arXiv subjects

A. Gilman

Publications and source records attributed to A. Gilman.

At least 109 records · Page 6Linked to original sources

arXiv2019

Measurement of the absolute branching fractions of $Λ_{c}^{+}\toΛηπ^{+}$ and $Σ(1385)^{+}η$

We study the decays $Λ_{c}^{+}\toΛηπ^{+}$ and $Σ(1385)^{+}η$ based on $Λ_{c}^{+}\barΛ_{c}^{-}$ pairs produced in $e^+e^-$ collisions at a center-of-mass energy of $\sqrt{s}=4.6~\mbox{GeV}$, corresponding to an integrated luminosity of $567\;\mbox{pb$^{-1}$}$. The data sample was accumulated with the BESIII detector at the BEPCII collider. The branching fractions are measured to be $\mathcal{B}(Λ_{c}^{+} \to Ληπ^{+})=(1.84\pm0.21({\rm{stat.}})\pm0.15({\rm{syst.}}))\%$ and $\mathcal{B}(Λ_{c}^{+} \to Σ(1385)^{+}η)=(0.91\pm0.18({\rm{stat.}})\pm0.09({\rm{syst.}}))\%$, constituting the most precise measurements to date.

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arXiv2019

Determination of the pseudoscalar decay constant $f_{D_s^+}$ via $D_s^+\toμ^+ν_μ$

Using a $3.19~\mathrm{fb}^{-1}$ data sample collected at an $e^+e^-$ center-of-mass energy of $E_{\rm cm}=4.178$ GeV with the BESIII detector, we measure the branching fraction of the leptonic decay $D_s^+\toμ^+ν_μ$ to be $\mathcal{B}_{D_s^+\toμ^+ν_μ}=(5.49\pm0.16_{\rm stat.}\pm0.15_{\rm syst.})\times10^{-3}$. Combining our branching fraction with the masses of the $D_s^+$ and $μ^+$ and the lifetime of the $D_s^+$, we determine $f_{D_s^+}|V_{cs}|=246.2\pm3.6_{\rm stat.}\pm3.5_{\rm syst.}~\mathrm{MeV}$. Using the $c\to s$ quark mixing matrix element $|V_{cs}|$ determined from a global standard model fit, we evaluate the $D_s^+$ decay constant $f_{D_s^+}=252.9\pm3.7_{\rm stat.}\pm3.6_{\rm syst.}$\,MeV. Alternatively, using the value of $f_{D_s^+}$ calculated by lattice quantum chromodynamics, we find $|V_{cs}| = 0.985\pm0.014_{\rm stat.}\pm0.014_{\rm syst.}$. These values of $\mathcal{B}_{D_s^+\toμ^+ν_μ}$, $f_{D_s^+}|V_{cs}|$, $f_{D_s^+}$ and $|V_{cs}|$ are each the most precise results to date.

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arXiv2019

Observation of $D^+ \to f_0(500) e^+ν_e$ and Improved Measurements of $D \toρe^+ν_e$

Using a data sample corresponding to an integrated luminosity of 2.93~fb$^{-1}$ recorded by the BESIII detector at a center-of-mass energy of $3.773$ GeV, we present an analysis of the decays $\bar{D}^0\toπ^+π^0 e^-\barν_e$ and $D^+\toπ^-π^+ e^+ν_e$. By performing a partial wave analysis, the $π^+π^-$ $S$-wave contribution to $D^+\toπ^-π^+ e^+ν_e$ is observed to be $(25.7\pm1.6\pm1.1)$% with a statistical significance greater than 10$σ$, besides the dominant $P$-wave contribution. This is the first observation of the $S$-wave contribution. We measure the branching fractions $\mathcal{B}(D^{0} \to ρ^- e^+ ν_e) = (1.445\pm 0.058 \pm 0.039) \times10^{-3}$, $\mathcal{B}(D^{+} \to ρ^0 e^+ ν_e) = (1.860\pm 0.070 \pm 0.061) \times10^{-3}$, and $\mathcal{B}(D^{+} \to f_0(500) e^+ ν_e, f_0(500)\toπ^+π^-) = (6.30\pm 0.43 \pm 0.32) \times10^{-4}$. An upper limit of $\mathcal{B}(D^{+} \to f_0(980) e^+ ν_e, f_0(980)\toπ^+π^-) < 2.8 \times10^{-5}$ is set at the 90% confidence level. We also obtain the hadronic form factor ratios of $D\to ρe^+ν_e$ at $q^{2}=0$ assuming the single-pole dominance parameterization: $r_{V}=\frac{V(0)}{A_{1}(0)}=1.695\pm0.083\pm0.051$, $r_{2}=\frac{A_{2}(0)}{A_{1}(0)}=0.845\pm0.056\pm0.039$.

