arXiv subjects

C. Dong

Publications and source records attributed to C. Dong.

At least 145 records · Page 8Linked to original sources

arXiv2019

Evidence for the decays of $Λ^+_{c}\toΣ^+η$ and $Σ^+η^\prime$

We study the hadronic decays of $Λ_{c}^{+}$ to the final states $Σ^{+}η$ and $Σ^+η^\prime$, using an $e^{+}e^{-}$ annihilation data sample of 567 pb$^{-1}$ taken at a center-of-mass energy of 4.6 GeV with the BESIII detector at the BEPCII collider. We find evidence for the decays $Λ_{c}^{+}\rightarrowΣ^{+}η$ and $Σ^+η^\prime$ with statistical significance of $2.5σ$ and $3.2σ$, respectively. Normalizing to the reference decays $Λ_c^+\toΣ^+π^0$ and $Σ^+ω$, we obtain the ratios of the branching fractions $\frac{{\mathcal B}(Λ_c^+\toΣ^+η)}{{\mathcal B}(Λ_c^+\toΣ^+π^0)}$ and $\frac{{\mathcal B}(Λ_c^+\toΣ^+η^\prime)}{{\mathcal B}(Λ_c^+\toΣ^+ω)}$ to be $0.35 \pm 0.16 \pm 0.03$ and $0.86 \pm 0.34 \pm 0.07$, respectively. The upper limits at the 90\% confidence level are set to be $\frac{{\mathcal B}(Λ_c^+\toΣ^+η)}{{\mathcal B}(Λ_c^+\toΣ^+π^0)}<0.58$ and $\frac{{\mathcal B}(Λ_c^+\toΣ^+η^\prime)}{{\mathcal B}(Λ_c^+\toΣ^+ω)}<1.2$. Using BESIII measurements of the branching fractions of the reference decays, we determine $\mathcal B({Λ_{c}^{+}\rightarrowΣ^{+}η})=(0.41\pm0.19\pm0.05)\%$ ($<0.68\%$) and $\mathcal B({Λ_{c}^{+}\rightarrowΣ^{+}η'})=(1.34\pm0.53\pm0.21)\%$ ($<1.9\%$). Here, the first uncertainties are statistical and the second systematic. The obtained branching fraction of $Λ_c^+\toΣ^+η$ is consistent with the previous measurement, and the branching fraction of $Λ_{c}^{+}\rightarrowΣ^{+}η^{\prime}$ is measured for the first time.

hep-ex↗

arXiv2019

Cross section measurements of $e^{+}e^{-} \to K^{+}K^{-}K^{+}K^{-} $ and $ ϕK^{+}K^{-}$ at center-of-mass energies from 2.10 to 3.08 GeV

We measure the Born cross sections of the process $e^{+}e^{-} \to K^{+}K^{-}K^{+}K^{-}$ at center-of-mass (c.m.) energies, $\sqrt{s}$, between 2.100 and 3.080 GeV. The data were collected using the BESIII detector at the BEPCII collider. An enhancement at $\sqrt{s}= 2.232$ GeV is observed, very close to the $e^{+}e^{-} \to Λ\overlineΛ$ production threshold. A similar enhancement at the same c.m. energy is observed in the $e^{+}e^{-} \to ϕK^{+}K^{-}$ cross section. The energy dependence of the $K^{+}K^{-}K^{+}K^{-}$ and $ϕK^{+}K^{-}$ cross sections differs significantly from that of $e^{+}e^{-} \to ϕπ^{+}π^{-}$.

hep-ex↗

arXiv2019

Search for the decay $η'\toγγη$

Using a data sample of $1.31\times10^{9} ~J/ψ$ events collected with the BESIII detector, a search for $η'\toγγη$ via $J/ψ\toγη'$ is performed for the first time. No significant $η'$ signal is observed in the $γγη$ invariant mass spectrum, and the %upper limit of the branching fraction of $η'\toγγη$ is determined to be less than $1.33 \times 10^{-4}$ at the 90$\%$ confidence level.

