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M. Ablikim

Publications and source records attributed to M. Ablikim.

At least 883 records · Page 49Linked to original sources
arXiv2005

Partial Wave Analysis of $χ_{c0}\toπ^+π^-K^+K^-$

A partial wave analysis of $χ_{c0}\toπ^+π^-K^+K^-$ in $ψ(2S)\toγχ_{c0}$ decay is presented using a sample of 14 million $ψ(2S)$ events accumulated by the BES II detector. The data are fitted to the sum of relativistic covariant tensor amplitudes for intermediate resonant decay modes. From the fit, significant contributions to $χ_{c0}$ decays from the channels $f_0(980)f_0(980)$, $f_0(980)f_0(2200)$, $f_0(1370)f_0(1710)$, $K^*(892)^0\bar K^*(892)^0$, $K^*_0(1430)\bar K^*_0(1430)$, $K^*_0(1430)\bar K^*_2(1430) + c.c.$, and $K_1(1270)K$ are found. Flavor-SU(3)-violating $K_1(1270)-K_1(1400)$ asymmetry is observed. Values obtained for the masses and widths of the resonances $f_0(1710)$, $f_0(2200)$, $f_0(1370)$, and $K^*_0(1430)$ are presented.

hep-ex↗
arXiv2005

First observations of $ψ(2S)$ and $χ_{cJ}(1P)$ decays to four-body final states $h^+h^- K^0_S K^0_S$

$χ_{c0}$, $χ_{c1}$, and $χ_{c2}$ decays to $π^+π^-K^0_SK^0_S$ and $K^+K^-K^0_SK^0_S$, as well as $ψ(2S)$ decay to $π^+π^-K^0_SK^0_S$ are presented. The branching fractions of these decay channels are determined using $14\times 10^6$ $ψ(2S)$ events collected at BESII/BEPC. The branching fractions of $χ_{c0},χ_{c2}\to K^0_SK^0_S$ are measured with improved statistical precision.

hep-ex↗
arXiv2005

Observation of a resonance X(1835) in J/ψ--> γπ^+ π^- η^{\prime}

The decay channel J/ψ--> γπ^+ π^- η^{\prime} is analyzed using a sample of 5.8\times 10^7 Jψevents collected with the BESII detector. A resonance, the X(1835), is observed in the π^+ π^- η^{\prime} invariant mass spectrum with a statistical significance of 7.7 σ. A fit with a Breit-Wigner function yields a mass M = 1833.7 \pm 6.1(stat) \pm 2.7(syst) MeV/c^2, a width Γ= 67.7 \pm 20.3(stat) \pm 7.7(syst) MeV/c^2 and a product branching fraction B(J/ψ--> γX) B(X --> π^+ π^- η^{\prime}) = (2.2 \pm 0.4(stat) \pm 0.4(syst)) \times 10^{-4}. The mass and width of the X(1835) are not compatible with any known meson resonance. Its properties are consistent with expectations for the state that produces the strong p\bar{p} mass threshold enhancement observed in the Jψ-->γp \bar{p} process at BESII.

hep-ex↗
arXiv2005

Experimental study of \etac decays into vector-vector final states

Using 58 million J/ψevents accumulated with the BES II detector, branching fractions for the η_{c} ->VV decays, η_{c} -> ρρ, η_{c} -> K^{*}{\bar K}^{*}, η_{c} -> ωω, and η_{c} -> ϕϕ, are measured. The branching fractions are Br(η_{c} -> ρρ) = (1.25 \pm 0.37 \pm 0.51) \times 10^{-2}, Br(η_{c} -> \K^{*}{\bar K}^{*}) = (10.4 \pm 2.6\pm 4.3) \times 10^{-3}, Br(η_{c} -> ωω) < 6.3 \times 10^{-3} (90 % CL), and Br(η_{c} -> ϕϕ) = (2.5 \pm 0.5 \pm 0.9) \times 10^{-3}. The process η_{c} -> ωϕis also searched for, and the 90% CL upper limit Br(eta_{c} -> ωϕ) < 1.3 \times 10^{-3} is obtained for this process.

