arXiv subjects

L. B. Guo

Publications and source records attributed to L. B. Guo.

At least 55 records · Page 3Linked to original sources

arXiv2021

Study of the decay $D_s^+\to K_S^0K_S^0π^+$ and observation an isovector partner to $f_0(1710)$

Using $e^+e^-$ annihilation data corresponding to a total integrated luminosity of 6.32 $\rm fb^{-1}$ collected at center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we perform an amplitude analysis of the decay $D_{s}^{+} \to K_{S}^{0}K_{S}^{0}π^{+}$ for the first time. An enhancement is observed in the $K_{S}^{0}K_{S}^{0}$ mass spectrum near 1.7 GeV/$c^2$, which was not seen in $D_{s}^{+} \to K^+K^-π^{+}$ in an earlier work, implying the existence of an isospin one partner of the $f_0(1710)$. The branching fraction of the decay $D_{s}^{+}\to K_{S}^{0}K_{S}^{0}π^{+}$ is determined to be $\mathcal{B}(D_{s}^{+} \to K_{S}^{0}K_{S}^{0}π^{+})=(0.68\pm0.04_{\rm stat}\pm0.01_{\rm syst})\%$.

hep-ex↗

arXiv2021

Measurement of Branching Fractions of $J/ψ$ and $ψ(3686)$ decays to $Σ^{+}$ and $\overlineΣ^-$

Using $1310.6\times10^{6}$ $J/ψ$ and $448.1\times10^{6}$ $ψ(3686)$ events collected with the BESIII detector, the branching fractions of $J/ψ$ and $ψ(3686)$ decays to $Σ^{+}\overlineΣ^{-}$ are measured to be $(10.61 \pm 0.04 \pm 0.36) \times 10^{-4}$ and $(2.52 \pm 0.04 \pm 0.09) \times 10^{-4}$, respectively. In addition, the ratio of $\mathcal{B}(ψ(3686) \rightarrow Σ^{+}\overlineΣ^{-})/\mathcal{B}(J/ψ\rightarrow Σ^{+}\overlineΣ^{-})$ is determined to be $(23.8 \pm 1.1)\%$ which violates the "$12\%$ rule".

hep-ex↗

arXiv2021

Measurement of the $e^{+}e^{-}\toΣ^{0}\barΣ^{0}$ cross sections at center-of-mass energies from $2.3864$ to $3.0200$ GeV

The Born cross sections of $e^{+}e^{-}\to Σ^{0}\barΣ^{0}$ are measured at center-of-mass energies from $2.3864$ to $3.0200$ GeV using data samples with an integrated luminosity of $328.5$ pb$^{-1}$ collected with the BESIII detector operating at the BEPCII collider. The analysis makes use of a novel reconstruction method for energies near production threshold, while a single-tag method is employed at other center-of-mass energies. The measured cross sections are consistent with earlier results from BaBar, with a substantially improved precision. The cross-section lineshape can be well described by a perturbative QCD-driven energy function. In addition, the effective form factors of the $Σ^{0}$ baryon are determined. The results provide precise experimental input for testing various theoretical predictions.

hep-ex↗

arXiv2021

Observation of $D^{0(+)}\to K^0_Sπ^{0(+)}ω$ and improved measurement of $D^0\to K^-π^+ω$

By analyzing an $e^+e^-$ annihilation data sample with an integrated luminosity of $2.93\ \rm fb^{-1}$ taken at the center-of-mass energy of 3.773 GeV with the BESIII detector, we determine the absolute branching fractions of the hadronic decays $D^0\to K^-π^+ω$, $D^0\to K^0_Sπ^0ω$, and $D^+\to K^0_Sπ^+ω$ to be $(3.392 \pm 0.044_{\rm stat} \pm 0.085_{\rm syst})\%$, $(0.848 \pm 0.046_{\rm stat} \pm 0.031_{\rm syst})\%$, and $(0.707 \pm 0.041_{\rm stat} \pm 0.029_{\rm syst})\%$, respectively. The accuracy of the branching fraction measurement of the decay $D^0\to K^-π^+ω$ is improved by a factor of seven compared to the world average value. The $D^{0}\to K^0_Sπ^{0}ω$ and $D^{+}\to K^0_Sπ^{+}ω$ decays are observed for the first time.

