G S Huang

Publications (367)733.72 Total impact

• Article: Observation of a structure at 1.84 GeV/c$^2$ in the $3(\pi^+\pi^-)$ mass spectrum in $J/\psi\rightarrow \gamma 3(\pi^+\pi^-)$ decays

  M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, R. Baldini Ferroli, Y. Ban, J. Becker, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: With a sample of 225.3 million $J/\psi$ events taken with the BESIII detector, the decay $J/\psi\rightarrow \gamma 3(\pi^+\pi^-)$ is analyzed. A structure at 1.84 GeV/c$^2$ is observed in the $3(\pi^+\pi^-)$ invariant mass spectrum with a statistical significance of 7.6$\sigma$ . The mass and width are measured to be $M=1842.2\pm 4.2^{+7.1}_{-2.6}$ MeV/c$^2$ and $\Gamma=83\pm 14 \pm 11$ MeV. The product branching fraction is determined to be $B(J/\psi\rightarrow\gamma X(1840))\times B(X(1840)\rightarrow 3(\pi^+\pi^-))=(2.44\pm0.36^{+0.60}_{-0.74})\times 10^{-5}$. No $\eta^\prime$ signals are observed in the $3(\pi^+\pi^-)$ invariant mass spectrum, and the upper limit of the branching fraction for the decay $\eta^\prime\rightarrow 3(\pi^+\pi^-)$ is set to be $3.1\times10^{-5}$ at a 90% confidence level.
  05/2013;
• Article: Search for Baryonic Decays of \psi(3770) and \psi(4040)

  BESIII Collaboration, M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, R. Baldini Ferroli, Y. Ban, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: By analyzing data samples of 2.9 fb^{-1} collected at \sqrt s=3.773 GeV, 482 pb^{-1} collected at \sqrt s=4.009 GeV and 67 pb^{-1} collected at \sqrt s=3.542, 3.554, 3.561, 3.600 and 3.650 GeV with the BESIII detector at the BEPCII storage ring, we search for \psi(3770) and \psi(4040) decay to baryonic final states, including \Lambda\bar\Lambda\pi^+\pi^-, \Lambda \bar\Lambda\pi^0, \Lambda\bar\Lambda\eta, \Sigma^+ \bar\Sigma^-, \Sigma^0 \bar\Sigma^0, \Xi^-\bar\Xi^+ and \Xi^0\bar\Xi^0 decays. None are observed, and upper limits are set at the 90% confidence level.
  05/2013;
• Article: Partial wave analysis of $\psi(2S) \to p \bar{p}\eta$

  M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, R. Baldini Ferroli, Y. Ban, J. Becker, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: Using a sample of $1.06 \times 10^{8}$ $\psi(2S)$ events collected with the BESIII detector at BEPCII, the decay $\psi(2S) \to p \bar{p}\eta$ is studied. A partial wave analysis determines that the intermediate state N(1535) with a mass of $1524\pm5^{+10}_{-4}$ MeV/$c^2$ and a width of $130^{+27+57}_{-24-10}$ MeV/$c^2$ is dominant in the decay; the product branching fraction is determined to be $B(\psi(2S) \to N(1535)\bar{p})\times B(N(1535)\to p\eta)+c.c. = (5.2\pm0.3^{+3.2}_{-1.2})\times 10^{-5}$. Furthermore, the branching fraction of $\psi(2S) \to \eta p \bar{p}$ is measured to be $(6.4\pm0.2\pm0.6)\times 10^{-5}$.
  04/2013;
• Article: Measurement of $\eta^\prime\rightarrow \pi^+\pi^- e^+e^-$ and $\eta^\prime\rightarrow \pi^+\pi^-\mu^+\mu^-$

