Showing papers by "Y. Ban published in 2006"

Observation of a near-threshold enhancement in the omega(phi) mass spectrum from the doubly OZI-suppressed decay J/psi-->gamma(omega)phi.

Abstract: An enhancement near threshold is observed in the omega(phi) invariant mass spectrum from the doubly Okubo-Zweig-Iizuka-suppressed decays of J/psi-->gamma(omega)phi, based on a sample of 5.8 x 10(7) J/psi events collected with the BESII detector. A partial wave analysis shows that this enhancement favors JP=0+, and its mass and width are M=1812(+19)(-26)(stat)+/-18(syst) MeV/c2 and Gamma=105+/-20(stat)+/-28(syst) MeV/c2. The product branching fraction is determined to be B(J/psi-->gammaX)B(X-->omega(phi))=[2.61+/-0.27(stat)+/-0.65(syst)]x10(-4).

Experimental constraints on the possible J**P quantum numbers of the Lambda(c)(2880)+

Abstract: We report the results of several studies of the {lambda}{sub c}{sup +}{pi}{sup +}{pi}{sup -}X final state in continuum e{sup +}e{sup -} annihilation data collected by the Belle detector. An analysis of angular distributions in {lambda}{sub c}(2880){sup +}{yields}{sigma}{sub c}(2455){sup 0,++}{pi}{sup +,-} decays strongly favors a {lambda}{sub c}(2880){sup +} spin assignment of (5/2) over (3/2) or (1/2). We find evidence for {lambda}{sub c}(2880){sup +}{yields}{sigma}{sub c}(2520){sup 0,++}{pi}{sup +,-} decay and measure the ratio of {lambda}{sub c}(2880){sup +} partial widths {gamma}({sigma}{sub c}(2520){pi})/{gamma}({sigma}{sub c}(2455){pi})=0.225{+-}0.062{+-}0.= 025. This value favors the {lambda}{sub c}(2880){sup +} spin-parity assignment of (5/2){sup +} over (5/2){sup -}. We also report the first observation of {lambda}{sub c}(2940){sup +}{yields}{sigma}{sub c}(2455){sup 0,++}{pi}{sup +,-} decay and measure {lambda}{sub c}(2880){sup +} and {lambda}{sub c}(2940){sup +} mass and width parameters. These studies are based on a 553 fb{sup -1} data sample collected at or near the {upsilon}(4S) resonance at the KEKB collider.

Measurements of the branching fractions for psi(3770)-->D(0)D[over ](0), D+D-, DD[over ], and the resonance parameters of psi(3770) and psi(2S).

Abstract: We measure the branching fractions for psi(3770)-->D(0)D[over ](0), D+D-, DD[over ], and non-DD[over ] to be (46.7+/-4.7+/-2.3)%, (36.9+/-3.7+/-2.8)%, (83.6+/-7.3+/-4.2)%, and (16.4+/-7.3+/-4.2)%, respectively. The resonance parameters of psi(3770) and psi(2S) are measured to be M_(psi(3770))=3772.2+/-0.7+/-0.3 MeV, Gamma_(psi(3770))(tot)=26.9+/-2.4+/-0.3 MeV, and Gamma_(psi(3770))(ee)=251+/-26+/-11 eV; M_(psi(2S))=3685.5+/-0.0+/-0.3 MeV, Gamma_(psi(2S))(tot)=331+/-58+/-2 keV, and Gamma_(psi(2S))(ee)=2.330+/-0.036+/-0.110 keV. We also measure the light hadron R value to be R(uds)=2.262+/-0.054+/-0.109 in the energy region from 3.660 to 3.872 GeV.

Measurements of the continuum R(uds) and R values in e+e- annihilation in the energy region between 3.650 and 3.872-GeV

Abstract: We report measurements of the continuum R{sub uds} near the center-of-mass energy of 3.70 GeV, the R{sub uds(c)+{psi}}{sub (3770)}(s) and the R{sub had}(s) values in e{sup +}e{sup -} annihilation at 68 energy points in the energy region between 3.650 and 3.872 GeV with the BES-II detector at the BEPC Collider. We obtain the R{sub uds} for the continuum light hadron (containing u, d, and s quarks) production near the DD threshold to be R{sub uds}=2.141{+-}0.025{+-}0.085.