hep-ex↗

arXiv2021

Cross Section Measurement of $e^+e^- \rightarrow π^+π^-ψ(3686)$ from $\sqrt{s}=4.0076$~GeV to 4.6984~GeV

Using data samples with a total integrated luminosity of $20.1~\rm fb^{-1}$ collected by the BESIII detector operating at the BEPCII collider, the cross section of the process $e^+e^- \rightarrow π^+π^-ψ(3686)$ is measured at center-of-mass energies between 4.0076 and 4.6984 GeV. The measured cross section is consistent with previous results, but with much improved precision. A fit to the measured energy-dependent cross section, which includes three Breit-Wigner functions and a non-resonant contribution, confirms the existence of the charmonium-like states $Y(4220)$, $Y(4390)$, and $Y(4660)$. This is the first observation of the $Y(4660)$ at the BESIII experiment.

hep-ex↗

arXiv2021

Study of the Decay $D^{+}_{s}\rightarrow π^{+}π^{+}π^{-}η$ and Observation of the W-annihilation Decay $D^{+}_{s}\rightarrow a_0(980)^+ρ^0$

The decay $D^{+}_{s}\rightarrow π^{+}π^{+}π^{-}η$ is observed for the first time, using $e^+e^-$ collision data corresponding to an integrated luminosity of 6.32 fb$^{-1}$, collected by the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV. The absolute branching fraction for this decay is measured to be $\mathcal{B}(D^+_s \to π^+ π^+ π^- η) = (3.12\pm0.13_{\rm stat.}\pm0.09_{\rm syst.})$%. The first amplitude analysis of this decay reveals the sub-structures in $D^{+}_{s}\rightarrow π^{+}π^{+}π^{-}η$ and determines the relative fractions and the phases among these sub-structures. The dominant intermediate process is $D^{+}_{s}\rightarrow a_1(1260)^+ η, a_1(1260)^+ \rightarrow ρ(770)^0π^+$ with a branching fraction of $(1.73 \pm 0.14_{\rm stat.} \pm 0.08_{\rm syst.})$%. We also observe the W-annihilation process $D^{+}_{s}\rightarrow a_0(980)^+ρ(770)^0$, $a_0(980)^+ \to π^+ η$ with a branching fraction of $(0.21\pm0.08_{\rm stat.}\pm0.05_{\rm syst.})$%, which is larger than the branching fractions of other measured pure W-annihilation decays by one order of magnitude.

hep-ex↗

arXiv2021

Amplitude analysis and branching fraction measurement of the decay $D_{s}^{+} \to π^{+}π^{0}π^{0}$

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 $D_{s}^{+} \to π^{+}π^{0}π^{0}$ is performed, and the relative fractions and phases of different intermediate processes are determined. The absolute branching fraction of the decay $D_{s}^{+} \to π^{+}π^{0}π^{0}$ is measured to be $(0.50\pm 0.04_{\text{stat}}\pm 0.02_{\text{syst}})\%$. The absolute branching fraction of the intermediate process $D_{s}^{+} \to f_0(980)π^{+}, f_0(980)\toπ^{0}π^{0}$ is determined to be $(0.21\pm 0.03_{\text{stat}}\pm 0.03_{\text{syst}})\%$.

hep-ex↗

arXiv2021

Measurement of the absolute branching fractions for purely leptonic $D_s^+$ decays

