arXiv subjects

M. Ablikim

Publications and source records attributed to M. Ablikim.

At least 847 records · Page 47Linked to original sources

arXiv2012

Two-photon widths of the $χ_{c0, 2}$ states and helicity analysis for $χ_{c2}\arγγ$}

Based on a data sample of 106 M $ψ^{\prime}$ events collected with the BESIII detector, the decays $ψ^{\prime}\arγχ_{c0, 2}$,$χ_{c0, 2}\arγγ$ are studied to determine the two-photon widths of the $χ_{c0, 2}$ states. The two-photon decay branching fractions are determined to be ${\cal B}(χ_{c0}\arγγ) = (2.24\pm 0.19\pm 0.12\pm 0.08)\times 10^{-4}$ and ${\cal B}(χ_{c2}\arγγ) = (3.21\pm 0.18\pm 0.17\pm 0.13)\times 10^{-4}$. From these, the two-photon widths are determined to be $Γ_{γγ}(χ_{c0}) = (2.33\pm0.20\pm0.13\pm0.17)$ keV, $Γ_{γγ}(χ_{c2}) = (0.63\pm0.04\pm0.04\pm0.04)$ keV, and $\cal R$ $=Γ_{γγ}(χ_{c2})/Γ_{γγ}(χ_{c0})=0.271\pm 0.029\pm 0.013\pm 0.027$, where the uncertainties are statistical, systematic, and those from the PDG ${\cal B}(ψ^{\prime}\arγχ_{c0,2})$ and $Γ(χ_{c0,2})$ errors, respectively. The ratio of the two-photon widths for helicity $λ=0$ and helicity $λ=2$ components in the decay $χ_{c2}\arγγ$ is measured for the first time to be $f_{0/2} =Γ^{λ=0}_{γγ}(χ_{c2})/Γ^{λ=2}_{γγ}(χ_{c2}) = 0.00\pm0.02\pm0.02$.

hep-ex↗

arXiv2012

First observation of $η(1405)$ decays into $f_{0}(980)π^0$

The decays $J/ψ\rightarrow γπ^+π^-π^0$ and $J/ψ\rightarrow γπ^0π^0π^0$ are analyzed using a sample of 225 million $\jpsi$ events collected with the BESIII detector. The decay of $η(1405)\ar f_{0}(980)π^0$ with a large isospin violation is observed for the first time. The width of the $f_{0}(980)$ observed in the dipion mass spectra is anomalously narrower than the world average. Decay rates for three-pion decays of the $η'$ are also measured precisely.

hep-ex↗

arXiv2012

Precision measurement of the branching fractions of J/psi -> pi+pi-pi0 and psi' -> pi+pi-pi0

We study the decays of the J/psi and psi' mesons to pi+pi-pi0 using data samples at both resonances collected with the BES III detector in 2009. We measure the corresponding branching fractions with unprecedented precision and provide mass spectra and Dalitz plots. The branching fraction for J/psi -> pi+pi-pi0 is determined to be (2.137 +- 0.004 (stat.) +0.058-0.056 (syst.) +0.027-0.026 (norm.))*10-2, and the branching fraction for psi' -> pi+pi-pi0 is measured as (2.14 +- 0.03 (stat.) +0.08-0.07 (syst.) +0.09-0.08 (norm.))*10-4. The J/psi decay is found to be dominated by an intermediate rho(770) state, whereas the psi' decay is dominated by di-pion masses around 2.2 GeV/c2, leading to strikingly different Dalitz distributions.

hep-ex↗

arXiv2011

Search for CP and $P$ violating pseudoscalar decays into $ππ$

Using a sample of $(225.2\pm 2.8)\times 10^6$ $J/ψ$ events collected with the Beijing Spectrometer (BESIII) at the Beijing Electron-Positron Collider, CP and $P$ violating decays of $η$, $η'$ and $\etac$ into $π^+π^-$ and $π^0 π^0$ are searched for in $\jpsi$ radiative decays. No significant $η$, $η'$ or $\etac$ signal is observed, and 90% confidence level upper limits of $\BR(η\to π^+π^-)<3.9\times 10^{-4}$, $\BR(η' \to π^+π^-)<5.5\times 10^{-5}$, $\BR(\etac \to π^+π^-)<1.3\times 10^{-4}$, $\BR(η\to π^0 π^0)<6.9\times 10^{-4}$, $\BR(η' \to π^0 π^0)<4.5\times 10^{-4}$ and $\BR(\etac \to π^0 π^0)<4.2\times 10^{-5}$ are obtained.

