arXiv subjects

K. Goetzen

Publications and source records attributed to K. Goetzen.

At least 397 records · Page 22Linked to original sources

arXiv2015

Observation of $e^+e^-\to π^0π^0 h_c$ and a neutral charmoniumlike structure $Z_c(4020)^0$

Using data collected with the BESIII detector operating at the Beijing Electron Positron Collider at center-of-mass energies of $\sqrt{s}=4.23$, 4.26, and 4.36~GeV, we observe $\EE\to \pphc$ for the first time. The Born cross sections are measured and found to be about half of those of $\EE\to π^+π^-h_c$ within less than 2$σ$. In the $π^0h_c$ mass spectrum, a structure at 4.02~GeV/$c^2$ is found. It is most likely to be the neutral isospin partner of the $\zcp^{\pm}$ observed in the process of $\EE\to π^+π^-h_c$ is found. A fit to the $π^0 h_c$ invariant mass spectrum, with the width of the $\zcpn$ fixed to that of its charged isospin partner and possible interferences with non-$\zcpn$ amplitudes neglected, gives a mass of ($4023.9\pm 2.2 \pm 3.8$)~MeV/$c^2$ for the $\zcpn$, where the first error is statistical and the second systematic.

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arXiv2015

Search for the $Y(4140)$ via $e^{+} e^{-} \to γϕJ/ψ$ at $\sqrt{s}=$ 4.23, 4.26 and 4.36 GeV

Using data samples collected at center-of-mass energies $\sqrt{s} = 4.23$, 4.26, and 4.36 GeV with the BESIII detector operating at the BEPCII storage ring, we search for the production of the charmoniumlike state $Y(4140)$ through a radiative transition followed by its decay to $ϕJ/ψ$. No significant signal is observed and upper limits on $σ[e^{+} e^{-} \rightarrow γY(4140)] \cdot \mathcal{B}(Y(4140)\rightarrow ϕJ/ψ)$ at the $90\%$ confidence level are estimated as 0.35, 0.28, and 0.33 pb at $\sqrt{s} = 4.23$, 4.26, and 4.36 GeV, respectively.

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arXiv2015

Study of $ψ(3686)\toπ^0 h_c, h_c\toγη_c$ via $η_c$ exclusive decays

The process $ψ(3686) \to π^0 h_c, h_c \to γη_c$ has been studied with a data sample of $106 \pm 4$ million $ψ(3686)$ events collected with the BESIII detector at the BEPCII storage ring. The mass and width of the $P$-wave charmonium spin-singlet state $h_c(^1P_1)$ are determined by simultaneously fitting distributions of the $π^0$ recoil mass for 16 exclusive $η_c$ decay modes. The results, $M(\hc) = 3525.31 \pm 0.11 {\rm (stat.)} \pm 0.14 {\rm (syst.)}$\,MeV/$c^2$ and $Γ(\hc) = 0.70 \pm 0.28 \pm 0.22$\,MeV, are consistent with and more precise than previous measurements. We also determine the branching ratios for the 16 exclusive $η_c$ decay modes, five of which have not been measured previously. New measurements of the $η_c$ line-shape parameters in the $E1$ transition $h_c\toγη_c$ are made by selecting candidates in the $h_c$ signal sample and simultaneously fitting the hadronic mass spectra for the 16 $η_c$ decay channels. The resulting $η_c$ mass and width values are $M(η_c) = 2984.49 \pm 1.16 \pm 0.52$\,MeV/$c^2$ and $Γ(η_c) = 36.4 \pm 3.2 \pm 1.7$\,MeV.