Charge asymmetry of same-sign dileptons in B0-B̅0 mixing

Abstract: Reference EPFL-ARTICLE-154552doi:10.1103/PhysRevD.73.112002View record in Web of Science Record created on 2010-11-05, modified on 2017-12-10

Pseudoscalar production atωωthreshold inJ/ψ→γωω

Abstract: M. Ablikim, J. Z. Bai, Y. Ban, J. G. Bian, X. Cai, H. F. Chen, H. S. Chen, H. X. Chen, J. C. Chen, Jin Chen, Y. B. Chen, S. P. Chi, Y. P. Chu, X. Z. Cui, Y. S. Dai, L. Y. Diao, Z. Y. Deng, Q. F. Dong, S. X. Du, J. Fang, S. S. Fang, C. D. Fu, C. S. Gao, Y. N. Gao, S. D. Gu, Y. T. Gu, Y. N. Guo, Y. Q. Guo, Z. J. Guo, F. A. Harris, K. L. He, M. He, Y. K. Heng, H. M. Hu, T. Hu, G. S. Huang, X. T. Huang, X. B. Ji, X. S. Jiang, X. Y. Jiang, J. B. Jiao, D. P. Jin, S. Jin, Yi Jin, Y. F. Lai, G. Li, H. B. Li, H. H. Li, J. Li, R. Y. Li, S. M. Li, W. D. Li, W. G. Li, X. L. Li, X. N. Li, X. Q. Li, Y. L. Li, Y. F. Liang, H. B. Liao, B. J. Liu, C. X. Liu, F. Liu, Fang Liu, H. H. Liu, H. M. Liu, J. Liu, J. B. Liu, J. P. Liu, Q. Liu, R. G. Liu, Z. A. Liu, Y. C. Lou, F. Lu, G. R. Lu, J. G. Lu, C. L. Luo, F. C. Ma, H. L. Ma, L. L. Ma, Q. M. Ma, X. B. Ma, Z. P. Mao, X. H. Mo, J. Nie, S. L. Olsen, H. P. Peng, R. G. Ping, N. D. Qi, H. Qin, J. F. Qiu, Z. Y. Ren, G. Rong, L. Y. Shan, L. Shang, C. P. Shen, D. L. Shen, X. Y. Shen, H. Y. Sheng, H. S. Sun, J. F. Sun, S. S. Sun, Y. Z. Sun, Z. J. Sun, Z. Q. Tan, X. Tang, G. L. Tong, G. S. Varner, D. Y. Wang, L. Wang, L. L. Wang, L. S. Wang, M. Wang, P. Wang, P. L. Wang, W. F. Wang, Y. F. Wang, Z. Wang, Z. Y. Wang, Zhe Wang, Zheng Wang, C. L. Wei, D. H. Wei, N. Wu, X. M. Xia, X. X. Xie, G. F. Xu, X. P. Xu, Y. Xu, M. L. Yan, H. X. Yang, Y. X. Yang, M. H. Ye, Y. X. Ye, Z. Y. Yi, G. W. Yu, C. Z. Yuan, J. M. Yuan, Y. Yuan, S. L. Zang, Y. Zeng, Yu Zeng, B. X. Zhang, B. Y. Zhang, C. C. Zhang, D. H. Zhang, H. Q. Zhang, H. Y. Zhang, J. W. Zhang, J. Y. Zhang, S. H. Zhang, X. M. Zhang, X. Y. Zhang, Yiyun Zhang, Z. P. Zhang, D. X. Zhao, J. W. Zhao, M. G. Zhao, P. P. Zhao, W. R. Zhao, Z. G. Zhao, H. Q. Zheng, J. P. Zheng, Z. P. Zheng, L. Zhou, N. F. Zhou, K. J. Zhu, Q. M. Zhu, Y. C. Zhu, Y. S. Zhu, Yingchun Zhu, Z. A. Zhu, B. A. Zhuang, X. A. Zhuang, B. S. Zou