hep-ex↗

arXiv2011

Observation of charged kappa in J/psi -> K(892)-+Kspi+-, K(892)-+ -> Kspi-+ at BESII

Using 58 million J/psi decays obtained by BESII, a charged kappa particle is observed in the analysis of the Kspi+- system recoiling against K*(892)-+ selected in J/psi -> KsKspi+pi-. The mass and width values of the charged kappa are obtained to be (826+-49_{-34}^{+49}) MeV/c^2 and (449+-156_{-81}^{+144}) MeV/c^2 for the Breit-Wigner parameters, and the pole position is determined to be (764+-63_{-54}^{+71})-i(306+-149_{-85}^{+143}) MeV/c^2. They are in good agreement with those of the neutral kappa observed by the BES collaboration.

hep-ex↗

arXiv2010

A study of charged kappa in $J/ψ\to K^{\pm} K_s π^{\mp} π^0$

Based on $58 \times 10^6 $ $J/ψ$ events collected by BESII, the decay $J/ψ\to K^{\pm} K_s π^{\mp} π^0$ is studied. In the invariant mass spectrum recoiling against the charged $K^*(892)^{\pm}$, the charged $κ$ particle is found as a low mass enhancement. If a Breit-Wigner function of constant width is used to parameterize the kappa, its pole locates at $(849 \pm 77 ^{+18}_{-14}) -i (256 \pm 40 ^{+46}_{-22})$ MeV/$c^2$. Also in this channel, the decay $J/ψ\to K^*(892)^+ K^*(892)^-$ is observed for the first time. Its branching ratio is $(1.00 \pm 0.19 ^{+0.11}_{-0.32}) \times 10^{-3}$.

hep-ex↗

arXiv2009

Study of J/Psi decays into eta Kstar Kstar-bar

We report the first observation of $\mPJpsi \to \mPeta\mPKst\mAPKst$ decay in a $\mPJpsi$ sample of 58 million events collected with the BESII detector. The branching fraction is determined to be $(1.15 \pm 0.13 \pm 0.22)\times 10^{-3}$. The selected signal event sample is further used to search for the $\mPY$ resonance through $\mPJpsi \to \mPeta \mPY, \mPY\to\mPKst\mAPKst$. No evidence of a signal is seen. An upper limit of \mathrm{Br}(\mPJpsi \to \mPeta \mPY)\cdot\mathrm{Br}(\mPY\to\mPKst\mAPKst) < 2.52\times 10^{-4} is set at the 90% confidence level.

hep-ex↗

arXiv2009

$R$ value measurements for $e^+e^-$ annihilation at 2.60, 3.07 and 3.65 GeV

Using a data sample with a total integrated luminosity of 10.0 pb$^{-1}$ collected at center-of-mass energies of 2.6, 3.07 and 3.65 GeV with BESII, cross sections for $e^+e^-$ annihilation into hadronic final states ($R$ values) are measured with statistical errors that are smaller than 1%, and systematic errors that are about 3.5%. The running strong interaction coupling constants $α_s^{(3)}(s)$ and $α_s^{(5)}(M_Z^2)$ are determined from the $R$ values.

hep-ex↗

arXiv2008

Search for the Invisible Decay of $\jpsi$ in $ψ(2S)\toπ+π^-J/ψ$

Using 14.0 million $ψ(2S) events collected with the BES-II detector, a search for the decay of the $\jpsi$ to an invisible final state in $\psipto$ is performed. The $\jpsi$ peak in the distribution of mass recoiling against the $π^+π^-$ is used to tag $ψ$ invisible decay. No signal is found, and an upper limit at the 90% confidence level is determined to be $1.2\times 10^{-2}$ for the ratio $\frac{{\cal B}(\jpsi\ar {invisible})}{{\cal B}(\jpsi\arμ^+μ^-)}$. This is the first search for $J/ψ$ decay to an invisible final state.