  BESIII Collaboration, M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, R. Baldini Ferroli, Y. Ban, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: Based on a sample of 225.3 million J/\psi events accumulated with the BESIII detector at the BEPCII, the decays of \eta' to pi+pi-l+l- are studied via J/\psi to \gamma\eta'. A clear \eta' signal is observed in the pi+pi-e+e- mass spectrum, and the branching fraction is measured to be \BR(\eta' to pi+pi-e+e-) = (2.11\pm0.12 (stat.)\pm0.15 (syst.))\times10^{-3}, which is in good agreement with theoretical predictions and the previous measurement, but is determined with much higher precision. No \eta' signal is found in the pi+ pi- mu+ mu- mass spectrum, and the upper limit is determined to be \BR(\eta' to pi+ pi- mu+ mu-)<2.9\times10^{-5} at the 90% confidence level.
  03/2013;
• Article: Observation of a charged charmoniumlike structure in e+e- to pi+pi-J/psi at \sqrt{s}=4.26 GeV

  BESIII Collaboration, M. Ablikim, M. N. Achasov, X. C. Ai, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, R. Baldini Ferroli, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: We study the process e+e- to pi+pi-J/psi at a center-of-mass energy of 4.260 GeV using a 525 pb^{-1} data sample collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross section is measured to be (62.9\pm 1.9\pm 3.7) pb, consistent with the production of the Y(4260). We observe a structure at around 3.9 GeV/c^2 in the \pi^\pm J/psi mass spectrum, which we refer to as the Z_c(3900). If interpreted as a new particle, it is unusual in that it carries an electric charge and couples to charmonium. A fit to the \pi^\pm J/psi invariant mass spectrum, neglecting interference, results in a mass of (3899.0\pm 3.6\pm 4.9) MeV/c^2 and a width of (46\pm 10\pm 20) MeV. Its production ratio is measured to be R=\frac{\sigma(e+e- to \pi^\pm Z_c(3900)^\mp to pi+pi-J/psi))} {\sigma(e+e- to pi+pi-J/psi)}=(21.5\pm 3.3\pm 7.5)%. In all measurements the first errors are statistical and the second are systematic.
  03/2013;
• Article: Study of $J/\psi \rightarrow \omega p \bar{p}$ at BESIII

  The BESIII Collaboration, M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, R. Baldini Ferroli, Y. Ban, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: The decay $J/\psi \rightarrow \omega p \bar{p}$ has been studied, using $225.3\times 10^{6}$ $J/\psi$ events accumulated at BESIII. No significant enhancement near the $p\bar{p}$ invariant-mass threshold (denoted as $X(p\bar{p})$) is observed. The upper limit of the branching fraction $\mathcal{B}(J/\psi \rightarrow \omega X(p\bar{p}) \rightarrow \omega p \bar{p})$ is determined to be $3.9\times10^{-6}$ at the 95% confidence level. The branching fraction of $J/\psi \rightarrow \omega p \bar{p}$ is measured to be $\mathcal{B}(J/\psi \rightarrow \omega p \bar{p}) =(9.0 \pm 0.2\ (\text{stat.})\pm 0.9\ (\text{syst.})) \times 10^{-4}$.
  03/2013;
• Article: Evidence for \eta_{c}(2S) in \psi(3686) \to \gamma K_{S}^{0}K^{\pm}\pi^{\mp}\pi^{+}\pi^{-}

  The BESIII Collaboration, M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, Y. Ban, J. Becker, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: We search for the M1 radiative transition \psi(3686) \to \gamma\eta_{c}(2S) by reconstructing the exclusive \eta_{c}(2S) \to K_{S}^{0}K^{\pm}\pi^{\mp}\pi^{+}\pi^{-} decay using 1.06 \times 10^8 \psi(3686) events collected with the BESIII detector. The signal is observed with a statistical significance of greater than 4 standard deviations. The measured mass of the \eta_{c}(2S) is 3646.9 \pm 1.6(stat) \pm 3.6(syst) MeV/c^2, and the width is 9.9 \pm 4.8(stat) \pm 2.9(syst) MeV/c^2. The product branching fraction is measured to be B(\psi(3686) \to \gamma\eta_{c}(2S)) \times B(\eta_{c}(2S) \to K_{S}^{0}K^{\pm}\pi^{\mp}\pi^{+}\pi^{-}) = (7.03 \pm 2.10(stat) \pm 0.70(syst)) \times 10^{-6}. This measurement complements a previous BESIII measurement of \psi(3686) \to \gamma\eta_{c}(2S) with \eta_{c}(2S) \to K_{S}^{0} K^{\pm}\pi^{\mp} and K^{+}K^{-}\pi^{0}.
  01/2013;
• Article: Partial wave analysis of $J/\psi \to \gamma \eta \eta$

