arXiv subjects

Frederick A. Harris

Publications and source records attributed to Frederick A. Harris.

12 recordsLinked to original sources

arXiv2016

Physics Accomplishments and Future Prospects of the BES Experiments at the BEPC Collider

The cornerstone of the Chinese experimental particle physics program consists of a series of experiments performed in the tau-charm energy region. China began building e+e- colliders at the Institute for High Energy Physics in Beijing more than three decades ago. Beijing Electron Spectrometer, BES, is the common root name for the particle physics detectors operated at these machines. The development of the BES program is summarized and highlights of the physics results across several topical areas are presented.

hep-ex↗

arXiv2010

Charmonium in China: BEPCII/BESIII

Results based on 106 M $ψ'$ events and about 226 M $J/ψ$ events acquired with the BESIII detector at BEPCII are reported, including a confirmation of the BESII $p\bar{p}$ threshold enhancement in $J/ψ\to γp\bar{p}$, branching ratios for $χ_{cJ} \to π^0 π^0$ and $ηη$, and first measurements of the branching ratios for $ψ' \to π^0 h_c$ and $h_c \to γη_c$, as well as measurements of the mass and width of the $h_c$. Also reported are first observations of the two photon process $ψ' \to γγJ/ψ$ and $f_0(980) - a_0(980)$ mixing.

hep-ex↗

arXiv2008

Light Hadron Spectroscopy and Charmonium

During the last few years there has been a renaissance in charm and charmonium spectroscopy with higher precision measurements at the $ψ^{'}$ and $ψ(3770)$ coming from BESII and CLEOc and many new discoveries coming from B-factories. In this paper, I review some new results on "classical" charmonium and $e^+ e^- \to$ hadrons using B-factory Initial State Radiation and two photon events.

hep-ex↗

arXiv2008

Bepcii and Besiii

The Beijing Electron Collider has been upgraded (BEPCII) to a two-ring collider with a design luminosity of $1 \times 10^{33}$cm$^{-2}$ s$^{-1}$ at a center-of-mass energy of 3.78 GeV. It will operate between 2 and 4.6 GeV in the center of mass. With this luminosity, the BESIII detector will be able to collect, for example, 10 billion $J/ψ$ events in one year of running. This will be a unique facility in the world opening many physics opportunities. BEPCII and BESIII are both currently being commissioned, first events have been obtained, and data taking will take place in fall 2008.

physics.ins-det↗

arXiv2007

Recent BES results and the BESIII upgrade

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 $ψ(2S) \to Λ\barΛ π^0$ and $Λ\barΛ η$ are measured, and the decays of $J/ψ$ and $ψ(2S)$ to $n K^0_S \barΛ+c.c.$ are observed and measured for the first time. Finally, $R$ measurement data taken with the BESII detector at center-of-mass energies between 3.7 and 5.0 GeV are fitted to determine resonance parameters of the high mass charmonium states, $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, and $ψ(4415)$. The Beijing Electron Collider is being upgraded to a two-ring collider (BEPCII) with a design luminosity of $1 \times 10^{33}$cm$^{-2}$ s$^{-1}$ at 3.89 GeV and will operate between 2 and 4.2 GeV in the center of mass. With this luminosity, the new BESIII detector will beable to collect, for example, 10 billion $J/ψ$ events in one year of running. BEPCII and BESIII are currently nearing completion, and commissioning of both is expected to begin in mid-2008.

hep-ex↗

arXiv2006

Charmonium Review

hep-ex↗

arXiv2006

BEPCII and BESIII

The Beijing Electron Collider is being upgraded (BEPCII) to a two-ring collider with a design luminosity of $1 \times 10^{33}$cm$^{-2}$ s$^{-1}$ at a center-of-mass energy of 3.89 GeV. It will operate between 2 and 4.2 GeV in the center of mass. With this luminosity, the BESIII detector will be able to collect, for example, 10 billion $J/ψ$ events in one year of running. This will be a unique facility in the world opening many physics opportunities. BEPCII and BESIII are currently under construction, and commissioning of both is expected to begin in summer 2007.

physics.ins-det↗

arXiv2004

BES Results on Charmonium Decays and Transitions

Results are reported based on samples of 58 million $J/ψ$ and 14 million $ψ(2S)$ decays obtained by the BESII experiment. Improved branching fraction measurements are determined, including branching fractions for $J/ψ\toπ^+π^-π^0$, $ψ(2S)\to π^0 J/ψ$, $ηJ/ψ$, $π^0 π^0 J/ψ$, anything $J/ψ$, and $ψ(2S)\toγχ_{c1},γχ_{c2}\toγγ\jpsi$. Using 14 million $ψ(2S)$ events, $f_0(980)f_0(980)$ production in $χ_{c0}$ decays and $K^*(892)^0\bar K^*(892)^0$ production in $χ_{cJ}~(J=0,1,2)$ decays are observed for the first time, and branching ratios are determined.

