arXiv subjects

F. DeMori

Publications and source records attributed to F. DeMori.

At least 19 recordsLinked to original sources

arXiv2025

Test of local realism via entangled $\Lambda\bar\Lambda$ system

The non-locality of quantum correlations is a fundamental feature of quantum theory. The Bell inequality serves as a benchmark for distinguishing between predictions made by quantum theory and local hidden variable theory (LHVT). Recent advancements in photon-entanglement experiments have addressed potential loopholes and have observed significant violations of variants of Bell inequality. However, examples of Bell inequalities violation in high energy physics are scarce. In this study, we utilize $(10.087\pm0.044)\times10^{9}$ $J/\psi$ events collected with the BES-III detector at the BEPCII collider, performing non-local correlation tests using the entangled hyperon pairs. The massive-entangled $\Lambda\bar\Lambda$ systems are formed and decay through strong and weak interactions, respectively. Through measurements of the angular distribution of $p\bar{p}$ in $J/\psi\to \gamma\eta_c$ and subsequent $\eta_c\to\Lambda(p\pi^-)\bar\Lambda(\bar{p}\pi^{+})$ cascade decays, a significant violation of LHVT predictions is observed. The exclusion of LHVT is found to be statistically significant at a level exceeding $5.2\sigma$ in the testing of three Bell-like inequalities.

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arXiv2024

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

The energy-dependent cross section for $e^+e^-\to \eta\psi(2S)$ 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 $e^+e^-\to\eta\tilde{X}(3872)$, but no evidence is found for the $\tilde{X}(3872)$ in the $\pi^+\pi^- J/\psi$ mass distribution. At each of the eighteen center of mass energies, upper limits at the 90\% confidence level on the cross section for $e^+e^-\to\eta\psi(2S)$ and on the product of the $e^+e^-\to\eta\tilde{X}(3872)$ cross section with the branching fraction of $\tilde{X}(3872)\to\pi^+\pi^- J/\psi$ are reported.

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arXiv2023

Precision Measurement of the Decay $Σ^{+} \rightarrow pγ$ in the Process $J/ψ\rightarrow Σ^{+}\barΣ^{-}$

Using $(10\:087\pm44)\times10^{6}$ $J/ψ$ events collected with the BESIII detector, the radiative hyperon decay $Σ\rightarrow pγ$ is studied at an electron-positron collider experiment for the first time. The absolute branching fraction is measured to be $\left(0.996 \pm 0.021_{\rm stat.}\pm 0.018_{\rm syst.}\right)\times 10^{-3}$, which is lower than its world average value by $4.2$ standard deviations. Its decay asymmetry parameter is determined to be $-0.652 \pm 0.056_{\rm stat.}\pm 0.020_{\rm syst.}$. The branching fraction and decay asymmetry parameter are the most precise to date, and the accuracies are improved by $78\%$ and $34\%$, respectively.

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arXiv2022

Observation of $Ξ^{-}$ Hyperon Transverse Polarization in $ψ(3686)\rightarrowΞ^{-}\barΞ^{+}$

Using a sample of $(448.1~\pm~2.9)$ $\times 10^{6}$ $ψ(3686)$ decays collected with the BESIII detector at BEPCII, we report an observation of $Ξ^{-}$ transverse polarization with a significance of $7.3 σ$ in the decay $ψ(3686)\rightarrowΞ^{-}\barΞ^{+}$ ($Ξ^{-}\rightarrowπ^{-}Λ$, $\barΞ^{+}\rightarrowπ^{+}\barΛ$, $Λ\to pπ^{-}$, $\barΛ\to\bar{p}π^{+}$). The relative phase of the electric and magnetic form factors is determined to be $ΔΦ= (0.667 \pm 0.111 \pm 0.058)$ rad. This is the first measurement of the relative phase for a $ψ(3686)$ decay into a pair of $Ξ^{-}\barΞ^{+}$ hyperons. The $Ξ^{-}$ decay parameters ($α_{Ξ^{-}}$, $ϕ_{Ξ^-}$) and their conjugates ($α_{\barΞ^{+}}$, $ϕ_{\barΞ^{+}}$), the angular-distribution parameter $α_ψ$, and the strong-phase difference $δ_{p}-δ_{s}$ for $Λ$-$π^-$ scattering are measured to be consistent with previous BESIII results.

