arXiv subjects

F. Cossio

Publications and source records attributed to F. Cossio.

At least 523 records · Page 29Linked to original sources

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.

hep-ex↗

arXiv2021

Study of the Dalitz decay $J/ψ\to e^+e^- η$

We report corrected results on a study of the electromagnetic Dalitz decay $J/ψ\to e^+e^- η$ and search for di-electron decays of a light dark gauge boson ($γ'$) in $J/ψ\to γ' η$ with the two $η$ decay modes $η\rightarrow γγ$ and $η\rightarrow π^+π^-π^0$, using $(1310.6\pm 7.0)\times10^6$ $J/ψ$ events collected with the BESIII detector. In particular we update the measurement of the pole mass of the transition form factor (TFF) of $J/ψ\to e^+e^- η$ to be $Λ= 2.56 \pm 0.04({\rm stat}) \pm 0.03({\rm syst})$ GeV/$c^2$. The branching fraction of $J/ψ\to e^+e^-η$ and the kinetic-mixing strength between the Standard Model photon and $γ'$ are also updated after taking the corrected $Λ$ value into account. The measured branching fraction of $J/ψ\to e^+e^- η$ is updated to be $(1.42 \pm 0.04({\rm stat}) \pm 0.07 ({\rm syst}))\times 10^{-5}$, where the first and second uncertainties are statistical and systematic, respectively.

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arXiv2021

Study of the decay $D_s^+\to K_S^0K_S^0π^+$ and observation an isovector partner to $f_0(1710)$

Using $e^+e^-$ annihilation data corresponding to a total integrated luminosity of 6.32 $\rm fb^{-1}$ collected at center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we perform an amplitude analysis of the decay $D_{s}^{+} \to K_{S}^{0}K_{S}^{0}π^{+}$ for the first time. An enhancement is observed in the $K_{S}^{0}K_{S}^{0}$ mass spectrum near 1.7 GeV/$c^2$, which was not seen in $D_{s}^{+} \to K^+K^-π^{+}$ in an earlier work, implying the existence of an isospin one partner of the $f_0(1710)$. The branching fraction of the decay $D_{s}^{+}\to K_{S}^{0}K_{S}^{0}π^{+}$ is determined to be $\mathcal{B}(D_{s}^{+} \to K_{S}^{0}K_{S}^{0}π^{+})=(0.68\pm0.04_{\rm stat}\pm0.01_{\rm syst})\%$.

hep-ex↗

arXiv2021

Measurement of Branching Fractions of $J/ψ$ and $ψ(3686)$ decays to $Σ^{+}$ and $\overlineΣ^-$

Using $1310.6\times10^{6}$ $J/ψ$ and $448.1\times10^{6}$ $ψ(3686)$ events collected with the BESIII detector, the branching fractions of $J/ψ$ and $ψ(3686)$ decays to $Σ^{+}\overlineΣ^{-}$ are measured to be $(10.61 \pm 0.04 \pm 0.36) \times 10^{-4}$ and $(2.52 \pm 0.04 \pm 0.09) \times 10^{-4}$, respectively. In addition, the ratio of $\mathcal{B}(ψ(3686) \rightarrow Σ^{+}\overlineΣ^{-})/\mathcal{B}(J/ψ\rightarrow Σ^{+}\overlineΣ^{-})$ is determined to be $(23.8 \pm 1.1)\%$ which violates the "$12\%$ rule".

hep-ex↗

arXiv2021

Measurement of the $e^{+}e^{-}\toΣ^{0}\barΣ^{0}$ cross sections at center-of-mass energies from $2.3864$ to $3.0200$ GeV

The Born cross sections of $e^{+}e^{-}\to Σ^{0}\barΣ^{0}$ are measured at center-of-mass energies from $2.3864$ to $3.0200$ GeV using data samples with an integrated luminosity of $328.5$ pb$^{-1}$ collected with the BESIII detector operating at the BEPCII collider. The analysis makes use of a novel reconstruction method for energies near production threshold, while a single-tag method is employed at other center-of-mass energies. The measured cross sections are consistent with earlier results from BaBar, with a substantially improved precision. The cross-section lineshape can be well described by a perturbative QCD-driven energy function. In addition, the effective form factors of the $Σ^{0}$ baryon are determined. The results provide precise experimental input for testing various theoretical predictions.

hep-ex↗

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.

