arXiv subjects

M. Destefanis

Publications and source records attributed to M. Destefanis.

At least 433 records · Page 24Linked to original sources

arXiv2024

Study of $e^{+}e^{-}\rightarrowπ^{+}π^{-}π^{0}$ at $\sqrt{s}$ from 2.00 to 3.08 GeV at BESIII

With the data samples taken at center-of-mass energies from 2.00 to 3.08 GeV with the BESIII detector at the BEPCII collider, a partial wave analysis on the $e^{+}e^{-}\rightarrowπ^{+}π^{-}π^{0}$ process is performed. The Born cross sections for $e^{+}e^{-}\rightarrowπ^{+}π^{-}π^{0}$ and its intermediate processes $e^{+}e^{-}\rightarrowρπ$ and $ρ(1450)π$ are measured as functions of $\sqrt{s}$. The results for $e^{+}e^{-}\rightarrowπ^{+}π^{-}π^{0}$ are consistent with previous results measured with the initial state radiation method within one standard deviation, and improve the uncertainty by a factor of ten. By fitting the line shapes of the Born cross sections for the $e^{+}e^{-}\rightarrowρπ$ and $ρ(1450)π$, a structure with mass $M = 2119\pm11\pm15\ {\rm MeV}/c^2$ and width $Γ=69\pm30\pm5 {\rm MeV}$ is observed with a significance of $5.9σ$, where the first uncertainties are statistical and the second ones are systematic. This structure can be intepreteted as an excited $ω$ state.

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arXiv2024

First Measurement of the Decay Asymmetry in the pure W-boson-exchange Decay $Λ_{c}^{+}\toΞ^{0}K^{+}$

Based on $4.4~\text{fb}^{-1}$ of $e^{+}e^{-}$ annihilation data collected at the center-of-mass energies between $4.60$ and $4.70~\text{GeV}$ with the BESIII detector at the BEPCII collider, the pure \textit{W}-boson-exchange decay $Λ_{c}^{+}\toΞ^{0}K^{+}$ is studied with a full angular analysis. The corresponding decay asymmetry is measured for the first time to be $α_{Ξ^{0}K^{+}}=0.01\pm0.16({\rm stat.})\pm0.03({\rm syst.})$. This result reflects the non-interference effect between the $S$- and $P$-wave amplitudes. The phase shift between $S$- and $P$-wave amplitudes has two solutions, which are $δ_{p}-δ_{s}=-1.55\pm0.25({\rm stat.})\pm0.05({\rm syst.})~\text{rad}$ or $1.59\pm0.25({\rm stat.})\pm0.05({\rm syst.})~\text{rad}$.

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arXiv2024

Search for the light hadron decay $χ_{c1}(3872) \to π^{+}π^{-}η$

With a data sample corresponding to an integrated luminosity of 11.5~fb$^{-1}$ collected with the BESIII detector operating at the BEPCII storage ring, for the first time the light hadron decay $χ_{c1}(3872) \rightarrow π^{+}π^{-}η$ is searched for. While no significant signal is observed, the upper limits at the 90\% confidence level for $σ[e^{+}e^{-} \rightarrow γχ_{c1}(3872)] \mathcal{B}[χ_{c1}(3872) \rightarrow π^{+}π^{-}η]$ at center-of-mass energies from 4.13 to 4.34 GeV are determined. By normalizing to the $χ_{c1}(3872)\toπ^+π^- J/ψ$ decay channel, a 90\% confidence level upper limit for the branching fraction ratio $\mathcal{R}=\mathcal{B}[χ_{c1}(3872) \rightarrowπ^{+}π^{-}η]/\mathcal{B}[χ_{c1}(3872) \rightarrow π^{+}π^{-} J/ψ] < 0.12$ is given. These measurements provide important inputs for understanding the internal structure of the $χ_{c1}(3872)$ resonance.