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arXiv2022

Measurement of the $e^+e^-\toπ^+π^-J/ψ$ cross section in the vicinity of 3.872 GeV

We report a measurement of the cross section for the process $e^+e^-\toπ^+π^-J/ψ$ around the $X(3872)$ mass in search for the direct formation of $e^+e^-\to X(3872)$ through the two-photon fusion process. No enhancement of the cross section is observed at the $X(3872)$ peak and an upper limit on the product of electronic width and branching fraction of $X(3872)\toπ^+π^-J/ψ$ is determined to be $Γ_{ee}\times\mathcal{B}(X(3872)\toπ^+π^-J/ψ)<7.5\times10^{-3}\,\text{eV}$ at $90\,\%$ confidence level under an assumption of total width of $1.19\pm0.21$ MeV. This is an improvement of a factor of about $17$ compared to the previous limit. Furthermore, using the latest result of $\mathcal{B}(X(3872)\toπ^+π^-J/ψ)$, an upper limit on the electronic width $Γ_{ee}$ of $X(3872)$ is obtained to be $<0.32\,\text{eV}$ at the $90\,\%$ confidence level.

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arXiv2021

Observation of the Decay $D^0\to ρ^-μ^+ν_μ$

By analyzing an $e^+e^-$ annihilation data sample corresponding to an integrated luminosity of $2.93~\mathrm{fb}^{-1}$ collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, we measure the branching fraction of the $D^0\to ρ^- μ^+ν_μ$ decay for the first time. We obtain ${\mathcal B}_{D^0\to ρ^- μ^+ν_μ}=(1.35\pm0.09_{\rm stat}\pm0.09_{\rm syst})\times 10^{-3}$. Using the world average of ${\mathcal B}_{D^0\to ρ^- e^+ν_e}$, we find a branching fraction ratio of ${\mathcal B}_{D^0\to ρ^- μ^+ν_μ}/{\mathcal B}_{D^0\to ρ^- e^+ν_e}=0.90\pm0.11$, which agrees with the theoretical expectation of lepton flavor universality within the uncertainty. Combining the world average of ${\mathcal B}_{D^+\to ρ^0 μ^+ ν_μ}$ and the lifetimes of $D^{0(+)}$, we obtain a partial decay width ratio of $Γ_{D^0\to ρ^- μ^+ ν_μ}/(2Γ_{D^+\to ρ^0 μ^+ ν_μ}) = 0.71\pm0.14$, which is consistent with the isospin symmetry expectation of one within $2.1σ$. For the reported values of ${\mathcal B}_{D^0\to ρ^- μ^+ν_μ}/{\mathcal B}_{D^0\to ρ^- e^+ν_e}$ and $Γ_{D^0\to ρ^- μ^+ ν_μ}/2Γ_{D^+\to ρ^0 μ^+ ν_μ}$, the uncertainty is the quadratic sum of the statistical and systematic uncertainties.

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arXiv2021

Measurement of the Born cross sections for $e^+e^- \to η^\prime π^{+}π^{-}$ at center-of-mass energies between $2.00$ and $3.08$ GeV

The Born cross sections for the process $e^+e^- \to η^\prime π^{+}π^{-}$ at different center-of-mass energies between $2.00$ and $3.08$ GeV are reported with improved precision from an analysis of data samples collected with the BESIII detector operating at the BEPCII storage ring. An obvious structure is observed in the Born cross section line shape. Fit as a Breit-Wigner resonance, it has a statistical significance of $6.3σ$ and a mass and width of $M=(2111\pm43\pm25)$~MeV/$c^2$ and $Γ=(135\pm34\pm30)$~MeV, where the uncertainties are statistical and systematic, respectively. These measured resonance parameters agree with the measurements of BABAR in $e^+e^- \to η^\prime π^{+}π^{-}$ and BESIII in $e^+e^- \to ωπ^0$ within two standard deviations.