hep-ex↗

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

Study of the Decay $D^{+}_{s}\rightarrow π^{+}π^{+}π^{-}η$ and Observation of the W-annihilation Decay $D^{+}_{s}\rightarrow a_0(980)^+ρ^0$

The decay $D^{+}_{s}\rightarrow π^{+}π^{+}π^{-}η$ is observed for the first time, using $e^+e^-$ collision data corresponding to an integrated luminosity of 6.32 fb$^{-1}$, collected by the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV. The absolute branching fraction for this decay is measured to be $\mathcal{B}(D^+_s \to π^+ π^+ π^- η) = (3.12\pm0.13_{\rm stat.}\pm0.09_{\rm syst.})$%. The first amplitude analysis of this decay reveals the sub-structures in $D^{+}_{s}\rightarrow π^{+}π^{+}π^{-}η$ and determines the relative fractions and the phases among these sub-structures. The dominant intermediate process is $D^{+}_{s}\rightarrow a_1(1260)^+ η, a_1(1260)^+ \rightarrow ρ(770)^0π^+$ with a branching fraction of $(1.73 \pm 0.14_{\rm stat.} \pm 0.08_{\rm syst.})$%. We also observe the W-annihilation process $D^{+}_{s}\rightarrow a_0(980)^+ρ(770)^0$, $a_0(980)^+ \to π^+ η$ with a branching fraction of $(0.21\pm0.08_{\rm stat.}\pm0.05_{\rm syst.})$%, which is larger than the branching fractions of other measured pure W-annihilation decays by one order of magnitude.

hep-ex↗

arXiv2021

Amplitude analysis and branching fraction measurement of the decay $D_{s}^{+} \to π^{+}π^{0}π^{0}$

Using a data set corresponding to an integrated luminosity of 6.32~$\rm fb^{-1}$ recorded by the BESIII detector at center-of-mass energies between 4.178 and 4.226~GeV, an amplitude analysis of the decay $D_{s}^{+} \to π^{+}π^{0}π^{0}$ is performed, and the relative fractions and phases of different intermediate processes are determined. The absolute branching fraction of the decay $D_{s}^{+} \to π^{+}π^{0}π^{0}$ is measured to be $(0.50\pm 0.04_{\text{stat}}\pm 0.02_{\text{syst}})\%$. The absolute branching fraction of the intermediate process $D_{s}^{+} \to f_0(980)π^{+}, f_0(980)\toπ^{0}π^{0}$ is determined to be $(0.21\pm 0.03_{\text{stat}}\pm 0.03_{\text{syst}})\%$.

hep-ex↗

arXiv2021

Measurement of the absolute branching fractions for purely leptonic $D_s^+$ decays

We report new measurements of the branching fraction $\cal B(D_s^+\to \ell^+ν)$, where $\ell^+$ is either $μ^+$ or $τ^+(\toπ^+\barν_τ)$, based on $6.32$ fb$^{-1}$ of electron-positron annihilation data collected by the BESIII experiment at six center-of-mass energy points between $4.178$ and $4.226$ GeV. Simultaneously floating the $D_s^+\toμ^+ν_μ$ and $D_s^+\toτ^+ν_τ$ components yields $\cal B(D_s^+\to τ^+ν_τ) = (5.21\pm0.25\pm0.17)\times10^{-2}$, $\cal B(D_s^+\to μ^+ν_μ) = (5.35\pm0.13\pm0.16)\times10^{-3}$, and the ratio of decay widths $R=\frac{Γ(D_s^+\to τ^+ν_τ)}{Γ(D_s^+\to μ^+ν_μ)} = 9.73^{+0.61}_{-0.58}\pm 0.36$, where the first uncertainties are statistical and the second systematic. No evidence of ${\it CP}$ asymmetry is observed in the decay rates $D_s^\pm\toμ^\pmν_μ$ and $D_s^\pm\toτ^\pmν_τ$: $A_{\it CP}(μ^\pmν) = (-1.2\pm2.5\pm1.0)\%$ and $A_{\it CP}(τ^\pmν) = (+2.9\pm4.8\pm1.0)\%$. Constraining our measurement to the Standard Model expectation of lepton universality ($R=9.75$), we find the more precise results $\cal B(D_s^+\to τ^+ν_τ) = (5.22\pm0.10\pm 0.14)\times10^{-2}$ and $A_{\it CP}(τ^\pmν_τ) = (-0.1\pm1.9\pm1.0)\%$. Combining our results with inputs external to our analysis, we determine the $c\to \bar{s}$ quark mixing matrix element, $D_s^+$ decay constant, and ratio of the decay constants to be $|V_{cs}| = 0.973\pm0.009\pm0.014$, $f_{D^+_s} = 249.9\pm2.4\pm3.5~\text{MeV}$, and $f_{D^+_s}/f_{D^+} = 1.232\pm0.035$, respectively.