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arXiv2024

First measurements of the absolute branching fraction of $Λ_{c}(2625)^{+}\to Λ^{+}_{c}π^+π^-$ and upper limit on $Λ_{c}(2595)^{+}\to Λ^{+}_{c}π^+π^-$

The absolute branching fraction of the decay $Λ_{c}(2625)^{+}\to Λ^{+}_{c}π^+π^-$ is measured for the first time to be $(50.7 \pm 5.0_{\rm{stat.}} \pm 4.9_{\rm{syst.}} )\%$ with 368.48 pb$^{-1}$ of $e^+e^-$ collision data collected by the BESIII detector at the center-of-mass energies of $\sqrt{s} = 4.918$ and $4.950$ GeV. This result is lower than the naive prediction of 67\%, obtained from isospin symmetry, by more than $2σ$, thereby indicating that the novel mechanism referred to as the \textit{threshold effect}, proposed for the strong decays of $Λ_{c}(2595)^{+}$, also applies to $Λ_{c}(2625)^{+}$. This measurement is necessary to obtain the coupling constants for the transitions between $s$-wave and $p$-wave charmed baryons in heavy hadron chiral perturbation theory. In addition, we search for the decay $Λ_{c}(2595)^{+}\to Λ^{+}_{c}π^+π^-$. No significant signal is observed, and the upper limit on its branching fraction is determined to be 80.8\% at the 90\% confidence level.

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arXiv2024

Investigation of the $ΔI = 1/2$ rule and test of CP violation through the measurement of decay asymmetry parameters in $Ξ^-$ decays

Using $(10087\pm44)\times 10^{6}$ $J/ψ$ events collected with the BESIII detector, numerous $Ξ^-$ and $Λ$ decay asymmetry parameters are simultaneously determined from the process $J/ψ\to Ξ^- \barΞ^+ \to Λ(pπ^-) π^- \barΛ(\bar{n} π^0) π^+$ and its charge-conjugate channel. The precisions of $α_0$ for $Λ\to nπ^0$ and $\barα_0$ for $\barΛ \to \bar{n}π^0$ compared to world averages are improved by factors of 4 and 1.7, respectively. The ratio of decay asymmetry parameters of $Λ\to nπ^0$ to that of $Λ\to pπ^-$, $\langle α_0 \rangle/ \langle α_{Λ-} \rangle $, is determined to be $ 0.873 \pm 0.012^{+0.011}_{-0.010}$, where the first and the second uncertainties are statistical and systematic, respectively. The ratio is smaller than unity more than $5σ$, which signifies the existence of the $ΔI = 3/2$ transition in $Λ$ for the first time. Beside, we test for CP violation in $Ξ^- \to Λπ^-$ and in $Λ\to n π^{0}$ with the best precision to date.

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arXiv2024

A test of lepton flavor universality with a measurement of $R(D^{*})$ using hadronic $B$ tagging at the Belle II experiment

The ratio of branching fractions $R(D^{*}) = \mathcal{B}(\overline{B} \rightarrow D^{*} τ^{-} \overlineν_τ)$/$\mathcal{B} (\overline{B} \rightarrow D^{*} \ell^{-} \overlineν_{\ell})$, where $\ell$ is an electron or muon, is measured using a Belle~II data sample with an integrated luminosity of $189~\mathrm{fb}^{-1}$ at the SuperKEKB asymmetric-energy $e^{+} e^{-}$ collider. Data is collected at the $Υ(\mathrm{4S})$ resonance, and one $B$ meson in the $Υ(\mathrm{4S})\rightarrow B\overline{B}$ decay is fully reconstructed in hadronic decay modes. The accompanying signal $B$ meson is reconstructed as $\overline{B}\rightarrow D^{*} τ^{-}\overlineν_τ$ using leptonic $τ$ decays. The normalization decay, $\overline{B}\rightarrow D^{*} \ell^{-} \overlineν_{\ell}$, where $\ell$ is an electron or muon, produces the same observable final state particles. The ratio of branching fractions is extracted in a simultaneous fit to two signal-discriminating variables in both channels and yields $R(D^{*}) = 0.262~_{-0.039}^{+0.041}(\mathrm{stat})~_{-0.032}^{+0.035}(\mathrm{syst})$. This result is consistent with the current world average and with standard model predictions.

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arXiv2024

Measurement of branching fractions and direct $CP$ asymmetries for $B \to Kπ$ and $B\toππ$ decays at Belle II

We report measurements of the branching fractions and direct $\it{CP}$ asymmetries of the decays $B^0 \to K^+ π^-$, $B^+ \to K^+ π^0$, $B^+ \to K^0 π^+$, and $B^0 \to K^0 π^0$, and use these for testing the standard model through an isospin-based sum rule. In addition, we measure the branching fraction and direct $\it{CP}$ asymmetry of the decay $B^+ \to π^+π^0$ and the branching fraction of the decay $B^0 \to π^+π^-$. The data are collected with the Belle II detector from $e^+e^-$ collisions at the $Υ(4S)$ resonance produced by the SuperKEKB asymmetric-energy collider and contain $387\times 10^6$ bottom-antibottom meson pairs. Signal yields are determined in two-dimensional fits to background-discriminating variables, and range from 500 to 3900 decays, depending on the channel. We obtain $-0.03 \pm 0.13 \pm 0.04$ for the sum rule, in agreement with the standard model expectation of zero and with a precision comparable to the best existing determinations.

