arXiv subjects

Y. Bai

Publications and source records attributed to Y. Bai.

At least 289 records · Page 16Linked to original sources

arXiv2024

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 $χ_{c1}(2P)$.

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arXiv2024

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.

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arXiv2024

Search for $C$-even states decaying to $D_{s}^{\pm}D_{s}^{*\mp}$ with masses between $4.08$ and $4.32~\mathrm{GeV}/c^{2}$

Six $C$-even states, denoted as $X$, with quantum numbers $J^{PC}=0^{-+}$, $1^{\pm+}$, or $2^{\pm+}$, are searched for via the $e^+e^-\toγD_{s}^{\pm}D_{s}^{*\mp}$ process using $(1667.39\pm8.84)~\mathrm{pb}^{-1}$ of $e^+e^-$ collision data collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energy of $\sqrt{s}=(4681.92\pm0.30)~\mathrm{MeV}$. No statistically significant signal is observed in the mass range from $4.08$ to $4.32~\mathrm{GeV}/c^{2}$. The upper limits of $σ[e^+e^- \to γX] \cdot \mathcal{B}[X \to D_{s}^{\pm} D_{s}^{*\mp}]$ at a $90\%$ confidence level are determined.

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arXiv2024

Precise Measurement of Born Cross Sections for $e^+e^-\to D\bar{D}$ at $\sqrt{s} = 3.80-4.95$ GeV

Using data samples collected with the BESIII detector at the BEPCII collider at center-of-mass energies ranging from 3.80 to 4.95 GeV, corresponding to an integrated luminosity of 20 fb$^{-1}$, a measurement of Born cross sections for the $e^+e^-\to D^{0}\bar{D}^{0}$ and $D^{+}D^{-}$ processes is presented with unprecedented precision. Many clear peaks in the line shape of $e^+e^-\to D^{0}\bar{D}^{0}$ and $D^{+}D^{-}$ around the mass range of $G(3900)$, $ψ(4040)$, $ψ(4160)$, $Y(4260)$, and $ψ(4415)$, etc., are foreseen. These results offer crucial experimental insights into the nature of hadron production in the open-charm region.

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arXiv2024

Search for the rare decay $J/ψ\to γD^0+c.c.$ at BESIII

Using $(10087\pm44)\times10^6J/ψ$ events collected with the BESIII detector, we search for the rare decay $J/ψ\to γD^0+c.c.$ for the first time. No obvious signal is observed and the upper limit on the branching fraction is determined to be ${\cal B}(J/ψ\to γD^{0}+c.c.)< 9.1 \times 10^{-8}$ at 90\% confidence level.

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arXiv2024

Measurements of $K_S^0$-$K_L^0$ asymmetries in the decays $Λ_c^+ \to pK_{L,S}^0$, $pK_{L,S}^0π^+π^-$ and $pK_{L,S}^0π^0$

Using $e^+e^-$ annihilation data sets corresponding to an integrated luminosity of 4.5 $\text{fb}^{-1}$, collected with the BESIII detector at center-of-mass energies between 4.600 and 4.699 GeV, we report the first measurements of the absolute branching fractions $\mathcal{B}(Λ_c^+\to pK_{L}^{0})=(1.67 \pm 0.06 \pm 0. 04)\%$, $\mathcal{B}(Λ_c^+\to pK_{L}^{0}π^+π^-)=(1.69 \pm 0.10 \pm 0.05)\%$, and $\mathcal{B}(Λ_c^+\to pK_{L}^{0}π^0)=(2.02 \pm 0.13 \pm 0.05)\%$, where the first uncertainties are statistical and the second systematic. Combining with the known branching fractions of $Λ_c^+ \to pK_{S}^{0}$, $Λ_c^+ \to pK_{S}^{0}π^+π^-$, and $Λ_c^+ \to pK_{S}^{0}π^0$, we present the first measurements of the $K_{S}^{0}$-$K_{L}^{0}$ asymmetries $R(Λ_c^+, K_{S,L}^0X) = \frac{\mathcal{B}(Λ_c^+ \to K_{S}^{0} X) - \mathcal{B}(Λ_c^+ \to K_{L}^{0} X)}{\mathcal{B}(Λ_c^+ \to K_{S}^{0} X) + \mathcal{B}(Λ_c^+ \to K_{L}^{0} X)}$ in charmed baryon decays: $R(Λ_c^+, pK_{S,L}^0) = -0.025 \pm 0.031$, $R(Λ_c^+, pK_{S,L}^0π^+π^-) = -0.027 \pm 0.048$, and $R(Λ_c^+, pK_{S,L}^0π^0) =-0.015 \pm 0.046$. No significant asymmetries within the uncertainties are observed.