hep-ex↗

arXiv2019

Observation and study of the decay $J/ψ\rightarrowϕηη'$

We report the observation and study of the decay $J/ψ\rightarrowϕηη'$ using $1.3\times{10^9}$ $J/ψ$ events collected with the BESIII detector. Its branching fraction, including all possible intermediate states, is measured to be $(2.32\pm0.06\pm0.16)\times{10^{-4}}$. We also report evidence for a structure, denoted as $X$, in the $ϕη'$ mass spectrum in the $2.0-2.1$ GeV/$c^2$ region. Using two decay modes of the $η'$ meson ($γπ^+π^-$ and $ηπ^+π^-$), a simultaneous fit to the $ϕη'$ mass spectra is performed. Assuming the quantum numbers of the $X$ to be $J^P = 1^-$, its significance is found to be 4.4$σ$, with a mass and width of $(2002.1 \pm 27.5 \pm 21.4)$ MeV/$c^2$ and $(129 \pm 17 \pm 9)$ MeV, respectively, and a product branching fraction $\mathcal{B}(J/ψ\rightarrowηX)\times{}\mathcal{B}(X\rightarrowϕη')=(9.8 \pm 1.2 \pm 1.7)\times10^{-5}$. Alternatively, assuming $J^P = 1^+$, the significance is 3.8$σ$, with a mass and width of $(2062.8 \pm 13.1 \pm 7.2)$ MeV/$c^2$ and $(177 \pm 36 \pm 35)$ MeV, respectively, and a product branching fraction $\mathcal{B}(J/ψ\rightarrowηX)\times{}\mathcal{B}(X\rightarrowϕη')=(9.6 \pm 1.4 \pm 2.0)\times10^{-5}$. The angular distribution of $J/ψ\rightarrowηX$ is studied and the two $J^P$ assumptions of the $X$ cannot be clearly distinguished due to the limited statistics. In all measurements the first uncertainties are statistical and the second systematic.

hep-ex↗

arXiv2019

Search for heavy Majorana neutrino in lepton number violating decays of D-> K pi e+ e+

Using the data sample of an integrated luminosity of 2.93 fb$^{-1}$ taken at the center-of-mass energy of 3.773 GeV, we search for the Majorana neutrino in the lepton number violating decays $D\to K πe^+ e^+$. No significant signal is observed, and the upper limits on the branching fraction at the 90\% confidence level are set to be $\mathcal{B}\,(D^0 \to K^- π^- e^+ e^+)<2.8\times10^{-6}$, $\mathcal{B}\,(D^+ \to K_S^0 π^- e^+ e^+)<3.3\times10^{-6}$ and $\mathcal{B}\,(D^+ \to K^- π^0 e^+ e^+)<8.5\times10^{-6}$. The Majorana neutrino is searched for with different mass assumptions ranging from 0.25 to 1.0 GeV/$c^2$ in the decays $D^0\to K^- e^+ ν_N(π^- e^+)$ and $D^+\to K_S^0 e^+ ν_N(π^- e^+)$, and the upper limits on the branching fraction at the 90\% confidence level are extracted to be at the level of $10^{-7} \sim 10^{-6}$, depending on the mass of Majorana neutrino. The constraints on the mixing matrix element $|V_{eN}|^2$ are also evaluated.

hep-ex↗

arXiv2019

Observation of $η_c\toωω$ in $J/ψ\toγωω$

Using a sample of $(1310.6\pm7.0)\times10^6$ $J/ψ$ events recorded with the BESIII detector at the symmetric electron positron collider BEPCII, we report the observation of the decay of the $(1^1 S_0)$ charmonium state $η_c$ into a pair of $ω$ mesons in the process $J/ψ\toγωω$. The branching fraction is measured for the first time to be $\mathcal{B}(η_c\toωω)= (2.88\pm0.10\pm0.46\pm0.68)\times10^{-3}$, where the first uncertainty is statistical, the second systematic and the third is from the uncertainty of $\mathcal{B}(J/ψ\toγη_c)$. The mass and width of the $η_c$ are determined as $M=(2985.9\pm0.7\pm2.1)\,$MeV/$c^2$ and $Γ=(33.8\pm1.6\pm4.1)\,$MeV.