Search for Invisible Decays ofηandη′inJ/ψ→ϕηandϕη′

Abstract: Using a data sample of $58\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $J/\ensuremath{\psi}$ decays collected with the Beijing Spectrometer II detector at the Beijing Electron Positron Collider, searches for invisible decays of $\ensuremath{\eta}$ and ${\ensuremath{\eta}}^{\ensuremath{'}}$ in $J/\ensuremath{\psi}$ to $\ensuremath{\phi}\ensuremath{\eta}$ and $\ensuremath{\phi}{\ensuremath{\eta}}^{\ensuremath{'}}$ are performed. The $\ensuremath{\phi}$ signals, which are reconstructed in ${K}^{+}{K}^{\ensuremath{-}}$ final states, are used to tag the $\ensuremath{\eta}$ and ${\ensuremath{\eta}}^{\ensuremath{'}}$ decays. No signals are found for the invisible decays of either $\ensuremath{\eta}$ or ${\ensuremath{\eta}}^{\ensuremath{'}}$, and upper limits at the 90% confidence level are determined to be $1.65\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ for the ratio $\frac{B(\ensuremath{\eta}\ensuremath{\rightarrow}\mathrm{invisible})}{B(\ensuremath{\eta}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma})}$ and $6.69\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}$ for $\frac{B({\ensuremath{\eta}}^{\ensuremath{'}}\ensuremath{\rightarrow}\mathrm{invisible})}{B({\ensuremath{\eta}}^{\ensuremath{'}}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma})}$. These are the first searches for $\ensuremath{\eta}$ and ${\ensuremath{\eta}}^{\ensuremath{'}}$ decays into invisible final states.

Measurement of the branching fractions for J/{psi}{yields}{gamma}{pi}{sup 0}, {gamma}{eta} and {gamma}{eta}{sup '}

Abstract: The decay modes J/{psi}{yields}{gamma}{pi}{sup 0}, {gamma}{eta} and {gamma}{eta}{sup '} are analyzed using a data sample of 58x10{sup 6} J/{psi} decays collected with the BESII detector at the BEPC. The branching fractions are determined to be: Br(J/{psi}{yields}{gamma}{pi}{sup 0})=(3.13{sub -0.47}{sup +0.65})x10{sup -5}, Br(J/{psi}{yields}{gamma}{eta})=(11.23{+-}0.89)x10{sup -4}, and Br(J/{psi}{yields}{gamma}{eta}{sup '})=(5.55{+-}0.44)x10{sup -3}, where the errors are combined statistical and systematic errors. The ratio of partial widths {gamma}(J/{psi}{yields}{gamma}{eta}{sup '})/{gamma}(J/{psi}{yields}{gamma}{eta}) is measured to be 4.94{+-}0.40, and the singlet-octet pseudoscalar mixing angle of {eta}-{eta}{sup '} system is determined.

First observation of ψ(2S)→pn̄π - +c.c.

Abstract: Using $14\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $\ensuremath{\psi}(2S)$ events collected with the Beijing Spectrometer (BESII) at the Beijing Electron-Positron Collider, the branching fractions of $\ensuremath{\psi}(2S)$ decays to $p\overline{n}{\ensuremath{\pi}}^{\ensuremath{-}}$ and $\overline{p}n{\ensuremath{\pi}}^{+}$ and the branching fractions of the main background channels $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}p\overline{n}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$, $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c0}\ensuremath{\rightarrow}\ensuremath{\gamma}p\overline{n}{\ensuremath{\pi}}^{\ensuremath{-}}$, $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c2}\ensuremath{\rightarrow}\ensuremath{\gamma}p\overline{n}{\ensuremath{\pi}}^{\ensuremath{-}}$, and $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{cJ}\ensuremath{\rightarrow}\ensuremath{\gamma}p\overline{n}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$ are determined. The contributions of the ${N}^{*}$ resonances in $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}p\overline{n}{\ensuremath{\pi}}^{\ensuremath{-}}+c.c.$ are also discussed.

Production and the quality control for the CMS endcap RPCs

Abstract: The production for the endcap RPCs in the CMS experiment has entered a mature stage of the production stream. In this paper, the production facilities and the selection procedures of the qualified RPC gaps are presented. The mass production and the quality control tests for the endcap RPCs have reached the maximum productivity. The yield to produce the qualified gaps is now above 80 % of the qualified bakelite sheets provided by Italy. We also report an intensive aging study for the endcap RPCs performed by using a 200 mCi 137 Cs gamma-ray source. A few diagnostic methods to observe aging phenomena are discussed. The test result is equivalent to approximately 12 years of Compact Muon Solenoid (CMS) RPC operation.