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arXiv2023

Observation of $χ_{cJ}\to 3(K^+K^-)$

By analyzing $(27.12\pm0.14)\times10^8$ $ψ(3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decay processes $χ_{cJ} \to 3(K^+K^-)$ ($J=0,1,2$) are observed for the first time with statistical significances of 8.2$σ$, 8.1$σ$, and 12.4$σ$, respectively. The product branching fractions of $ψ(3686)\toγχ_{cJ}$, $χ_{cJ}\to 3(K^+K^-)$ are presented and the branching fractions of $χ_{cJ}\to 3(K^+K^-)$ decays are determined to be $\mathcal{B}_{χ_{c0}\to 3(K^+K^-)}$=$(10.7\pm1.8\pm1.1)$$\times10^{-6}$, $\mathcal{B}_{χ_{c1}\to 3(K^+K^-)}$=$(4.2\pm0.9\pm0.5)$$\times10^{-6}$, and $\mathcal{B}_{χ_{c2}\to 3(K^+K^-)}$=$(7.2\pm1.1\pm0.8)$$\times10^{-6}$, where the first uncertainties are statistical and the second are systematic.

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arXiv2023

Precise measurement of the branching fractions of $J/ψ\rightarrow\barΛπ^{+}Σ^{-}+c.c.$ and $J/ψ\rightarrow\barΛπ^{-}Σ^{+}+c.c.$

Based on a data sample of $(10087\pm44)\times10^6$ $J/ψ$ events collected with the BESIII detector, the branching fraction of $J/ψ\rightarrow\barΛπ^{+}Σ^{-}+c.c.$ is measured to be $(1.221\pm 0.002\pm 0.038)\times10^{-3}$, and the branching fraction of its isospin partner mode $J/ψ\rightarrow\barΛπ^{-}Σ^{+}+c.c.$ is measured to be $(1.244\pm 0.002\pm 0.045)\times10^{-3}$ with improved precision. Here the first uncertainties are statistical and the second ones systematic. The isospin symmetry of the $Σ$ baryon in charmonium hadronic decay and the "$12\%$ rule" are tested, and no violation is found. The potential of using these channels as $Σ$ baryon sources for nuclear physics research is studied, and the momentum and angular distributions of these sources are provided.

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arXiv2023

Precise measurement of the $D^+_s$ lifetime at Belle II

We measure the lifetime of the $D_s^+$ meson using a data sample of 207 fb$^{-1}$ collected by the Belle II experiment running at the SuperKEKB asymmetric-energy $e^+ e^-$ collider. The lifetime is determined by fitting the decay-time distribution of a sample of $116\times 10^3$ $D_s^+\rightarrowϕπ^+$ decays. Our result is $τ^{}_{D^+_s} = (499.5\pm 1.7\pm 0.9)$ fs, where the first uncertainty is statistical and the second is systematic. This result is significantly more precise than previous measurements.

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arXiv2023

Measurements of $Σ$ electromagnetic form factors in the time-like region using the untagged initial-state radiation technique

The process $e^{+}e^{-}\toΣ^{+}\barΣ^{-}$ is studied from threshold up to 3.04 GeV/$c^2$ via the initial-state radiation technique using data with an integrated luminosity of 12.0 fb$^{-1}$, collected at center-of-mass energies between 3.773 and 4.258 GeV with the BESIII detector at the BEPCII collider. The pair production cross sections and the effective form factors of $Σ$ are measured in eleven $Σ^{+}\barΣ^{-}$ invariant mass intervals from threshold to 3.04 GeV/$c^2$. The results are consistent with the previous results from Belle and BESIII. Furthermore, the branching fractions of the decays $J/ψ\toΣ^{+}\barΣ^{-}$ and $ψ(3686)\toΣ^{+}\barΣ^{-}$ are determined and the obtained results are consistent with the previous results of BESIII.