hep-ex↗

arXiv2019

Study of the Decays $D_{s}^{+} \rightarrow K_{S}^{0}K^{+}$ and $K_{L}^{0}K^{+}$

Using an $e^{+}e^{-}$ annihilation data sample corresponding to an integrated luminosity of $3.19~\mathrm{fb}^{-1}$ and collected at a center-of-mass energy $\sqrt{s} = 4.178~\mathrm{GeV}$ with the BESIII detector, we measure the absolute branching fractions $\mathcal{B}(D_{s}^{+} \rightarrow K_{S}^{0}K^{+}) = (1.425\pm0.038_{\rm stat.}\pm0.031_{\rm syst.})\%$ and $\mathcal{B}(D_{s}^{+} \rightarrow K_{L}^{0}K^{+}) =(1.485\pm0.039_{\rm stat.}\pm0.046_{\rm syst.})\%$. The branching fraction of $D_{s}^{+} \rightarrow K_{S}^{0}K^{+}$ is compatible with the world average and that of $D_{s}^{+} \rightarrow K_{L}^{0}K^{+}$ is measured for the first time. We present the first measurement of the $K_{S}^{0}$-$K_{L}^{0}$ asymmetry in the decays $D_{s}^{+} \rightarrow K_{S,L}^{0}K^{+}$, and $R(D_{s}^{+} \rightarrow K_{S,L}^{0}K^{+})=\frac{\mathcal{B}(D_{s}^{+} \rightarrow K_{S}^{0}K^{+}) -\mathcal{B}(D_{s}^{+} \rightarrow K_{L}^{0}K^{+})}{\mathcal{B}(D_{s}^{+} \rightarrow K_{S}^{0}K^{+}) +\mathcal{B}(D_{s}^{+} \rightarrow K_{L}^{0}K^{+})}= (-2.1\pm1.9_{\rm stat.}\pm1.6_{\rm syst.})\%$. In addition, we measure the direct $CP$ asymmetries $A_{\rm CP}(D_{s}^{\pm} \rightarrow K_{S}^{0}K^{\pm}) = (0.6\pm2.8_{\rm stat.}\pm0.6_{\rm syst.})\%$ and $A_{\rm CP}(D_{s}^{\pm} \rightarrow K_{L}^{0}K^{\pm}) = (-1.1\pm2.6_{\rm stat.}\pm0.6_{\rm syst.})\%$.

hep-ex↗

arXiv2019

Study of the process $e^+ e^- \to p \bar p$ via initial state radiation at BESIII

The Born cross section for the process $e^+ e^- \to p \bar p $ is measured using the initial state radiation technique with an undetected photon. This analysis is based on datasets corresponding to an integrated luminosity of 7.5 fb$^{-1}$, collected with the BESIII detector at the BEPCII collider at center of mass energies between 3.773 and 4.600 GeV. The Born cross section for the process $e^+ e^- \to p \bar p $ and the proton effective form factor are determined in the $p\bar p$ invariant mass range between 2.0 and 3.8 GeV/$c^2$ divided into 30 intervals. The proton form factor ratio ($|G_E|/|G_M|$) is measured in 3 intervals of the $p\bar p$ invariant mass between 2.0 and 3.0 GeV/$c^2$.

hep-ex↗

arXiv2019

First observations of $h_c \to$ hadrons

Based on $(4.48 \pm 0.03) \times 10^{8}$ $ψ(3686)$ events collected with the BESIII detector, five $h_c$ hadronic decays are searched for via process $ψ(3686) \to π^0 h_c$. Three of them, $h_c \to p \bar{p} π^+ π^-$, $π^+ π^- π^0$, and $2(π^+ π^-) π^0$ are observed for the first time, with statistical significances of 7.4$σ$, $4.9σ$, and 9.1$σ$, and branching fractions of $(2.89\pm0.32\pm0.55)\times10^{-3}$, $(1.60\pm0.40\pm0.32)\times10^{-3}$, and $(7.44\pm0.94\pm1.56)\times10^{-3}$, respectively, where the first uncertainties are statistical and the second systematic. No significant signal is observed for the other two decay modes, and the corresponding upper limits of the branching fractions are determined to be $B(h_c \to 3(π^+ π^-) π^0)<8.7\times10^{-3}$ and $B(h_c \to K^+ K^- π^+ π^-)<5.8\times10^{-4}$ at 90% confidence level.

