arXiv subjects

F. Feldbauer

Publications and source records attributed to F. Feldbauer.

At least 253 records · Page 14Linked to original sources

arXiv2024

Determination of the number of $ψ(3686)$ events taken at BESIII

The number of $ψ(3686)$ events collected by the BESIII detector during the 2021 run period is determined to be $(2259.3\pm 11.1)\times 10^6$ by counting inclusive $ψ(3686)$ hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of $ψ(3686)$ events collected during the 2009 and 2012 run periods are updated to be $(107.7\pm0.6)\times 10^6$ and $(345.4\pm 2.6)\times 10^6$, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of $ψ(3686)$ events in the three data samples is $(2712.4\pm14.3)\times10^6$.

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arXiv2024

Study of the decays $χ_{cJ}\toΛ\barΛω$

Using $(27.12\pm 0.14)\times10^{8}$ $ψ(3686)$ events collected with the BESIII detector, we present the first observation of the decays $χ_{cJ}\toΛ\barΛω$, where $J=0, 1, 2$, with statistical significances of $11.7 σ, 11.2 σ$, and $11.8 σ$. The branching fractions of these decays are determined to be $\mathcal{B}(χ_{c0}\toΛ\barΛω)=({2.37 \pm 0.22 \pm 0.23}) \times 10^{-4}$, $\mathcal{B}(χ_{c1}\toΛ\barΛω)=({1.01 \pm 0.10 \pm 0.11}) \times 10^{-4}$, and $\mathcal{B}(χ_{c2}\toΛ\barΛω)=({1.40 \pm 0.13 \pm 0.17}) \times 10^{-4}$, where the first uncertainties are statistical and the second are systematic. We observe no clear intermediate structures.

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arXiv2024

Precision measurement of the branching fraction of \boldmath $J/ψ\rightarrow K^+K^-$ via $ψ(2S)\rightarrow π^+π^-J/ψ$

Using a sample of $448.1 \times 10^6$ $ψ(2S)$ events collected with the BESIII detector, we perform a study of the decay $J/ψ\rightarrow K^+K^-$ via $ψ(2S)\rightarrow π^+π^-J/ψ$. The branching fraction of $J/ψ\rightarrow K^+K^-$ is determined to be $\mathcal{B}_{K^+K^-}=(3.072\pm 0.023({\rm stat.})\pm 0.050({\rm syst.}))\times 10^{-4}$, which is consistent with previous measurements but with significantly improved precision.

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arXiv2024

First study of antihyperon-nucleon scattering $\barΛp\rightarrow\barΛp$ and measurement of $Λp\rightarrowΛp$ cross section

Using $(10.087\pm0.044)\times10^{9}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring, the processes $Λp\rightarrowΛp$ and $\barΛp\rightarrow\barΛp$ are studied, where the $Λ/\barΛ$ baryons are produced in the process $J/ψ\rightarrowΛ\barΛ$ and the protons are the hydrogen nuclei in the cooling oil of the beam pipe. Clear signals are observed for the two reactions. The cross sections in $-0.9\leq\rm{cos}θ_{Λ/\barΛ}\leq0.9$ are measured to be $σ(Λp\rightarrowΛp)=(12.2\pm1.6_{\rm{stat}}\pm1.1_{\rm{sys}})$ mb and $σ(\barΛ p\rightarrow\barΛ p)=(17.5\pm2.1_{\rm{stat}}\pm1.6_{\rm{sys}})$ mb at the $Λ/\barΛ$ momentum of $1.074$ GeV/$c$ within a range of $\pm0.017$ GeV/$c$, where the $θ_{Λ/\barΛ}$ are the scattering angles of the $Λ/\barΛ$ in the $Λp/\barΛp$ rest frames. Furthermore, the differential cross sections of the two reactions are also measured, where there is a slight tendency of forward scattering for $Λp\rightarrowΛp$, and a strong forward peak for $\barΛp\rightarrow\barΛp$. We present an approach to extract the total elastic cross sections by extrapolation. The study of $\barΛp\rightarrow\barΛp$ represents the first study of antihyperon-nucleon scattering, and these new measurements will serve as important inputs for the theoretical understanding of the (anti)hyperon-nucleon interaction.