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arXiv2019

Observation of OZI suppressed decays $χ_{cJ}\toωϕ$

Decays $χ_{cJ}~(J=0,1,2)\toωϕ$ are studied using $(448.1\pm2.9)\times 10^{6} ~ψ(3686)$ events collected with the BESIII detector in 2009 and 2012. In addition to the previously established $χ_{c0}\toωϕ$, first observation of $χ_{c1} \to ωϕ$ is reported in this paper. The measured product branching fractions are ${\cal{B}}(ψ(3686)\toγχ_{c0})\times{\cal{B}}(χ_{c0}\toωϕ)=(13.83\pm 0.70\pm 1.01)\times10^{-6}$ and ${\cal{B}}(ψ(3686)\toγχ_{c1})\times{\cal{B}}(χ_{c1}\toωϕ)=(2.67\pm 0.31\pm 0.27)\times10^{-6}$, and the absolute branching fractions are ${\cal{B}}(χ_{c0}\toωϕ)=(13.84\pm 0.70\pm 1.08)\times10^{-5}$ and ${\cal{B}}(χ_{c1}\toωϕ)=(2.80\pm 0.32\pm 0.30)\times10^{-5}$. We also find a strong evidence for $χ_{c2}\toωϕ$ with a statistical significance of 4.8$σ$, and the corresponding product and absolute branching fractions are measured to be ${\cal{B}}(ψ(3686)\toγχ_{c2})\times{\cal{B}}(χ_{c2}\toωϕ)=(0.91\pm0.23\pm0.12)\times10^{-6} $ and ${\cal{B}}(χ_{c2}\toωϕ)=(1.00\pm0.25\pm0.14)\times10^{-5}$. Here, the first errors are statistical and the second ones systematic.

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arXiv2019

Study of the decay $D^0\rightarrow \bar{K}^0π^-e^+ν_e$

We report a study of the decay $D^0 \rightarrow \bar{K}^0π^-e^+ν_{e}$ based on a sample of $2.93~\mathrm{fb}^{-1}$ $e^+e^-$ annihilation data collected at the center-of-mass energy of 3.773~GeV with the BESIII detector at the BEPCII collider. The total branching fraction is determined to be $\mathcal{B}(D^0\rightarrow \bar{K}^0π^-e^+ν_{e})=(1.434\pm0.029({\rm stat.})\pm0.032({\rm syst.}))\%$, which is the most precise to date. According to a detailed analysis of the involved dynamics, we find this decay is dominated with the $K^{*}(892)^-$ contribution and present an improved measurement of its branching fraction to be $\mathcal{B}(D^0\rightarrow K^{*}(892)^-e^+ν_e)=(2.033\pm0.046({\rm stat.})\pm0.047({\rm syst.}))\%$. We further access their hadronic form-factor ratios for the first time as $r_{V}=V(0)/A_1(0)=1.46\pm0.07({\rm stat.})\pm0.02({\rm syst.})$ and $r_{2}=A_2(0)/A_1(0)=0.67\pm0.06({\rm stat.})\pm0.01({\rm syst.})$. In addition, we observe a significant $\bar{K}^0π^-$ $S$-wave component accounting for $(5.51\pm0.97({\rm stat.})\pm0.62({\rm syst.}))\%$ of the total decay rate.