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arXiv2023

Search for the $e^+e^-\toη_{b}(1S)ω$ and $e^+e^-\toχ_{b0}(1P)ω$ processes at $\sqrt{s}=10.745\,\mathrm{GeV}$

We search for the $e^+e^-\toη_b(1S)ω$ and $e^+e^-\toχ_{b0}(1P)ω$ processes at a center-of-mass energy of 10.745 GeV, which is close to the peak of the $Υ(10753)$ state. We use data collected by the Belle II experiment during a special run, corresponding to an integrated luminosity of $9.8\,\mathrm{fb}^{-1}$. We reconstruct $ω\toπ^+π^-π^0$ decays and use the $ω$ meson's recoil mass to search for the signals. We do not find evidence for either process, and set upper limits on the corresponding Born-level cross sections of 2.5 pb and 7.8 pb, respectively, at the 90% confidence level. The $χ_{b0}(1P)ω$ limit is the result of a combination of this analysis and a previous search using full reconstruction.

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arXiv2023

Observation of significant flavor-SU(3) breaking in the kaon wave function at $12~{\rm GeV}^2<Q^2<25~{\rm GeV}^2$ and discovery of the charmless decay $ψ(3770)\to K_S^0K_L^0$

We present cross sections for the reaction $e^+e^-\to K_S^0K_L^0$ at center-of-mass energies ranging from 3.51 GeV to 4.95 GeV using data samples collected in the BESIII experiment, corresponding to a total integrated luminosity of 26.5 fb$^{-1}$. The ratio of neutral-to-charged kaon form factors at large momentum transfers ($12~{\rm GeV}^2<Q^2<25~{\rm GeV}^2$) is determined to be $0.21\pm 0.01$, which indicates a small but significant effect of flavor-SU(3) breaking in the kaon wave function, and consequently excludes the possibility that flavor-SU(3) breaking is the primary reason for the strong experimental violation of the pQCD prediction $|F(π^{\pm})|/|F(K^{\pm})|=f^2_π/f^2_{K}$, where $F(π^{\pm})$ and $F(K^{\pm})$ are the form factors, and $f_π$ and $f_{K}$ are the decay constants of charged pions and kaons, respectively. We also observe a significant signal for the charmless decay $ψ(3770)\to K_S^0K_L^0$ for the first time. Within a $1σ$ contour of the likelihood value, the the branching fraction for $ψ(3770)\to K_S^0K_L^0$ is determined to be ${\cal B}=(2.63_{-1.59}^{+1.40})\times 10^{-5}$, and the relative phase between the continuum and $ψ(3770)$ amplitudes is $ϕ=(-0.39_{-0.10}^{+0.05})π$. The branching fraction is in good agreement with the $\mathcal{S}$- and $\mathcal{D}$-wave charmonia mixing scheme proposed in the interpretation of the "$ρπ$ puzzle" between $J/ψ$ and $ψ(3686)$ decays.

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arXiv2023

Search for the semi-muonic charmonium decay $J/ψ\to D^{-}μ^{+}ν_μ+c.c.$

Using $(10087\pm44)\times10^{6}$ $J/ψ$ events collected with the BESIII detector at the BEPCII $e^+e^-$ storage ring at the center-of-mass energy of $\sqrt{s}=3.097~\rm{GeV}$, we present a search for the rare semi-muonic charmonium decay $J/ψ\to D^{-}μ^{+}ν_μ+c.c.$. Since no significant signal is observed, we set an upper limit of the branching fraction to be $\mathcal{B}(J/ψ\to D^{-}μ^{+}ν_μ+c.c.)<5.6\times10^{-7}$ at $90\%$ confidence level. This is the first search for the weak decay of charmonium with a muon in the final state.

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arXiv2023

Search for $D^{0}\to K_{S}^{0} K^{-} e^{+}ν_{e}$, $D^{+}\to K_{S}^{0} K_{S}^{0} e^{+}ν_{e}$, and $D^{+}\to K^{+}K^{-} e^{+}ν_{e}$

A search has been performed for the semileptonic decays $D^{0}\to K_{S}^{0} K^{-} e^{+}ν_{e}$, $D^{+}\to K_{S}^{0} K_{S}^{0} e^{+}ν_{e}$ and $D^{+}\to K^{+}K^{-} e^{+}ν_{e}$, using $7.9~\mathrm{fb}^{-1}$ 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 upper limits are set at the 90\% confidence level of $2.13\times10^{-5}$, $1.54\times10^{-5}$ and $2.10\times10^{-5}$ for the branching fractions of $D^{0}\to K_{S}^{0} K^{-} e^{+}ν_{e}$, $D^{+}\to K_{S}^{0} K_{S}^{0} e^{+}ν_{e}$ and $D^{+}\to K^{+}K^{-} e^{+}ν_{e}$, respectively.