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arXiv2024

Search for the leptonic decays $D^{+}\to e^+ν_e$ and $D^{+}\to μ^+ν_μ$

We present the first search for the leptonic decays $D^{*+}\to e^+ν_e$ and $D^{*+}\to μ^+ν_μ$ by analyzing a data sample of electron-positron collisions recorded with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, corresponding to an integrated luminosity of 6.32~fb$^{-1}$. No significant signal is observed. The upper limits on the branching fractions for $D^{*+}\to e^+ν_e$ and $D^{*+}\to μ^+ν_μ$ are set to be $1.1 \times 10^{-5}$ and $4.3 \times 10^{-6}$ at 90\% confidence level, respectively.

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arXiv2024

First Observation of a Three-Resonance Structure in $e^+e^-\rightarrow$Nonopen Charm Hadrons

We report the measurement of the inclusive cross sections for $e^+e^-$$\rightarrow$nOCH (where nOCH denotes non-open charm hadrons) with improved precision at center-of-mass (c.m.) energies from 3.645 to 3.871 GeV. We observe three resonances: $\mathcal R(3760)$, $\mathcal R(3780)$, and $\mathcal R(3810)$ with significances of $8.1σ$, $13.7σ$, and $8.8σ$, respectively. The $\mathcal R(3810)$ state is observed for the first time, while the $\mathcal R(3760)$ and $\mathcal R(3780)$ states are observed for the first time in the nOCH cross sections. Two sets of resonance parameters describe the energy-dependent line shape of the cross sections well. In set I [set II], the $\mathcal R(3810)$ state has mass $(3805.7 \pm 1.1 \pm 2.7)$ [$(3805.7 \pm 1.1 \pm 2.7)$] MeV/$c^2$, total width $(11.6 \pm 2.9 \pm 1.9)$ [$(11.5 \pm 2.8 \pm 1.9)$] MeV, and an electronic width multiplied by the nOCH decay branching fraction of $(10.9\pm 3.8\pm 2.5)$ [$(11.0\pm 3.4\pm 2.5)$] eV. In addition, we measure the branching fractions ${\mathcal B}[{\mathcal R}(3760)$$\rightarrow$nOCH$]=(25.2 \pm 16.1 \pm 30.4)\% [(6.4 \pm 4.8 \pm 7.7)\%]$ and ${\mathcal B}[\mathcal R(3780)$$\rightarrow$nOCH$]=(12.3 \pm 6.6 \pm 8.3)\% [(10.4 \pm 4.8 \pm 7.0)\%]$ for the first time. The $\mathcal R(3760)$ state can be interpreted as an open-charm (OC) molecular state, but containing a simple four-quark state component. The $\mathcal R(3810)$ state can be interpreted as a hadrocharmonium state.

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arXiv2024

Measurement of the ${e}^{+}{e}^{-}\to p \bar{p}π^{0}$ cross section at $\sqrt{s}=2.1000-3.0800$ GeV

The process $e^{+}e^{-}\to p\bar{p}π^{0}$ is studied at 20 center-of-mass energies ranging from 2.1000 to 3.0800 GeV using 636.8 pb$^{-1}$ of data collected with the BESIII detector operating at the BEPCII collider. The Born cross sections for $e^{+}e^{-}\to p\bar{p}π^{0}$ are measured with high precision. Since the lowest center-of-mass energy, 2.1000 GeV, is less than 90 MeV above the $p\bar{p}π^0$ energy threshold, we can probe the threshold behavior for this reaction. However, no anomalous threshold enhancement is found in the cross sections for $e^{+}e^{-}\to p\bar{p}π^{0}$.

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arXiv2024

Measurement of the absolute branching fraction of the three-body decay $Λ_{c}^+ \to Ξ^{0}K^{+}π^{0}$ and search for $Λ_{c}^+ \to nK^+π^0$, $Σ^{0}K^{+}π^{0}$ and $ΛK^{+}π^{0}$