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arXiv2019

First measurement of the form factors in $D^+_{s}\rightarrow K^0 e^+ν_e$ and $D^+_{s}\rightarrow K^{*0} e^+ν_e$ decays

We report on new measurements of Cabibbo-suppressed semileptonic $D_s^+$ decays using $3.19~\mathrm{fb}^{-1}$ of $e^+e^-$ annihilation data sample collected at a center-of-mass energy of 4.178~GeV with the BESIII detector at the BEPCII collider. Our results include branching fractions $\mathcal B({D^+_s\rightarrow K^0 e^+ν_{e}})=(3.25\pm0.38({\rm stat.})\pm0.16({\rm syst.}))\times10^{-3}$ and $\mathcal B({D^+_s\rightarrow K^{*0} e^+ν_{e}})=(2.37\pm0.26({\rm stat.})\pm0.20({\rm syst.}))\times10^{-3}$ which are much improved relative to previous measurements, and the first measurements of the hadronic form-factor parameters for these decays. For $D^+_s\rightarrow K^0 e^+ν_{e}$, we obtain $f_+(0)=0.720\pm0.084({\rm stat.})\pm0.013({\rm syst.})$, and for $D^+_s\rightarrow K^{*0} e^+ν_{e}$, we find form-factor ratios $r_V=V(0)/A_1(0)=1.67\pm0.34({\rm stat.})\pm0.16({\rm syst.})$ and $r_2=A_2(0)/A_1(0)=0.77\pm0.28({\rm stat.})\pm0.07({\rm syst.})$.

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arXiv2019

Search for rare decay $J/ ψ\to ϕe^+ e^-$

Using a data sample of $448.1\times10^6$ $ψ(3686)$ events collected at $\sqrt{s}=$ 3.686 GeV with the BESIII detector at the BEPCII, we search for the rare decay $J/ψ\to ϕe^+ e^-$ via $ψ(3686) \to π^+π^- J/ψ$. No signal events are observed and the upper limit on the branching fraction is set to be $\mathcal{B}(J/ψ\to ϕe^+ e^-) < 1.2 \times 10^{-7}$ at the 90\% confidence level, which is still about one order of magnitude higher than the Standard Model prediction.

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arXiv2019

Measurement of $\mathcal{B}(J/ψ\to η' e^+ e^- $) and search for a dark photon

Using a data sample of $(1310.6\pm7.0)\times10^{6}$ $J/ψ$ decay events collected with the BESIII detector at BEPCII, we study the electromagnetic Dalitz decay $J/ψ\to η' e^+e^-$ with two dominant $η'$ decay modes, $η' \to γπ^+ π^-$ and $η' \to π^+π^-η$. The branching fraction is determined to be $\mathcal{B}(J/ψ\to η' e^+e^-) = (6.59\pm0.07\pm0.17) \times 10^{-5}$, which improves in precision by a factor of 2 over the previous BESIII measurement. A search for the dark photon ($γ'$) is performed via $J/ψ\toη' γ', γ' \to e^{+}e^{-}$. Excluding the $ω$ and $ϕ$ mass regions, no significant signal is observed in the mass range from 0.1 to 2.1 GeV/$c^{2}$. We set upper limits at the 90\% confidence level on $\mathcal{B}(J/ψ\to η' γ')\times\mathcal{B}(γ' \to e^+e^-)$, $\mathcal{B}(J/ψ\toη' γ'$) and the mixing strength as a function of dark photon mass. This is among the first searches for dark photons in charmonium decays.

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arXiv2019

Observation of $χ_{cJ}\to4K_{S}^{0}$

By analyzing $(448.1\pm2.9)\times10^6$ $ψ(3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decays of $χ_{cJ} \to 4K_S^0$ ($J=0,1,2$) are observed for the first time with statistical significances of 26.5$σ$, 5.9$σ$ and 11.4$σ$, respectively. The product branching fractions of $ψ(3686)\toγχ_{cJ}$, $χ_{cJ}\to4K_{S}^{0}$ are presented and the branching fractions of $χ_{cJ}\to4K_{S}^{0}$ decays are determined to be $\mathcal{B}_{χ_{c0}\to 4K_S^0}$=$(5.76\pm0.34\pm0.38)$$\times10^{-4}$, $\mathcal{B}_{χ_{c1}\to 4K_S^0}$=$(0.35\pm0.09\pm0.03)$$\times10^{-4}$ and $\mathcal{B}_{χ_{c2}\to 4K_S^0}$=$(1.14\pm0.15\pm0.08)$$\times10^{-4}$, where the first uncertainties are statistical and the second are systematic, respectively.

