arXiv subjects

H. Gao

Publications and source records attributed to H. Gao.

At least 73 records · Page 4Linked to original sources

arXiv2025

Observation of the charmonium decay $η_c\toγγ$ in $J/ψ\toγη_c$

Using $(2712.4\pm14.3)\times10^{6}$ $ψ(3686)$ events collected with the BESIII detector at the BEPCII collider, the decay $η_c\toγγ$ in $J/ψ\toγη_c$ is observed. We determine the product branching fraction $\mathcal{B}(J/ψ\toγη_c)\times\mathcal{B}(η_c\toγγ)=(5.23\pm0.26_{\rm{stat.}}\pm0.30_{\rm{syst.}})\times10^{-6}$. This result is consistent with the LQCD calculation $(5.34\pm0.16)\times10^{-6}$ from HPQCD in 2023. By using the world-average values of $\mathcal{B}(J/ψ\toγη_c)$ and the total decay width of $η_c$, the partial decay width $Γ(η_c\toγγ)$ is determined to be $(11.30\pm0.56_{\rm{stat.}}\pm0.66_{\rm{syst.}}\pm1.14_{\rm{ref.}})~\rm{keV}$, which deviates from the corresponding world-average value by $3.4σ$.

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arXiv2025

Precursor Activity Preceding Interacting Supernovae I: Bridging the Gap with SN 2022mop

Over the past two decades, an increasing number of transients have shown luminous activity at their explosion sites weeks to years before an interacting supernova (SN) is observed. For some objects, this pre-SN activity is typically linked to large-scale mass-loss events preceding core collapse, yet its triggering mechanism and the underlying explosion process remain uncertain. We present SN 2022mop, which was initially observed in August 2022, exhibiting nebular emission, including [O I], Mg I], and [Ca II], resembling the late-time (~200 days post-explosion) spectrum of a stripped-envelope SN (SESN) from a progenitor with M[ZAMS] < 18 Msun. SN 2022mop shows strong (~ 1 mag) repeating undulations in its light curve, suggesting late-time interaction. In mid-2024, the transient re-brightened for several months before a Type IIn SN (r[peak] = -18.2 mag) was observed in December 2024, closely resembling the evolution of SN 2009ip. By triangulating both transients using Pan-STARRS images, we determine that both transients are coincident within approximately 3 parsecs. Given the environment, the chance alignment of two isolated SNe is unlikely. We propose a merger-burst scenario: a compact object formed in 2022, is kicked into an eccentric orbit, interacts with its hydrogen-rich companion over subsequent months, and ultimately merges, triggering a Type IIn SN-like transient.

astro-ph.HE↗

arXiv2025

Measurement of the branching fractions of doubly Cabibbo-suppressed $D$ decays

By analyzing $e^+e^-$ collision data collected at the center-of-mass energy of 3.773~GeV with the BESIII detector, corresponding to an integrated luminosity of 20.3~fb$^{-1}$, we measure the branching fractions of the doubly Cabibbo-suppressed (DCS) decays $D^0\to K^+π^-$, $D^0\to K^+π^-π^-π^+$, $D^0\to K^+π^-π^0$, $D^0\to K^+π^-π^0π^0$, $D^+\to K^+π^+π^-$, and $D^+\to K^+K^+K^-$. We also perform the first searches for $D^0\to K^+π^-η$, $D^0\to K^+π^-π^0η$, $D^+\to K^+π^+π^-η$, $D^{+} \to K^{+} \left(π^{+} π^{-} η\right)_{{\rm non}-η^{\prime}}$, and $D^+\to K^+ηη$ and report the first observations and evidence for some of these final states. Combining the measurements with the world averages of the corresponding Cabibbo-favored (CF) decays, the ratios of the DCS/CF branching fractions are obtained. For the $D^{+} \to K^{+} \left(π^{+} π^{-} η\right)_{{\rm non}-η^{\prime}}$ decay, the ratio is significantly larger than the corresponding ratios of the other DCS decays.

