\eta \to \pi^0 \pi^0)<6.9\times 10^{-4}, \BR(\eta' \to \pi^0 \pi^0)<4.5\times 10^{-4} and \BR(\etac \to \pi^0 \pi^0)<4.2\times 10^{-5} are obtained.Comment: 15 pages, 6 figure

Measurements of h_c(^1P_1) in psi' Decays

We present measurements of the charmonium state $h_c(^1P_1)$ made with 106M $\psi'$ events collected by BESIII at BEPCII. Clear signals are observed for $\psi'\to\pi^0 h_c$ with and without the subsequent radiative decay $h_c\to\gamma\eta_c$. First measurements of the absolute branching ratios $\mathcal{B}(\psi' \to\pi^0 h_c) = (8.4 \pm 1.3 \pm 1.0) \times 10^{-4}$ and $\mathcal{B}(h_c \to \gamma \eta_c) = (54.3 \pm 6.7 \pm5.2)$ are presented. A statistics-limited determination of the previously unmeasured $h_c$ width leads to an upper limit $\Gamma(h_c)<1.44$MeV (90% confidence). Measurements of $M(h_c) = 3525.40 \pm 0.13 \pm 0.18$MeV/$c^2$ and $\mathcal{B}(\psi'\to \pi^0 h_c) \times \mathcal{B}(h_c \to \gamma\eta_c) = (4.58 \pm 0.40 \pm 0.50) \times 10^{-4}$ are consistent with previous results.Comment: 5 pages, 1 figure, accepted for publication in Physical Review Letter

Study of resonant structure around 1.8 GeV/c2c^2 and η(1405)\eta(1405) in J/ψ→ωηπ+π−J/\psi\rightarrow\omega\eta\pi^+\pi^-

We present results of a study of the decay $J/\psi\rightarrow\omega\eta\pi^+\pi^-$ using a sample of $(225.2\pm2.8)\times10^6$ $J/\psi$ events collected by the BESIII detector, and report the observation of a new process of $J/\psi\rightarrow \omega X(1870)$ in which X(1870) decays to $a_0(980)\pi$. The statistical significance of this process is larger than $7.2\sigma$. Signals for $J/\psi\rightarrow \omega f_1(1285)$ and $J/\psi\rightarrow \omega\eta(1405)$ are also observed in $\eta\pi^+\pi^-$ spectrum, with statistical significances much larger than $10\sigma$.Comment: 6 pages, 7 figure

Search for ηc′\eta_{c}^{\prime} decays into vector meson pairs

The processes \etacpto \rho^{0}\rho^{0}, $K^{*0}\bar{K}^{*0}$, and $\phi\phi$ are searched for using a sample of $1.06 \times 10^8$ \psip events collected with the BESIII detector at the BEPCII collider. No signals are observed in any of the three final states. The upper limits on the decay branching fractions are determined to be \mathcal{B}(\etacpto\rho^{0}\rho^{0})<3.1\times10^{-3}, \mathcal{B}(\etacpto K^{*0}\bar{K}^{*0})<5.4 \times10^{-3}, and \mathcal{B}(\etacpto\phi\phi)<2.0\times10^{-3} at the 90% confidence level. The upper limits are lower than the existing theoretical predictions.Comment: 7 pages, 9 figures, 2 table