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arXiv2015

Search for the $η_c(2S)/h_c\to p\bar{p}$ decays and measurements of the $χ_{cJ}\to p\bar{p}$ branching fractions

Using a sample of $1.06\times10^{8}~ψ(3686)$ events collected with the BESIII detector at BEPCII, the decays $η_{c}(2S)\to p\bar{p}$ and $h_{c}\to p\bar{p}$ are searched for, where $η_c(2S)$ and $h_c$ are reconstructed in the decay chains $ψ(3686)\toγη_{c}(2S)$, $η_{c}(2S)\to p\bar{p}$ and $ψ(3686)\toπ^{0}h_{c}$, $h_{c}\to p\bar{p}$, respectively. No significant signals are observed. The upper limits of the product branching fractions are determined to be $\mathcal{B}(ψ(3686)\toγη_c(2S))\times\mathcal{B}(η_{c}(2S)\to p\bar{p})<1.4\times10^{-6}$ and $\mathcal{B}(ψ(3686)\toπ^0h_c)\times\mathcal{B}(h_{c}\to p\bar{p})<1.3\times10^{-7}$ at the 90% C.L.. The branching fractions for $χ_{cJ}\to p\bar{p}$ $(J=0,~1,~2)$ are also measured to be $(24.5\pm0.8\pm1.3,~8.6\pm0.5\pm0.5,~8.4\pm0.5\pm0.5)\times10^{-5}$, which are the world's most precise measurements.

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arXiv2015

Precision measurement of the $D^{*0}$ decay branching fractions

Using 482 pb$^{-1}$ of data taken at $\sqrt{s}=4.009$ GeV, we measure the branching fractions of the decays of $D^{*0}$ into $D^0π^0$ and $D^0γ$ to be $\BR(D^{*0} \to D^0π^0)=(65.5\pm 0.8\pm 0.5)%$ and $\BR(D^{*0} \to D^0γ)=(34.5\pm 0.8\pm 0.5)%$ respectively, by assuming that the $D^{*0}$ decays only into these two modes. The ratio of the two branching fractions is $\BR(D^{*0} \to D^0π^0)/\BR(D^{*0} \to D^0γ) =1.90\pm 0.07\pm 0.05$, which is independent of the assumption made above. The first uncertainties are statistical and the second ones systematic. The precision is improved by a factor of three compared to the present world average values.

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arXiv2015

Study of $e^+e^-\toωχ_{cJ}$ at center-of-mass energies from 4.21 to 4.42 GeV

Based on data samples collected with the BESIII detector at the BEPCII collider at 9 center-of-mass energies from 4.21 to 4.42 GeV, we search for the production of $e^+e^-\to ωχ_{cJ}$ ($J$=0, 1, 2). The process $e^+e^-\to ωχ_{c0}$ is observed for the first time, and the Born cross sections at $\sqrt{s}$=4.23 and 4.26 GeV are measured to be $(55.4\pm 6.0\pm 5.9)$ and $(23.7\pm 5.3\pm 3.5)$ pb, respectively, where the first uncertainties are statistical and the second are systematic. The $ωχ_{c0}$ signals at the other 7 energies and $e^+e^-\to ωχ_{c1}$ and $ωχ_{c2}$ signals are not significant, and the upper limits on the cross sections are determined. By examining the $ωχ_{c0}$ cross section as a function of center-of-mass energy, we find that it is inconsistent with the line shape of the $Y(4260)$ observed in $e^+ e^-\toπ^+π^-J/ψ$. Assuming the $ωχ_{c0}$ signals come from a single resonance, we extract mass and width of the resonance to be $(4230\pm8\pm6)$ MeV/$c^2$ and $(38\pm12\pm2)$ MeV, respectively, and the statistical significance is more than $9σ$.

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arXiv2015

Search for the weak decays $J/ψ\to D^{(*)}_{s}eν_{e}$

Using a sample of $2.25\times 10^8$ $J/ψ$ events collected with the BESIII detector at the BEPCII collider, we search for the $J/ψ$ semi-leptonic weak decay $J/ψ\to D^{-}_{s} e^{+}ν_{e}+c.c.$ with a much higher sensitivity than previous searches. We also perform the first search for $J/ψ\to D^{*-}_{s} e^{+}ν_{e}+c.c.$ No significant excess of a signal above background is observed in either channel. At the $90\%$ confidence level, the upper limits are determined to be $\mathcal{B}(J/ψ\to D^{-}_{s}e^{+}ν_{e}+c.c.)<1.3\times10^{-6}$ and $\mathcal{B}(J/ψ\to {D^{*}_{s}}^{-}e^{+}ν_{e}+c.c.)<1.8\times10^{-6}$, respectively. Both are consistent with Standard Model predictions.