  M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, R. Baldini Ferroli, Y. Ban, J. Becker, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: Based on a sample of $2.25\times 10^{8}$ $J/\psi$ events collected with the BESIII detector at BEPCII, a full partial wave analysis on $J/\psi\to\gamma\eta\eta$ was performed using the relativistic covariant tensor amplitude method. The results show that the dominant $0^{++}$ and $2^{++}$ components are from the $f_0(1710)$, $f_0(2100)$, $f_0(1500)$, $f_2'(1525)$, $f_2(1810)$ and $f_2(2340)$. The resonance parameters and branching fractions are also presented.
  12/2012;
• Article: Assessment of Cam-Type Femoroacetabular Impingement by Ultrasonography: Value of Anterior Femoral Distance Measurements.

  Y-C Hsu, Y-C Wu, H-H Wang, M-S Lee, G-S Huang
  [show abstract] [hide abstract]
  ABSTRACT: Purpose: To retrospectively determine the reproducibility and performance of a quantitative measurement for cam-type femoroacetabular impingement (FAI) designated as the anterior femoral distance (AFD) of the femoral head-neck junction identified at ultrasonography (US). Materials and Methods: 72 patients with clinically suspected FAI were retrospectively evaluated, and US studies were performed during a 20-month period. Of these, we selected 53 patients who underwent subsequent magnetic resonance (MR) arthrography and had adequate recorded US images. All the longitudinal US images of the anterior and anterosuperior contours of the femoral head-neck junction were recorded by a radiologist. 33 of these US images were also recorded by a technician. An alpha angle of > 55° on MR arthrography was indicative of cam-type FAI. Two independent radiology residents blinded to the clinical data and MR arthrography measured the maximal femoral head-neck overgrowth defined as the AFD on US (AFD-US). Reproducibility was assessed using intra-class correlation coefficients (ICCs) and Bland-Altman plots, and diagnostic performance was assessed using receiver operating characteristic (ROC) analysis. Results: AFD-US showed high intra- and inter-rater agreement (ICC = 0.913 - 0.968) in all measurements and good reproducibility among different operators in the anterior contour measurements (ICC = 0.881) but not in the anterosuperior contour measurements (ICC = 0.196). An AFD-US cut-off value of 4.0 mm in the anterior contour yielded the greatest sensitivity (80.9 %) and specificity (87.5 %) for the diagnosis of cam-type FAI by ROC analysis. Conclusion: AFD-US of the anterior contour of the femoral head-neck junction is helpful in diagnosing cam-type FAI.
  Ultraschall in der Medizin 12/2012; · 2.40 Impact Factor
• Article: Study of the near-threshold $\omega\phi$ mass enhancement in doubly OZI suppressed $J/\psi \to \gamma\omega\phi$ decays