Assembly and Quality Certification for the First Station of CMS Endcap RPCs (RE1)

Abstract: The production of Resistive Plate Chambers (RPCs) for the first Endcap station (RE1) of CMS experiment at Large Hadron Collider (LHC) has started at CERN since June 2004. For good performance of CMS muon and trigger systems these chambers have been assembled in accordance with strict QC (quality control) and QA (quality assurance) procedures during various assembly steps. Up to October 2005, more than 140 chambers have been constructed and more than 100 of them have been tested with cosmic rays. The chambers are assembled with the sensitive volumes (namely gas gaps) which were manufactured in Korea and all relevant mechanical parts were made in China. The procedure of chamber construction and the experience we have accumulated during the assembly will be described.

Experimental study of {psi}2S decays to K{sup +}K{sup -}{pi}{sup +}{pi}{sup -}{pi}{sup 0} final states

Abstract: K{sup +}K{sup -}{pi}{sup +}{pi}{sup -}{pi}{sup 0} final states are studied using a sample of 14x10{sup 6} {psi}(2S) decays collected with the Beijing Spectrometer (BESII) at the Beijing Electron-Positron Collider. The branching fractions of {psi}(2S) decays to K{sup +}K{sup -}{pi}{sup +}{pi}{sup -}{pi}{sup 0}, {omega}K{sup +}K{sup -}, {omega}f{sub 0}(1710), K*(892){sup 0}K{sup -}{pi}{sup +}{pi}{sup 0}+c.c., K*(892){sup +}K{sup -}{pi}{sup +}{pi}{sup -}+c.c., K*(892){sup +}K{sup -}{rho}{sup 0}+c.c. and K*(892){sup 0}K{sup -}{rho}{sup +}+c.c. are determined. The first two agree with previous measurements, and the last five are first measurements.

Measurement of χ c J decays to 2(π + π - )pp̄ final states

Abstract: Using ${\ensuremath{\chi}}_{{c}_{J}}\ensuremath{\rightarrow}2({\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})p\overline{p}$ decays from $14\ifmmode\times\else\texttimes\fi{}{10}^{6}\ensuremath{\psi}(2S)$ events accumulated by the BESII detector at the BEPC, the intermediate states ${\ensuremath{\Xi}}^{\ensuremath{-}}{\overline{\ensuremath{\Xi}}}^{+}$, $\ensuremath{\Lambda}\overline{\ensuremath{\Lambda}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, and ${K}_{S}^{0}{K}_{S}^{0}p\overline{p}$ are studied, and their branching ratios or upper limits are measured.

Cosmic Ray Test Certification of the First 100 CMS Endcap RPCs and the Corresponding Construction Database

Abstract: In June 2004, production began for the first set of Resistive Plate Chambers (RPCs), which will be installed in the endcap of the CMS experiment at the CERN Large Hadron Collider (LHC). More than 140 such “RE” chambers have been produced and about 100 of them have been tested with cosmic rays. The detectors are assembled at CERN with gas gaps made in Korea and mechanics manufactured in China. They are equipped with the final front-end electronics, as well as, high/low-voltage distribution and threshold controls. The performance of these chambers in terms of detection efficiency, noise, and cluster size during cosmic ray testing will be described. After these tests, chambers are systematically put on a high voltage stand to monitor the dark current for a longer term. Once certified, the data from each chamber are organized in a MySQL construction database to ensure traceability of key chamber components and measured chamber performance parameters. The stringent quality control and assurance criteria that have been applied for each certified chamber to be installed in CMS will be described.

Experimental study ofψ2Sdecays toK+K−π+π−π0final states

Abstract: ${K}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$ final states are studied using a sample of $14\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $\ensuremath{\psi}(2S)$ decays collected with the Beijing Spectrometer (BESII) at the Beijing Electron-Positron Collider. The branching fractions of $\ensuremath{\psi}(2S)$ decays to ${K}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$, $\ensuremath{\omega}{K}^{+}{K}^{\ensuremath{-}}$, $\ensuremath{\omega}{f}_{0}(1710)$, ${K}^{*}(892{)}^{0}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{0}+\mathrm{c}.\mathrm{c}.$, ${K}^{*}(892{)}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}+\mathrm{c}.\mathrm{c}.$, ${K}^{*}(892{)}^{+}{K}^{\ensuremath{-}}{\ensuremath{\rho}}^{0}+\mathrm{c}.\mathrm{c}.$ and ${K}^{*}(892{)}^{0}{K}^{\ensuremath{-}}{\ensuremath{\rho}}^{+}+\mathrm{c}.\mathrm{c}.$ are determined. The first two agree with previous measurements, and the last five are first measurements.