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arXiv2014

Study of J/psi->eta phi pi+pi- at BESIII

Based on a sample of $2.25\times 10^{8} J/ψ$ events taken with the BESIII detector at the BEPCII collider, we present the results of a study of the decay $J/ψ\to ηϕπ^{+}π^{-}$. The $Y(2175)$ resonance is observed in the invariant mass spectrum of $ϕf_{0}(980)$ with a statistical significance of greater than $10σ$. The corresponding mass and width are determined to be $M=2200\pm 6 \mathrm{(stat.)} \pm 5\mathrm{(syst.)} \mathrm{MeV}/c^{2}$ and $Γ=104\pm 15\mathrm{(stat.)}\pm 15\mathrm{(syst.)}$ MeV, respectively, and the product branching fraction is measured to be $\mathcal{B}(J/ψ\toηY(2175)$, $Y(2175)\to ϕf_{0}(980)$, $f_{0}(980)\to π^{+}π^{-})= (1.20\pm 0.14\mathrm{(stat.)}\pm 0.37 \mathrm{(syst.)})\times 10^{-4}$. The results are consistent within errors with those of previous experiments. We also measure the branching fraction of $J/ψ\to ϕf_1(1285)$ with $f_1(1285)\to ηπ^{+}π^{-}$ and set upper limits on the branching fractions for $J/ψ\to ϕη(1405)$/$ϕX(1835)$/$ϕX(1870)$ with $η(1405)$/$X(1835)$/$X(1870)\to ηπ^{+}π^{-}$ at the 90\% confidence level.

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arXiv2014

Evidence for $e^+e^-\toγχ_{c1, 2}$ at center-of-mass energies from 4.009 to 4.360 GeV

Using data samples collected at center-of-mass energies of $\sqrt{s}$ = 4.009, 4.230, 4.260, and 4.360 GeV with the BESIII detector operating at the BEPCII collider, we perform a search for the process $e^+e^-\toγχ_{cJ}$ $(J = 0, 1, 2)$ and find evidence for $e^+e^-\toγχ_{c1}$ and $e^+e^-\toγχ_{c2}$ with statistical significances of 3.0$σ$ and 3.4$σ$, respectively. The Born cross sections $σ^{B}(e^+e^-\toγχ_{cJ})$, as well as their upper limits at the 90% confidence level are determined at each center-of-mass energy.

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arXiv2014

Search for C-parity violation in $J/ ψ\to γγ$ and $ γϕ$

Using $1.06\times10^8$ $ψ(3686)$ events recorded in $e^{+}e^{-}$ collisions at $\sqrt{s}=$ 3.686 GeV with the BESIII at the BEPCII collider, we present searches for C-parity violation in $J/ψ\to γγ$ and $ γϕ$ decays via $ψ(3686) \to J/ψπ^+π^-$. No significant signals are observed in either channel. Upper limits on the branching fractions are set to be $\mathcal{B}(J/ψ\to γγ) < 2.7 \times 10^{-7}$ and $\mathcal{B}(J/ψ\to γϕ) < 1.4 \times 10^{-6}$ at the 90\% confidence level. The former is one order of magnitude more stringent than the previous upper limit, and the latter represents the first limit on this decay channel.

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arXiv2014

Updated Measurement of the Single Top Quark Production Cross Section and $V{tb}$ in the Missing Transverse Energy Plus Jets Topology in $p\bar{p}$ Collisions at $\sqrt{s} = 1.96$ TeV

An updated measurement of the single top quark production cross section is presented using the full data set collected by the Collider Detector at Fermilab (CDF) and corresponding to 9.5 fb${}^{-1}$ of integrated luminosity from proton-antiproton collisions at 1.96 TeV center-of-mass energy. The events selected contain an imbalance in the total transverse energy, jets identified as originating from $b$ quarks, and no identified leptons. The sum of the $s$- and $t$-channel single top quark cross sections is measured to be $3.53_{-1.16}^{+1.25}$ pb and a lower limit on $V_{tb}$ of 0.63 is obtained at the 95% credibility level. These measurements are combined with previously reported CDF results obtained from events with an imbalance in total transverse energy, jets identified as originating from $b$ quarks, and exactly one identified lepton. The combined cross section is measured to be $3.02_{-0.48}^{+0.49}$ pb and a lower limit on $V{tb}$ of 0.84 is obtained at the 95% credibility level.