  M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, Y. Ban, J. Becker, J. V. Bennett, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: A 2.25$\times10^8$ $\jpsi$ event sample accumulated with the BESIII detector is used to study the doubly OZI suppressed decay modes $\jpsi\to\gamma\of$, $\omega\to\ppp$, $\phi\to\kk$. A strong deviation ($>$ 30$\sigma$) from three-body $\jpsi\to\gamma\omega\phi$ phase space is observed near the $\omega\phi$ mass threshold that is consistent with a previous observation reported by the BESII experiment. A partial wave analysis with a tensor covariant amplitude that assumes that the enhancement is due to the presence of a resonance, the X(1810), is performed, and confirms that the spin-parity of the X(1810) is $0^{++}$. The mass and width of the X(1810) are determined to be $M=1795\pm7$(stat)$^{+13}_{-5}$(syst)$\pm$19(mod) MeV/$c^2$ and $\Gamma=95\pm10$(stat)$^{+21}_{-34}$(syst)$\pm$75(mod) MeV/$c^2$, respectively, and the product branching fraction is measured to be ${\cal B}(\jpsi\to\gamma X(1810))\times{\cal B}(X(1810)\to\of)=(2.00\pm0.08$(stat)$^{+0.45}_{-1.00}$(syst)$\pm$1.30(mod))$\times10^{-4}$. %where the first error is the statistical error and the second the systematical error. These results are consistent within errors with those of the BESII experiment.
  11/2012;
• Article: Search for $\eta$ and $\eta^\prime\to \pi^+ e^- \bar{\nu}_e +c.c.$ decays in $\jpsi \to \phi \eta$ and $\phi \eta^\prime$

  M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, R. Baldini Ferroli, Y. Ban, J. Becker, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: Using a sample of 225.3 million $\jpsi$ events collected with the BESIII detector at the BEPCII $e^+e^-$ collider in 2009, searches for the decays of $\eta$ and $\eta^\prime\to\pi^+ e^- \bar{\nu}_e +c.c.$ in $\jpsi \to \phi \eta$ and $\phi\eta^\prime$ are performed. The $\phi$ signals, which are reconstructed in $K^+K^-$ final states, are used to tag $\eta$ and $\eta^\prime$ semileptonic decays. No signals are observed for either $\eta$ or $\eta^\prime$, and upper limits at the 90% confidence level are determined to be $7.3\times 10^{-4}$ and $5.0\times 10^{-4}$ for the ratios $\frac{{\mathcal B}(\eta\to \pi^+ e^- \bar{\nu}_e +c.c.)}{{\mathcal B}(\eta \to \pip\pim\piz)}$ and $\frac{{\mathcal B}(\eta^\prime\to \pi^+ e^-\bar{\nu}_e +c.c.)}{{\mathcal B}(\eta^\prime \to \pip\pim\eta)}$, respectively. These are the first upper limit values determined for $\eta$ and $\eta^\prime$ semileptonic weak decays.
  11/2012;
• Article: Measurements of Baryon Pair Decays of $\chi_{cJ}$ Mesons

  M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, Y. Ban, J. Becker, J. V. Bennett, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: Using 106 $\times 10^{6}$ $\psi^{\prime}$ decays collected with the BESIII detector at the BEPCII, three decays of $\chi_{cJ}$ ($J=0,1,2$) with baryon pairs ($\llb$, $\ssb$, $\SSB$) in the final state have been studied. The branching fractions are measured to be $\cal{B}$$(\chi_{c0,1,2}\rightarrow\Lambda\bar\Lambda) =(33.3 \pm 2.0 \pm 2.6)\times 10^{-5}$, $(12.2 \pm 1.1 \pm 1.1)\times 10^{-5}$, $(20.8 \pm 1.6 \pm 2.3)\times 10^{-5}$; $\cal{B}$$(\chi_{c0,1,2}\rightarrow\Sigma^{0}\bar\Sigma^{0})$ = $(47.8 \pm 3.4 \pm 3.9)\times 10^{-5}$, $(3.8 \pm 1.0 \pm 0.5)\times 10^{-5}$, $(4.0 \pm 1.1 \pm 0.5) \times 10^{-5}$; and $\cal{B}$$(\chi_{c0,1,2}\rightarrow\Sigma^{+}\bar\Sigma^{-})$ = $(45.4 \pm 4.2 \pm 3.0)\times 10^{-5}$, $(5.4 \pm 1.5 \pm 0.5)\times 10^{-5}$, $(4.9 \pm 1.9 \pm 0.7)\times 10^{-5}$, where the first error is statistical and the second is systematic. Upper limits on the branching fractions for the decays of $\chi_{c1,2}\rightarrow\Sigma^{0}\bar\Sigma^{0}$, $\Sigma^{+}\bar\Sigma^{-}$, are estimated to be $\cal{B}$$(\chi_{c1}\rightarrow\Sigma^{0}\bar\Sigma^{0}) < 6.2\times 10^{-5}$, $\cal{B}$$(\chi_{c2}\rightarrow\Sigma^{0}\bar\Sigma^{0}) < 6.5\times 10^{-5}$, $\cal{B}$$(\chi_{c1}\rightarrow\Sigma^{+}\bar\Sigma^{-}) < 8.7\times 10^{-5}$ and $\cal{B}$$(\chi_{c2}\rightarrow\Sigma^{+}\bar\Sigma^{-}) < 8.8\times 10^{-5}$ at the 90% confidence level.
  11/2012;
• Article: Precision measurements of branching fractions for $ \psi'\to\pi^0 J\psi$ and $\eta J\psi$