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arXiv2019

Amplitude analysis of $D^{+} \rightarrow K_{S}^{0} π^{+} π^{+} π^{-}$

The decay $D^{+} \rightarrow K_{S}^{0} π^{+} π^{+} π^{-}$ is studied with an amplitude analysis using a data set of 2.93${\mbox{\,fb}^{-1}}$ of $e^+e^+$ collisions at the $ψ(3770)$ peak accumulated by the BESIII detector. Intermediate states and non-resonant components, and their relative fractions and phases have been determined. The significant amplitudes, which contribute to the model that best fits the data, are composed of five quasi-two-body decays $ K_{S}^{0} a_{1}(1260)^{+}$, $ \bar{K}_{1}(1270)^{0} π^{+}$ $ \bar{K}_{1}(1400)^{0} π^{+}$, $ \bar{K}_{1}(1650)^{0} π^{+}$, and $ \bar{K}(1460)^{0} π^{+}$, a three-body decays $K_{S}^{0}π^{+}ρ^{0}$, as well as a non-resonant component $ K_{S}^{0}π^{+}π^{+}π^{-}$. The dominant amplitude is $ K_{S}^{0} a_{1}(1260)^{+}$, with a fit fraction of $(40.3\pm2.1\pm2.9)\%$, where the first and second uncertainties are statistical and systematic, respectively.

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arXiv2019

Observation of the decay $X(3872) \to π^0 χ_{c1}(1P)$

Using a total of $9.0~\mathrm{fb}^{-1}$ of $e^+e^-$ collision data with center-of-mass energies between 4.15 and 4.30 GeV collected by the BESIII detector, we search for the processes $e^+e^-\to γX(3872)$ with $X(3872)\toπ^0χ_{cJ}$ for $J=0,1,2$. We report the first observation of $X(3872)\toπ^{0}χ_{c1}$, a new decay mode of the $X(3872)$, with a statistical significance of more than 5$σ$. Normalizing to the previously established process $e^+e^-\to γX(3872)$ with $X(3872)\toπ^+π^-J/ψ$, we find ${\cal B}(X(3872) \to π^0 χ_{c1})/{\cal B}(X(3872) \to π^+π^- J/ψ) = 0.88^{+0.33}_{-0.27}\pm0.10$, where the first error is statistical and the second is systematic. We set 90% confidence level upper limits on the corresponding ratios for the decays to $π^0χ_{c0}$ and $π^0χ_{c2}$ of 19 and 1.1, respectively.

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arXiv2019

Observation of $D^+_s\rightarrow p\bar{n}$ and confirmation of its large branching fraction

The baryonic decay $D^+_s\rightarrow p\bar{n}$ is observed, and the corresponding branching fraction is measured to be $(1.21\pm0.10\pm0.05)\times10^{-3}$, where the first uncertainty is statistical and second systematic. The data sample used in this analysis was collected with the BESIII detector operating at the BEPCII $e^+e^-$ double-ring collider with a center-of-mass energy of 4.178~GeV and an integrated luminosity of 3.19~fb$^{-1}$. The result confirms the previous measurement by the CLEO Collaboration and is of greatly improved precision, which may deepen our understanding of the dynamical enhancement of the W-annihilation topology in the charmed meson decays.