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arXiv2014

Observation of $J/ψ\rightarrow p\bar{p}a_{0}(980)$ at BESIII

Using $2.25\times10^{8}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage rings, we observe for the first time the process $J/ψ\rightarrow p\bar{p}a_{0}(980)$, $a_{0}(980)\rightarrow π^{0}η$ with a significance of $6.5σ$ ($3.2σ$ including systematic uncertainties). The product branching fraction of $J/ψ\rightarrow p\bar{p}a_{0}(980)\rightarrow p\bar{p}π^{0}η$ is measured to be $(6.8\pm1.2\pm1.3)\times 10^{-5}$, where the first error is statistical and the second is systematic. This measurement provides information on the $a_{0}$ production near threshold coupling to $p\bar{p}$ and improves the understanding of the dynamics of $J/ψ$ decays to four body processes.

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arXiv2014

Study of e$^+$e$^-$ $\rightarrow \text{p} \overline{\text{p}}π^0$ in the Vicinity of the $ψ\text{(3770)}$

The process $e^+e^-\rightarrow p\overline{p}π^0$ has been studied by analyzing data collected at $\sqrt{s}=3.773$ GeV, at $\sqrt{s}=3.650$ GeV, and during a $ψ(3770)$ line shape scan with the BESIII detector at the BEPCII collider. The Born cross section of $p \overline{p} π^0$ in the vicinity of the $ψ(3770)$ is measured and the Born cross section of $ψ(3770)\rightarrow p \overline{p} π^0$ is extracted considering interference between resonant and continuum production amplitudes. Two solutions with the same probability and a significance of 1.5$σ$ are found, and the Born cross section of $ψ(3770)\rightarrow p \overline{p} π^0$ is determined to be less than 0.22 pb at 90% confidence level and $33.8\pm1.8\pm2.1$ pb, respectively. Using the estimated cross section and a constant decay amplitude approximation, the cross section $σ(p\overline{p} \rightarrow ψ(3770) π^0)$ is calculated for the kinematic situation of the planned $\overline{\text{P}}\text{ANDA}$ experiment. The maximum cross section corresponding to the two solutions is expected to be less than $0.79$ nb at 90% confidence level and $122\pm10$ nb at a center of mass energy of 5.26 GeV.

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arXiv2014

Study of $e^+e^- \rightarrow p\bar{p}$ in the vicinity of $ψ(3770)$

Using 2917 $\rm{pb}^{-1}$ of data accumulated at 3.773~$\rm{GeV}$, 44.5~$\rm{pb}^{-1}$ of data accumulated at 3.65~$\rm{GeV}$ and data accumulated during a $ψ(3770)$ line-shape scan with the BESIII detector, the reaction $e^+e^-\rightarrow p\bar{p}$ is studied considering a possible interference between resonant and continuum amplitudes. The cross section of $e^+e^-\rightarrowψ(3770)\rightarrow p\bar{p}$, $σ(e^+e^-\rightarrowψ(3770)\rightarrow p\bar{p})$, is found to have two solutions, determined to be ($0.059\pm0.032\pm0.012$) pb with the phase angle $ϕ= (255.8\pm37.9\pm4.8)^\circ$ ($<$0.11 pb at the 90% confidence level), or $σ(e^+e^-\rightarrowψ(3770)\rightarrow p\bar{p}) = (2.57\pm0.12\pm0.12$) pb with $ϕ= (266.9\pm6.1\pm0.9)^\circ$ both of which agree with a destructive interference. Using the obtained cross section of $ψ(3770)\rightarrow p\bar{p}$, the cross section of $p\bar{p}\rightarrow ψ(3770)$, which is useful information for the future PANDA experiment, is estimated to be either ($9.8\pm5.7$) nb ($<17.2$ nb at 90% C.L.) or $(425.6\pm42.9)$ nb.