  M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, Y. Ban, J. Becker, J. V. Bennett, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: We present a precision study of the $\psip\to\pi^0 J/\psi$ and $\eta J/\psi$ decay modes. The measurements are obtained using $106\times10^6$ $\psi'$ events accumulated with the BESIII detector at the BEPCII $\ee$ collider operating at a center-of-mass energy corresponding to the $\psip$ mass. We obtain $\mathcal{B}(\psip\to\pi^0 J/\psi)=(1.26\pm0.02{\rm (stat.)}\pm0.03{\rm (syst.)})\times 10^{-3}$ and $\mathcal{B}(\psip\to\eta J/\psi)=(33.75\pm0.17{\rm (stat.)}\pm0.86{\rm (syst.)})\times 10^{-3}$. The branching fraction ratio $R=\frac{\mathcal{B}(\psip\to\pi^0 J/\psi)}{\mathcal{B}(\psip\to\eta J/\psi)}$ is determined to be $(3.74\pm0.06 {\rm(stat.)}\pm0.04 {\rm(syst.)})\times 10^{-2}$. The precision of these measurements of $\mathcal{B}(\psip\to\pi^{0} J/\psi)$ and $R$ represent a significant improvement over previously published values.
  10/2012;
• Article: Observation of $\eta_{c}$ decay into $\Sigma^{+}\bar{\Sigma}^{-}$ and $\Xi^{-}\bar{\Xi}^{+}$ final states

  The BESIII Collaboration, M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, Y. Ban, J. Becker, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: Using a data sample of $2.25\times10^{8}$ $J/\psi$ events collected with the BESIII detector, we present the first observation of the decays of $\eta_{c}$ mesons to $\Sigma^{+}\bar{\Sigma}^{-}$ and $\Xi^{-}\bar{\Xi}^{+}$. The branching fractions are measured to be $(2.11\pm0.28_{\rm stat.}\pm0.18_{\rm syst.}\pm0.50_{\rm PDG})\times10^{-3}$ and $(0.89\pm0.16_{\rm stat.}\pm0.08_{\rm syst.}\pm0.21_{\rm PDG})\times10^{-3}$ for $\eta_{c} \to \Sigma^{+}\bar{\Sigma}^{-}$ and $\Xi^{-}\bar{\Xi}^{+}$, respectively. These branching fractions provide important information on the helicity selection rule in charmonium-decay processes.
  10/2012;
• Article: Study of $\psi(3686)\to\pi^0 h_c, h_c\to\gamma\eta_c$ via $\eta_c$ exclusive decays