hep-ex↗

arXiv2019

Precision measurements of $σ_{B}(e^+e^- \to K_{S}^{0}K^{\pm}π^{\mp})$ at center-of-mass energies between 3.8 and 4.6 GeV

Using data samples collected by the BESIII detector operating at the BEPCII storage ring, we measure the $e^+e^- \to K_{S}^{0}K^{\pm}π^{\mp}$ Born cross sections at center-of-mass energies between 3.8 and 4.6\,GeV, corresponding to a luminosity of about 5.0~fb$^{-1}$. The results are compatible with the BABAR measurements, but with the precision significantly improved. A simple $1/s^n$ dependence for the continuum process can describe the measured cross sections, but a better fit is obtained by an additional resonance near 4.2\,GeV, which could be an excited charmonium or a charmonium-like state.

hep-ex↗

arXiv2019

Measurements of Weak Decay Asymmetries of $Λ_c^+\to pK_S^0$, $Λπ^+$, $Σ^+π^0$, and $Σ^0π^+$

Using $e^+e^-\toΛ_c^+\barΛ_c^-$ production from a 567 pb$^{-1}$ data sample collected by BESIII at 4.6 GeV, a full angular analysis is carried out simultaneously on the four decay modes of $Λ_c^+\to pK_S^0$, $Λπ^+$, $Σ^+π^0$, and $Σ^0π^+$. For the first time, the $Λ_c^+$ transverse polarization is studied in unpolarized $e^+e^-$ collisions, where a non-zero effect is observed with a statistical significance of 2.1$σ$. The decay asymmetry parameters of the $Λ_c^+$ weak hadronic decays into $pK_S^0$, $Λπ^+$, $Σ^+π^0$ and $Σ^0π^+$ are measured to be $0.18\pm0.43(\rm{stat})\pm0.14(\rm{syst})$, $-0.80\pm0.11(\rm{stat})\pm0.02(\rm{syst})$, $-0.57\pm0.10(\rm{stat})\pm0.07(\rm{syst})$, and $-0.73\pm0.17(\rm{stat})\pm0.07(\rm{syst})$, respectively. In comparison with previous results, the measurements for the $Λπ^+$ and $Σ^+π^0$ modes are consistent but with improved precision, while the parameters for the $pK_S^0$ and $Σ^0π^+$ modes are measured for the first time.

hep-ex↗

arXiv2019

Directly Imaging Rocky Planets from the Ground

Over the past three decades instruments on the ground and in space have discovered thousands of planets outside the solar system. These observations have given rise to an astonishingly detailed picture of the demographics of short-period planets, but are incomplete at longer periods where both the sensitivity of transit surveys and radial velocity signals plummet. Even more glaring is that the spectra of planets discovered with these indirect methods are either inaccessible (radial velocity detections) or only available for a small subclass of transiting planets with thick, clear atmospheres. Direct detection can be used to discover and characterize the atmospheres of planets at intermediate and wide separations, including non-transiting exoplanets. Today, a small number of exoplanets have been directly imaged, but they represent only a rare class of young, self-luminous super-Jovian-mass objects orbiting tens to hundreds of AU from their host stars. Atmospheric characterization of planets in the <5 AU regime, where radial velocity (RV) surveys have revealed an abundance of other worlds, is technically feasible with 30-m class apertures in combination with an advanced AO system, coronagraph, and suite of spectrometers and imagers. There is a vast range of unexplored science accessible through astrometry, photometry, and spectroscopy of rocky planets, ice giants, and gas giants. In this whitepaper we will focus on one of the most ambitious science goals --- detecting for the first time habitable-zone rocky (<1.6 R_Earth) exoplanets in reflected light around nearby M-dwarfs

astro-ph.EP↗

arXiv2019

Cross section measurements of $e^+ e^-\toωχ_{c0}$ from $\sqrt{s}=$4.178 to 4.278 GeV