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arXiv2024

Search for $η_c(2S)\toωω$ and $ωϕ$ decays and measurements of $χ_{cJ}\toωω$ and $ωϕ$ in $ψ(2S)$ radiative processes

Using $(2712\pm 14)$ $\times$ 10$^{6}$ $ψ(2S)$ events collected with the BESIII detector at the BEPCII collider, we search for the decays $η_{c}(2S)\toωω$ and $η_{c}(2S)\toωϕ$ via the process $ψ(2S)\toγη_{c}(2S)$. Evidence of $η_{c}(2S)\toωω$ is found with a statistical significance of $3.2σ$. The branching fraction is measured to be $\mathcal{B}(η_{c}(2S)\toωω)=(5.65\pm3.77(\rm stat.)\pm5.32(\rm syst.))\times10^{-4}$. No statistically significant signal is observed for the decay $η_{c}(2S)\toωϕ$. The upper limit of the branching fraction at the 90\% confidence level is determined to be $\mathcal{B}(ψ(2S)\toγη_{c}(2S),η_{c}(2S)\toωϕ)<2.24\times 10^{-7}$. We also update the branching fractions of $χ_{cJ}\to ωω$ and $χ_{cJ}\toωϕ$ decays via the $ψ(2S)\toγχ_{cJ}$ transition. The branching fractions are determined to be $\mathcal{B}(χ_{c0}\toωω)=(10.63\pm0.11\pm0.46)\times 10^{-4}$, $\mathcal{B}(χ_{c1}\toωω)=(6.39\pm0.07\pm0.29)\times 10^{-4}$, $\mathcal{B}(χ_{c2}\toωω)=(8.50\pm0.08\pm0.38)\times 10^{-4}$, $\mathcal{B}(χ_{c0}\toωϕ)=(1.18\pm0.03\pm0.05)\times 10^{-4}$, $\mathcal{B}(χ_{c1}\toωϕ)=(2.03\pm0.15\pm0.12)\times 10^{-5}$, and $\mathcal{B}(χ_{c2}\toωϕ)=(9.37\pm1.07\pm0.59)\times 10^{-6}$, where the first uncertainties are statistical and the second are systematic.

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arXiv2024

Search for $e^{+}e^{-}\toη'ψ(2S)$ at center-of-mass energies from 4.66 to 4.95 GeV

Using data samples with an integrated luminosity of $4.67~\mathrm{fb}^{-1}$ collected by the BESIII detector operating at the BEPCII collider, we search for the process $e^+e^- \rightarrow η' ψ(2S)$ at center-of-mass energies from $4.66$ to $4.95~\mathrm{GeV}$. No significant signal is observed, and upper limits for the Born cross sections $σ^B(e^+e^-\rightarrowη'ψ(2S))$ at the 90\% confidence level are determined.

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arXiv2024

Measurement of the Branching Fraction of \boldmath{$ψ(2S) \to γπ^0$}

Based on $(2712.4\pm14.1)\times10^{6}~ψ(2S)$ events, 7.9 fb$^{-1}$ $ψ(3773)$ data, and 0.8 fb$^{-1}$ off-resonance data samples collected with the BESIII detector, we measure the branching fraction of $ψ(2S)\rightarrowγπ^{0}$ and $e^{+}e^{-}\rightarrowγπ^{0}$ form factor at momentum transfers $Q^{2}\sim13$ GeV$^{2}$. The $e^{+}e^{-}\rightarrowγπ^{0}$ cross section is fitted with considering the interference between the $ψ(2S)$ and continuum amplitudes and two solutions are found, ${\cal B}=3.74\times10^{-7}$ with $ϕ=3.93$ rad and ${\cal B}=7.87\times10^{-7}$ with $ϕ=2.08$ rad. Here, ${\cal B}$ is the branching fraction of $ψ(2S)\rightarrowγπ^{0}$ and $ϕ$ is the relative phase angle between the $ψ(2S)$ and continuum amplitudes. Due to insufficient off-resonance data, the branching fraction ${\cal B}(ψ(2S)\rightarrowγπ^{0})$ is determined to be in the range $[2.7, 9.7]\times10^{-7}$ within one standard deviation of the contour region.