hep-ex↗

arXiv2004

BES Results on J/psi decays and Charmonium Transitions

Results are reported based on samples of 58 million $\jpsi$ and 14 million $\psip$ decays obtained by the BESII experiment. Improved branching fraction measurements are determined, including branching fractions for $\jpsi\to\ppp$, $\psip\ra π^0\J$, $η\J$, $π^0 π^0 J/ψ$, anything $J/ψ$, and $ψ(2S)\arγχ_{c1},γχ_{c2}\arγγ\jpsi$. The decay $J/ψ\to ωπ^+π^-$ is studied. At low $ππ$ mass, a large, broad peak due to the $σ$ is observed, and its pole position is determined. Results are presented on $ψ(2S)$ and $J/ψ$ hadronic decays to $K^0_SpK^-\bar n$ and $K^0_S\bar p K^+n$ final states. No significant $Θ(1540)$ signal, the pentaquark candidate, is observed, and upper limits are set. An enhancement near the $m_p + M_Λ$ mass threshold is observed in the $p\barΛ$ invariant mass spectrum from $J/ψ\to p K^- \barΛ + c.c.$ decays. It can be fit with an S-wave Breit-Wigner resonance with a mass $m=2075\pm 12 (stat) \pm 5 (syst)$ MeV and a width of $Γ=90 \pm 35 (stat) \pm 9 (syst)$ MeV.

hep-ex↗

arXiv2003

Recent BES charmonium results

Using 58 million $J/ψ$ decays, we have investigated the $p \bar{p}$ invariant mass spectrum in the radiative decay $J/ψ\to γp \bar{p}$ and observe a prominent structure with mass near $2m_p$. Fitting with an S-wave Breit-Wigner, we obtain a peak mass of $M= 1859^{+3}_{-10}(\rm stat)^{+5}_{-25}(sys) MeV/c^2$. $J/ψ\to γη_c$ decays from the same sample are used to determine the mass, width, and hadronic branching ratios of the $η_c$. From a sample of 14 million $ψ(2S)$ events, the first observation of $χ_{cJ}$ (J=0,1,2) decays to $Λ\barΛ$ is made, and branching ratios are determined, which are larger than expected from the Color Octet Model. Branching ratios of $K_s^0K_L^0$ in both $ψ(2S)$ and $J/ψ$ decays are measured, and a more than four sigma deviation from the pQCD predicted "12% rule" is observed. In $ψ(3770)$ decays, evidence for the non-$D\bar{D}$ decay to $π^+π^-J/ψ$ is observed.

hep-ex↗

arXiv2003

Recent Charmonium Physics from BES

Measurements of branching fractions for nine different final states, based on a data sample of approximately 4 million psi(2S) events collected with the BESI detector at the BEPC, are reported. Using the same event sample, radiative decays of the psi (2S) into pi pi, K K-bar and eta eta final states have been measured. Cross sections for e e -> e e, hadrons, pi pi J/psi, and mu mu have been measured in the vicinity of the psi(2S) resonance using the BESII detector. The psi(2S) total width; partial widths to hadrons, pi pi J/psi and muons; and corresponding branching fractions have been determined. Decays of J/psi -> gamma eta_c are used to determine the mass and width of the eta_c using a sample of 58 M J/psi events. $M_{η_c} = (2977.5 \pm 1.0 \pm 1.2)$ MeV and $Γ_{η_c} = (17.0 \pm 3.7 \pm 7.4)$ MeV. The first observation of chicJ (J=0,1,2) decays to lambda lambda-bar is reported using psi(2S) data collected with the BESII detector. Results are compared with model predictions.

hep-ex↗

arXiv1999

Recent Charmonium Results from BES

This paper summarizes recent results obtained from the BES psi(2S) data, which with 3.8 M events, is the world's largest data set. Distributions for psi(2S) -> pi^+ pi^- J/psi are fit to the Novikov-Shifman model. Preliminary branching fractions are reported for psi(2S) -> gamma f_2(1270) and gamma f_J(1710), as well as for decays into states containing an omega or phi. Finally recent measurements of the mass of the chi_c0 and eta_c are reported.

hep-ex↗