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arXiv2025

Cross section measurement of $e^+e^-\to ηψ(2S)$ and search for $e^+e^-\toη\tilde{X}(3872)$

The energy-dependent cross section for $e^+e^-\to ηψ(2S)$ is measured at eighteen center of mass energies from 4.288 GeV to 4.951 GeV using the BESIII detector. Using the same data samples, we also perform the first search for the reaction $e^+e^-\toη\tilde{X}(3872)$, but no evidence is found for the $\tilde{X}(3872)$ in the $π^+π^- J/ψ$ mass distribution. At each of the eighteen center of mass energies, upper limits at the 90\% confidence level on the cross section for $e^+e^-\toηψ(2S)$ and on the product of the $e^+e^-\toη\tilde{X}(3872)$ cross section with the branching fraction of $\tilde{X}(3872)\toπ^+π^- J/ψ$ are reported.

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arXiv2025

Observation of $D^+\toη^\primeμ^+ν_μ$ and First Study of $D^+\to η^\prime \ell^+ν_\ell$ Decay Dynamics

Using $20.3\,\rm fb^{-1}$ of $e^+e^-$ collision data collected at the center-of-mass energy 3.773\,GeV with the BESIII detector, we report the first observation of the semileptonic decay $D^+\to η^\prime μ^+ν_μ$ with significance of $8.6σ$ including systematic uncertainties, and an improved measurement of $D^+\to η^\prime e^+ν_e$. The branching fractions of $D^+\to η^\prime μ^+ν_μ$ and $D^+\to η^\prime e^+ν_e$ are determined to be $(1.92\pm0.28_{\rm stat}\pm 0.08_{\rm syst})\times 10^{-4}$ and $(1.79\pm0.19_{\rm stat}\pm 0.07_{\rm syst})\times 10^{-4}$, respectively. The ratio of the two branching fractions is determined to be ${\mathcal R}_{μ/e}=1.07\pm0.19_{\rm stat}\pm 0.03_{\rm syst}$, which agrees with the theoretical expectation of lepton flavor universality within the Standard Model.From an analysis of the $D^+\to η^\prime \ell^+ν_\ell$ decay dynamics, the product of the hadronic form factor $f_+^{η^{\prime}}(0)$ and the CKM matrix element $|V_{cd}|$ is measured for the first time, giving $f^{η^\prime}_+(0)|V_{cd}| = (5.92\pm0.56_{\rm stat}\pm0.13_{\rm syst})\times 10^{-2}$. The $η-η^\prime$ mixing angle in the quark flavor basis is determined to be $ϕ_{\rm P} =(39.8\pm0.8_{\rm stat}\pm0.3_{\rm syst})^\circ$.

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arXiv2025

Measurement of Born cross section of $e^+e^-\toΣ^0\barΣ^0$ at $\sqrt{s} = 3.50-4.95$ GeV

Using $e^+e^-$ collision data collected with the BESIII detector at the BEPCII collider at thirty-two center-of-mass energies from 3.50 to 4.95 GeV, corresponding to an integrated luminosity of 25 $\rm{fb^{-1}}$, we measure the Born cross section of the $e^+e^-\toΣ^0\barΣ^0$ reaction and the effective form factor. No significant charmonium(-like) state, i.e., $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, $ψ(4230)$, $ψ(4360)$, $ψ(4415)$, or $ψ(4660)$, decaying into the $Σ^0\barΣ^0$ final state is observed by fitting the $e^+e^- \to Σ^0\barΣ^0$ dressed cross section. The upper limits for the product of the branching fraction and the electronic partial width at the 90% confidence level are provided for each assumed charmonium(-like) state. In addition, the ratios of the Born cross section and the effective form factor between the $e^+e^-\toΣ^0\barΣ^0$ and the $e^+e^-\toΣ^+\barΣ^-$ reactions are provided, which can be used to validate the prediction of the vector meson dominance model.

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arXiv2025

Search for a $1^{-+}$ molecular state via $e^{+}e^{-} \to γD^{+}_{s} D_{s1}^{-}(2536) +c.c.$

We search, for the first time, for an exotic molecular state with quantum numbers $J^{PC}=1^{-+}$, called $X$, via the process $e^{+}e^{-} \to γD^{+}_{s} D_{s1}^{-}(2536) +c.c.$ using data samples corresponding to a luminosity of $5.8~\mathrm{fb^{-1}}$ across center-of-mass energies from 4.612 to 4.951~GeV, collected with the BESIII detector operating at the BEPCII collider. No statistically significant signal is observed. The upper limits on the product of cross-section and branching fraction $σ({e^{+}e^{-} \to γX}) \times \mathcal{B}(X \to D^{+}_{s} D_{s1}^{-}(2536) +c.c.)$ at 90\% confidence level are reported for each energy point, assuming the $X$ mass to be 4.503~GeV/$c^{2}$ and the width 25, 50, 75, and 100~MeV, respectively.

