arXiv subjects

M. Ablikim

Publications and source records attributed to M. Ablikim.

At least 865 records · Page 48Linked to original sources

arXiv2006

Direct Measurements of the Branching Fractions for the Semileptonic Decays $D^0 \to K^-μ^+ν_μ$ and $D^0 \to π^-μ^+ν_μ$

Based on the data sample of 33 pb$^{-1}$ collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, the absolute branching fractions for the semileptonic decays $D^0\to K^-μ^+ν_μ$ and $D^0\toπ^-μ^+ν_μ$ have been measured. In the system recoiling against $7584\pm198\pm341$ singly tagged $\bar D^0$ mesons, $87.2\pm13.6$ events for $D^0\to K^-μ^+ν_μ$ and $9.3\pm7.4$ events for $D^0\toπ^-μ^+ν_μ$ are observed. These yield the absolute branching fractions to be $BF(D^0\to K^-μ^+ν_μ)= (3.55\pm0.56\pm0.59)%$ and $BF(D^0\toπ^-μ^+ν_μ)= (0.38\pm0.30\pm0.10)%$. The measured branching fraction for $D^0\to K^-μ^+ν_μ$ was previously used to determine the ratio $Γ(D^0\to K^-μ^+ν_μ)/ Γ(D^+\to \bar K^0μ^+ν_μ)$ combining the previously measured branching fraction for $D^+\to \bar K^0μ^+ν_μ$ by the BES Collaboration.

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arXiv2006

Measurements of branching fractions for inclusive K0~/K0 and K*(892)+- decays of neutral and charged D mesons

Using the data sample of about 33 pb-1 collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we have studied inclusive K0~/K0 and K*(892)+- decays of D0 and D+ mesons. The branching fractions for the inclusive K0~/K0 and K*(892)- decays are measured to be BF(D0 to K0~/K0 X)=(47.6+-4.8+-3.0)%, BF(D+ to K0~/K0 X)=(60.5+-5.5+-3.3)%, BF(D0 to K*- X)=(15.3+- 8.3+- 1.9)% and BF(D+ to K*- X)=(5.7+- 5.2+- 0.7)%. The upper limits of the branching fractions for the inclusive K*(892)+ decays are set to be BF(D0 to K*+ X)<3.6% and BF(D+ to K*+ X) <20.3% at 90% confidence level.

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arXiv2006

Production of $σ$ in $ψ(2S)\to π^{+}π^{-}J/ψ$

Using 14M $ψ(2S)$ events accumulated by BESII at the BEPC, a Covariant Helicity Amplitude Analysis is performed for $ψ(2S)\toπ^+π^-J/ψ, J/ψ\to μ^+μ^-$. The $π^+π^-$ mass spectrum, distinctly different from phase space, suggests $σ$ production in this process. Two different theoretical schemes are used in the global fit to the data. The results are consistent with the existence of the $σ$. The $σ$ pole position is determined to be $(552^{+84}_{-106})-i(232^{+81}_{-72})$ MeV/$c^2$.

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arXiv2006

Direct measurement of the absolute branching fraction for $D^+ \to {\bar K}^0μ^+ν_μ$ and determination of $ Γ(D^0 \to K^-μ^+ν_μ)/Γ(D^+ \to {\bar K}^0μ^+ν_μ)$

The absolute branching fraction for the decay $D^+ \to {\bar K}^0μ^+ν_μ$ is determined using $5321 \pm 149 \pm160$ singly tagged $D^-$ sample from the data collected around 3.773 GeV with the BESII detector at the BEPC collider. In the system recoiling against the singly tagged $D^-$ mesons, $28.7 \pm 6.4$ events for $D^+ \to {\bar K}^0μ^+ν_μ$ are observed. These yield the absolute branching fraction to be $BF(D^+ \to {\bar K}^0μ^+ν_μ) = (10.3\pm2.3\pm0.8)%$. The ratio of the two partial widths for the decays $D^0 \to K^-μ^+ν_μ$ and $D^+ \to {\bar K}^0μ^+ν_μ$ is determined to be $Γ(D^0 \to K^-μ^+ν_μ)/Γ(D^+ \to {\bar K}^0μ^+ν_μ) = 0.87 \pm 0.24 \pm 0.15$.