  The BESIII Collaboration, M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, Y. Ban, J. Becker, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: The process $\psi(3686) \to \pi^0 h_c, h_c \to \gamma \eta_c$ has been studied with a data sample of $106 \pm 4$ million $\psi(3686)$ events collected with the BESIII detector at the BEPCII storage ring. The mass and width of the $P$-wave charmonium spin-singlet state $h_c(^1P_1)$ are determined by simultaneously fitting distributions of the $\pi^0$ recoil mass for 16 exclusive $\eta_c$ decay modes. The results, $M(\hc) = 3525.31 \pm 0.11 {\rm (stat.)} \pm 0.14 {\rm (syst.)}$\,MeV/$c^2$ and $\Gamma(\hc) = 0.70 \pm 0.28 \pm 0.22$\,MeV, are consistent with and more precise than previous measurements. We also determine the branching ratios for the 16 exclusive $\eta_c$ decay modes, five of which have not been measured previously. New measurements of the $\eta_c$ line-shape parameters in the $E1$ transition $h_c\to\gamma\eta_c$ are made by selecting candidates in the $h_c$ signal sample and simultaneously fitting the hadronic mass spectra for the 16 $\eta_c$ decay channels. The resulting $\eta_c$ mass and width values are $M(\eta_c) = 2984.49 \pm 1.16 \pm 0.52$\,MeV/$c^2$ and $\Gamma(\eta_c) = 36.4 \pm 3.2 \pm 1.7$\,MeV.
  09/2012;
• Article: Search for $\eta$ and $\eta'$ Invisible Decays in $J/\psi\to\phi\eta$ and $\phi\eta'$

  M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, Y. Ban, J. Becker, J. V. Bennett, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: Using a sample of $(225.3\pm 2.8)\times 10^{6}$ $J/\psi$ decays collected with the BESIII detector at BEPCII, searches for invisible decays of $\eta$ and $\eta^\prime$ in $J/\psi\to\phi\eta$ and $\phi\eta^\prime$ are performed. Decays of $\phi \to K^{+}K^{-}$ are used to tag the $\eta$ and $\eta^\prime$ decays. No signals above background are found for the invisible decays, and upper limits at the 90% confidence level are determined to be $2.58\times10^{-4}$ for the ratio $\frac{\mathcal{B}(\eta\to\rm{invisible})}{\mathcal{B}(\eta\to\gamma\gamma)}$ and $2.39\times10^{-2}$ for $\frac{\mathcal{B}(\eta^\prime\to\rm{invisible})}{\mathcal{B}(\eta^\prime \to\gamma\gamma)}$.
  09/2012;
• Article: Measurement of $\chi_{cJ}$ decaying into $p\bar{n}\pi^{-}$ and $p\bar{n}\pi^{-}\pi^{0}$

  M. Ablikim, M. N. Achasov, O. Albayrak, D. J. Ambrose, F. F. An, Q. An, J. Z. Bai, Y. Ban, J. Becker, J. V. Bennett, [......], K. J. Zhu, S. H. Zhu, X. L. Zhu, Y. C. Zhu, Y. M. Zhu, Y. S. Zhu, Z. A. Zhu, J. Zhuang, B. S. Zou, J. H. Zou
  [show abstract] [hide abstract]
  ABSTRACT: Using a data sample of $1.06 \times 10^{8}$ $\psip$ events collected with the BESIII detector in 2009, the branching fractions of $\chi_{cJ}\to p\bar{n}\pi^{-}$ and $\chi_{cJ}\to p\bar{n}\pi^{-}\pi^{0}$ ($J$=0,1,2) are measured{Throughout the text, inclusion of charge conjugate modes is implied if not stated otherwise.}. The results for $\chi_{c0}\to p\bar{n}\pi^{-}$ and $\chi_{c2}\to p\bar{n}\pi^{-}$ are consistent with, but much more precise than those of previous measurements. The decays of $\chi_{c1}\to p\bar{n}\pi^{-}$ and $\chi_{cJ}\to p\bar{n}\pi^{-}\pi^{0}$ are observed for the first time.
  08/2012;
• Source

  Available from: Ehud Duchovni

  Article: Search for down-type fourth generation quarks with the ATLAS detector in events with one lepton and hadronically decaying W bosons.

