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H. Gao

Publications and source records attributed to H. Gao.

At least 127 records · Page 7Linked to original sources

Measurement of the branching fractions of the decays $Λ_{c}^{+}\rightarrowΛK_{S}^{0}K^{+}$, $Λ_{c}^{+}\rightarrowΛK_{S}^{0}π^{+}$ and $Λ_{c}^{+}\rightarrowΛK^{*+}$

Studies are performed of the Cabibbo-favored decay $Λ_{c}^{+}\toΛK_{S}^{0}K^+$ and the singly Cabibbo-suppressed decay $Λ_{c}^{+}\toΛK_{S}^{0}π^+$, based on a sample of $e^{+}e^{-}$ collision data, corresponding to an integrated luminosity of 4.5 fb$^{-1}$, accumulated at center-of-mass energies between $4599.53$ MeV and $4698.82$ MeV with the BESIII detector. The decay $Λ_{c}^{+}\toΛK_{S}^{0}π^+$ is observed for the first time. The branching fractions of $Λ_{c}^{+}\toΛK_{S}^{0}K^+$ and $Λ_{c}^{+}\toΛK_{S}^{0}π^+$ are measured to be $(3.04\pm0.30\pm0.16)\times 10^{-3}$ and $(1.73\pm0.27\pm0.10)\times 10^{-3}$, respectively, where the first uncertainties are statistical and the second are systematic. These results correspond to the most precise measurement of these quantities for both decays. Evidence of a $K^{*+}$ contribution in the $Λ_{c}^{+}\toΛK_{S}^{0}π^+$ decay is found with a statistical significance of $4.7σ$. The branching fraction of $Λ_{c}^{+}\toΛK^{*+}$ is calculated under three possible interference scenarios.

hep-ex↗

Observation of $χ_{c0}\toΣ^{+}\barΣ^{-}η$ and evidence for $χ_{c1,2}\toΣ^{+}\barΣ^{-}η$

Using $(27.12\pm 0.14)\times10^{8}$ $ψ(3686)$ events collected with the BESIII detector, the decay $χ_{c0}\toΣ^{+}\barΣ^{-}η$ is observed for the first time with a statistical significance of $7.0σ$, and evidence for $χ_{c1}\toΣ^{+}\barΣ^{-}η$ and $χ_{c2}\toΣ^{+}\barΣ^{-}η$ is found with statistical significances of $4.3σ$ and $4.6σ$, respectively. The branching fractions are determined to be $\mathcal{B}(χ_{c0}\toΣ^{+}\barΣ^{-}η)=({1.26 \pm 0.20 \pm 0.13}) \times 10^{-4}, ~\mathcal{B}(χ_{c1}\toΣ^{+}\barΣ^{-}η)=({5.10 \pm 1.21 \pm 0.67}) \times 10^{-5}$, and $\mathcal{B}(χ_{c2}\toΣ^{+}\barΣ^{-}η)=({5.46 \pm 1.18 \pm 0.50}) \times 10^{-5}$, where the first uncertainties are statistical, and the second ones are systematic.

hep-ex↗

Observation of the Singly Cabibbo-Suppressed Decay $Λ_c^{+}\to pπ^0$

Utilizing 4.5${~\rm{fb}}^{-1}$ of $e^+e^-$ annihilation data collected with the BESIII detector at the BEPCII collider at center-of-mass energies between 4.600 and 4.699 GeV, the first observation of the singly Cabibbo-suppressed decay $Λ_c^{+}\to pπ^0$ is presented, with a statistical significance of $5.4σ$. The ratio of the branching fractions of $Λ_c^{+}\to pπ^0$ and $Λ_c^{+}\to pη$ is measured as $\mathcal{B}(Λ_c^{+}\to pπ^0)/\mathcal{B}(Λ_c^{+}\to pη)=(0.120\pm0.026_{\rm stat.}\pm0.007_{\rm syst.})$. This result resolves the longstanding discrepancy between earlier experimental searches, providing both a decisive conclusion and valuable input for QCD-inspired theoretical models. A sophisticated deep learning approach using a Transformer-based architecture is employed to distinguish the signal from the prevalent hadronic backgrounds, complemented by thorough validation and systematic uncertainty quantification.

hep-ex↗

Search for $η_c(2S)\to 2(π^+π^-)$ and improved measurement of $χ_{cJ}\to 2(π^+π^-)$