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arXiv2006

Partial wave analyses of J/psi to gamma pi^+ pi^- and gamma pi^0 pi^0

Results are presented on J/psi radiative decays to pi^+pi^- and pi^0pi^0 based on a sample of 58M J/psi events taken with the BESII detector. Partial wave analyses are carried out using the relativistic covariant tensor amplitude method in the 1.0 to 2.3 GeV/c^2 pipi mass range. There are conspicuous peaks due to the f_2(1270) and two 0^++ states in the 1.45 and 1.75 GeV/c^2 mass regions. The first 0^++ state has a mass of 1466\pm 6\pm 20 MeV/c^2, a width of 108^{+14}_{-11}\pm 25 MeV/c^2, and a branching fraction B(J/psi \to γf_0(1500) \toγπ^+π^-) = (0.67\pm0.02\pm0.30) \times 10^{-4}. Spin 0 is strongly preferred over spin 2. The second 0^++ state peaks at 1765^{+4}_{-3}\pm 13 MeV/c^2 with a width of 145\pm8\pm69 MeV/c^2. If this 0^++ is interpreted as coming from f_0(1710), the ratio of its branching fractions to pipi and K\bar K is 0.41^{+0.11}_{-0.17}.

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arXiv2006

First observation of $ψ(2S) \to p \bar{n} π^- +c.c.$

Using 14 million $ψ(2S)$ events collected with the Beijing Spectrometer (BESII) at the Beijing Electron-Positron Collider, the branching fractions of $ψ(2S)$ decays to $p \bar{n} π^-$ and $\bar{p} n π^+$ and the branching fractions of the main background channels $ψ(2S) \to p \bar{n} π^-π^0$, $ψ(2S) \to γχ_{c0} \to γp \bar{n} π^-$, $ψ(2S) \to γχ_{c2} \to γp \bar{n} π^-$, and $ψ(2S) \to γχ_{cJ} \to γp \bar{n} π^- π^0$ are determined. The contributions of the $N^{\ast}$ resonances in $ψ(2S) \to p \bar{n} π^- +c.c.$ are also discussed.

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arXiv2006

Measurements of $\psip$ decays into $γK\bar{K}π$ and $γη\pipi$

Radiative decays of the $\psip$ into $γK\bar{K}π$ and $γη\pipi$ final states are studied using 14 million $\psip$ events collected with the BESII detector. Branching fractions or upper limits on the branching fractions of $\psip$ and $\xcj$ decays are reported. No significant signal for $\etafl/\etafh$ is observed in the $K\bar{K}π$ or $η\pipi$ mass spectra, and upper limits on the branching fractions of $\psip\rarγ\etaf$, $\etaf\rar K\bar{K}π$ and $η\pipi$ are determined.

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arXiv2006

Observation of a broad 1^-- resonant structure around 1.5 GeV/$c^2$ in the K^+K^- mass spectrum in J/psi --> K^+K^-pi^0

A broad peak is observed at low K^+K^- invariant mass in J/psi --> K^+K^-pi^0 decays found in a sample of 5.8\times 10^7 J/psi events collected with the BESII detector. A partial wave analysis shows that the J^PC of this structure is 1^--. Its pole position is determined to be (1576^{+49}_{-55}(stat)^{+98}_{-91}(syst)) MeV/c^2 - i(409^{+11}_{-12}$(stat)^{+32}_{-67}(syst)) MeV/c^2. These parameters are not compatible with any known meson resonances.

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arXiv2006

Measurements of the absolute branching fractions for D->Kbar pi e+ nu_e, D-> Kbar e+nu_e and determination of Gamma(D+ -> K0bar e+ nu_e)/Gamma(D+ -> K0bar e+nu_e)

