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

Updated measurements of the M1 transition ψ(3686)→γηc(2S)\psi(3686) \to \gamma \eta_{c}(2S) with ηc(2S)→KKˉπ\eta_{c}(2S) \to K \bar{K} \pi

Based on a data sample of $(27.08 \pm 0.14 ) \times 10^8~\psi(3686)$ events collected with the BESIII detector at the BEPCII collider, the M1 transition $\psi(3686) \to \gamma \eta_{c}(2S)$ with $\eta_{c}(2S) \to K\bar{K}\pi$ is studied, where $K\bar{K}\pi$ is $K^{+} K^{-} \pi^{0}$ or $K_{S}^{0}K^{\pm}\pi^{\mp}$. The mass and width of the $\eta_{c}(2S)$ are measured to be $(3637.8 \pm 0.8 (\rm {stat}) \pm 0.2 (\rm {syst}))$ MeV/$c^{2}$ and $(10.5 \pm 1.7 (\rm {stat}) \pm 3.5 (\rm {syst}))$ MeV, respectively. The product branching fraction $\mathcal{B}\left(\psi(3686) \rightarrow \gamma \eta_{c}(2 S)\right) \times \mathcal{B}(\eta_{c}(2 S) \rightarrow K \bar{K} \pi)$ is determined to be $(0.97 \pm 0.06 (\rm {stat}) \pm 0.09 (\rm {syst})) \times 10^{-5}$. Using $\mathcal{BR}(\eta_{c}(2S)\to K\bar{K}\pi)=(1.86^{+0.68}_{-0.49})\%$, we obtain the branching fraction of the radiative transition to be $\mathcal{BR}(\psi(3686) \to \gamma \eta_{c}(2S)) = (5.2 \pm 0.3 (\rm {stat}) \pm 0.5 (\rm {syst}) ^{+1.9}_{-1.4} (extr)) \times 10^{-4}$, where the third uncertainty is due to the quoted $\mathcal{BR}(\eta_{c}(2S) \to K\bar{K}\pi)$

Study of the decay J/ψ→ϕπ0ηJ/\psi \to \phi \pi^{0}\eta

Based on $(10.09 \pm 0.04) \times 10^9$ $J/\psi$ events collected with the BESIII detector operating at the BEPCII collider, a partial wave analysis of the decay $J/\psi \to \phi \pi^{0}\eta$ is performed. We observe for the first time two new structures on the $\phi\eta$ invariant mass distribution, with statistical significances of $24.0\sigma$ and $16.9\sigma$; the first with $J^{\rm PC}$ = $1^{+-}$, mass M = (1911 $\pm$ 6 (stat.) $\pm$ 14 (sys.))~MeV/$c^{2}$, and width $\Gamma =$ (149 $\pm$ 12 (stat.) $\pm$ 23 (sys.))~MeV, the second with $J^{\rm PC}$ = $1^{--}$, mass M = (1996 $\pm$ 11 (stat.) $\pm$ 30 (sys.))~MeV/$c^{2}$, and width $\Gamma$ = (148 $\pm$ 16 (stat.) $\pm$ 66 (sys.))~MeV. These measurements provide important input for the strangeonium spectrum. In addition, the $f_0(980)-a_0(980)^0$ mixing signal in $J/\psi \to \phi f_0(980) \to \phi a_0(980)^0$ and the corresponding electromagnetic decay $J/\psi \to \phi a_0(980)^0$ are measured with improved precision, providing crucial information to understand the nature of $a_0(980)^0$ and $f_0(980)$

Measurement of the e+e−→KS0KL0π0e^{+}e^{-} \to K_{S}^{0} K_{L}^{0} \pi^{0} cross sections from s=\sqrt{s}= 2.000 to 3.080 GeV

Based on $e^{+}e^{-}$ collision data collected at center-of-mass energies from 2.000 to 3.080 GeV by the BESIII detector at the BEPCII collider, a partial wave analysis is performed for the process $e^{+}e^{-}\to K_{S}^{0} K_{L}^{0} \pi^{0}$. The results allow the Born cross sections of the process $e^{+}e^{-}\to K_{S}^{0} K_{L}^{0} \pi^{0}$, as well as its subprocesses $e^{+}e^{-}\to K^{*}(892)^{0}\bar{K}$ and $K^{*}_{2}(1430)^{0}\bar{K}$ to be measured. The Born cross sections for $e^{+}e^{-}\to K_{S}^{0} K_{L}^{0}\pi^{0}$ are consistent with previous measurements by BaBar and SND, but with substantially improved precision. The Born cross section lineshape of the process $e^{+}e^{-}\to K^{*}(892)^{0}\bar{K}$ is consistent with a vector meson state around 2.2 GeV with a statistical significance of 3.2$\sigma$. A Breit-Wigner fit determines its mass as $M_Y=(2164.1\pm9.6\pm3.1)~{\rm{MeV}}/c^{2}$ and its width as $\Gamma_{Y}=(32.4\pm21.1\pm1.5)~\rm{MeV}$, where the first uncertainties are statistical and the second ones are systematic, respectively

Measurement of e+e−→ϕη′e^{+}e^{-}\to\phi\eta' cross sections at center-of-mass energies from 3.508 to 4.951 GeV and search for the decay ψ(3770)→ϕη′\psi(3770)\to\phi\eta'

The cross sections of the $e^{+}e^{-}\to\phi\eta'$ process at center-of-mass energies from 3.508 to 4.951 GeV are measured with high precision using 26.1 fb$^{-1}$ data collected with the BESIII detector operating at the BEPCII storage ring. The cross sections are of the order of a few picobarn, and decrease as the center-of-mass energy increases as $s^{-n/2}$ with $n=4.35\pm 0.14$. This result is in agreement with the Nambu-Jona-Lasinio model prediction of $n=3.5\pm 0.9$. In addition, the charmless decay $\psi(3770)\to\phi\eta'$ is searched for by fitting the measured cross sections, yet no significant signal is observed. The upper limit of ${\cal B}(\psi(3770)\to\phi\eta')$ at the 90\% confidence level is determined to be $2.3\times 10^{-5}$

Investigating the ΔI=1/2\Delta I = 1/2 rule and CP violation through the measurement of decay asymmetry parameters in Ξ−\Xi^- decays

Using $(10087\pm44)\times 10^{6}$ $J/\psi$ events collected with the BESIII detector, numerous $\Xi^-$ and $\Lambda$ decay asymmetry parameters are simultaneously determined from the process $J/\psi \to \Xi^- \bar{\Xi}^+ \to \Lambda(p\pi^-) \pi^- \bar{\Lambda}(\bar{n} \pi^0) \pi^+$ and its charge-conjugate channel. The precisions of $\alpha_0$ for $\Lambda \to n\pi^0$ and $\bar{\alpha}_0$ for $\bar{\Lambda} \to \bar{n}\pi^0$ compared to world averages are improved by factors of 4 and 1.7, respectively. The ratio of decay asymmetry parameters of $\Lambda \to n\pi^0$ to that of $\Lambda \to p\pi^-$, $\langle \alpha_0 \rangle/ \langle \alpha_{\Lambda -} \rangle$, is determined to be $0.873 \pm 0.012^{+0.011}_{-0.010}$, where the first and the second uncertainties are statistical and systematic, respectively. The ratio is smaller than unity, which is predicted by the $\Delta I = 1/2$ rule, with a statistical significance of more than $5\sigma$. We test for CP violation in $\Xi^- \to \Lambda \pi^-$ and in $\Lambda \to n \pi^{0}$ with the best precision to date.Comment: 8 pages, 2 figures, 1 tabl