We report new measurements of the branching fraction $\cal B(D_s^+\to \ell^+ν)$, where $\ell^+$ is either $μ^+$ or $τ^+(\toπ^+\barν_τ)$, based on $6.32$ fb$^{-1}$ of electron-positron annihilation data collected by the BESIII experiment at six center-of-mass energy points between $4.178$ and $4.226$ GeV. Simultaneously floating the $D_s^+\toμ^+ν_μ$ and $D_s^+\toτ^+ν_τ$ components yields $\cal B(D_s^+\to τ^+ν_τ) = (5.21\pm0.25\pm0.17)\times10^{-2}$, $\cal B(D_s^+\to μ^+ν_μ) = (5.35\pm0.13\pm0.16)\times10^{-3}$, and the ratio of decay widths $R=\frac{Γ(D_s^+\to τ^+ν_τ)}{Γ(D_s^+\to μ^+ν_μ)} = 9.73^{+0.61}_{-0.58}\pm 0.36$, where the first uncertainties are statistical and the second systematic. No evidence of ${\it CP}$ asymmetry is observed in the decay rates $D_s^\pm\toμ^\pmν_μ$ and $D_s^\pm\toτ^\pmν_τ$: $A_{\it CP}(μ^\pmν) = (-1.2\pm2.5\pm1.0)\%$ and $A_{\it CP}(τ^\pmν) = (+2.9\pm4.8\pm1.0)\%$. Constraining our measurement to the Standard Model expectation of lepton universality ($R=9.75$), we find the more precise results $\cal B(D_s^+\to τ^+ν_τ) = (5.22\pm0.10\pm 0.14)\times10^{-2}$ and $A_{\it CP}(τ^\pmν_τ) = (-0.1\pm1.9\pm1.0)\%$. Combining our results with inputs external to our analysis, we determine the $c\to \bar{s}$ quark mixing matrix element, $D_s^+$ decay constant, and ratio of the decay constants to be $|V_{cs}| = 0.973\pm0.009\pm0.014$, $f_{D^+_s} = 249.9\pm2.4\pm3.5~\text{MeV}$, and $f_{D^+_s}/f_{D^+} = 1.232\pm0.035$, respectively.

hep-ex↗

arXiv2021

Search for the hyperon semileptonic decay $Ξ^{-} \rightarrow Ξ^{0} e^{-} \bar{ν_{e}}$

Using $(10.087\pm0.044)\times10^{9}$ $J/ψ$ events collected by the BESIII detector at the BEPCII collider, we search for the hyperon semileptonic decay $Ξ^{-} \rightarrow Ξ^{0} e^{-} \barν_{e}$. No significant signal is observed and the upper limit on the branching fraction $\mathcal B(Ξ^{-} \rightarrow Ξ^{0} e^{-} \barν_{e})$ is set to be $2.59\times10^{-4}$ at 90 % confidence level. This result is one order of magnitude more strict than the previous best limit.

hep-ex↗

arXiv2021

Determination of the absolute branching fractions of $D^0\to K^-e^+ν_e$ and $D^+\to \bar K^0 e^+ν_e$

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 $D^0\to K^-e^+ν_e$ and $D^+\to \bar K^0 e^+ν_e$ to be $(3.567\pm0.031_{\rm stat}\pm 0.025_{\rm syst})\%$ and $(8.68\pm0.14_{\rm stat}\pm 0.16_{\rm syst})\%$, respectively. Starting with the process $e^+e^-\to D\bar{D}$, a new reconstruction method is employed to select events that contain candidates for both $D\to \bar Ke^+ν_e$ and $\bar D\to Ke^-\bar ν_e$ decays. The branching fractions reported in this work are consistent within uncertainties with previous BESIII measurements that selected events containing $D\to \bar Ke^+ν_e$ and hadronic $\bar D$ decays. Combining our results with the lifetimes of the $D^0$ and $D^+$ mesons and the previous BESIII measurements leads to a ratio of the two decay partial widths of $\frac{\bar Γ_{D^0\to K^{-}e^+ν_{e}}}{\bar Γ_{D^{+}\to \bar K^{0}e^+ν_{e}}}=1.039\pm0.021$. This ratio supports isospin symmetry in the $D^0\to K^-e^+ν_e$ and $D^+\to \bar K^0 e^+ν_e$ decays within $1.9σ$.