The Cabbibo-favored decay $Λ_{c}^+ \to Ξ^{0}K^{+}π^{0}$ is studied for the first time using 6.1 fb$^{-1}$ of $e^+e^-$ collision data at center-of-mass energies between 4.600 and 4.840 GeV, collected with the BESIII detector at the BEPCII collider. With a double-tag method, the branching fraction of the three-body decay $Λ_{c}^+ \to Ξ^{0}K^{+}π^{0}$ is measured to be $(7.79 \pm 1.46 _{\rm} \pm0.71 _{\rm}) \times 10^{ - 3}$, where the first and second uncertainties are statistical and systematic, respectively. The branching fraction of the two-body decay $Λ_{c}^+ \to Ξ(1530)^{0}K^+$ is $(5.99\pm1.04\pm0.29)\times10^{-3}$, which is consistent with the previous result of $(5.02\pm0.99\pm0.31)\times 10^{-3}$. In addition, the upper limit on the branching fraction of the doubly Cabbibo-suppressed decay $Λ_{c}^+ \to nK^+π^0$ is $7.1 \times 10^{-4}$ at the 90$\%$ confidence level. The upper limits on the branching fractions of $Λ_{c}^+ \to Σ^{0}K^{+}π^{0}$ and $ΛK^{+}π^{0}$ are also determined to be $1.8\times 10^{-3}$ and $ 2.0 \times 10^{-3}$, respectively.

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arXiv2024

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

The singly Cabibbo-suppressed decay $Λ_{c}^{+}\to Σ^{-}K^{+}π^{+}$ is observed for the first time with a statistical significance of $6.4σ$ by using 4.5 fb$^{-1}$ of $e^+e^-$ collision data collected at center-of-mass energies between 4.600 and 4.699 GeV with the BESIII detector at BEPCII. The absolute branching fraction of $Λ_{c}^{+}\to Σ^{-}K^{+}π^{+}$ is measured to be $(3.8\pm1.3_{\rm stat}\pm0.2_{\rm syst})\times 10^{-4}$ in a model-independent approach. This is the first observation of a Cabibbo-suppressed $Λ_{c}^{+}$ decay involving $Σ^-$ in the final state. The ratio of branching fractions between $Λ_{c}^{+}\to Σ^{-}K^{+}π^{+}$ and the Cabibbo-favored decay $Λ_{c}^{+}\to Σ^- π^+π^+$ is calculated to be $(0.4 \pm 0.1)s_{c}^{2}$, where $s_{c} \equiv \sinθ_c = 0.2248$ with $θ_c$ the Cabibbo mixing angle. This ratio significantly deviates from $1.0s_{c}^{2}$ and provides important information for the understanding of nonfactorization contributions in $Λ_{c}^{+}$ decays.

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arXiv2024

Measurements of Born Cross Sections for $e^+e^-\to Λ_{c}^+ \barΛ_{c}(2595)^- + {\rm c.c.}$ and $e^+e^-\to Λ_{c}^+ \barΛ_{c}(2625)^- + {\rm c.c.}$ at $\sqrt{s}=$4918.0 and 4950.9 MeV

Using $e^+e^-$ collision data collected with the BESIII detector operating at the BEPCII collider, the Born cross sections of $e^+e^-\to Λ_{c}^+ \barΛ_{c}(2595)^- + \rm{c.c.}$ and $e^+e^-\to Λ_{c}^+ \barΛ_{c}(2625)^- + \rm{c.c.}$ are measured for the first time at center-of-mass energies of $\sqrt{s}=4918.0$ and 4950.9 MeV. Non-zero cross sections are observed very close to the production threshold. The measured Born cross sections of $e^+e^-\to Λ_{c}^+ \barΛ_{c}(2625)^- + \rm{c.c.}$ are about $2\sim3$ times greater than those of $e^+e^-\to Λ_{c}^+ \barΛ_{c}(2595)^- + \rm{c.c.}$, thereby indicating that the exotic structure potentially exists in the excited charmed baryons. The Born cross sections are $15.6\pm3.1\pm0.9$ pb and $29.4\pm3.7\pm2.7$ pb for $e^+e^-\to Λ_{c}^+ \barΛ_{c}(2595)^- + \rm{c.c.}$, and are $43.4\pm4.0\pm4.1$ pb and $76.8\pm6.5\pm4.2$ pb for $e^+e^-\to Λ_{c}^+ \barΛ_{c}(2625)^- +\rm{c.c.}$ at $\sqrt s=4918.0$ and 4950.9 MeV, respectively. Based on the polar angle distributions of the $\barΛ_{c}(2625)^-$ and $Λ_{c}(2625)^+$, the form-factor ratios $\sqrt{|G_{E}|^2 + 3|G_{M}|^2}/|G_{C}|$ are determined for $e^+e^-\to Λ_{c}^+ \barΛ_{c}(2625)^- + \rm{c.c.}$ for the first time, which are $5.95\pm4.07\pm0.15$ and $0.94\pm0.32\pm0.02$ at $\sqrt s=4918.0$ and 4950.9 MeV, respectively. All of these first uncertainties are statistical and second systematic.