We search for the hadronic decay $η_c(2S)\to 2(π^+π^-)$ in the $ψ(3686)\toγη_c(2S)$ radiative decay using $(27.12\pm 0.14)\times 10^8$ $ψ(3686)$ events collected by the BESIII detector at the BEPCII collider. No significant signal is found, and the upper limit of $\mathcal{B}[ψ(3686)\toγη_c(2S)]\mathcal{B}[η_c(2S)\to 2(π^+π^-)]$ is determined to be $0.78\times 10^{-6}$ at the 90\% confidence level. Using $ψ(3686)\toγχ_{cJ}$ transitions, we also measure the branching fractions of $\mathcal{B}[χ_{cJ(J=0,1,2)}\to 2(π^+π^-)]$, which are $\mathcal{B}[χ_{c0}\to 2(π^+π^-)]=(2.127\pm 0.002~(\mathrm{stat.})\pm 0.101~(\mathrm{syst.}))$\%, $\mathcal{B}[χ_{c1}\to 2(π^+π^-)]=(0.685\pm 0.001~(\mathrm{stat.})\pm 0.031~\mathrm{syst.}))$\%, and $\mathcal{B}[χ_{c2}\to 2(π^+π^-)]=(1.153\pm 0.001~(\mathrm{stat.})\pm 0.063~(\mathrm{syst.}))$\%.

hep-ex↗

Search for $e^{+}e^{-} \to ϕχ_{c0}$ and $ϕη_{c2}(1D)$ at center-of-mass energies from 4.47 to 4.95 GeV

Utilizing a data set of $6.7$ fb$^{-1}$ from electron-positron collisions recorded by the BESIII detector at the BEPCII storage ring, a search is conducted for the processes $e^{+}e^{-} \to ϕχ_{c0}$ and $ϕη_{c2}(1D)$ across center-of-mass energies from 4.47 to 4.95 GeV. In the absence of any significant signals, upper limits are set. These include limits on the Born cross sections for $e^{+}e^{-} \to ϕχ_{c0}$, as well as the product of the Born cross section for $e^{+}e^{-} \to ϕη_{c2}(1D)$ and a sum of five branching fractions. Furthermore, the product of the electronic width of $Y(4660)$ and the branching fraction of the $Y(4660) \to ϕχ_{c0}$, denoted as $Γ^{Y(4660)}_{e^{+}e^{-}} \mathcal{B}_{Y(4660) \to ϕχ_{c0}}$, is determined to be $< 0.40$ eV at the 90\% confidence level.

hep-ex↗

Observation of $χ_{cJ}\to p \bar p K^0_S K^- π^+ + c.c.$

By analyzing $(27.12\pm0.14)\times10^8$ $ψ(3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decays of $χ_{cJ} \to p \bar{p} K^0_S K^- π^+ +c.c.(J=0, 1, 2)$ are observed for the first time with statistical significances greater than $10σ$. The branching fractions of these decays are determined to be $\mathcal{B}(χ_{c0}\to p \bar p K^{0}_{S} K^- π^+ + c.c.)=(2.61\pm0.27\pm0.32)\times10^{-5},$ $\mathcal{B}(χ_{c1}\to p \bar p K^{0}_{S} K^- π^+ + c.c.)=(4.16\pm0.24\pm0.46)\times10^{-5},$ and $\mathcal{B}(χ_{c2}\to p \bar p K^{0}_{S} K^- π^+ + c.c.)=(5.63\pm0.28\pm0.46)\times10^{-5}$, respectively. The processes $χ_{c1,2} \to \bar{p} Λ(1520) K^0_S π^{+} + c.c.$ are also observed, with statistical significances of 5.7$σ$ and 7.0$σ$, respectively. Evidence for $χ_{c0} \to\bar{p} Λ(1520) K^0_S π^{+} + c.c.$ is found with statistical significances of 3.3$σ$ each. The corresponding branching fractions are determined to be $\mathcal{B}(χ_{c0}\to \bar{p} Λ(1520) K^0_S π^{+} + c.c.) =(1.61^{+0.68}_{-0.64}\pm0.23)\times10^{-5}$, $\mathcal{B}(χ_{c1}\to \bar{p} Λ(1520) K^0_S π^{+} + c.c.)=(4.06^{+0.80}_{-0.76}\pm0.52)\times10^{-5}$, and $\mathcal{B}(χ_{c2}\to \bar{p} Λ(1520) K^0_S π^{+} + c.c.)=(4.09^{+0.87}_{-0.84}\pm0.42)\times10^{-5}$. Here, the first uncertainties are statistical and the second ones are systematic.