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arXiv2025

Measurement of Branching Fractions for $Λ_{c}^{+} \rightarrow n K_{S}^{0} π^{+}$ and $Λ_{c}^{+} \rightarrow n K_{S}^{0} K^{+}$

Based on 4.5 fb$^{-1}$ of $e^{+}e^{-}$ collision data accumulated at center-of-mass energies between $4.600\,\mathrm{GeV}$ and $4.699\,\mathrm{GeV}$ with the BESIII detector, we measure the absolute branching fraction of the Cabibbo-favored decay $Λ_{c}^{+} \rightarrow n K_{S}^{0} π^{+}$ with the precision improved by a factor of 2.8 and report the first evidence for the singly-Cabibbo-suppressed decay $Λ_{c}^{+} \rightarrow n K_{S}^{0} K^{+}$. The branching fractions for $Λ_{c}^{+} \rightarrow n K_{S}^{0} π^{+}$ and $Λ_{c}^{+} \rightarrow n K_{S}^{0} K^{+}$ are determined to be $(1.86\pm0.08\pm0.04)\times10^{-2}$ and $\left(3.9^{+1.7}_{-1.4}\pm0.3\right)\times10^{-4}$, respectively, where the first uncertainties are statistical and the second ones are systematic.

hep-ex↗

arXiv2025

Measurement of cross sections of $e^+e^-\to K^0_S K^0_S ψ(3686)$ from $\sqrt{s}=$ 4.682 to 4.951 GeV

The process $e^+e^-\to K^0_S K^0_S ψ(3686)$ is studied by analyzing $e^+e^-$ collision data samples collected at eight center-of-mass energies ranging from 4.682 to 4.951 GeV with the BESIII detector operating at the BEPCII collider, corresponding to an integrated luminosity of $4.1~{\rm fb}^{-1}$. Observation of the $e^+e^-\to K^0_S K^0_S ψ(3686)$ process is found for the first time with a statistical significance of $6.3σ$, and the cross sections at each center-of-mass energy are measured. The ratio of cross sections of $e^+e^-\to K_S^0 K_S^0 ψ(3686)$ relative to $e^+e^-\to K^+ K^- ψ(3686)$ is determined to be $\frac{σ(e^+e^-\to K_S^0 K_S^0 ψ(3686))}{σ(e^+e^-\to K^+ K^- ψ(3686))}=0.45 \pm 0.25$, which is consistent with the prediction based on isospin symmetry. The uncertainty includes both statistical and systematic contributions. Additionally, the $K_S^0ψ(3686)$ invariant mass distribution is found to be consistent with three-body phase space. The significance of a contribution beyond three-body phase space is only $0.8σ$.

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arXiv2025

Partial wave analysis of $ψ(3686)\toΛ\barΣ^0π^0+c.c.$

Based on a sample of $(2712.4\pm14.3)\times10^6\;ψ(3686)$ events collected with the BESIII detector, a partial wave analysis of the decay $ψ(3686)\toΛ\barΣ^0π^0+c.c.$ is performed to investigate $Λ^*$ and $Σ^*$ resonances in the $π^0\barΣ^0$ and $π^0Λ$ invariant mass distributions. Significant contributions are found from the $Λ(1405)$, $Λ(1520)$, $Λ(1600)$, $Λ(1670)$, $Λ(1690)$, $Λ(1800)$, $Λ(1890)$, $Λ(2325)$, $Σ(1385)$, $Σ(1660)$, $Σ(1670)$, $Σ(1750)$, and $Σ(1910)$. The masses, widths, and production branching fractions for each component are determined. In addition, the branching fraction of $ψ(3686)\toΛ\barΣ^0π^0+c.c.$ is measured to be $(1.544\pm0.013\pm0.069)\times10^{-4}$ for the first time, where the first uncertainty is statistical and the second systematic.

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arXiv2025

Search for $Λ$-$\barΛ $ oscillation in $J/ψ\rightarrowΛ\barΛ$ decay

Using $(10087\pm44)\times 10^{6}$ $J/ψ$ decays collected by the BESIII detector at the BEPCII collider, we search for baryon number violation via $Λ-\barΛ$ oscillation in the decay $J/ψ\to Λ\barΛ$. No evidence for $Λ-\barΛ$ oscillation is observed. The upper limit on the time-integrated probability of $Λ-\barΛ$ oscillation is estimated to be $1.4\times 10^{-6}$, corresponding to an oscillation parameter less than $2.1\times 10^{-18}~\mathrm{GeV}$ at $90\%$ confidence level.

