arXiv subjects

Y. P. Guo

Publications and source records attributed to Y. P. Guo.

At least 19 recordsLinked to original sources

arXiv2024

Observation of the Electromagnetic Dalitz Transition $h_c \rightarrow e^+e^-η_c$

Using $(27.12\pm 0.14)\times10^8$ $ψ(3686)$ decays and data samples of $e^+e^-$ collisions with $\sqrt{s}$ from 4.130 to 4.780~GeV collected with the BESIII detector, we report the first observation of the electromagnetic Dalitz transition $h_c\to e^+e^-η_c$ with a statistical significance of $5.4σ$. We measure the ratio of the branching fractions $\frac{\mathcal{B}(h_c\rightarrow e^+e^-η_c)}{\mathcal{B}(h_c\rightarrow γη_c)}$ separately for the $h_c$ samples produced via $ψ(3686)\toπ^0h_c$ and $e^+e^-\toπ^+π^-h_c$. The average ratio is determined to be $(0.59\pm0.10(\text{stat.})\pm0.04(\text{syst.}))\%$, where the uncertainty includes both statistical and systematic components.

hep-ex↗

arXiv2024

Study of light scalar mesons through $D_s^+ \to π^0 π^0 e^+ ν_e$ and $K_S^0 K_S^0 e^+ ν_e$ decays

Using 6.32~fb$^{-1}$ of $e^+e^-$ collision data recorded by the BESIII detector at center-of-mass energies between $4.178$ to $4.226$ GeV, we present the first measurement of the decay $D_s^+\to f_0(980)e^+ν_e,\,f_0(980)\to π^0π^0$. The product branching fraction of $D_s^+\to f_0(980)e^+ν_e,\,f_0(980)\to π^0π^0$ is measured to be $(7.9\pm1.4_{\rm stat} \pm0.3_{\rm syst})\times 10^{-4}$, with a statistical significance of $7.8σ$. Furthermore, the upper limits on the product branching fractions of $D_s^+\to f_0(500)e^+ν_e$ with $f_0(500)\to π^0π^0$ and the branching fraction of $D_s^+\to K_{S}^{0}K_{S}^{0}e^+ν_e$ are set to be $7.3\times 10^{-4}$ and $3.8\times 10^{-4}$ at 90\% confidence level, respectively. Our results provide valuable inputs to the understanding of the structures of light scalar mesons.

hep-ex↗

arXiv2023

STCF Conceptual Design Report: Volume 1 -- Physics & Detector

The Super $τ$-Charm facility (STCF) is an electron-positron collider proposed by the Chinese particle physics community. It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of $0.5\times 10^{35}{\rm cm}^{-2}{\rm s}^{-1}$ or higher. The STCF will produce a data sample about a factor of 100 larger than that by the present $τ$-Charm factory -- the BEPCII, providing a unique platform for exploring the asymmetry of matter-antimatter (charge-parity violation), in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions, as well as searching for exotic hadrons and physics beyond the Standard Model. The STCF project in China is under development with an extensive R\&D program. This document presents the physics opportunities at the STCF, describes conceptual designs of the STCF detector system, and discusses future plans for detector R\&D and physics case studies.

hep-ex↗

arXiv2023

Search for $\barΛ$-$Λ$ oscillations in the decay $J/ψ\to p K^- \barΛ+c.c.$

We report the first search for $\barΛ$--$Λ$ oscillations in the decay $J/ψ\to p K^- \barΛ + c.c.$ by analyzing $1.31\times10^9$ $J/ψ$ events accumulated with the BESIII detector at the BEPCII collider. The $J/ψ$ events are produced using $e^+e^-$ collisions at a center of mass energy $\sqrt{s}= 3.097$~GeV. No evidence for hyperon oscillations is observed. The upper limit for the oscillation rate of $\barΛ$ to $Λ$ hyperons is determined to be $\mathcal{P}(Λ)=\frac{\mathcal{B}(J/ψ\to pK^-Λ+c.c.)}{\mathcal{B}(J/ψ\to pK^-\barΛ+c.c.)}<4.4\times10^{-6}$ corresponding to an oscillation parameter $δm_{Λ\barΛ}$ of less than $3.8\times10^{-18}$~GeV at the 90\% confidence level.