hep-ex↗

arXiv2008

Direct Measurements of Absolute Branching Fractions for D0 and D+ Inclusive Semimuonic Decays

By analyzing about 33 $\rm pb^{-1}$ data sample collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we directly measure the branching fractions for the neutral and charged $D$ inclusive semimuonic decays to be $BF(D^0 \to μ^+ X) =(6.8\pm 1.5\pm 0.7)%$ and $BF(D^+ \to μ^+ X) =(17.6 \pm 2.7 \pm 1.8)%$, and determine the ratio of the two branching fractions to be $\frac{BF(D^+ \to μ^+ X)}{BF(D^0 \to μ^+ X)}=2.59\pm 0.70 \pm 0.25$.

hep-ex↗

arXiv2008

psi(2S) Radiative Decay Measurements

Using a sample of 14 million $\psip$ events collected with the BESII detector, branching fractions or upper limits on the branching fractions of $\psip$ decays into $γ\ppb$, $γ2(\pip\pim)$, $γ\kskp$, $γ\kap\kam\pip\pim$, $γ\kstarz\kam\pip+c.c.$, $γ\kstarz \kstarzb$, $γ\pip\pim\ppb$, $\gamma2(\kap\kam)$, $\gamma3(\pip\pim)$ and $\gamma2(\pip\pim)\kap\kam$ with hadron invariant mass less than 2.9$\gev/c^2$ are reported. We also report branching fractions of $\psip$ decays into $γ\ppb\piz$, $\ppb\piz\piz$, $2(\pip\pim)\piz$, $ω\pp$, $ωf_2(1270)$, $b_1^\pmπ^\mp$, $\piz\kskp$, $K^\pmρ^\mp\ks$, $\piz2(\pip\pim)\kap\kam$ and $γ\piz2(\pip\pim)\kap\kam$.

hep-ex↗

arXiv2008

Observation of Y(2175) in $J/ψ\to ηϕf_0(980)$

The decays of $J/ψ\to ηϕf_0(980) (η\to γγ, ϕ\to K^+K^-, f_0(980)\toπ^+π^-)$ are analyzed using a sample of $5.8 \times 10^{7}$ $J/ψ$ events collected with the BESII detector at the Beijing Electron-Positron Collider (BEPC). A structure at around $2.18 $GeV/$c^2$ with about $5σ$ significance is observed in the $ϕf_0(980)$ invariant mass spectrum. A fit with a Breit-Wigner function gives the peak mass and width of $m=2.186\pm 0.010 (stat)\pm 0.006 (syst) $GeV/$c^2$ and $Γ=0.065\pm 0.023 (stat)\pm 0.017 (syst) $GeV/$c^2$, respectively, that are consistent with those of Y(2175), observed by the BABAR collaboration in the initial-state radiation (ISR) process $e^+e^-\toγ_{ISR}ϕf_0(980)$. The production branching ratio is determined to be $Br(J/ψ\toηY(2175))\cdot Br(Y(2175)\toϕf_0(980))\cdot Br(f_0(980)\toπ^+π^-)=(3.23\pm 0.75 (stat)\pm0.73 (syst))\times 10^{-4}$, assuming that the Y(2175) is a $1^{--}$ state.

hep-ex↗

arXiv2007

Search for the C-parity violating process J/psi->gamma gamma via psi(2S)->pi+pi- J/psi

Using 14.0\times 10^6 ψ(2S) events collected with the BES-II detector, the C-parity violating process J/psi->gamma gamma via psi(2S)->pi+pi- J/psi is studied. We determine a new upper limit for the J/psi->gamma gamma branching ratio of B(J/psi->gamma gamma)<2.2\times 10^{-5} at the 90% C.L., which is about 20 times lower than the previous measurement.