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arXiv2014

Observation of $χ_{c1}$ decays into vector meson pairs $ϕϕ$, $ωω$, and $ωϕ$

Decays of $χ_{c1}$ to vector meson pairs $ϕϕ$, $ωω$ and $ωϕ$ are observed for the first time using $(106\pm4)\times 10^6$ $\psip$ events accumulated at the BESIII detector at the BEPCII $e^+e^-$ collider. The branching fractions are measured to be $(4.4\pm 0.3\pm 0.5)\times 10^{-4}$, $(6.0\pm 0.3\pm 0.7)\times 10^{-4}$, and $(2.2\pm 0.6\pm 0.2)\times 10^{-5}$, for $χ_{c1}\to ϕϕ$, $ωω$, and $ωϕ$, respectively. The observation of $χ_{c1}$ decays into a pair of vector mesons $ϕϕ$, $ωω$ and $ωϕ$ indicates that the hadron helicity selection rule is significantly violated in $χ_{cJ}$ decays. In addition, the measurement of $χ_{cJ}\to ωϕ$ gives the rate of doubly OZI-suppressed decay. Branching fractions for $χ_{c0}$ and $χ_{c2}$ decays into other vector meson pairs are also measured with improved precision.

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arXiv2014

Measurement of $χ_{cJ}$ decaying into $η^{\prime}K^+K^-$

Using $(106.41\pm 0.86) \times 10^{6}$ $ψ(3686)$ events collected with the BESIII detector at BEPCII, we study for the first time the decay $χ_{cJ}\toη'K^+K^-$, where $η'\toγρ^{0}$ and $η'\toηπ^+π^-$. A partial wave analysis in the covariant tensor amplitude formalism is performed for the decay $χ_{c1}\toη'K^+K^-$. Intermediate processes $χ_{c1}\toη' f_0(980)$, $χ_{c1}\toη' f_0(1710)$, $χ_{c1}\toη' f_2'(1525)$ and $χ_{c1}\to K^*_0(1430)^{\pm}K^{\mp}$ ($K^*_0(1430)^{\pm}\toη' K^{\pm}$) are observed with statistical significances larger than 5$σ$, and their branching fractions are measured.

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arXiv2014

Precision Measurement of the Mass of the $τ$ Lepton

An energy scan near the $τ$ pair production threshold has been performed using the BESIII detector. About $24$ pb$^{-1}$ of data, distributed over four scan points, was collected. This analysis is based on $τ$ pair decays to $ee$, $eμ$, $eh$, $μμ$, $μh$, $hh$, $eρ$, $μρ$ and $πρ$ final states, where $h$ denotes a charged $π$ or $K$. The mass of the $τ$ lepton is measured from a maximum likelihood fit to the $τ$ pair production cross section data to be $m_τ = (1776.91\pm0.12 ^{+0.10}_{-0.13}$) MeV/$c^2$, which is currently the most precise value in a single measurement.

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arXiv2014

Search for the radiative transitions $ψ(3770)\toγη_c$ and $γη_c(2S)$

By using a 2.92 fb$^{-1}$ data sample taken at $\sqrt{s} = 3.773$ GeV with the BESIII detector operating at the BEPCII collider, we search for the radiative transitions $ψ(3770)\toγη_c$ and $γη_c(2S)$ through the hadronic decays $η_c(η_c(2S))\to K^0_SK^\pmπ^\mp$. No significant excess of signal events above background is observed. We set upper limits at a 90% confidence level for the product branching fractions to be $\mathcal{B}(ψ(3770)\toγη_c)\times \mathcal{B}(η_c\to K^0_SK^\pmπ^\mp) < 1.6\times10^{-5}$ and $\mathcal{B}(ψ(3770)\toγη_c(2S))\times \mathcal{B}(η_c(2S)\to K^0_SK^\pmπ^\mp) < 5.6\times10^{-6}$. Combining our result with world-average values of $\mathcal{B}(η_c(η_c(2S))\to K^0_SK^\pmπ^\mp)$, we find the branching fractions $\mathcal{B}(ψ(3770)\toγη_c) < 6.8\times10^{-4}$ and $\mathcal{B}(ψ(3770)\toγη_c(2S)) < 2.0\times10^{-3}$ at a 90% confidence level.

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