  G Aad, B Abbott, J Abdallah, A A Abdelalim, A Abdesselam, O Abdinov, B Abi, M Abolins, O S AbouZeid, H Abramowicz, [......], R Zitoun, L Živković, V V Zmouchko, G Zobernig, A Zoccoli, Y Zolnierowski, A Zsenei, M zur Nedden, V Zutshi, L Zwalinski
  [show abstract] [hide abstract]
  ABSTRACT: This Letter presents a search for pair production of heavy down-type quarks decaying via b' → Wt in the lepton + jets channel, as b'b' → W- tW+ t → bbW+ W- W+ W- → l± νbbqqqqqq. In addition to requiring exactly one lepton, large missing transverse momentum, and at least six jets, the invariant mass of nearby jet pairs is used to identify high transverse momentum W bosons. In data corresponding to an integrated luminosity of 1.04  fb(-1) from pp collisions at sqrt[s] = 7  TeV recorded with the ATLAS detector, a heavy down-type quark with mass less than 480 GeV can be excluded at the 95% confidence level.
  Physical Review Letters 07/2012; 109(3):032001. · 7.37 Impact Factor
• Source

  Available from: Maksym Deliyergiyev

  Article: Determination of the Strange-Quark Density of the Proton from ATLAS Measurements of the W→ℓν and Z→ℓℓ Cross Sections.

  G Aad, B Abbott, J Abdallah, A A Abdelalim, A Abdesselam, O Abdinov, B Abi, M Abolins, O S Abouzeid, H Abramowicz, [......], R Zitoun, L Zivković, V V Zmouchko, G Zobernig, A Zoccoli, Y Zolnierowski, A Zsenei, M Zur Nedden, V Zutshi, L Zwalinski
  [show abstract] [hide abstract]
  ABSTRACT: A QCD analysis is reported of ATLAS data on inclusive W^{±} and Z boson production in pp collisions at the LHC, jointly with ep deep-inelastic scattering data from HERA. The ATLAS data exhibit sensitivity to the light quark sea composition and magnitude at Bjorken x∼0.01. Specifically, the data support the hypothesis of a symmetric composition of the light quark sea at low x. The ratio of the strange-to-down sea quark distributions is determined to be 1.00_{-0.28}^{+0.25} at absolute four-momentum transfer squared Q^{2}=1.9  GeV^{2} and x=0.023.
  Physical Review Letters 07/2012; 109(1):012001. · 7.37 Impact Factor
• Source

  Available from: Ilya O. Orlov

  Article: Search for massive colored scalars in four-jet final states in proton–proton collisions with the ATLAS detector

  The ATLAS Collaboration, G. Aad, B. Abbott, J. Abdallah, A. A. Abdelalim, A. Abdesselam, O. Abdinov, B. Abi, M. Abolins, H. Abramowicz, [......], R. Zitoun, L. Živković, V. V. Zmouchko, G. Zobernig, A. Zoccoli, Y. Zolnierowski, A. Zsenei, M. zur Nedden, V. Zutshi, L. Zwalinski
  [show abstract] [hide abstract]
  ABSTRACT: A search for pair-produced scalar particles decaying to a four-jet final state is presented. The analysis is performed using an integrated luminosity of 34pb−1 recorded by the ATLAS detector in 2010. No deviation from the Standard Model is observed. For a scalar mass of 100GeV (190GeV) the limit on the scalar gluon pair production cross section at 95% confidence level is 1nb (0.28nb). When these results are interpreted as mass limits, scalar-gluons (hyperpions) with masses of 100 to 185GeV (100 to 155GeV) are excluded at 95% confidence level with the exception of a mass window of width about 5GeV (15GeV) around 140GeV.
  European Physical Journal C 05/2012; 71(12):1-19. · 3.63 Impact Factor