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arXiv2005

Obervation of χ_{cJ}--> omega omega decays

Decays of $χ_{c0,2}\ar\ww$ are observed for the first time using a sample of $14.0\times 10^6$ $ψ(2S)$ events collected with the BESII detector. The branching ratios are determined to be ${\cal B}(χ_{c0}\ar \ww)=(2.29\pm 0.58\pm 0.41)\times 10^{-3}$ and ${\cal B}(χ_{c2}\ar\ww)=(1.77\pm 0.47\pm 0.36)\times 10^{-3}$, where the first errors are statistical and the second systematic. The significances of the two signals are $4.4σ$ and $4.7σ$, respectively.

hep-ex↗
arXiv2005

First Measurements of eta_c Decaying into K^+K^-2(pi^+pi^-) and 3(pi^+pi^-)

The decays of eta_c to K^+K^-2(pi^+pi^-) and 3(pi^+pi^-) are observed for the first time using a sample of 5.8X10^7 J/ψevents collected by the BESII detector. The product branching fractions are determined to be B(J/ψ-->gamma eta_c)*B(eta_c-->K^+K^-pi^+pi^-pi^+pi^-)=(1.21+-0.32+- 0.23)X10^{-4}$,B(J/ψ-->gamma eta_c)*B(eta_c-->K^{*0}\bar{K}^{*0}pi^+pi^-)= (1.29+-0.43+-0.32)X10^{-4}$, and (J/ψ-->gamma eta_c)* B(eta_c-->pi^+pi^-pi^+pi^-pi^+pi^-)= (2.59+-0.32+-0.48)X10^{-4}. The upper limit for eta_c-->phi pi^+pi^-pi^+pi^- is also obtained as B(J/ψ-->gamma eta_c)*B(eta_c--> phi pi^+pi^-pi^+pi^-)< 6.03 X10^{-5} at the 90% confidence level.

hep-ex↗
arXiv2005

Observation of the decay $\psip\rar\kstark$

Using 14 million $ψ(2S)$ events collected with the BESII detector, branching fractions of $\psip\rar\kstarkpm$ and $\kstarknn$ are determined to be: $\calB(\psip\rar\kstarkpm)=(2.9^{+1.3}_{-1.7}\pm0.4)\times 10^{-5}$ and $\calB(\psip\rar\kstarknn)=(13.3^{+2.4}_{-2.7}\pm1.9)\times 10^{-5}$. The results confirm the violation of the "12%" rule for these two decay channels with higher precision. A large isospin violation between the charged and neutral modes is observed.

hep-ex↗
arXiv2005

Precise measurement of spin-averaged chi_{cJ}(1P) mass using photon conversions in psi(2S) -> gamma chi_{cJ}

Using photon conversions to e^+e^- pairs, the energy spectrum of inclusive photons from psi(2S) radiative decays is measured by BESII at the Beijing Electron-Positron Collider. The chi_{cJ}(1P) states (J=0,1,2) are clearly observed with energy resolution between 2.3 to 3.8 MeV, and their masses and the spin-averaged chi_{cJ} mass are determined to be M_{chi_{c0}}=3414.21\pm 0.39 \pm 0.27, M_{chi_{c1}}=3510.30\pm 0.14\pm 0.16, M_{chi_{c2}}=3555.70\pm 0.59 \pm 0.39 and M(^3P_{cog})=3524.85\pm 0.32 \pm 0.30 MeV/c^2.

hep-ex↗
arXiv2005

Measurement of the branching fractions of psi(2S) -> 3(pi+pi-) and J/psi -> 2(pi+pi-)

Using data samples collected at sqrt(s) = 3.686GeV and 3.650GeV by the BESII detector at the BEPC, the branching fraction of psi(2S) -> 3(pi+pi-) is measured to be [4.83 +- 0.38(stat) +- 0.69(syst)] x 10^-4, and the relative branching fraction of J/psi -> 2(pi+pi-) to that of J/psi -> mu+mu- is measured to be [5.86 +- 0.19(stat) +- 0.39(syst)]% via psi(2S) -> (pi+pi-)J/psi, J/psi -> 2(pi+pi-). The electromagnetic form factor of 3(pi+pi-) is determined to be 0.21 +- 0.02 and 0.20 +- 0.01 at sqrt(s) = 3.686GeV and 3.650GeV, respectively.

hep-ex↗
arXiv2005

Observation of p pbar pi^0 and p pbar eta in psi' decays

The processes psi'-->p pbar pi^0 and psi'-->p pbar eta are studied using a sample of 14 million psi' decays collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider. The branching fraction of psi'-->p pbar pi^0 is measured with improved precision as (13.2\pm 1.0\pm 1.5)\times 10^{-5}, and psi'-->p pbar eta is observed for the first time with a branching fraction of (5.8\pm 1.1\pm 0.7)\times 10^{-5}, where the first errors are statistical and the second ones are systematic.