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arXiv2024

Analysis of the dynamics of the decay $D^{+}\to K_{S}^{0} π^{0} e^{+}ν_{e}$

The branching fraction of $D^+\to K_{S}^{0} π^{0}e^+ν_e$ is measured for the first time using $7.93~\mathrm{fb}^{-1}$ of $e^+e^-$ annihilation data collected at the center-of-mass energy $\sqrt{s}=3.773$~GeV with the BESIII detector operating at the BEPCII collider, and is determined to be ${\mathcal B}$($D^+\to K_S^0π^0e^+ν_e$) = $(0.881~\pm~0.017_{\rm stat.}~\pm~0.016_{\rm syst.})$\%. Based on an analysis of the $D^+\to K_S^0π^0e^+ν_e$ decay dynamics, we observe the $S\text{-}{\rm wave}$ and $P$-wave components with fractions of $f_{S\text{-}{\rm wave}}$ = $(6.13~\pm~0.27_{\rm stat.}~\pm ~0.30_{\rm syst.})\%$ and $f_{\bar K^{*}(892)^0}$ = $(93.88~\pm~0.27_{\rm stat.}~\pm~0.29_{\rm syst.})$\%, respectively. From these results, we obtain the branching fractions ${\mathcal B}$($D^+\to (K_S^0π^0)_{S\text{-}{\rm wave}}~e^+ν_e$) = $(5.41~\pm~0.35_{\rm stat.}~\pm~0.37_{\rm syst.})\times10^{-4}$ and ${\mathcal B}$($D^+\to \bar K^{*}(892)^0e^+ν_e$) = $(4.97~\pm~0.11_{\rm stat.}~\pm~0.12_{\rm syst.})$\%. In addition, the hadronic form-factor ratios of $D^{+} \to \bar {K}^{*}(892)^0e^+ν_e$ at $q^2=0$, assuming a single-pole dominance parameterization, are determined to be $r_V=\frac{V(0)}{A_1(0)}= 1.43~\pm~0.07_{\rm stat.}~\pm~0.03_{\rm syst.}$ and $r_2=\frac{A_2(0)}{A_1(0)}=0.72~\pm~0.06_{\rm stat.}~\pm~0.02_{\rm syst.}$.

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arXiv2024

Observation of $η_{c}(2S) \to K^{+}K^{-}η$

By analyzing $(27.12 \pm 0.14)\times10^{8}$ $ψ(3686)$ events accumulated with the BESIII detector, the decay $η_{c}(2S) \to K^{+} K^{-} η$ is observed for the first time with a significance of $6.2σ$ after considering systematic uncertainties. The product of the branching fractions of $ψ(3686) \to γη_{c}(2S)$ and $η_{c}(2S) \to K^{+} K^{-} η$ is measured to be $\mathcal{B}(ψ(3686) \toγη_{c}(2S))\times \mathcal{B}(η_{c}(2S)\to K^{+} K^{-}η)=(2.39 \pm 0.32 \pm 0.34) \times 10^{-6}$, where the first uncertainty is statistical, and the second one is systematic. The branching fraction of $η_{c}(2S)\to K^{+} K^{-}η$ is determined to be $\mathcal{B}(η_{c}(2S)\to K^{+} K^{-}η) = (3.42 \pm 0.46 \pm 0.48 \pm 2.44) \times 10^{-3}$, where the third uncertainty is due to the branching fraction of $ψ(3686) \to γη_{c}(2S)$. Using a recent BESIII measurement of $\mathcal{B} (η_{c}(2S) \to K^{+} K^{-}π^{0})$, we also determine the ratio between the branching fractions of $η_{c}(2S) \to K^{+} K^{-}η$ and $η_{c}(2S) \to K^{+} K^{-}π^{0}$ to be $1.49 \pm 0.22 \pm 0.25$, which is consistent with the previous result of BaBar at a comparable precision level.