hep-ex↗

arXiv2021

Observation of $ψ(3686)\toΞ(1530)^{0}\barΞ(1530)^{0}$ and $Ξ(1530)^{0}\barΞ^0$

Using $(448.1\pm2.9)\times 10^{6}$ $ψ(3686)$ events collected with the BESIII detector and a single-baryon tagging technique, we present the first observation of the decays $ψ(3686)\toΞ(1530)^{0}\barΞ(1530)^{0}$ and $Ξ(1530)^{0}\barΞ^0$. The branching fractions are measured to be ${\cal{B}}(ψ(3686)\toΞ(1530)^{0}\barΞ(1530)^{0}) = (6.77\pm0.14\pm0.39)\times10^{-5}$ and ${\cal{B}}(ψ(3686)\toΞ(1530)^{0}\barΞ^{0}) = (0.53\pm0.04\pm0.03)\times10^{-5}$. Here, the first and second uncertainties are statistical and systematic, respectively. In addition, the parameter associated with the angular distribution for the decay $ψ(3686)\toΞ(1530)^{0}\barΞ(1530)^0$ is determined to be $α= 0.32\pm0.19\pm0.07$, in agreement with theoretical predictions within one standard deviation.

hep-ex↗

arXiv2021

Measurement of the inclusive branching fraction for $ψ(3686)\rightarrow K_{S}^{0} + \text{anything}$

Using 5.9~pb$^{-1}$ of $e^+e^-$ annihilation data collected at center-of-mass energies from 3.640 to 3.701 GeV with the BESIII detector at the BEPCII Collider, we measure the observed cross sections of $e^+e^-\rightarrow K_{S}^{0} X$ (where $X= \text{anything}$). From a fit to these observed cross sections with the sum of continuum and $ψ(3686)$ and $J/ψ$ Breit-Wigner functions and considering initial state radiation and the BEPCII beam energy spread, we obtain for the first time the product of $ψ(3686)$ leptonic width and inclusive decay branching fraction $Γ^{ee}_{ψ(3686)}\mathcal B(ψ(3686)\rightarrow K_{S}^{0} X) = (373.8 \pm 6.7 \pm 20.0)$ eV, and assuming $Γ^{ee}_{ψ(3686)}$ is $(2.33 \pm 0.04)$ keV from PDG value, we measure $\mathcal B(ψ(3686)\rightarrow K_{S}^{0} X) = (16.04 \pm 0.29 \pm 0.90)\%$, where the first uncertainty is statistical and the second is systematic.

hep-ex↗

arXiv2021

Measurements of the center-of-mass energies of $e^{+}e^{-}$ collisions at BESIII

During the 2016-17 and 2018-19 running periods, the BESIII experiment collected 7.5~fb$^{-1}$ of $e^+e^-$ collision data at center-of-mass energies ranging from 4.13 to 4.44 GeV. These data samples are primarily used for the study of excited charmonium and charmoniumlike states. By analyzing the di-muon process $e^{+}e^{-} \to (γ_{\rm ISR/FSR}) μ^{+}μ^{-}$, we measure the center-of-mass energies of the data samples with a precision of 0.6 MeV. Through a run-by-run study, we find that the center-of-mass energies were stable throughout most of the data-taking period.

hep-ex↗

arXiv2021

Observation of a near-threshold enhancement in the $Λ\barΛ$ mass spectrum from $e^+e^-\toϕΛ\barΛ$ at $\sqrt{s}$ from 3.51 to 4.60 GeV

The process $e^+ e^- \to ϕΛ\barΛ$ is studied using data samples collected with the BESIII detector at the BEPCII collider at center-of-mass energies $\sqrt{s}$ ranging from $3.51$ to $4.60~{\rm GeV}$ . An intermediate resonance structure is observed near the threshold of $Λ\barΛ$. It has a mass of $(2262 \pm 4 \pm 28)~{\rm{MeV}}/c^{2}$ and a width of $(72 \pm 5 \pm 43)~\rm{MeV}$, where the quoted uncertainties are statistical and systematic, respectively. The $J^{PC}$ quantum numbers of $0^{-+}$ and $0^{++}$ are rejected, while other $J^{PC}$ hypotheses are possible, according to the helicity angle study. The energy-dependent cross section of the $e^+ e^- \to ϕΛ\barΛ$ process is measured for the first time in this energy region, and contributions from excited $ψ$ states and vector charmonium-like $Y$-states are investigated.