hep-ex↗
arXiv2004

Measurements of J/psi Decays into 2(pi+pi-)eta and 3(pi+pi-)eta

Based on a sample of 5.8X 10^7 J/psi events taken with the BESII detector, the branching fractions of J/psi--> 2(pi+pi-)eta and J/psi-->3(pi+pi-)eta are measured for the first time to be (2.26+-0.08+-0.27)X10^{-3} and (7.24+-0.96+-1.11)X10^{-4}, respectively.

hep-ex↗
arXiv2004

Resonances in $J/ψ\to ϕπ^+π^-$ and $ϕK^+K^-$

A partial wave analysis is presented of $J/ψ\to ϕπ^+π^-$ and $ϕK^+K^-$ from a sample of 58M $J/ψ$ events in the BES II detector. The $f_0(980)$ is observed clearly in both sets of data, and parameters of the Flatt\' e formula are determined accurately: $M = 965 \pm 8$ (stat) $\pm 6$ (syst) MeV/c$^2$, $g_1 = 165 \pm 10 \pm 15 $ MeV/c$^2$, $g_2/g_1 = 4.21 \pm 0.25 \pm 0.21$. The $ϕππ$ data also exhibit a strong $ππ$ peak centred at $M = 1335$ MeV/c$^2$. It may be fitted with $f_2(1270)$ and a dominant $0^+$ signal made from $f_0(1370)$ interfering with a smaller $f_0(1500)$ component. There is evidence that the $f_0(1370)$ signal is resonant, from interference with $f_2(1270)$. There is also a state in $ππ$ with $M = 1790 ^{+40}_{-30}$ MeV/c$^2$ and $Γ= 270 ^{+60}_{-30}$ MeV/c$^2$; spin 0 is preferred over spin 2. This state, $f_0(1790)$, is distinct from $f_0(1710)$. The $ϕK\bar K$ data contain a strong peak due to $f_2'(1525)$. A shoulder on its upper side may be fitted by interference between $f_0(1500)$ and $f_0(1710)$.

hep-ex↗
arXiv2004

Measurements of J/psi decays into phi pi^0, phi eta, and phi eta^prime

Based on 5.8x10^7 J/psi events detected in BESII, the branching fractions of J/psi--> phi eta and phi eta^prime are measured for different eta and eta^prime decay modes. The results are significantly higher than previous measurements. An upper limit on B(J/psi--> phi pi^0) is also obtained.

hep-ex↗
arXiv2004

Measurement of the final states $ωπ^0$, $ρη$, and $ρη^{'}$ from $\psip$ electromagnetic decays and $\ee$ annihilations

Cross sections and form factors for $\ee \to \wpi$, $ρη$, and $ρ\etap$ at center of mass energies of 3.650, 3.686, and 3.773 GeV are measured using data samples collected with the BESII detector at the BEPC. Also, the branching fractions of $ψ(2S) \rar \wpi$, $ρη$, and $ρ\etap$ are determined to be $(1.87^{+0.68}_{-0.62}\pm0.28)\times 10^{-5}$, $(1.78^{+0.67}_{-0.62}\pm0.17)\times 10^{-5}$, and $(1.87^{+1.64}_{-1.11}\pm0.33)\times10^{-5}$, respectively.

hep-ex↗
arXiv2004

Measurement of the chi_{c2} Polarization in psi(2S) to gamma chi_{c2}

The polarization of the chi_{c2} produced in psi(2S) decays into gamma chi_{c2} is measured using a sample of 14*10^6 psi(2S) events collected by BESII at the BEPC. A fit to the chi_{c2} production and decay angular distributions in psi(2S) to gamma chi_{c2}, chi_{c2} to pi pi and KK yields values x=A_1/A_0=2.08+/-0.44 and y=A_2/A_0=3.03 +/-0.66, with a correlation rho=0.92 between them, where A_{0,1,2} are the chi_{c2} helicity amplitudes. The measurement agrees with a pure E1 transition, and M2 and E3 contributions do not differ significantly from zero.

hep-ex↗
arXiv2004

Study of $J/ψ\to ωK^+K^-$

New data are presented on $J/ψ\to ωK^+K^-$ from a sample of 58M $J/ψ$ events in the upgraded BES II detector at the BEPC. There is a conspicuous signal for $f_0(1710) \to K^+K^-$ and a peak at higher mass which may be fitted with $f_2(2150) \to K\bar K$. From a combined analysis with $ωπ^+ π^-$ data, the branching ratio $BR(f_0(1710)\toππ)/BR(f_0(1710) \to K\bar K)$ is $< 0.11$ at the 95% confidence level.

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