hep-ex↗

arXiv2023

Partial wave analysis of $J/ψ\rightarrowγηη'$

Based on a sample of (10.09$\pm$0.04)$\times$10$^{9}$ $J/ψ$ events collected with the BESIII detector operating at the BEPCII storage ring, a partial wave analysis of the decay $J/ψ\rightarrow γηη'$ is performed. An isoscalar state with exotic quantum numbers $J^{PC}=1^{-+}$, denoted as $η_1(1855)$, has been observed for the first time with statistical significance larger than 19$σ$. Its mass and width are measured to be (1855$\pm$9$_{-1}^{+6}$)~MeV/$c^{2}$ and (188$\pm$18$_{-8}^{+3}$)~MeV, respectively. The product branching fraction ${\cal B}(J/ψ$$\rightarrow$$ γη_1(1855)$$\rightarrow$$γηη')$ is measured to be (2.70$\pm 0.41 _{-0.35}^{+0.16}) \times$10$^{-6}$. The first uncertainties are statistical and the second are systematic. In addition, an upper limit on the branching ratio ${\cal B}(f_0(1710)$$\rightarrow$$ηη')$/${\cal B}(f_0(1710)$$\rightarrow$$ππ)$ is determined to be $1.61 \times 10^{-3}$ at 90\% confidence level, which lends support to the hypothesis that the $f_0(1710)$ has a large glueball component.

hep-ex↗

arXiv2023

Observation of an isoscalar resonance with exotic $J^{PC}=1^{-+}$ quantum numbers in $J/ψ\rightarrowγηη'$

Using a sample of (10.09$\pm$0.04)$\times$10$^{9}$ $J/ψ$ events collected with the BESIII detector operating at the BEPCII storage ring, a partial wave analysis of the decay $J/ψ\rightarrow γηη'$ is performed. The first observation of an isoscalar state with exotic quantum numbers $J^{PC}=1^{-+}$, denoted as $η_1(1855)$, is reported in the process $J/ψ\rightarrow γη_1(1855)$ with $η_1(1855)\rightarrowηη'$. Its mass and width are measured to be (1855$\pm$9$_{-1}^{+6}$)MeV/$c^{2}$ and (188$\pm$18$_{-8}^{+3}$)MeV, respectively, where the first uncertainties are statistical and the second are systematic, and its statistical significance is estimated to be larger than 19$σ$.

hep-ex↗

arXiv2022

Amplitude analysis of $D_s^{+} \rightarrow π^{+} π^{-} π^{+}$

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 $D_s^+\toπ^+π^-π^+$ decay. The sample contains 13,797 candidates with a signal purity of $\sim$80%. The amplitude and phase of the contributing $ππ$ ${\cal S}$ 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.

hep-ex↗

arXiv2022

Study of the processes $χ_{cJ} \to Ξ^- \barΞ^+$ and $Ξ^0 \barΞ^0$

Using $448.1\times 10 ^6$ $ψ(3686)$ decays collected with the BESIII detector at the BEPCII $e^+e^-$ storage rings, the branching fractions and angular distributions of the decays $χ_{cJ}\toΞ^-\barΞ^+$ and $Ξ^0\barΞ^0$ $(J = 0, 1, 2)$ are measured based on a partial-reconstruction technique. The decays $χ_{c1}\toΞ^0\barΞ^0$ and $χ_{c2}\toΞ^0\barΞ^0$ are observed for the first time with statistical significances of 7$σ$ and 15$σ$, respectively. The results of this analysis are in good agreement with previous measurements and have significantly improved precision.

hep-ex↗

arXiv2022

Observation of the doubly Cabibbo-Suppressed decays $D^+\to K^+π^0π^0$ and $D^+\to K^+π^0η$

By analyzing $e^+e^-$ annihilation data corresponding to an integrated luminosity of $2.93\,\rm fb^{-1}$ collected at the center-of-mass energy of 3.773\,GeV with the BESIII detector, we report the first observations of the doubly Cabibbo-suppressed decays $D^+\to K^+π^0π^0$ and $D^+\to K^+π^0η$. The branching fractions of $D^+\to K^+π^0π^0$ and $D^+\to K^+π^0η$ are measured to be $(2.1 \pm 0.4_{\rm stat} \pm 0.1_{\rm syst})\times 10^{-4}$ and $(2.1 \pm 0.5_{\rm stat} \pm 0.1_{\rm syst})\times 10^{-4}$ with statistical significances of 8.8$σ$ and 5.5$σ$, respectively. In addition, we search for the subprocesses $D^+\to K^{*}(892)^{+}π^0$ and $D^+\to K^{*}(892)^{+}η$ with $K^{*}(892)^+\to K^+π^0$. The branching fraction of $D^+\to K^{*}(892)^{+}η$ is determined to be $({4.4^{+1.8}_{-1.5}}_{\rm stat}\pm0.2_{\rm syst})\times10^{-4}$, with a statistical significance of 3.2$σ$. No significant signal for $D^+\to K^{*}(892)^{+}π^0$ is found and we set an upper limit on the branching fraction of this decay at the 90\% confidence level to be $5.4\times10^{-4}$.