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arXiv2024

Search for di-photon decays of an axion-like particle in radiative $J/ψ$ decays

We search for the di-photon decay of a light pseudoscalar axion-like particle, $a$, in radiative $J/ψ$ decays, using 10 billion $J/ψ$ events collected with the BESIII detector. We find no evidence of a signal and set upper limits at the $95\%$ confidence level on the product branching fraction $\mathcal{B}(J/ψ\to γa) \times \mathcal{B}(a \to γγ)$ and the axion-like particle photon coupling constant $g_{a γγ}$ in the ranges of $(3.7-48.5) \times 10^{-8}$ and $(2.2 -101.8)\times 10^{-4}$ GeV$^{-1}$, respectively, for $0.18 \le m_a \le 2.85$ GeV/$c^2$. These are the most stringent limits to date in this mass region.

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arXiv2024

Measurement of the $\boldsymbol{e^{+}e^{-}\to K^+K^-ψ(2S)}$ Cross Section at Center-of-Mass Energies from 4.699 to 4.951 GeV and Search for $\boldsymbol{Z_{cs}^{\pm}}$ in the $\boldsymbol{Z_{cs}^\pm\to K^\pmψ(2S)}$ Decay

We perform the first investigation of the process $e^{+}e^{-}\to K^+K^-ψ(2S)$ and report its Born cross sections over a range of center-of-mass energies from 4.699 to 4.951~GeV. The measurements are carried out using several partial reconstruction techniques using data samples collected by the BESIII detector with a total integrated luminosity of 2.5~fb$^{-1}$. We search for new tetraquark candidates $Z_{cs}^\pm$ in the decays $Z_{cs}^\pm\to K^\pmψ(2S)$. No significant $Z_{cs}^\pm$ signals are observed.

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arXiv2024

Measurement of the cross sections of $e^+e^-\to K^{-}\barΞ^{+}Λ/Σ^{0}$ at center-of-mass energies between 3.510 and 4.914 GeV

Using $e^+e^-$ collision data collected with the BESIII detector at the BEPCII collider at center-of-mass energies between 3.510 and 4.914GeV, corresponding to an integrated luminosity of 25 fb$^{-1}$, we measure the Born cross sections for the process $e^+e^-\to K^-\barΞ^+Λ/Σ^{0}$ at thirty-five energy points with a partial-reconstruction strategy. By fitting the dressed cross sections of $e^+e^-\to K^-\barΞ^+Λ/Σ^{0}$, evidence for $ψ(4160) \to K^{-}\barΞ^{+}Λ$ is found for the first time with a significance of 4.4$σ$, including systematic uncertainties. No evidence for other possible resonances is found. In addition, the products of electronic partial width and branching fraction for all assumed resonances decaying into $K^{-}\barΞ^{+}Λ/Σ^{0}$ are determined.

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arXiv2024

Improved measurement of the branching fraction of $h_{c}\rightarrowγη^\prime/η$ and search for $h_{c}\rightarrowγπ^0$

The processes $h_c\toγP(P = η^\prime,~η,~π^0)$ are studied with a sample of $(27.12\pm0.14)\times10^{8}$ $ψ(3686)$ events collected by the BESIII detector at the BEPCII collider. The decay $h_{c}\rightarrowγη$ is observed for the first time with the significance of $9.0\,σ$, and the branching fraction is determined to be $(3.77\pm0.55\pm0.13\pm0.26)\times10^{-4}$, while $\mathscr{B}(h_{c}\rightarrowγη^\prime)$ is measured to be $(1.40\pm0.11\pm0.04\pm0.10)\times10^{-3}$, where the first uncertainties are statistical, the second systematic, and the third from the branching fraction of $ψ(3686)\rightarrowπ^{0}h_c$. The combination of these results allows for a precise determination of $R_{h_c}=\frac{\mathscr{B}(h_c\rightarrowγη)}{\mathscr{B}(h_c\rightarrowγη^\prime)}$, which is calculated to be $(27.0\pm4.4\pm1.0)\%$. The results are valuable for gaining a deeper understanding of $η-η^\prime$ mixing, and its manifestation within quantum chromodynamics. No significant signal is found for the decay $h_c\rightarrowγπ^{0}$, and an upper limit is placed on its branching fraction of $\mathscr{B}(h_c\rightarrowγπ^{0})<5.0\times10^{-5}$, at the 90$\%$ confidence level.