hep-ex↗

Search for the massless dark photon with $D^0\toωγ'$ and $D^0\toγγ'$

Using $7.9~\rm{fb^{-1}}$ of $e^+e^-$ collision data collected at $\sqrt{s}=3.773$ GeV with the BESIII detector at the BEPCII collider, we search for the massless dark photon with the flavor-changing neutral current processes $D^0\toωγ'$ and $D^0\toγγ'$ for the first time. No significant signals are observed, and the upper limits at the 90% confidence level on the massless dark photon branching fraction are set to be $1.1\times10^{-5}$ and $2.0\times10^{-6}$ for $D^0\toωγ'$ and $D^0\toγγ'$, respectively. These results provide the most stringent constraint on the new physics energy scale associated with $cuγ'$ coupling in the world, with the new physics energy scale related parameter $|\mathbb{C}|^2+|\mathbb{C}_5|^2<8.2\times10^{-17}~\rm{GeV}^{-2}$ at the 90% confidence level.

hep-ex↗

Search for the radiative decays $D^+\toγρ^+$ and $D^+\toγK^{*+}$

We search for the radiative decays $D^{+} \to γρ^+$ and $D^{+} \to γK^{*+}$ using 20.3~fb$^{-1}$ of $e^+e^-$ annihilation data collected at the center-of-mass energy $\sqrt{s}=3.773$ GeV by the BESIII detector operating at the BEPCII collider. No significant signals are observed, and the upper limits on the branching fractions of $D^{+} \to γρ^+$ and $D^{+} \to γK^{*+}$ at 90\% confidence level are set to be $1.3\times10^{-5}$ and $1.8\times10^{-5}$, respectively.

hep-ex↗

Observation of an axial-vector state in the study of $ψ(3686) \to ϕηη'$ decay

Using (2712.4 $\pm$ 14.3)$\times 10^{6}$ $ψ(3686)$ events collected with the BESIII detector at BEPCII, a partial wave analysis of the decay $ψ(3686) \to ϕηη' $ is performed with the covariant tensor approach. An axial-vector state with a mass near 2.3 $\rm GeV/c^2$ is observed for the first time. Its mass and width are measured to be 2316 $\pm 9_{\mathrm{stat}} \pm 30_{\mathrm{syst}}\,\rm MeV/c^2$ and 89 $\pm 15_{\mathrm{stat}} \pm 26_{\mathrm{syst}}\,\rm MeV$, respectively. The product branching fractions of $\mathcal{B}(ψ(3686) \to X(2300) η') \mathcal{B}(X(2300)\to ϕη)$ and $\mathcal{B}(ψ(3686) \to X(2300) η)\mathcal{B}(X(2300)\to ϕη')$ are determined to be (4.8 $\pm 1.3_{\mathrm{stat}} \pm 0.7_{\mathrm{syst}})\times 10^{-6}$ and (2.2 $\pm 0.7_{\mathrm{stat}} \pm 0.7_{\mathrm{syst}})\times 10^{-6}$, respectively. The branching fraction $\mathcal{B}(ψ(3686) \to ϕηη')$ is measured for the first time to be (3.14$\pm0.17_{\mathrm{stat}}\pm0.24_{\mathrm{syst}})\times10^{-5}$. The first uncertainties are statistical and the second are systematic.

hep-ex↗

Search for $D^0\to K^-ηe^+ν_e$, $D^+\to K_S^0 ηe^+ν_e$ and $D^+\to ηηe^+ν_e$ decays

By analyzing $e^+e^-$ annihilation data corresponding to an integrated luminosity of 7.93 fb$^{-1}$, collected at the center-of-mass energy of 3.773 GeV with the BESIII detector, we search for the semileptonic decays $D^0\to K^-ηe^+ν_e$, $D^+\to K_S^0 ηe^+ν_e$ and $D^+\to ηηe^+ν_e$ for the first time. We present evidence for $D^0\to K^-ηe^+ν_e$ with a significance of $3.3σ$. The branching fraction of $D^0\to K^-ηe^+ν_e$ is measured to be $(0.84_{-0.34}^{+0.29}\pm0.22)\times 10^{-4}$. Here, the first uncertainties are statistical and the second ones are systematic. No significant signals are observed for the decays $D^+\to K_S^0 ηe^+ν_e$ and $D^+\to ηηe^+ν_e$ and we set the upper limits on their branching fractions.

hep-ex↗

Quasielastic $\overrightarrow{^{3}\mathrm{He}}(\overrightarrow{e},{e'})$ Asymmetry in the Threshold Region