hep-ex↗

arXiv2021

Search for the hyperon semileptonic decay $Ξ^{-} \rightarrow Ξ^{0} e^{-} \bar{ν_{e}}$

Using $(10.087\pm0.044)\times10^{9}$ $J/ψ$ events collected by the BESIII detector at the BEPCII collider, we search for the hyperon semileptonic decay $Ξ^{-} \rightarrow Ξ^{0} e^{-} \barν_{e}$. No significant signal is observed and the upper limit on the branching fraction $\mathcal B(Ξ^{-} \rightarrow Ξ^{0} e^{-} \barν_{e})$ is set to be $2.59\times10^{-4}$ at 90 % confidence level. This result is one order of magnitude more strict than the previous best limit.

hep-ex↗

arXiv2021

Determination of the absolute branching fractions of $D^0\to K^-e^+ν_e$ and $D^+\to \bar K^0 e^+ν_e$

Using 2.93 fb$^{-1}$ of $e^+e^-$ collision data collected with the BESIII detector at a center-of-mass energy of 3.773 GeV, we measure the absolute branching fractions of the decays $D^0\to K^-e^+ν_e$ and $D^+\to \bar K^0 e^+ν_e$ to be $(3.567\pm0.031_{\rm stat}\pm 0.025_{\rm syst})\%$ and $(8.68\pm0.14_{\rm stat}\pm 0.16_{\rm syst})\%$, respectively. Starting with the process $e^+e^-\to D\bar{D}$, a new reconstruction method is employed to select events that contain candidates for both $D\to \bar Ke^+ν_e$ and $\bar D\to Ke^-\bar ν_e$ decays. The branching fractions reported in this work are consistent within uncertainties with previous BESIII measurements that selected events containing $D\to \bar Ke^+ν_e$ and hadronic $\bar D$ decays. Combining our results with the lifetimes of the $D^0$ and $D^+$ mesons and the previous BESIII measurements leads to a ratio of the two decay partial widths of $\frac{\bar Γ_{D^0\to K^{-}e^+ν_{e}}}{\bar Γ_{D^{+}\to \bar K^{0}e^+ν_{e}}}=1.039\pm0.021$. This ratio supports isospin symmetry in the $D^0\to K^-e^+ν_e$ and $D^+\to \bar K^0 e^+ν_e$ decays within $1.9σ$.

hep-ex↗

arXiv2021

Observation of $ψ(3686)\toΞ(1530)^{0}\barΞ(1530)^{0}$ and $Ξ(1530)^{0}\barΞ^0$

Using $(448.1\pm2.9)\times 10^{6}$ $ψ(3686)$ events collected with the BESIII detector and a single-baryon tagging technique, we present the first observation of the decays $ψ(3686)\toΞ(1530)^{0}\barΞ(1530)^{0}$ and $Ξ(1530)^{0}\barΞ^0$. The branching fractions are measured to be ${\cal{B}}(ψ(3686)\toΞ(1530)^{0}\barΞ(1530)^{0}) = (6.77\pm0.14\pm0.39)\times10^{-5}$ and ${\cal{B}}(ψ(3686)\toΞ(1530)^{0}\barΞ^{0}) = (0.53\pm0.04\pm0.03)\times10^{-5}$. Here, the first and second uncertainties are statistical and systematic, respectively. In addition, the parameter associated with the angular distribution for the decay $ψ(3686)\toΞ(1530)^{0}\barΞ(1530)^0$ is determined to be $α= 0.32\pm0.19\pm0.07$, in agreement with theoretical predictions within one standard deviation.

hep-ex↗

arXiv2021

Measurement of the inclusive branching fraction for $ψ(3686)\rightarrow K_{S}^{0} + \text{anything}$