hep-ex↗

arXiv2022

Measurement of the branching fraction for $ψ(3686)\to ωK^0_SK^0_S$

Analyzing $(448.1\pm2.9)\times10^6$ $ψ(3686)$ events collected with the BESIII detector at the BEPCII collider, the $ψ(3686)\to ωK_{S}^{0}K_{S}^{0}$ decay is observed for the first time. The branching fraction for this decay is determined to be $\mathcal{B}_{ψ(3686)\to ωK_{S}^{0}K^{0}_{S}}$=$(7.04\pm0.39\pm0.36)$$\times10^{-5}$, where the first uncertainty is statistical and the second is systematic.

hep-ex↗

arXiv2022

Search for baryon and lepton number violating decays $D^{0}\to \bar{p}e^{+}$ and $D^{0}\to pe^{-}$

Using an electron-positron collision data sample corresponding to an integrated luminosity of 2.93~fb$^{-1}$ collected with the BESIII detector at a center-of-mass energy of 3.773 GeV, we search for the baryon and lepton number violating decays $D^{0}\to \bar{p}e^{+}$ and $D^{0}\to pe^{-}$. No obvious signals are found with the current statistics. The upper limits on the branching fractions for $D^{0}\to \bar{p}e^{+}$ and $D^{0}\to pe^{-}$ are set to be $1.2\times 10^{-6}$ and $2.2\times 10^{-6}$ at 90\% confidence level, respectively.

hep-ex↗

arXiv2022

Measurements of Absolute Branching Fractions of $D^0\to K_L^0ϕ$, $K_L^0η$, $K_L^0ω$, and $K_L^0η^{\prime}$

We report the first measurements of the absolute branching fractions of $D^0\to K_L^0ϕ$, $D^0\to K_L^0η$, $D^0\to K_L^0ω$, and $D^0\to K_L^0η^{\prime}$, obtained by analyzing $2.93\,\rm fb^{-1}$ of $e^+e^-$ collision data taken at a center-of-mass energy of 3.773 GeV with the BESIII detector. Taking the world averages of the branching fractions of $D^0\to K_S^0ϕ$, $D^0\to K_S^0η$, $D^0\to K_S^0ω$, and $D^0\to K_S^0η^{\prime}$, the $K_S^0$-$K_L^0$ asymmetry $\mathcal{R}(D^0)$ in these decay modes are obtained. The CP asymmetries in these decays are also determined. No significant $CP$ violation is observed.

hep-ex↗

arXiv2022

Measurements of the absolute branching fractions of hadronic $D$-meson decays involving kaons and pions

By analyzing an electron-positron collision data sample corresponding to 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 obtain for the first time the absolute branching fractions for seven $D^0$ and $D^+$ hadronic decay modes and search for the hadronic decay $D^0\to K^0_S K^0_Sπ^0$ with much improved sensitivity. The results are ${\mathcal B}(D^0\to K^0_Sπ^0π^0π^0 )=( 7.64\pm 0.30\pm 0.29)\times 10^{-3}$, ${\mathcal B}(D^0\to K^-π^+π^0π^0π^0 )=( 9.54\pm 0.30\pm 0.31)\times 10^{-3}$, ${\mathcal B}(D^0\to K^0_Sπ^+π^-π^0π^0)=(12.66\pm 0.45\pm 0.43)\times 10^{-3}$, ${\mathcal B}(D^+\to K^0_Sπ^+π^0π^0 )=(29.04\pm 0.62\pm 0.87)\times 10^{-3}$, ${\mathcal B}(D^+\to K^0_Sπ^+π^+π^-π^0)=(15.28\pm 0.57\pm 0.60)\times 10^{-3}$, ${\mathcal B}(D^+\to K^0_Sπ^+π^0π^0π^0)=( 5.54\pm 0.44\pm 0.32)\times 10^{-3}$, ${\mathcal B}(D^+\to K^-π^+π^+π^0π^0 )=( 4.95\pm 0.26\pm 0.19)\times 10^{-3}$, ${\mathcal B}({D^0\to K^0_S K^0_Sπ^0}) < 1.57 \times 10^{-4}$ at the 90\% confidence level. Here the first uncertainties are statistical and the second ones systematic. The newly studied decays greatly enrich the knowledge of the $D\to \bar Kπππ$ and $D\to \bar Kππππ$ hadronic decays, and open a bridge to access more two-body hadronic $D$ decays containing scalar, vector, axial and tensor mesons in the charm sector.