A measurement of the double-spin asymmetry from electron-$^{3}$He scattering in the threshold region of two- and three-body breakup of $^{3}$He was performed at Jefferson Lab, for Q$^{2}$ values of 0.1 and 0.2 (GeV/$c$)$^{2}$. The results of this measurement serve as a stringent test of our understanding of few-body systems. When compared with calculations from plane wave impulse approximation and Faddeev theory, we found that the Faddeev calculations, which use modern nuclear potentials and prescriptions for meson-exchange currents, demonstrate an overall good agreement with data.

nucl-ex↗

Search for $X(3872)\toπ^0π^0χ_{c1,2}$

Using 10.1 fb$^{-1}$ of $e^+e^-$ collision data collected by the BESIII detector with center-of-mass energies between 4.15 GeV and 4.30 GeV, we search for the decays $X(3872)\toπ^0π^0χ_{c1,2}$, where the $X(3872)$ is produced in $e^+e^-\toγX(3872)$. No evidence above $3σ$ is found for either decay. Upper limits at the $90\%$ C.L. on the branching fractions of $X(3872)\toπ^0π^0χ_{c1,2}$ normalized to the branching fraction of $X(3872)\toπ^+π^-J/ψ$ are set to be $\mathcal{B}(X(3872)\toπ^0π^0χ_{c1})/\mathcal{B}(X(3872)\toπ^+π^-J/ψ) < 1.1$ and $\mathcal{B}(X(3872)\toπ^0π^0χ_{c2})/\mathcal{B}(X(3872)\toπ^+π^-J/ψ) < 0.5$, taking into account both statistical and systematic uncertainties.

hep-ex↗

Measurements of the $CP$-even fractions of $D^0\toπ^{+}π^{-}π^{0}$ and $D^0\to K^{+}K^{-}π^{0}$ at BESIII

The $CP$-even fractions ($F_{+}$) of the decays $D^0\toπ^{+}π^{-}π^{0}$ and $D^0\to K^{+}K^{-}π^{0}$ are measured with a quantum-correlated $ψ(3770)\to D\bar{D}$ data sample collected by the BESIII experiment corresponding to an integrated luminosity of 7.93 $\mathrm{fb}^{-1}$. The results are $F_{+}^{π^{+}π^{-}π^{0}}=0.9406\pm0.0036\pm0.0021$ and $F_{+}^{K^{+}K^{-}π^{0}}=0.631\pm0.014\pm0.011$, where the first uncertainties are statistical and the second systematic. These measurements are consistent with the previous determinations, and the uncertainties for $F_{+}^{π^{+}π^{-}π^{0}}$ and $F_{+}^{K^{+}K^{-}π^{0}}$ are reduced by factors of 3.9 and 2.6, respectively. The reported results provide important inputs for the precise measurement of the angle $γ$ of the Cabibbo-Kobayashi-Maskawa matrix and indirect $CP$ violation in charm mixing.

hep-ex↗

Study of the decay $D^0\rightarrow ρ(770)^-e^+ν_e$

We present a study of the semileptonic decay $D^0\rightarrow π^-π^0e^{+}ν_{e}$ using an $e^+e^-$ annihilation data sample of $7.93~\mathrm{fb}^{-1}$ collected at the center-of-mass energy of 3.773 GeV with the BESIII detector. The branching fraction of $D^0\to ρ(770)^-e^+ν_e$ is measured to be $(1.439 \pm 0.033(\rm stat.) \pm 0.027(\rm syst.)) \times10^{-3}$, which is a factor 1.6 more precise than previous measurements. By performing an amplitude analysis, we measure the hadronic form-factor ratios of $D^0\to ρ(770)^-e^+ν_e$ at $q^2=0$ assuming the single-pole-dominance parametrization: $r_{V}=V(0)/A_1(0)=1.548\pm0.079(\rm stat.)\pm0.041(\rm syst.)$ and $r_{2}=A_2(0)/A_1(0)=0.823\pm0.056(\rm stat.)\pm0.026(\rm syst.)$.

hep-ex↗

Double "acct": a distinct double-peaked supernova matching pulsational pair-instability models