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arXiv2024

Measurement of Born cross section of $e^{+}e^{-}\rightarrowΣ^{+}\barΣ^{-}$ at center-of-mass energies between 3.510 and 4.951 GeV

Using 24.1 fb$^{-1}$ of $e^{+}e^{-}$ collision data collected with the BESIII detector at the BEPCII collider, the Born cross sections and effective form factors of the $e^{+}e^{-}\rightarrowΣ^{+}\barΣ^{-}$ reaction are measured. The measurements are performed at center-of-mass energies ranging from 3.510 to 4.951 GeV. No significant evidence for the decay of the charmonium(-like) states, $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, $Y(4230)$, $Y(4360)$, $ψ(4415)$, and $Y(4660)$, into a $Σ^{+}\barΣ^{-}$ final state is observed. Consequently, upper limits for the products of the branching fractions and the electronic partial widths at the 90% confidence level are reported for these decays.

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arXiv2024

Determination of spin-parity quantum numbers of X(2370) as $0^{-+}$ from $J/ψ\rightarrowγK^{0}_{S}K^{0}_{S}η^{\prime}$

Based on $(10087\pm44)\times10^{6}$ $J/ψ$ events collected with the BESIII detector, a partial wave analysis of the decay $J/ψ\rightarrowγK^{0}_{S}K^{0}_{S}η^{\prime}$ is performed. The mass and width of the $X(2370)$ are measured to be $2395 \pm 11 ({\rm stat})^{+26}_{-94}({\rm syst})\ \mathrm{MeV}/c^{2}$ and $188^{+18}_{-17}({\rm stat})^{+124}_{-33}({\rm syst})~\mathrm{MeV}$, respectively. The corresponding product branching fraction is $\mathcal{B}[J/ψ\rightarrowγX(2370)] \times \mathcal{B}[X(2370) \rightarrow f_{0}(980)η^{\prime}] \times \mathcal{B}[f_{0}(980) \rightarrow K^{0}_{S}K^{0}_{S}] = \left( 1.31 \pm 0.22 ({\rm stat})^{+2.85}_{-0.84}({\rm syst}) \right) \times 10^{-5}$. The statistical significance of the $X(2370)$ is greater than $11.7σ$ and the spin-parity is determined to be $0^{-+}$ for the first time. The measured mass and spin-parity of the $X(2370)$ are consistent with the predictions of the lightest pseudoscalar glueball.

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arXiv2024

Study of excited $Ξ$ states in $ψ(3686)\rightarrow{}K^{-}Λ\overlineΞ^{+}+c.c.$

Based on a sample of $(448.1\pm2.9)\times10^{6}$ $ψ(3686)$ events collected with the BESIII detector at BEPCII, the decays of $ψ(3686)\to{}K^{-}Λ\overlineΞ^{+} + c.c.$ with $\overlineΞ^+ \to \overlineΛ π^+$, $\overlineΛ\to \overline{p} π^+$ are studied.Two excited hyperons, $Ξ(1690)^-$ and $Ξ(1820)^-$, are observed with large significance ($ \gg 10 σ$) in the $K^{-}Λ$ invariant mass distributions. A partial wave analysis is performed, and the spin-parities of $Ξ(1690)^-$ and $Ξ(1820)^-$ are determined to be $\frac{1}{2}^{-}$ and $\frac{3}{2}^{-}$, respectively. The masses, widths, and product branching fractions of $Ξ(1690)^-$ and $Ξ(1820)^-$ are also measured.

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arXiv2024

Observation of the Anomalous Shape of $X(1840)$ in $J/ψ\rightarrow γ3(π^+ π^-)$ Indicating a Second Resonance Near $p\bar{p}$ Threshold

Using a sample of $(10087\pm44)\times 10^6$ $J/ψ$ events, which is about 45 times larger than that was previously analyzed, a further investigation on the $J/ψ\rightarrow γ3(π^+π^-)$ decay is performed. A significant distortion at 1.84 GeV/$c^2$ in the line-shape of the $3(π^+π^-)$ invariant mass spectrum is observed for the first time, which could be resolved by two overlapping resonant structures, $X(1840)$ and $X(1880)$. The new state $X(1880)$ is observed with a statistical significance larger than $10σ$. The mass and width of $X(1880)$ are determined to be $1882.1\pm1.7\pm0.7$ MeV/$c^2$ and $30.7\pm5.5 \pm2.4$ MeV, respectively, which indicates the existence of a $p\bar{p}$ bound state.