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arXiv2023

Determination of $|V_{cb}|$ using $\overline{B}^0\to D^{*+}\ell^-\barν_\ell$ decays with Belle II

We determine the CKM matrix-element magnitude $|V_{cb}|$ using $\overline{B}^0\to D^{*+}\ell^-\barν_\ell$ decays reconstructed in $189 \, \mathrm{fb}^{-1}$ of collision data collected by the Belle II experiment, located at the SuperKEKB $e^+e^-$ collider. Partial decay rates are reported as functions of the recoil parameter $w$ and three decay angles separately for electron and muon final states. We obtain $|V_{cb}|$ using the Boyd-Grinstein-Lebed and Caprini-Lellouch-Neubert parametrizations, and find $|V_{cb}|_\mathrm{BGL}=(40.57\pm 0.31 \pm 0.95\pm 0.58)\times 10^{-3}$ and $|V_{cb}|_\mathrm{CLN}=(40.13 \pm 0.27 \pm 0.93\pm 0.58 )\times 10^{-3}$ with the uncertainties denoting statistical components, systematic components, and components from the lattice QCD input, respectively. The branching fraction is measured to be ${\cal B}(\overline{B}^0\to D^{*+}\ell^-\barν_\ell)=(4.922 \pm 0.023 \pm 0.220)\%$. The ratio of branching fractions for electron and muon final states is found to be $0.998 \pm 0.009 \pm 0.020$. In addition, we determine the forward-backward angular asymmetry and the $D^{*+}$ longitudinal polarization fractions. All results are compatible with lepton-flavor universality in the Standard Model.

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arXiv2023

Measurement of the cross section of $e^+e^-\rightarrowΞ^{-}\barΞ^{+}$ at center-of-mass energies between 3.510 and 4.843 GeV

Using $e^+e^-$ collision data corresponding to a total integrated luminosity of 12.9 $fb^{-1}$ collected with the BESIII detector at the BEPCII collider, the exclusive Born cross sections and the effective form factors of the reaction $e^+e^-\rightarrowΞ^{-}\barΞ^{+}$ are measured via the single baryon-tag method at 23 center-of-mass energies between 3.510 and 4.843 GeV. Evidence for the decay $ψ(3770)\rightarrowΞ^{-}\barΞ^{+}$ is observed with a significance of 4.5$σ$ by analyzing the measured cross sections together with earlier BESIII results. For the other charmonium(-like) states $ψ(4040)$, $ψ(4160)$, $Y(4230)$, $Y(4360)$, $ψ(4415)$, and $Y(4660)$, no significant signal of their decay to $Ξ^-\bar Ξ^+$ is found. For these states, upper limits of the products of the branching fraction and the electronic partial width at the 90% confidence level are provided.

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arXiv2023

Measurement of the cross sections for $e^+e^-\toηπ^+π^-$ at center-of-mass energies between 2.00 and 3.08 GeV

Using data samples collected at center-of-mass energies between 2.000 and 3.080 GeV with the BESIII detector operating at the BEPCII collider, a partial-wave analysis is performed on the process $e^+e^-\toηπ^+π^-$. In addition to the dominant $e^+e^-\toρη$ component, the $e^+e^-\to a_2(1320)π$ process is also sizeable, contributing up to 24% of the total reaction. The measured cross sections of the process $e^+e^-\toηπ^+π^-$ are systematically higher than those of BaBar by more than $3σ$ at center-of-mass energies between 2.000 and 2.300 GeV. In the cross section lineshape for $e^+e^-\to a_2(1320)π$, a resonant structure is observed with a significance of $5.5σ$, with $M=(2044\pm31\pm4)$ MeV/$c^2$, $Γ=(163\pm69\pm24)$ MeV and $\mathcal{B_{R}}\cdotΓ_{e^+e^-}^{R}=(34.6\pm17.1\pm6.0)$ eV or $(137.1\pm73.3\pm2.1)$ eV. In the cross section lineshape for $e^+e^-\toρη$, an evidence of a dip structure around 2180 MeV/$c^2$ is observed with statistical significance of $3.0σ$.

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