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arXiv2024

Search for $η_{c}(2S)\to K^+ K^- η^{\prime}$ decay

Using $(2.712\pm0.014)\times10^{9}$ $ψ(3686)$ events collected with the BESIII detector operating at the BEPCII, we find an evidence of the $η_{c}(2S)\to K^+ K^- η^{\prime}$ decay with a statistical significance of 3.1$σ$. Its decay branching fraction is measured to be $(12.24\pm4.60(\mathrm{stat.})\pm2.37(\mathrm{syst.})\pm4.68(\mathrm{extr.}))\times 10^{-4}$, where the first uncertainty is statistical, the second is systematic, and the third uncertainty is from the branching fraction of the $ψ(3686)\toγη_{c}(2S)$ decay. The upper limit on the product branching fraction $B[ψ(3686)\toγη_{c}(2S)] \times$ $B[η_{c}(2S)\to K^+ K^- η^{\prime}]$ is set to be $1.14 \times 10^{-6}$ at $90\%$ confidence level. In addition, the branching fractions of $χ_{c1}\to K^+ K^- η^{\prime}$ and $χ_{c2}\to K^+ K^- η^{\prime}$ are updated to be $(8.47\pm0.09(\mathrm{stat.})\pm0.47(\mathrm{syst.}))\times 10^{-4}$ and $(1.53\pm0.04(\mathrm{stat.})\pm0.08(\mathrm{syst.}))\times 10^{-4}$, respectively. The precision is improved by twofold.

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arXiv2024

Strong and weak $CP$ tests in sequential decays of polarized $Σ^0$ hyperons

The $J/ψ, ψ(3686) \to Σ^0 \barΣ^{0}$ processes and subsequent decays are studied using the world's largest $J/ψ$ and $ψ(3686)$ data samples collected with the BESIII detector. The strong-$CP$ symmetry is tested in the decays of the $Σ^0$ hyperons for the first time by measuring the decay parameters, $α_{Σ^0} = -0.0017 \pm 0.0021 \pm 0.0018$ and $\barα_{Σ^0} = 0.0021 \pm 0.0020 \pm 0.0022$. The weak-$CP$ test is performed in the subsequent decays of their daughter particles $Λ$ and $\barΛ$. Also for the first time, the transverse polarizations of the $Σ^0$ hyperons in $J/ψ$ and $ψ(3686)$ decays are observed with opposite directions, and the ratios between the S-wave and D-wave contributions of the $J/ψ, ψ(3686) \to Σ^0 \barΣ^{0}$ decays are obtained. These results are crucial to understand the decay dynamics of the charmonium states and the production mechanism of the $Σ^0-\barΣ^0$ pairs.

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arXiv2024

Measurements of Normalized Differential Cross Sections of Inclusive $η$ Production in $e^{+}e^{-}$ Annihilation at Energy from 2.0000 to 3.6710 GeV

Using data samples collected with the BESIII detector operating at the BEPCII storage ring, the cross section of the inclusive process $e^{+}e^{-} \to η+ X$, normalized by the total cross section of $e^{+}e^{-} \to \text{hadrons}$, is measured at eight center-of-mass energy points from 2.0000 GeV to 3.6710 GeV. These are the first measurements with momentum dependence in this energy region. Our measurement shows a significant discrepancy from calculations with the existing fragmentation functions. To address this discrepancy, a new QCD analysis is performed at the next-to-next-to-leading order with hadron mass corrections and higher twist effects, which can explain both the established high-energy data and our measurements reasonably well.

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