hep-ex↗

arXiv2021

Observation of $D^0\to K_1(1270)^- e^+ν_e$

Using 2.93 fb$^{-1}$ of $e^+e^-$ collision data taken with the BESIII detector at a center-of-mass energy of 3.773 $\rm \,GeV$, the observation of the $D^0\to K_1(1270)^- e^+ν_e$ semileptonic decay is presented. The statistical significance of the decay $D^0\to K_1(1270)^- e^+ν_e$ is greater than $10σ$. The branching fraction of $D^0\to K_1(1270)^- e^+ν_e$ is measured to be $(1.09\pm0.13^{+0.09}_{-0.16} \pm 0.12)\times10^{-3}$. Here, the first uncertainty is statistical, the second is systematic, and the third originates from the assumed branching fraction of $K_1(1270)^- \rightarrow K^-π^+π^-$. The fraction of longitudinal polarization in $D^0\to K_1(1270)^- e^+ν_e$ is determined for the first time to be $0.50\pm0.19_{\rm stat}\pm0.08_{\rm syst}$.

hep-ex↗

arXiv2021

Measurement of the branching fraction of leptonic decay $D_s^+\toτ^+ν_τ$ via $τ^+\toπ^+π^0\bar ν_τ$

By analyzing $6.32~\mathrm{fb}^{-1}$ of $e^+e^-$ annihilation data collected at the center-of-mass energies between 4.178 and 4.226\,GeV with the BESIII detector, we determine the branching fraction of the leptonic decay $D_s^+\toτ^+ν_τ$ with $τ^+\toπ^+π^0\bar ν_τ$, to be $\mathcal{B}_{D_s^+\toτ^+ν_τ}=(5.29\pm0.25_{\rm stat}\pm0.20_{\rm syst})\%$. We estimate the product of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cs}|$ and the $D_s^+$ decay constant $f_{D^+_s}$ to be $f_{D_s^+}|V_{cs}|=(244.8\pm5.8_{\rm stat}\pm4.8_{\rm syst})~\mathrm{MeV}$ using the known values of the $τ^+$ and $D_s^+$ masses as well as the $D_s^+$ lifetime, together with our branching fraction measurement. Combining with the value of $|V_{cs}|$ obtained from a global fit in the standard model and $f_{D_s^+}$ from lattice quantum chromodynamics, we obtain $f_{D_s^+}=(251.6\pm5.9_{\rm stat}\pm4.9_{\rm syst})$\,MeV and $|V_{cs}| = 0.980\pm0.023_{\rm stat}\pm0.019_{\rm syst}$.

hep-ex↗

arXiv2021

Measurement of cross section for $e^{+}e^{-}\rightarrowΞ^{0}\barΞ^{0}$ near threshold

Using $e^+e^-$ collision data at ten center-of-mass energies between 2.644 and 3.080 GeV collected with the BESIII detector at BEPCII and corresponding to an integrated luminosity of about 500 pb$^{-1}$, we measure the cross sections and effective form factors for the process $e^{+}e^{-}\rightarrowΞ^{0}\barΞ^{0}$ utilizing a single-tag method. A fit to the cross section of $e^{+}e^{-}\rightarrowΞ^{0}\barΞ^{0}$ with a pQCD-driven power function is performed, from which no significant resonance or threshold enhancement is observed. In addition, the ratio of cross sections for the processes $e^{+}e^{-}\rightarrowΞ^{-}\barΞ^{+}$ and $Ξ^{0}\barΞ^{0}$ is calculated using recent BESIII measurement and is found to be compatible with expectation from isospin symmetry.

hep-ex↗

arXiv2021

Measurements of Born Cross Sections of $e^+e^-\to D_s^{*+} D_{sJ}^{-} +c.c.$

The Born cross sections are measured for the first time for the processes $e^+e^-\to D_s^{*+}D_{s0}^*(2317)^- +c.c.$ and $e^+e^-\to D_s^{*+}D_{s1}(2460)^- +c.c.$ at the center-of-mass energy $\sqrt{s}=$ 4.600~GeV, 4.612~GeV, 4.626~GeV, 4.640~GeV, 4.660~GeV, 4.68~GeV, and 4.700~GeV, and for $e^+e^-\to D_s^{*+}D_{s1}(2536)^- +c.c.$ at $\sqrt{s}=$ 4.660~GeV, 4.680~GeV, and 4.700~GeV, using data samples collected with the BESIII detector at the BEPCII collider. No structures are observed in cross-section distributions for any of the processes.

hep-ex↗