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arXiv2025

Evidence for an Instability-Induced Binary Merger in the Double-Peaked, Helium-Rich Type IIn Supernova 2023zkd

We present ultraviolet to infrared observations of the extraordinary Type IIn supernova 2023zkd (SN 2023zkd). Photometrically, it exhibits persistent and luminous precursor emission spanning $\sim$4 years preceding discovery ($M_r\approx-15$ mag, 1,500~days in the observer frame), followed by a secondary stage of gradual brightening in its final year. Post-discovery, it exhibits two photometric peaks of comparable brightness ($M_r\lesssim-18.7$ mag and $M_r\approx-18.4$ mag, respectively) separated by 240 days. Spectroscopically, SN 2023zkd exhibits highly asymmetric and multi-component Balmer and He I profiles that we attribute to ejecta interaction with fast-moving ($1,\!000-2,\!000\;\mathrm{km}\;\mathrm{s}^{-1}$) He-rich polar material and slow-moving ($\sim$$400\;\mathrm{km}\;\mathrm{s}^{-1}$) equatorially-distributed H-rich material. He II features also appear during the second light curve peak and evolve rapidly. Shock-driven models fit to the multi-band photometry suggest that the event is powered by interaction with $\sim$$5-6\;M_{\odot}$ of CSM, with $2-3\;M_{\odot}$ associated with each light curve peak, expelled during mass-loss episodes $\sim$$3-4$ and $\sim$$1-2$ years prior to explosion. The observed precursor emission, combined with the extreme mass-loss rates required to power each light curve peak, favors either super-Eddington accretion onto a black hole or multiple long-lived eruptions from a massive star to luminosities that have not been previously observed. We consider multiple progenitor scenarios for SN 2023zkd, and find that the brightening optical precursor and inferred explosion properties are most consistent with a massive ($M_{\mathrm{ZAMS}}\geq30\;M_{\odot}$) and partially-stripped He star undergoing an instability-induced merger with a black hole companion.

astro-ph.HE↗

arXiv2025

Measurement of the Decay $Ξ^{0}\toΛγ$ with Entangled $Ξ^{0}\barΞ^{0}$ Pairs

In this Letter, a systematic study of the weak radiative hyperon decay $Ξ^{0}\toΛγ$ at an electron-positron collider using entangled $Ξ^{0}\barΞ^{0}$ pair events is presented. The absolute branching fraction for this decay has been measured for the first time, and is $\left(1.347 \pm 0.066_{\mathrm stat.}\pm0.054_{\mathrm syst.}\right)\times 10^{-3}$. The decay asymmetry parameter, which characterizes the effect of parity violation in the decay, is determined to be $-0.741 \pm 0.062_{\mathrm stat.}\pm 0.019_{\mathrm syst.}$. The obtained results are consistent with the world average values within the uncertainties, offering valuable insights into the underlying mechanism governing the weak radiative hyperon decays. The charge conjugation parity ($CP$) symmetries of branching fraction and decay asymmetry parameter in the decay are also studied. No statistically significant violation of charge conjugation parity symmetry is observed.

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arXiv2025

New insight into the Rapid Burster by Insight-HXMT

We report the timing and spectral analyses upon of the type II X-ray bursts from the Rapid Burster (MXB 1730--335) observed by Insight-HXMT and Swift/XRT. By stacking the long-duration bursts, we find for the first time that the hard X-rays are lagging than the soft X-rays by 3 seconds. However, such a lag is not visible for the short-duration bursts, probably because of the poor statistics. For all bursts the energy spectrum is found to be non-thermal, thanks to the broad band coverage of Insight-HXMT. These findings put new insights into the type-II bursts and require a temporally showing-up corona for possible interpretation.