Using the data of about 33 pb$^{-1}$ collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we have studied the exclusive semileptonic decays $D^+ \to K^-π^+ e^+ν_e$, $D^0 \to \bar K^0π^-e^+ν_e$, $D^+ \to \bar K^{*0}e^+ν_e$ and $D^0 \to K^{*-}e^+ν_e$. The absolute branching fractions for the decays are measured to be ${BF}(D^+ \to K^-π^+e^+ν_e)=(3.50\pm0.75\pm0.27)%$, ${BF}(D^0 \to \bar K^0π^-e^+ν_e)=(2.61\pm1.04\pm0.28)%$, ${BF}(D^+ \to \bar K^{*0}e^+ν_e)=(5.06\pm1.21\pm0.40)%$ and ${BF}(D^0 \to K^{*-}e^+ν_e)=(2.87\pm 1.48\pm 0.39)%$. The ratio of the vector to pseudoscalar semileptonic decay rates $Γ(D^+\to\bar K^{*0}e^+ν_e)/Γ(D^+\to\bar K^0e^+ν_e)$ is determined to be $0.57\pm0.17\pm0.02$.

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arXiv2006

Search for D to phi l nu and measurement of the branching fraction for D to phi pi

Using a data sample of integrated luminosity of about 33 pb$^{-1}$ collected around 3.773 GeV with the BESII detector at the BEPC collider, the semileptonic decays $D^+ \to ϕe ^+ν_e$, $D^+ \to ϕμ^+ν_μ$ and the hadronic decay $D^+ \to ϕπ^+$ are studied. The upper limits of the branching fractions are set to be $BF(D^+ \to ϕe ^+ν_e) <$ 2.01% and $BF(D^+ \to ϕμ^+ ν_μ) <$ 2.04% at the 90% confidence level. The ratio of the branching fractions for $D^+ \to ϕπ^+$ relative to $D^+ \to K^-π^+π^+$ is measured to be $0.057 \pm 0.011 \pm 0.003$. In addition, the branching fraction for $D^+ \to ϕπ^+$ is obtained to be $(5.2 \pm 1.0 \pm 0.4) \times 10^{-3}$.

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arXiv2006

Measurements of $Jψ$ decays into $ωπ^0$, $ωη$, and $ωη'$

Based on $5.8 \times 10^7 Jψ$ events collected with BESII at the Beijing Electron-Positron Collider (BEPC), the decay branching fractions of $Jψ\toωπ^0$, $ωη$, and $ωη'$ are measured using different $η$ and $η'$ decay modes. The results are higher than previous measurements. The $ωπ^0$ electromagnetic form factor is also obtained.

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arXiv2006

Experimental study of $ψ(2S)$ decays to $\K^+ K^- π^+ π^- π^0$ final states

$K^+K^-π^+π^-π^0$ final states are studied using a sample of $14\times10^6$ $ψ(2S)$ decays collected with the Beijing Spectrometer (BESII) at the Beijing Electron-Position Collider. The branching fractions of $ψ(2S)$ decays to $ K^+K^-π^+π^-π^0$, $ωK^+ K^-$, $ωf_0(1710)$, $ K^{\ast}(892)^0 K^- π^+π^0+c.c.$, $K^{\ast}(892)^{+} K^- π^+π^- +c.c.$, $K^{\ast}(892)^{+} K^- ρ^0+c.c.$ and $K^{\ast}(892)^0 K^-ρ^+ + c.c.$ are determined. The first two agree with previous measurements, and the last five are first measurements.

hep-ex↗

arXiv2006

Measurement of chi_cJ Decays to 2(pi^+pi^-)ppbar Final States

Using chi_cJ -> 2(π^+π^-) ppbar decays from 14 \times 10^6 psi(2S) events accumulated by the BESII detector at the BEPC, the intermediate states Xi^+Xi^-, Lambda Lambdabar pi^+ pi^-, and K_SK_S p pbar are studied, and their branching ratios or upper limits are measured.

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arXiv2006

Evidence for kappa Meson Production in J/psi -> bar{K}^*(892)^0K^+pi^- Process

Based on 58 million BESII J/psi events, the bar{K}^*(892)^0K^+pi^- channel in K^+K^-pi^+pi^- is studied. A clear low mass enhancement in the invariant mass spectrum of K^+pi^- is observed. The low mass enhancement does not come from background of other J/psi decay channels, nor from phase space. Two independent partial wave analyses have been performed. Both analyses favor that the low mass enhancement is the kappa, an isospinor scalar resonant state. The average mass and width of the kappa in the two analyses are 878 +- 23^{+64}_{-55} MeV/c^2 and 499 +- 52^{+55}_{-87} MeV/c^2, respectively, corresponding to a pole at (841 +- 30^{+81}_{-73}) - i(309 +- 45^{+48}_{-72}) MeV/c^2.