We present multi-wavelength data of SN2020acct, a double-peaked stripped-envelope supernova (SN) in NGC2981 at ~150 Mpc. The two peaks are temporally distinct, with maxima separated by 58 rest-frame days, and a factor of 20 reduction in flux between. The first is luminous (M$_{r}$ = -18.00 $\pm$ 0.02 mag), blue (g - r = 0.27 $\pm$ 0.03 mag), and displays spectroscopic signatures of interaction with hydrogen-free circumstellar material. The second peak is fainter (M$_{r}$ = -17.29 $\pm$ 0.03 mag), and spectroscopically similar to an evolved stripped-envelope SNe, with strong blended forbidden [Ca II] and [O II] features. No other known double-peak SN exhibits a light curve similar to that of SN 2020acct. We find the likelihood of two individual SNe occurring in the same star-forming region within that time to be highly improbable, while an implausibly fine-tuned configuration would be required to produce two SNe from a single binary system. We find that the peculiar properties of SN2020acct match models of pulsational pair instability (PPI), in which the initial peak is produced by collisions of shells of ejected material, shortly followed by a terminal explosion. Pulsations from a star with a 72 M$_{\odot}$ helium core provide an excellent match to the double-peaked light curve. The local galactic environment has a metallicity of 0.4 Z$_{\odot}$, a level where massive single stars are not expected retain enough mass to encounter the PPI. However, late binary mergers or a low-metallicity pocket may allow the required core mass. We measure the rate of SN 2020acct-like events to be $<3.3\times10^{-8}$ Mpc$^{-3}$ yr$^{-1}$ at z = 0.07, or <0.1% of the total core-collapse SN rate.

astro-ph.HE↗

Quasi-periodic X-ray eruptions years after a nearby tidal disruption event

Quasi-periodic Eruptions (QPEs) are luminous bursts of soft X-rays from the nuclei of galaxies, repeating on timescales of hours to weeks. The mechanism behind these rare systems is uncertain, but most theories involve accretion disks around supermassive black holes (SMBHs), undergoing instabilities or interacting with a stellar object in a close orbit. It has been suggested that this disk could be created when the SMBH disrupts a passing star, implying that many QPEs should be preceded by observable tidal disruption events (TDEs). Two known QPE sources show long-term decays in quiescent luminosity consistent with TDEs, and two observed TDEs have exhibited X-ray flares consistent with individual eruptions. TDEs and QPEs also occur preferentially in similar galaxies. However, no confirmed repeating QPEs have been associated with a spectroscopically confirmed TDE or an optical TDE observed at peak brightness. Here we report the detection of nine X-ray QPEs with a mean recurrence time of approximately 48 hours from AT2019qiz, a nearby and extensively studied optically-selected TDE. We detect and model the X-ray, ultraviolet and optical emission from the accretion disk, and show that an orbiting body colliding with this disk provides a plausible explanation for the QPEs.

astro-ph.HE↗

Search for the radiative transition $χ_{c1}(3872)\toγψ_2(3823)$

Using 9.0 $\rm fb^{-1}$ of $e^+e^-$ collision data collected at center-of-mass energies from 4.178 to 4.278 GeV with the BESIII detector at the BEPCII collider, we perform the first search for the radiative transition $χ_{c1}(3872)\toγψ_2(3823)$. No $χ_{c1}(3872)\toγψ_2(3823)$ signal is observed. The upper limit on the ratio of branching fractions $\mathcal{B}(χ_{c1}(3872)\toγψ_2(3823), ψ_2(3823)\toγχ_{c1})/\mathcal{B}(χ_{c1}(3872)\toπ^+π^- J/ψ)$ is set as 0.075 at the 90\% confidence level. Our result contradicts theoretical predictions under the assumption that the $χ_{c1}(3872)$ is the pure charmonium state $χ_{c1}(2P)$.

hep-ex↗

Study of $D^{+} \to K_{S}^{0}K^{*}(892)^{+}$ in $D^{+} \to K_{S}^{0} K_{S}^{0} π^{+}$

Using a data sample of $e^+e^-$ collisions corresponding to an integrated luminosity of 7.93 $\rm fb^{-1}$ collected with the BESIII detector at the center-of-mass energy 3.773~GeV, we perform the first amplitude analysis of the decay $D^{+} \to K_{S}^{0} K_{S}^{0} π^{+}$. The absolute branching fraction of $D^{+} \to K_{S}^{0}K_{S}^{0} π^{+}$ is measured to be $(2.97 \pm 0.09_{\rm stat.} \pm 0.05_{\rm syst.})\times10^{-3}$. The dominant intermediate process is $D^{+} \to K_{S}^{0}K^{*}(892)^{+}$, whose branching fraction is determined to be $(8.72 \pm 0.28_{\rm stat.} \pm 0.15_{\rm syst.}) \times 10^{-3}$, including all the $K^*(892)^+$ decays.

hep-ex↗