The cross section of the process $e^+e^- \rightarrow ωχ_{c0}$ is measured at center-of-mass energies from $\sqrt{s} =$ 4.178 to 4.278 GeV using a data sample of 7 fb$^{-1}$ collected with the BESIII detector operating at the BEPCII storage ring. The dependence of the cross section on $\sqrt{s}$ shows a resonant structure with mass of $(4218.5\pm1.6(\text{stat.})\pm4.0(\text{syst.}))$ MeV/$c^2$ and width of $(28.2\pm3.9(\text{stat.})\pm1.6(\text{syst.}))$ MeV, respectively. This observation confirms and improves upon the result of a previous study. The angular distribution of the $e^+e^- \rightarrow ωχ_{c0}$ process is extracted for the first time.

hep-ex↗

arXiv2019

Search for the decay $D_s^+\rightarrow γe^+ν_e$

A search for the rare radiative leptonic decay $D_s^+\toγe^+ν_e$ is performed for the first time using electron-positron collision data corresponding to an integrated luminosity of 3.19 fb$^{-1}$, collected with the BESIII detector at a center-of-mass energy of 4.178 GeV. No evidence for the $D_s^+\toγe^+ν_e$ decay is seen and an upper limit of $\mathcal B(D_s^+\toγe^+ν_e)<1.3\times 10^{-4}$ is set on the partial branching fraction at a 90\% confidence level for radiative photon energies $E_γ^*>0.01$~GeV.

hep-ex↗

arXiv2019

Measurement of the phase between strong and electromagnetic amplitudes of $J/ψ$ decays

Using 16 energy points of $e^{+}e^{-}$ annihilation data collected in the vicinity of the $J/ψ$ resonance with the BESIII detector and with a total integrated luminosity of around 100 pb$^{-1}$, we study the relative phase between the strong and electromagnetic amplitudes of $J/ψ$ decays. The relative phase between $Jψ$ electromagnetic decay and the continuum process ($e^{+}e^{-}$ annihilation without the $J/ψ$ resonance) is confirmed to be zero by studying the cross section lineshape of $μ^{+}μ^{-}$ production. The relative phase between $J/ψ$ strong and electromagnetic decays is then measured to be $(84.9\pm3.6)^\circ$ or $(-84.7\pm3.1)^\circ$ for the $2(π^{+}π^{-})π^{0}$ final state by investigating the interference pattern between the $J/ψ$ decay and the continuum process. This is the first measurement of the relative phase between $J/ψ$ strong and electromagnetic decays into a multihadron final state using the lineshape of the production cross section. We also study the production lineshape of the multihadron final state $ηπ^{+}π^{-}$ with $η\toπ^{+}π^{-}π^{0}$, which provides additional information about the phase between the $J/ψ$ electromagnetic decay amplitude and the continuum process. Additionally, the branching fraction of $J/ψ\to 2(π^{+}π^{-})π^{0}$ is measured to be $(4.73\pm0.44)\%$ or $(4.85\pm0.45)\%$, and the branching fraction of $J/ψ\toηπ^{+}π^{-}$ is measured to be $(3.78\pm0.68)\times10^{-4}$. Both of them are consistent with the world average values. The quoted uncertainties include both statistical and systematic uncertainties, which are mainly caused by the low statistics.

hep-ex↗

arXiv2019

Evidence of a resonant structure in the $e^+e^-\to π^+D^0D^{*-}$ cross section between 4.05 and 4.60 GeV

