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M. Ablikim

Publications and source records attributed to M. Ablikim.

897 records · Page 50Linked to original sources
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.

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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.

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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 $f_0(1710)$.

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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.

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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.

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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.

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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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arXiv2004

Observation of $\psp$ decays to $ρ(770)π$ and $ρ(2150)π$

\pspto ρπis observed for the fisrt time in a data sample of 14M \psp decays collected by the BESII detector at BEPC. The branching fraction is measured to be \BR(psptoρπ)=(5.1+-0.7+-0.8)10-5, where the first error is statistical and the second one is systematic. A high mass excited ρstate wirh mass around 2.15GeV/c2 is also observed wirh \BR(pspto ρ(2150)π) \ra pi+pi-pi0) =(19.4+-2.5+11.2-2.1)10-5. The branching fraction of \pspto pi+pi-pi0 is measued with improved precision, \BR(\pspto pi+pi-pi0)=(18.1+-1.8+-1.9)10-5. The results may shed light on the understanding of the longstanding "\rhopi puzzle" between \jpsi and \psp hadronic decays.

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arXiv2004

Search for K_S K_L in psi'' decays

K_S K_L from psi'' decays is searched for using the psi'' data collected by BESII at BEPC, the upper limit of the branching fraction is determined to be B(psi''--> K_S K_L) < 2.1\times 10^{-4} at 90% C. L. The measurement is compared with the prediction of the S- and D-wave mixing model of the charmonia, based on the measurements of the branching fractions of J/psi-->K_S K_L and psi'-->K_S K_L.

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arXiv2004

First Measurement of the Branching Ratio of $J/ψ\toγf_{2}(1270) f_{2}(1270)$

Using 58 million $J/ψ$ events taken with the BES II detector at the Beijing Electron Positron Collider, a new decay mode $J/ψ\toγf_{2}(1270) f_{2}(1270) \to γπ^+π^-π^+π^-$ is observed for the first time. The branching ratio is determined to be $Br(J/ψ\toγf_{2}(1270) f_{2}(1270))=(9.5\pm0.7\pm1.6)\times 10^{-4}$, where the quoted errors are statistical and systematic, respectively.

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arXiv2004

Observation of $K^*(892)^0\bar K^*(892)^0$ in $χ_{cJ}$ Decays

$K^*(892)^0\bar K^*(892)^0$ signals from $χ_{cJ} (J=0,1,2)$ decays are observed for the first time using a data sample of 14 million $ψ(2S)$ events accumulated at the BES II detector. The branching fractions ${\cal B}(χ_{cJ}\to K^*(892)^0\bar K^*(892)^0)$ $(J = 0,1,2)$ are determined to be $(1.55 \pm 0.35 \pm 0.30)\times 10^{-3}$, $(1.58 \pm 0.32 \pm 0.29)\times 10^{-3}$, and $(4.67 \pm 0.55 \pm 0.85)\times 10^{-3}$ for the $χ_{c0}$, $χ_{c1}$ and $χ_{c2}$ decays, respectively, where the first errors are statistical and the second are systematic. The significances of these signals are about 4.2$σ$, 4.3$σ$, and 7.5$σ$, respectively.

hep-ex↗
arXiv2004

Evidence for f0(980)f0(980) production in chi_c0 decays

Using a sample of 14 million $ψ(2S)$ events accumulated with the BES II detector, evidence for $f_0(980)f_0(980)$ production in $χ_{c0}$ decays is obtained for the first time; the branching ratio is determined to be ${\cal B}(χ_{c0}\to f_0(980)f_0(980)\toπ^+π^-π^+π^-) = (7.6 \pm 1.9 ({\rm stat}) \pm 1.6 ({\rm syst})) \times 10^{-4}$. The significance of the $f_0(980)$ signal is about 4.6$σ$.

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arXiv2004

Observation of a threshold enhancement in the p \bar{Lambda} invariant mass spectrum

An enhancement near the m_p + M_Λ mass threshold is observed in the combined p \barΛ and \bar{p}Λinvariant mass spectrum from J/ψ--> p K^- \bar{Lambda} + c.c. decays. It can be fit with an S-wave Breit-Wigner resonance with a mass m = 2075 +- 12 (stat) +- 5 (syst) MeV and a width of Γ= 90 +- 35 (stat) +- 9 (syst) MeV; it can also be fit with a P-wave Breit-Wigner resonance. Evidence for a similar enhancement is also observed in ψ' --> p K^- \barΛ + c.c. decays. The analysis is based on samples of 5.8 X 10^7 J/ψand 1.4 X 10^7 ψ' decays accumulated in the BES II detector at the Beijing Electron-Positron Collider.

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arXiv2004

Study of psi(2S) decays to X J/psi

Using J/psi -> mu^+ mu^- decays from a sample of approximately 4 million psi(2S) events collected with the BESI detector, the branching fractions of psi(2S) -> eta J/psi, pi^0 pi^0 J/psi, and anything J/psi normalized to that of psi(2S) -> pi^+ pi^- J/psi are measured. The results are B(psi(2S) -> eta J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 0.098 \pm 0.005 \pm 0.010, B(psi(2S) -> pi^0 pi^0 J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 0.570 \pm 0.009 \pm 0.026, and B(psi(2S) -> anything J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 1.867 \pm 0.026 \pm 0.055.

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