astro-ph.HE↗

arXiv2025

Partial wave analyses of $ψ(3686)\to p\bar{p}π^0$ and $ψ(3686)\to p\bar{p}η$

Using a sample of $(2712\pm14)\times10^6$ $ψ(3686)$ events collected with the BESIII detector, we perform partial wave analyses of the decays $ψ(3686)\to p\bar{p}π^0$ and $ψ(3686)\to p\bar{p}η$. The branching fractions of $ψ(3686)\to p\bar{p}π^0$ and $ψ(3686)\to p\bar{p}η$ are determined to be $(133.9\pm11.2\pm2.3)\times10^{-6}$ or $(183.7\pm13.7\pm3.2)\times10^{-6}$ and $(61.5\pm6.5\pm1.1)\times10^{-6}$ or $(84.4\pm6.9\pm1.4)\times10^{-6}$, respectively, where the two solutions are caused by an ambiguous phase angle between resonant and continuum processes. Several well-established $N^*$ states are observed in the $pπ^0$ and $pη$ systems, and the corresponding branching fractions are measured. The ratio of decay widths $Γ_{N(1535)\to Nη}/Γ_{N(1535)\to Nπ}$ is determined to be $0.99\pm0.05\pm0.19$.

hep-ex↗

arXiv2025

Measurement of the Inclusive Cross Sections of Prompt $J/ψ$ and $ψ(3686)$ Production in $e^{+}e^{-}$ Annihilation from $\sqrt{s}=3.808$ to $4.951$ GeV

The inclusive cross sections of prompt $J/ψ$ and $ψ(3686)$ production are measured at center-of-mass energies from 3.808 to 4.951 GeV. The dataset used is 22 fb$^{-1}$ of $e^{+}e^{-}$ annihilation data collected with the BESIII detector operating at the BEPCII storage ring. The results obtained are in agreement with the previous BESIII measurements of exclusive $J/ψ$ and $ψ(3686)$ production. The average values obtained for the cross sections measured in the center-of-mass energy ranges from 4.527 to 4.951 GeV for $J/ψ$ and from 4.843 to 4.951 GeV for $ψ(3686)$, where the impact of known resonances is negligible, are $14.0\pm1.7\pm3.1$ pb and $15.3\pm3.0$ pb, respectively. For $J/ψ$, the first and the second uncertainties are statistical and systematic, respectively. For $ψ(3686)$, the uncertainty is total. These values are useful for testing charmonium production models.

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arXiv2025

Search for the decay $χ_{c1}(3872)\toπ^{+}π^{-}χ_{c1}$

Using a data sample corresponding to an integrated luminosity of 10.9 fb$^{-1}$ collected at center-of-mass energies from 4.16 to 4.34 GeV with the BESIII detector, we search for the decay $χ_{c1}(3872) \to π^{+}π^{-}χ_{c1}$ in the radiative production $e^{+}e^{-} \to γχ_{c1}(3872)$. No significant signal is observed, and the ratio for the branching fraction of $χ_{c1}(3872) \to π^{+}π^{-}χ_{c1}$ to $χ_{c1}(3872) \to π^{+}π^{-}J/ψ$ is measured as $\mathcal{R}\equiv\frac{\mathcal{B}[χ_{c1}(3872) \to π^{+}π^{-}χ_{c1}]}{\mathcal{B}[χ_{c1}(3872) \to π^{+}π^{-} J/ψ]}<0.18$ at 90$\%$ confidence level. The upper limit on the product of the cross section $σ[e^{+}e^{-}\toγχ_{c1}(3872)]$ and the branching fraction $\mathcal{B}[χ_{c1}(3872)\toπ^{+}π^{-}χ_{c1}]$ at each center-of-mass energy is also given. These measurements favor the non-conventional charmonium nature of the $χ_{c1}(3872)$ state.

hep-ex↗

arXiv2025

Search for the $e^+e^- \to ϕχ_{c1}(3872)$ process at BESIII

Based on 368.5 pb$^{-1}$ of $e^+e^-$ collision data collected at center-of-mass energies 4.914 and 4.946 GeV by the BESIII detector, the $e^+e^- \to ϕχ_{c1}(3872)$ process is searched for the first time. No significant signal is observed and the upper limits at the 90\% confidence level on the product of the Born cross section $σ(e^+e^- \to ϕχ_{c1}(3872))$ and the branching fraction $\mathcal{B}[χ_{c1}(3872)\toπ^+π^- J/ψ]$ at 4.914 and 4.946 GeV are set to be 0.85 and 0.96 pb, respectively. These measurements provide useful information for the production of the $χ_{c1}(3872)$ at $e^+e^-$ collider and deepen our understanding about the nature of this particle.

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