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arXiv2021

Measurement of the Absolute Branching Fraction of $D_s^+ \to τ^+ ν_τ$ via $τ^+ \to e^+ ν_e \barν_τ$

Using a dataset of 6.32 fb$^{-1}$ of $e^+ e^-$ annihilation data collected with the BESIII detector at center-of-mass energies between 4178 and 4226 MeV, we have measured the absolute branching fraction of the leptonic decay $D_s^+ \to τ^+ ν_τ$ via $τ^+ \to e^+ ν_e \barν_τ$, and find $\mathcal{B}_{D_s^+ \to τ^+ ν_τ}=(5.27\pm0.10\pm0.12)\times10^{-2}$, where the first uncertainty is statistical and the second is systematic. The precision is improved by a factor of 2 compared to the previous best measurement. Combining with $f_{D_s^+}$ from Lattice quantum chromodynamics calculations or the $|V_{cs}|$ from the CKMfitter group, we extract $|V_{cs}|=0.978\pm0.009\pm0.012$ and $f_{D_s^+}= (251.1\pm2.4\pm3.0)$ MeV, respectively. Combining our result with the world averages of $\mathcal{B}_{D_s^+ \to τ^+ ν_τ}$ and $\mathcal{B}_{D_s^+ \to μ^+ ν_μ}$, we obtain the ratio of the branching fractions $\mathcal{B}_{D_s^+ \to τ^+ ν_τ} / \mathcal{B}_{D_s^+ \to μ^+ ν_μ} = 9.72\pm0.37$, which is consistent with the standard model prediction of lepton flavor universality.

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arXiv2021

Observation of $D^{0(+)}\to K^0_Sπ^{0(+)}ω$ and improved measurement of $D^0\to K^-π^+ω$

By analyzing an $e^+e^-$ annihilation data sample with 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 determine the absolute branching fractions of the hadronic decays $D^0\to K^-π^+ω$, $D^0\to K^0_Sπ^0ω$, and $D^+\to K^0_Sπ^+ω$ to be $(3.392 \pm 0.044_{\rm stat} \pm 0.085_{\rm syst})\%$, $(0.848 \pm 0.046_{\rm stat} \pm 0.031_{\rm syst})\%$, and $(0.707 \pm 0.041_{\rm stat} \pm 0.029_{\rm syst})\%$, respectively. The accuracy of the branching fraction measurement of the decay $D^0\to K^-π^+ω$ is improved by a factor of seven compared to the world average value. The $D^{0}\to K^0_Sπ^{0}ω$ and $D^{+}\to K^0_Sπ^{+}ω$ decays are observed for the first time.

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arXiv2021

Cross Section Measurement of $e^+e^- \rightarrow π^+π^-ψ(3686)$ from $\sqrt{s}=4.0076$~GeV to 4.6984~GeV

Using data samples with a total integrated luminosity of $20.1~\rm fb^{-1}$ collected by the BESIII detector operating at the BEPCII collider, the cross section of the process $e^+e^- \rightarrow π^+π^-ψ(3686)$ is measured at center-of-mass energies between 4.0076 and 4.6984 GeV. The measured cross section is consistent with previous results, but with much improved precision. A fit to the measured energy-dependent cross section, which includes three Breit-Wigner functions and a non-resonant contribution, confirms the existence of the charmonium-like states $Y(4220)$, $Y(4390)$, and $Y(4660)$. This is the first observation of the $Y(4660)$ at the BESIII experiment.

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arXiv2021

Measurements of Born Cross Sections of $e^+e^-\to D_s^{*+} D_{sJ}^{-} +c.c.$

The Born cross sections are measured for the first time for the processes $e^+e^-\to D_s^{*+}D_{s0}^*(2317)^- +c.c.$ and $e^+e^-\to D_s^{*+}D_{s1}(2460)^- +c.c.$ at the center-of-mass energy $\sqrt{s}=$ 4.600~GeV, 4.612~GeV, 4.626~GeV, 4.640~GeV, 4.660~GeV, 4.68~GeV, and 4.700~GeV, and for $e^+e^-\to D_s^{*+}D_{s1}(2536)^- +c.c.$ at $\sqrt{s}=$ 4.660~GeV, 4.680~GeV, and 4.700~GeV, using data samples collected with the BESIII detector at the BEPCII collider. No structures are observed in cross-section distributions for any of the processes.