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arXiv2019

Study of the $D^0\to K^-μ^+ν_μ$ dynamics and test of lepton flavor universality with $D^0\to K^-\ell^+ν_\ell$ decays

Using $e^+e^-$ annihilation data of $2.93~\mathrm{fb}^{-1}$ collected at center-of-mass energy $\sqrt{s}=3.773$ GeV with the BESIII detector, we measure the absolute branching fraction of $D^{0}\to K^{-}μ^{+}ν_μ$ with significantly improved precision: ${\mathcal B}_{D^{0}\to K^{-}μ^{+}ν_μ}=(3.413\pm0.019_{\rm stat.}\pm0.035_{\rm syst.})\%$. Combining with our previous measurement of ${\mathcal B}_{D^0\to K^-e^+ν_e}$, the ratio of the two branching fractions is determined to be ${\mathcal B}_{D^0\to K^-μ^+ν_μ}/{\mathcal B}_{D^0\to K^-e^+ν_e}=0.974\pm0.007_{\rm stat.}\pm0.012_{\rm syst.}$, which agrees with the theoretical expectation of lepton flavor universality within the uncertainty. A study of the ratio of the two branching fractions in different four-momentum transfer regions is also performed, and no evidence for lepton flavor universality violation is found with current statistics. Taking inputs from global fit in the standard model and lattice quantum chromodynamics separately, we determine $f_{+}^{K}(0)=0.7327\pm0.0039_{\rm stat.}\pm0.0030_{\rm syst.}$ and $|V_{cs}| = 0.955\pm0.005_{\rm stat.}\pm0.004_{\rm syst.}\pm0.024_{\rm LQCD}$.

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arXiv2018

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

By analyzing $2.93\ \rm fb^{-1}$ of data taken at a center-of-mass energy of 3.773~GeV with the BESIII detector, we measure the branching fractions of the Cabibbo-favored hadronic decays $D^0\to K^-π^+η^\prime$, $D^0\to K^0_Sπ^0η^\prime$ and $D^+\to K^0_Sπ^+η^\prime$, which are determined to be $(6.43 \pm 0.15_{\rm stat.} \pm 0.31_{\rm syst.})\times 10^{-3}$, $(2.52 \pm 0.22_{\rm stat.} \pm 0.15_{\rm syst.})\times 10^{-3}$ and $(1.90 \pm 0.17_{\rm stat.} \pm 0.13_{\rm syst.})\times 10^{-3}$, respectively. The precision of the branching fraction of $D^0\to K^-π^+η^\prime$ is significantly improved, and the processes $D^0\to K^0_Sπ^0η^\prime$ and $D^+\to K^0_Sπ^+η^\prime$ are observed for the first time.

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arXiv2018

Observation of $e^+e^- \rightarrow D_s^+ \overline{D}{}^{(*)0} K^-$ and study of the $P$-wave $D_s$ mesons

Studies of $e^+e^- \to D_s^+ \overline{D}{}^{(*)0}K^-$ and the $P$-wave charmed-strange mesons are performed based on an $e^+e^-$ collision data sample corresponding to an integrated luminosity of 567 pb$^{-1}$ collected with the BESIII detector at $\sqrt{s}= 4.600$ GeV. The processes of $e^+e^-\to D_s^+ \overline{D}{*}^{0} K^-$ and $D_s^+ \overline{D}{}^{0} K^-$ are observed for the first time and are found to be dominated by the modes $D_s^+ D_{s1}(2536)^-$ and $D_s^+ D^*_{s2}(2573)^-$, respectively. The Born cross sections are measured to be $σ^{B}(e^+e^-\to D_s^+ \overline{D}{*}^{0} K^-) = (10.1\pm2.3\pm0.8) pb$ and $σ^{B}(e^+e^-\to D_s^+ \overline{D}{}^{0} K^-) = (19.4\pm2.3\pm1.6) pb$, and the products of Born cross section and the decay branching fraction are measured to be $σ^{B}(e^+e^-\to D_s^+D_{s1}(2536)^- + c.c.)\cdot\mathcal{B}(D_{s1}(2536)^- \to \overline{D}{*}^{0} K^-) = (7.5 \pm 1.8 \pm 0.7) pb$ and $σ^{B}(e^+e^-\to D_s^+ D^*_{s2}(2573)^- + c.c.)\cdot\mathcal{B}(D^*_{s2}(2573)^- \to \overline{D}{}^{0} K^-) = (19.7 \pm 2.9 \pm 2.0) pb$. For the $D_{s1}(2536)^-$ and $D^*_{s2}(2573)^-$ mesons, the masses and widths are measured to be $M(D_{s1}(2536)^-) = (2537.7 \pm 0.5 \pm 3.1)~MeV/c^2,$ $ Γ(D_{s1}(2536)^-)) = (1.7\pm 1.2 \pm 0.6)~\rm MeV,$ and $M(D^*_{s2}(2573)^-) = (2570.7\pm 2.0 \pm 1.7)~MeV/c^2,$ $Γ(D^*_{s2}(2573)^-) = (17.2 \pm 3.6 \pm 1.1)~\rm MeV.$ The spin-parity of the $D^*_{s2}(2573)^-$ meson is determined to be $J^P=2^{+}$. In addition, the process $e^+e^-\to D_s^+ \overline{D}{}^{(*)0} K^-$ are searched for using the data samples taken at four (two) center-of-mass energies between 4.416 (4.527) and 4.575 GeV, and upper limits at the $90\%$ confidence level on the cross sections are determined.