hep-ex↗

arXiv2007

Measurements of $J/ψ$ and $ψ(2S)$ decays into $Λ\barΛπ^0$ and $Λ\barΛη$

Using 58 million $J/ψ$ and 14 million $ψ(2S)$ events collected by the BESII detector at the BEPC, branching fractions or upper limits for the decays $J/ψ$ and $ψ(2S) \to Λ\barΛπ^0$ and $Λ\barΛη$ are measured. For the isospin violating decays, the upper limits are determined to be ${\cal B}(J/ψ\to Λ\barΛπ^0)<6.4\times 10^{-5}$ and ${\cal B}(ψ(2S) \to Λ\barΛπ^0)<4.9\times 10^{-5}$ at the 90% confidence level. The isospin conserving process $J/ψ\to Λ\barΛη$ is observed for the first time, and its branching fraction is measured to be ${\cal B}(J/ψ\to Λ\barΛη)=(2.62\pm 0.60\pm 0.44)\times 10^{-4}$, where the first error is statistical and the second one is systematic. No $Λ\barΛη$ signal is observed in $ψ(2S)$ decays, and ${\cal B}(ψ(2S) \to Λ\barΛη)<1.2\times 10^{-4}$ is set at the 90% confidence level. Branching fractions of $J/ψ$ decays into $Σ^+ π^- barΛ$ and $\barΣ^- π^+ Λ$ are also reported, and the sum of these branching fractions is determined to be ${\cal B}(J/ψ\to Σ^+π^- \barΛ + c.c.)=(1.52\pm 0.08\pm 0.16)\times 10^{-3}$.

hep-ex↗

arXiv2007

Measurement of $\psip$ Radiative Decays

Using 14 million psi(2S) events accumulated at the BESII detector, we report first measurements of branching fractions or upper limits for psi(2S) decays into gamma ppbar, gamma 2(pi^+pi^-), gamma K_s K^-pi^++c.c., gamma K^+ K^- pi^+pi^-, gamma K^{*0} K^- pi^+ +c.c., gamma K^{*0}\bar K^{*0}, gamma pi^+pi^- p pbar, gamma 2(K^+K^-), gamma 3(pi^+pi^-), and gamma 2(pi^+pi^-)K^+K^- with the invariant mass of hadrons below 2.9GeV/c^2. We also report branching fractions of psi(2S) decays into 2(pi^+pi^-) pi^0, omega pi^+pi^-, omega f_2(1270), b_1^\pm pi^\mp, and pi^0 2(pi^+pi^-) K^+K^-.

hep-ex↗

arXiv2007

Determination of the $ψ(3770)$, $ψ(4040)$, $ψ(4160)$ and $ψ(4415)$ resonance parameters

$R$ measurement data taken with the BESII detector at center-of-mass energies between 3.7 and 5.0 GeV is fitted to determine resonance parameters (mass, total width, electron width) of the high mass charmonium states, $ψ(3770)$, $ψ(4040)$, $ψ(4160)$ and $ψ(4415)$. Various effects, including the relative phases between the resonances, interferences, the energy-dependence of the full widths, and the initial state radiative correction, are examined. The results are compared to previous studies.

hep-ex↗

arXiv2007

Measurements of psi(2S) decays to octet baryon-antibaryon pairs

With a sample of 14 million psi(2S) events collected by the BESII detector at the Beijing Electron Positron Collider (BEPC), the decay channels psi(2S)->p p-bar, Lambda Lambda-bar, Sigma0 Sigma0-bar, Xi Xi-bar are measured, and their branching ratios are determined to be (3.36+-0.09+-0.24)*10E-4, (3.39+-0.20+-0.32)*10E-4, (2.35+-0.36+-0.32)*10E-4, (3.03+-0.40+-0.32)*10E-4, respectively. In the decay psi(2S)->p p-bar, the angular distribution parameter alpha is determined to be 0.82+-0.17+-0.04.

hep-ex↗

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.

hep-ex↗