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arXiv2021

Measurement of the absolute branching fraction of $Λ_c^+\to p K^0_{\mathrm{S}}η$ decays

Based on 586 $\rm{pb^{-1}}$ of $e^+e^-$ annihilation data collected at a center-of-mass energy of $\sqrt{s}=4.6~\rm{GeV}$ with the BESIII detector at the BEPCII collider, the absolute branching fraction of $Λ_c^+ \to p K^0_{\mathrm{S}}η$ decays is measured for the first time to be $\mathcal{B}(Λ_c^+ \to p K^0_{\mathrm{S}}η) = (0.414 \pm 0.084 \pm 0.028)\%$, where the first uncertainty is statistical and the second is systematic. The result is compatible with a previous CLEO result on the relative branching fraction $\frac{\mathcal{B}(Λ_c^+ \to p K^0_{\mathrm{S}}η)}{\mathcal{B}(Λ_c^+ \to p K^-π^+)}$, and consistent with theoretical predictions of SU(3) flavor symmetry.

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arXiv2021

New Features in the Electromagnetic Structure of the Neutron

Here we present new results for the Born cross section and the effective form factor of the neutron at the center-of-mass energies ${\bf \sqrt{s}}$ between 2.0 and 3.08 GeV, using 18 data sets corresponding to an integrated luminosity of 647.9 pb${\bf ^{-1}}$ from e${\bf ^+}$e${\bf ^-}$ annihilation reactions collected at the BESIII experiment. The process $e^{+}e^{-}\to n\bar{n}$ is analyzed with three individual categories to improve the efficiency of $n\bar{n}$ reconstruction. The cross section of $e^{+}e^{-}\to n\bar{n}$ is measured at 18 c.m. energies where the best precision is 8.1\% at $\sqrt{s}=2.396$ GeV. The corresponding effective form factors are extracted under the assumption $|G_{E}|=|G_{M}|$. Our results improve the statistical precision on the neutron form factor by more than a factor of 60 over previous measurements from the FENICE and DM2 experiments and usher in a new era where neutron form factor data from annihilation in the time-like regime is on par with that from electron scattering experiments. In addition, an oscillatory behavior of the effective form factor observed for the proton is discussed for the neutron.

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arXiv2021

Evidence for $Z_{c}^{\pm}$ decays into the $ρ^{\pm} η_{c}$ final state

We study $e^{+}e^{-}$ collisions with a $π^{+}π^{-}π^{0}η_{c}$ final state using data samples collected with the BESIII detector at center-of-mass energies $\sqrt{s}=4.226$, $4.258$, $4.358$, $4.416$, and $4.600$ GeV. Evidence for the decay $\zcpm\to\rhopm\etac$ is reported with a statistical significance of $3.9σ$ with various systematic uncertainties taken into account at $\sqrt{s} = 4.226$ GeV, and the Born cross section times branching fraction $σ^{B}(\EE\to \pimp\zcpm)\times \BR(\zcpm\to\rhopm\etac)$ is measured to be $(48 \pm 11 \pm 11)\,\rm{pb}$. The $\zcpm\to \rhopm\etac$ signal is not significant at the other center-of-mass energies and the corresponding upper limits are determined. In addition, no significant signal is observed in a search for $\zcppm\to ρ^{\pm}\etac$ with the same data samples. The ratios $R_{\zc}=\BR(\zcpm\to ρ^{\pm} \etac)/\BR(\zcpm\to π^{\pm} \jpsi)$ and $R_{\zcp}=\BR(\zcppm\to ρ^{\pm} \etac)/\BR(\zcppm\to π^{\pm} \hc)$ are obtained and used to discriminate between different theoretical interpretations of the $\zcpm$ and $\zcppm$.

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arXiv2020

Precise Measurements of Branching Fractions for $D_s^+$ Meson Decays to Two Pseudoscalar Mesons