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arXiv2018

Observation of $ψ(3686) \to p \bar{p} η^{\prime}$ and improved measurement of $J/ψ\to p \bar{p} η^{\prime}$

We observe the process $ψ(3686) \to p \bar{p} η^{\prime}$ for the first time, with a statistical significance higher than 10$σ$, and measure the branching fraction of $J/ψ\to p \bar{p} η^{\prime}$ with an improved accuracy compared to earlier studies. The measurements are based on $4.48 \times 10^8$ $ψ(3686)$ and $1.31 \times 10^{9}$ $J/ψ$ events collected by the BESIII detector operating at the BEPCII. The branching fractions are determined to be $B(ψ(3686) \to p \bar{p} η^{\prime}) = (1.10\pm0.10\pm0.08)\times10^{-5}$ and $B(J/ψ\to p \bar{p} η^{\prime})=(1.26\pm0.02\pm 0.07)\times10^{-4}$, where the first uncertainties are statistical and the second ones systematic. Additionally, the $η-η^{\prime}$ mixing angle is determined to be $-24^{\circ} \pm 11^{\circ}$ based on $ψ(3686) \to p \bar{p} η^{\prime}$, and $-24^{\circ} \pm 9^{\circ}$ based on $J/ψ\to p \bar{p} η^{\prime}$, respectively.

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arXiv2018

Measurement of $e^{+} e^{-} \rightarrow K^{+} K^{-}$ cross section at $\sqrt{s} = 2.00 - 3.08$ GeV

The cross section of the process $e^{+} e^{-} \rightarrow K^{+} K^{-}$ is measured at a number of center-of-mass energies $\sqrt{s}$ from 2.00 to 3.08 GeV with the BESIII detector at the Beijing Electron Positron Collider (BEPCII). The results provide the best precision achieved so far. A resonant structure around 2.2 GeV is observed in the cross section line shape. A Breit-Wigner fit yields a mass of $M=2239.2 \pm 7.1 \pm 11.3$~and a width of $Γ=139.8\pm12.3\pm20.6$ MeV, where the first uncertainties are statistical and the second ones are systematic. In addition, the time-like electromagnetic form factor of the kaon is determined at the individual center-of-mass energy points.

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arXiv2018

Dalitz Plot Analysis of the Decay $ω\rightarrow π^{+}π^{-}π^{0}$

Using a low-background sample of $2.6\times 10^5$ $J/ψ\rightarrowωη(ω\rightarrowπ^{+}π^{-}π^{0},η\rightarrowγγ)$ events, about 5 times larger statistics than previous experiments, we present a Dalitz plot analysis of the decay $ω\rightarrowπ^{+}π^{-}π^{0}$. It is found that the Dalitz plot distribution differs from the pure $P$-wave phase space with a statistical significance of $18.9σ$. The parameters from the fit to data are in reasonable agreement with those without the cross-channel effect within the dispersive framework, which indicates that the cross-channel effect in $ω\rightarrowπ^+π^-π^0$ is not significant.

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