hep-ex↗

arXiv2005

Search for psi(3770)\raρπat the BESII detector at the Beijing Electron-Positron Collider

Non-$D\bar{D}$ decay $\psppto \rhopi$ is searched for using a data sample of $(17.3\pm 0.5) pb^{-1}$ taken at the center-of-mass energy of 3.773 GeV by the BESII detector at the BEPC. No $\rhopi$ signal is observed, and the upper limit of the cross section is measured to be $σ(\EETO \rhopi)<6.0 pb$ at 90% C. L. Considering the interference between the continuum amplitude and the $\pspp$ resonance amplitude, the branching fraction of $\pspp$ decays to $ρπ$ is determined to be $\BR(\pspp\raρπ)\in(6.0\times10^{-6}, 2.4\times10^{-3})$ at 90% C. L. This is in agreement with the prediction of the $S$- and $D$-wave mixing scheme of the charmonium states for solving the ``$\rhopi$ puzzle'' between $\jpsi$ and $\psp$ decays.

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arXiv2005

Measurement of branching fractions for the inclusive Cabibbo-favored ~K0(892) and Cabibbo-suppressed K0(892) decays of neutral and charged D mesons

The branching fractions for the inclusive Cabibbo-favored ~K*0 and Cabibbo-suppressed K*0 decays of D mesons are measured based on a data sample of 33 pb-1 collected at and around the center-of-mass energy of 3.773 GeV with the BES-II detector at the BEPC collider. The branching fractions for the decays D+(0) -> ~K*0(892)X and D0 -> K*0(892)X are determined to be BF(D0 -> K*0X) = (8.7 +/- 4.0 +/- 1.2)%, BF(D+ -> ~K*0X) = (23.2 +/- 4.5 +/- 3.0)% and BF(D0 -> K*0X) = (2.8 +/- 1.2 +/- 0.4)%. An upper limit on the branching fraction at 90% C.L. for the decay D+ -> K*0(892)X is set to be BF(D+ -> K*0X) < 6.6%.

hep-ex↗

arXiv2005

Search for eta_c decays into pi pi and K Bar K

Using 58 million $J/ψ$ events taken with the BESII detector, a search for $eta_{c}$ CP violating decays into $ππ$ and $\bar{K}K$ has been performed. No clear $eta_{c}$ is observed, and upper limits for $B(eta_{c}->ππ)$and $B(eta_{c}->\bar{K} K)$ are given at the 90% confidence level, $B(J/ψ->γη_{c})\times B(eta_{c}->π^{+}π^{-})<1.1\times 10^{-5}$ , $B(J/ψ->γη_{c})\times B(eta_{c}->π^{0}π^{0})<0.71\times 10^{-5}$, $B(J/ψ->γη_{c})\times B(eta_{c}->K^{+}K^{-})<0.96\times 10^{-5}$ and $B(J/ψ->γη_{c})\times B(eta_{c}->{K_{s}}^{0}{K_{s}}^{0})<0.53\times 10^{-5}$.

hep-ex↗

arXiv2005

Measurement of the branching fractions for $J/ψ\toγπ^0$, $γη$ and $γη^{\prime}$

The decay modes $\jpsi\arγπ^0, γη$ and $γ\etap$ are analyzed using a data sample of 58 million $\jpsi$ decays collected with the BESII detector at BEPC. The branching fractions are determined to be: $Br(\jpsi\arγπ^0)=(3.13^{+0.65}_{-0.44})\times10^{-5}$, $Br(\jpsi\arγη)=(11.23\pm0.89)\times10^{-4}$, and $Br(\jpsi\arγ\etap)=(5.55\pm0.44)\times10^{-3}$, where the errors are combined statistical and systematic errors. The ratio of partial widths $Γ(\jpsi\arγ\etap)/Γ(\jpsi\arγη)$ is measured to be $4.94\pm0.40$, and the singlet-octet pseudoscalar mixing angle of $η-\etap$ system is determined to be $θ_{P}=(-22.08\pm0.81)^{\circ}$.

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