We measure the branching fractions for seven $D_{s}^{+}$ two-body decays to pseudo-scalar mesons, by analyzing data collected at $\sqrt{s}=4.178\sim4.226$ GeV with the BESIII detector at the BEPCII collider. The branching fractions are determined to be $\mathcal{B}(D_s^+\to K^+η^{\prime})=(2.68\pm0.17\pm0.17\pm0.08)\times10^{-3}$, $\mathcal{B}(D_s^+\toη^{\prime}π^+)=(37.8\pm0.4\pm2.1\pm1.2)\times10^{-3}$, $\mathcal{B}(D_s^+\to K^+η)=(1.62\pm0.10\pm0.03\pm0.05)\times10^{-3}$, $\mathcal{B}(D_s^+\toηπ^+)=(17.41\pm0.18\pm0.27\pm0.54)\times10^{-3}$, $\mathcal{B}(D_s^+\to K^+K_S^0)=(15.02\pm0.10\pm0.27\pm0.47)\times10^{-3}$, $\mathcal{B}(D_s^+\to K_S^0π^+)=(1.109\pm0.034\pm0.023\pm0.035)\times10^{-3}$, $\mathcal{B}(D_s^+\to K^+π^0)=(0.748\pm0.049\pm0.018\pm0.023)\times10^{-3}$, where the first uncertainties are statistical, the second are systematic, and the third are from external input branching fraction of the normalization mode $D_s^+\to K^+K^-π^+$. Precision of our measurements is significantly improved compared with that of the current world average values.

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arXiv2020

Observation of a cross-section enhancement near mass threshold in $e^{+}e^{-}\rightarrowΛ\barΛ$

The process $e^{+}e^{-}\rightarrowΛ\barΛ$ is studied using data samples at $\sqrt{s}=2.2324$, 2.400, 2.800 and 3.080 GeV collected with the BESIII detector operating at the BEPCII collider. The Born cross section is measured at $\sqrt{s}$=2.2324 GeV, which is 1.0 MeV above the $Λ\barΛ$ mass threshold, to be $305\pm45^{+66}_{-36}$ pb, where the first uncertainty is statistical and the second systematic. The substantial cross section near threshold is significantly larger than that expected from theory, which predicts the cross section to vanish at threshold. The Born cross sections at $\sqrt{s}$=2.400, 2.800 and 3.080 GeV are measured and found to be consistent with previous experimental results, but with improved precision. Finally, the corresponding effective electromagnetic form factors of $Λ$ are deduced.

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arXiv2019

Search for the rare decay $η'\rightarrowπ^{0}π^{0}π^{0}π^{0}$ at BESIII

Based on a sample of 1.31 billion $J/ψ$ events collected with the BESIII detector, we perform a search for the rare decay $η'\rightarrow 4π^{0}$ via $J/ψ\rightarrowγη'$. No significant $η'$ signal is observed in the invariant mass spectrum of 4$π^{0}$. With a Bayesian approach, the upper limit on the branching fraction of $η'\rightarrow 4π^{0}$ is determined to be $\mathcal{B}(η'\rightarrow 4π^{0})$ $< 4.94\times10^{-5}$ at the 90\% confidence level, which is a factor of six smaller than the previous experimental limit.

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arXiv2019

Measurements of Weak Decay Asymmetries of $Λ_c^+\to pK_S^0$, $Λπ^+$, $Σ^+π^0$, and $Σ^0π^+$

Using $e^+e^-\toΛ_c^+\barΛ_c^-$ production from a 567 pb$^{-1}$ data sample collected by BESIII at 4.6 GeV, a full angular analysis is carried out simultaneously on the four decay modes of $Λ_c^+\to pK_S^0$, $Λπ^+$, $Σ^+π^0$, and $Σ^0π^+$. For the first time, the $Λ_c^+$ transverse polarization is studied in unpolarized $e^+e^-$ collisions, where a non-zero effect is observed with a statistical significance of 2.1$σ$. The decay asymmetry parameters of the $Λ_c^+$ weak hadronic decays into $pK_S^0$, $Λπ^+$, $Σ^+π^0$ and $Σ^0π^+$ are measured to be $0.18\pm0.43(\rm{stat})\pm0.14(\rm{syst})$, $-0.80\pm0.11(\rm{stat})\pm0.02(\rm{syst})$, $-0.57\pm0.10(\rm{stat})\pm0.07(\rm{syst})$, and $-0.73\pm0.17(\rm{stat})\pm0.07(\rm{syst})$, respectively. In comparison with previous results, the measurements for the $Λπ^+$ and $Σ^+π^0$ modes are consistent but with improved precision, while the parameters for the $pK_S^0$ and $Σ^0π^+$ modes are measured for the first time.

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