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arXiv2024

Observation of $ψ(3686) \to Ω^- K^+ \barΞ^0 $+c.c

Using $(27.12 \pm 0.14) \times 10^{8}$ $ψ(3686)$ events collected with the BESIII detector at BEPCII, the decay of $ψ(3686) \to Ω^- K^+ \barΞ^0 +c.c.$ is observed for the first time. The branching fraction of this decay is measured to be $\mathcal{B}_{ψ(3686) \to Ω^- K^+ \barΞ^0 +c.c.}=(2.78 \pm 0.40 \pm 0.18 ) \times 10^{-6}$, where the first uncertainty is statistical and the second is systematic. Possible baryon excited states are searched for in this decay, but no evident intermediate state is observed with the current sample size.

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arXiv2024

Search for $ΔS=2$ nonleptonic hyperon decays $Ω^-\toΣ^{0}π^{-}$ and $Ω^-\to nK^{-}$

Using $(27.12 \pm 0.14) \times 10^{8}$ $ψ(3686)$ events collected by the BESIII detector at the center-of-mass energy of $\sqrt{s} = 3.686$ GeV, we search for the first time for two nonleptonic hyperon decays that change strangeness by two units, $Ω^-\toΣ^{0}π^-$ and $Ω^-\to nK^{-}$. No significant signal is observed. The upper limits on their decay branching fractions are determined to be $\mathcal{B}(Ω^-\toΣ^{0}π^-) < 5.4\times 10^{-4}$ and $\mathcal{B}(Ω^-\to nK^{-}) < 2.4\times 10^{-4}$ at the $90\%$ confidence level.

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arXiv2024

Observation of $D \to a_{0}(980)π$ in the decays $D^{0} \rightarrow π^{+}π^{-}η$ and $D^{+} \rightarrow π^{+}π^{0}η$

We report the first amplitude analysis of the decays $D^{0} \to π^{+} π^{-} η$ and $D^{+} \rightarrow π^{+}π^{0}η$ using a data sample taken with the BESIII detector at the center-of-mass energy of 3.773 GeV, corresponding to an integrated luminosity of 7.9 ${\rm fb}^{-1}$. The contribution from the process $D^{0(+)} \to a_{0}(980)^{+} π^{-(0)}$ is significantly larger than the $D^{0(+)} \to a_{0}(980)^{-(0)} π^{+}$ contribution. The ratios $\mathcal{B}(D^{0} \rightarrow a_{0}(980)^{+}π^{-})/\mathcal{B}(D^{0} \rightarrow a_{0}(980)^{-}π^{+})$ and $\mathcal{B}(D^{+} \rightarrow a_{0}(980)^{+}π^{0})/\mathcal{B}(D^{+} \rightarrow a_{0}(980)^{0}π^{+})$ are measured to be $7.5^{+2.5}_{-0.8\,\mathrm{stat.}}\pm1.7_{\mathrm{syst.}}$ and $2.6\pm0.6_{\mathrm{stat.}}\pm0.3_{\mathrm{syst.}}$, respectively. The measured $D^{0}$ ratio disagrees with the theoretical predictions by orders of magnitudes, thus implying a substantial contribution from final-state interactions.

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arXiv2024

Measurement of $e^{+}e^{-}\to ωη^{\prime}$ cross sections at $\sqrt{s}=$ 2.000 to 3.080 GeV

The Born cross sections for the process $e^{+}e^{-}\to ωη^{\prime}$ are measured at 22 center-of-mass energies from 2.000 to 3.080 GeV using data collected with the BESIII detector at the BEPCII collider. A resonant structure is observed with a statistical significance of 9.6$σ$. A Breit-Wigner fit determines its mass to be $M_R=(2153\pm30\pm31)~{\rm{MeV}}/c^{2}$ and its width to be $Γ_{R}=(167\pm77\pm7)~\rm{MeV}$, where the first uncertainties are statistical and the second are systematic.

hep-ex↗