The cross section of the process $e^+e^-\to π^+D^0D^{*-}$ for center-of-mass energies from 4.05 to 4.60~GeV is measured precisely using data samples collected with the BESIII detector operating at the BEPCII storage ring. Two enhancements are clearly visible in the cross section around 4.23 and 4.40~GeV. Using several models to describe the dressed cross section yields stable parameters for the first enhancement, which has a mass of $4228.6 \pm 4.1 \pm 6.3 \un{MeV}/c^2$ and a width of $77.0 \pm 6.8 \pm 6.3 \un{MeV}$, where the first uncertainties are statistical and the second ones are systematic. Our resonant mass is consistent with previous observations of the $Y(4220)$ state and the theoretical prediction of a $D\bar{D}_1(2420)$ molecule. This result is the first observation of $Y(4220)$ associated with an open-charm final state. Fits with three resonance functions with additional $Y(4260)$, $Y(4320)$, $Y(4360)$, $ψ(4415)$, or a new resonance, do not show significant contributions from either of these resonances. The second enhancement is not from a single known resonance. It could contain contributions from $ψ(4415)$ and other resonances, and a detailed amplitude analysis is required to better understand this enhancement.

hep-ex↗

arXiv2019

Measurement of the Dynamics of the Decays ${ D_s^+ \rightarrow η^{(\prime)} e^{+} ν_e}$

Using $e^+e^-$ annihilation data corresponding to an integrated luminosity of 3.19\,fb$^{-1}$ collected at a center-of-mass energy of 4.178~GeV with the BESIII detector, we measure the absolute branching fractions $\mathcal{B}_{D_s^+ \rightarrow ηe^{+} ν_e }$ = $(2.323\pm0.063_{\rm stat}\pm0.063_{\rm syst})\%$ and $\mathcal{B}_{D_s^+ \rightarrow η^{\prime} e^{+} ν_e}$ = $(0.824\pm0.073_{\rm stat}\pm0.027_{\rm syst})\%$ via a tagged analysis technique, where one $D_s$ is fully reconstructed in a hadronic mode. Combining these measurements with previous BESIII measurements of $\mathcal{B}_{D^+\toη^{(\prime)} e^{+} ν_e}$, the $η-η^\prime$ mixing angle in the quark flavour basis is determined to be $ϕ_{\rm P} = (40.1\pm2.1_{\rm stat}\pm0.7_{\rm syst})^\circ$. From the first measurements of the dynamics of $D^+_s\to η^{(\prime)}e^+ν_e$ decays, the products of the hadronic form factors $f_+^{η^{(\prime)}}(0)$ and the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cs}|$ are determined with different form factor parameterizations. For the two-parameter series expansion, the results are $f^η_+(0)|V_{cs}| = 0.4455\pm0.0053_{\rm stat}\pm0.0044_{\rm syst}$ and $f^{η^{\prime}}_+(0)|V_{cs}| = 0.477\pm0.049_{\rm stat}\pm0.011_{\rm syst}$.

hep-ex↗

arXiv2019

Precision measurement of the branching fractions of $η^\prime$ decays

Based on a sample of $(1310.6 \pm 7.0) \times 10^6~J/ψ$ events collected with the BESIII detector, we present measurements of $J/ψ$ and $η^\prime$ absolute branching fractions using the process $J/ψ\rightarrowγη^\prime$. By analyzing events where the radiative photon converts into an $e^+e^-$ pair, the branching fraction for $J/ψ\rightarrow γη^\prime$ is measured to be $(5.27\pm0.03\pm0.05)\times 10^{-3}$. The absolute branching fractions of the five dominant decay channels of the $η^\prime$ are then measured independently for the first time and are determined to be $\mathcal{B}(η^\prime \rightarrow γπ^{+} π^{-})$ = (29.90$\pm$0.03$\pm$0.55)%, $\mathcal{B}(η^\prime \rightarrow ηπ^{+} π^{-})$ = (41.24$\pm$0.08$\pm$1.24)%, $\mathcal{B}(η^\prime \rightarrow ηπ^{0} π^{0})$ = (21.36$\pm$0.10$\pm$0.92)%, $\mathcal{B}(η^\prime \rightarrow γω)$ = (2.489$\pm$0.018$\pm$0.074)%, and $\mathcal{B}(η^\prime \rightarrow γγ)$ = (2.331$\pm$0.012$\pm$0.035)%, where the first uncertainties are statistical and the second systematic.

hep-ex↗