Using 5.9~pb$^{-1}$ of $e^+e^-$ annihilation data collected at center-of-mass energies from 3.640 to 3.701 GeV with the BESIII detector at the BEPCII Collider, we measure the observed cross sections of $e^+e^-\rightarrow K_{S}^{0} X$ (where $X= \text{anything}$). From a fit to these observed cross sections with the sum of continuum and $ψ(3686)$ and $J/ψ$ Breit-Wigner functions and considering initial state radiation and the BEPCII beam energy spread, we obtain for the first time the product of $ψ(3686)$ leptonic width and inclusive decay branching fraction $Γ^{ee}_{ψ(3686)}\mathcal B(ψ(3686)\rightarrow K_{S}^{0} X) = (373.8 \pm 6.7 \pm 20.0)$ eV, and assuming $Γ^{ee}_{ψ(3686)}$ is $(2.33 \pm 0.04)$ keV from PDG value, we measure $\mathcal B(ψ(3686)\rightarrow K_{S}^{0} X) = (16.04 \pm 0.29 \pm 0.90)\%$, where the first uncertainty is statistical and the second is systematic.

hep-ex↗

arXiv2021

Measurements of the center-of-mass energies of $e^{+}e^{-}$ collisions at BESIII

During the 2016-17 and 2018-19 running periods, the BESIII experiment collected 7.5~fb$^{-1}$ of $e^+e^-$ collision data at center-of-mass energies ranging from 4.13 to 4.44 GeV. These data samples are primarily used for the study of excited charmonium and charmoniumlike states. By analyzing the di-muon process $e^{+}e^{-} \to (γ_{\rm ISR/FSR}) μ^{+}μ^{-}$, we measure the center-of-mass energies of the data samples with a precision of 0.6 MeV. Through a run-by-run study, we find that the center-of-mass energies were stable throughout most of the data-taking period.

hep-ex↗

arXiv2021

Observation of a near-threshold enhancement in the $Λ\barΛ$ mass spectrum from $e^+e^-\toϕΛ\barΛ$ at $\sqrt{s}$ from 3.51 to 4.60 GeV

The process $e^+ e^- \to ϕΛ\barΛ$ is studied using data samples collected with the BESIII detector at the BEPCII collider at center-of-mass energies $\sqrt{s}$ ranging from $3.51$ to $4.60~{\rm GeV}$ . An intermediate resonance structure is observed near the threshold of $Λ\barΛ$. It has a mass of $(2262 \pm 4 \pm 28)~{\rm{MeV}}/c^{2}$ and a width of $(72 \pm 5 \pm 43)~\rm{MeV}$, where the quoted uncertainties are statistical and systematic, respectively. The $J^{PC}$ quantum numbers of $0^{-+}$ and $0^{++}$ are rejected, while other $J^{PC}$ hypotheses are possible, according to the helicity angle study. The energy-dependent cross section of the $e^+ e^- \to ϕΛ\barΛ$ process is measured for the first time in this energy region, and contributions from excited $ψ$ states and vector charmonium-like $Y$-states are investigated.

hep-ex↗

arXiv2021

Observation of $D^0\to K_1(1270)^- e^+ν_e$

Using 2.93 fb$^{-1}$ of $e^+e^-$ collision data taken with the BESIII detector at a center-of-mass energy of 3.773 $\rm \,GeV$, the observation of the $D^0\to K_1(1270)^- e^+ν_e$ semileptonic decay is presented. The statistical significance of the decay $D^0\to K_1(1270)^- e^+ν_e$ is greater than $10σ$. The branching fraction of $D^0\to K_1(1270)^- e^+ν_e$ is measured to be $(1.09\pm0.13^{+0.09}_{-0.16} \pm 0.12)\times10^{-3}$. Here, the first uncertainty is statistical, the second is systematic, and the third originates from the assumed branching fraction of $K_1(1270)^- \rightarrow K^-π^+π^-$. The fraction of longitudinal polarization in $D^0\to K_1(1270)^- e^+ν_e$ is determined for the first time to be $0.50\pm0.19_{\rm stat}\pm0.08_{\rm syst}$.

hep-ex↗

arXiv2021

The CGEM-IT readout chain

An innovative Cylindrical Gas Electron Multiplier (CGEM) detector is under construction for the upgrade of the inner tracker of the BESIII experiment. A novel system has been worked out for the readout of the CGEM detector, including a new ASIC, dubbed TIGER -Torino Integrated GEM Electronics for Readout, designed for the amplification and digitization of the CGEM output signals. The data output by TIGER are collected and processed by a first FPGA-based module, GEM Read Out Card, in charge of configuration and control of the front-end ASICs. A second FPGA-based module, named GEM Data Concentrator, builds the trigger selected event packets containing the data and stores them via the main BESIII data acquisition system. The design of the electronics chain, including the power and signal distribution, will be presented together with its performance.

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