hep-ex↗

arXiv2022

Impact of the interference between the resonance and continuum amplitudes on vector quarkonia decay branching fraction measurements

The measurement of the branching fraction of a heavy quarkonium decaying into light hadronic final state at $e^+e^-$ colliders is revisited. In $e^+e^-$ annihilation experiments, background contributions from the continuum amplitude and its interference with the resonance amplitude are irreducible. These effects become more and more significant as the precision of experimental measurements improves. While the former can be easily subtracted with data taken off the resonance peak, the latter depends on the relative size and phase between the resonance and continuum amplitudes. Two ratios are defined to estimate the size of these effects, $r_{R}^{f}$ for the ratio of the contribution of the interference term to the resonance term and $r_{c}^{f}$ for that to the continuum term. We find that $r_{R}^{f}$ could be as large as a few percent for narrow resonances, and both $r_{R}^{f}$ and $r_{c}^{f}$ could be large for broad resonances. This indicates that the interference effect is crucial for the measurements of the branching fractions aiming at the percent level or better precision and needs to be measured or estimated properly.

hep-ph↗

arXiv2022

Search for the decay $D^{0} \to π^{0} ν\barν$

We present the first experimental search for the rare charm decay $D^{0} \to π^{0} ν\barν$. It is based on an $e^+e^-$ collision sample consisting of $10.6\times10^{6}$ pairs of $D^0\bar{D}^0$ mesons collected by the BESIII detector at $\sqrt{s}$=3.773 GeV, corresponding to an integrated luminosity of 2.93~fb$^{-1}$. A data-driven method is used to ensure the reliability of the background modeling. No significant $D^{0} \to π^{0} ν\barν$ signal is observed in data and an upper limit of the branching fraction is set to be $2.1\times 10^{-4}$ at the 90$\%$ confidence level. This is the first experimental constraint on charmed-hadron decays into dineutrino final states.

hep-ex↗

arXiv2022

Search for invisible decays of the $Λ$ baryon

A search for invisible decays of the $Λ$ baryon is carried out in the process $J/ψ\toΛ\barΛ$ based on $(1.0087\pm0.0044)\times10^{10}$ $J/ψ$ events collected with the BESIII detector located at the BEPCII storage ring. No signals are found for the invisible decays of $Λ$ baryon, and the upper limit of the branching fraction is determined to be $7.4 \times 10^{-5}$ at the 90% confidence level. This is the first search for invisible decays of baryons; such searches will play an important role in constraining dark sector models related to the baryon asymmetry.

hep-ex↗

arXiv2022

Physics in the tau-charm Region at BESIII

The Beijing Spectrometer (BESIII) collaboration uses $e^+e^-$ collisions in the tau-charm energy region to study a broad spectrum of topics. These include studies of light mesons and light baryons, studies of charmonium, including exotic mesons and baryons containing charmonium, studies of charmed mesons and baryons, studies of QCD and tau physics, as well as searches for new physics. The following is a Snowmass white paper that outlines the BESIII accomplishments and potential in each of these areas.

hep-ex↗

arXiv2022

Observation of the Singly Cabibbo-Suppressed Decay $Λ_{c}^{+} \to nπ^{+}$

The singly Cabibbo-suppressed decay $Λ_{c}^{+} \to nπ^{+}$ is observed for the first time with a statistical significance of $7.3σ$ by using 3.9 $\mathrm{fb}^{-1}$ of $e^{+}e^{-}$ collision data collected at center-of-mass energies between 4.612 and 4.699 GeV with the BESIII detector at BEPCII. The branching fraction of $Λ_{c}^{+} \to nπ^{+}$ is measured to be $(6.6\pm1.2_{\rm stat}\pm0.4_{\rm syst})\times 10^{-4}$. By taking the upper limit of branching fractions of $Λ_{c}^{+} \to pπ^0$ from the Belle experiment, the ratio of branching fractions between $Λ_{c}^{+} \to nπ^{+}$ and $Λ_{c}^{+} \to pπ^0$ is calculated to be larger than 7.2 at the 90% confidence level, which disagrees with the current predictions of available phenomenological models. In addition, the branching fractions of the Cabibbo-favored decays $Λ_{c}^{+} \to Λπ^{+}$ and $Λ_{c}^{+} \to Σ^{0}π^{+}$ are measured to be $(1.31\pm0.08_{\rm stat}\pm0.05_{\rm syst})\times 10^{-2}$ and $(1.22\pm0.08_{\rm stat}\pm0.07_{\rm syst})\times 10^{-2}$, respectively, which are consistent with previous results.

hep-ex↗