Bulletin of the American Physical Society
2016 Fall Meeting of the APS Division of Nuclear Physics
Volume 61, Number 13
Thursday–Sunday, October 13–16, 2016; Vancouver, BC, Canada
Session CC: Mini-symposium on Light Meson Spectroscopy: First Results from GlueX IMini-Symposium
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Chair: Zisis Papandreou, University of Regina Room: Junior Ballroom B |
Friday, October 14, 2016 8:30AM - 9:06AM |
CC.00001: Light Meson Spectroscopy: First Results from GlueX Invited Speaker: Matthew Shepherd The GlueX experiment is optimized to search for and study light hybrid mesons utilizing a 9~GeV linearly polarized photon beam that is derived from the 12~GeV electron beam of the recently upgraded CEBAF at Jefferson Lab. Construction of the GlueX detector was completed in winter 2015, and it was commissioned and calibrated using data collected in 2015 and 2016. During the spring of 2016 the first substantial data acquisition period was conducted with the detector and beamline in its design configuration. The data from this pilot physics run exceed the statistical capability of existing polarized photoproduction data sets in this energy regime by orders of magnitude. In this talk the broad objectives of the GlueX physics program will be reviewed along with the status and performance of the detector. Ongoing data analysis activities will be summarized, and the plan for both additional data acquisition and analysis to pursue the goal of searching for hybrid mesons will be outlined. [Preview Abstract] |
Friday, October 14, 2016 9:06AM - 9:18AM |
CC.00002: Single Meson Photoproduction at JLab Energies Vincent Mathieu In this talk, I present the results from the Joint Physics Analysis Center about the photoproduction of a single meson (pseudoscalar or vector meson). We have developed the theoretical formalism to analysis forthcoming data at the, recently upgraded, JLab facility. We also present prediction for observables in the energy range of Eg = 5-11 GeV. Material (codes, notes, sim- ulations, etc) can be found online at the JPAC interactive website: http://www.indiana.edu/ jpac/index.html [Preview Abstract] |
Friday, October 14, 2016 9:18AM - 9:30AM |
CC.00003: Photoproduction of the $\rho^0$(770) meson at GlueX Alexander Austregesilo The GlueX experiment at Jefferson Lab was designed to study the spectrum of light mesons with a 9$\,$GeV linearly-polarized photon beam. The data recorded during its final commissioning run in spring 2016 already outperforms previous experiments in terms of both quantity and quality, and can provide valuable measurements of single-meson photoproduction. We will present preliminary results for the reaction $\gamma\,p \rightarrow \rho^0(770)\,p$, where the linearly-polarized photon beam asymmetry independently confirms the beam polarization measurement. Furthermore, the production mechanism is studied using the spin density matrix elements and their dependence on the squared four-momentum transfer to the target. [Preview Abstract] |
Friday, October 14, 2016 9:30AM - 9:42AM |
CC.00004: Beam asymmetry $\Sigma$ for $\pi^0$ and $\eta$ photoproduction on the proton at GlueX Zhenyu Zhang Measurements of meson photoproduction at high energies began almost 50 years ago with bubble chamber experiments at SLAC, DESY, and Cambridge. These data have been successfully described through Regge theory in terms of $t$-channel quasi-particle exchange. High statistics measurements of pseudoscalar meson photoproduction at GlueX, using the 9 GeV linearly-polarized, tagged photon beam in Jefferson Lab's Hall D, will provide important new constraints on these Regge models. These measurements will test our understanding of the photoproduction mechanism at high energy, which is a necessary first step toward the broader meson spectroscopy program at GlueX. Through finite energy sum rules, these measurements can also impose new constraints on the extraction of nucleon resonances from low energy photoproduction data. In this talk, preliminary results for the linearly polarized photon beam asymmetry $\Sigma$ for the exclusive reactions $\gamma p \rightarrow p \pi^0$ and $\gamma p \rightarrow p\eta$ will be presented. These are the first measurements of the $\eta$ beam asymmetry at these energies. [Preview Abstract] |
Friday, October 14, 2016 9:42AM - 9:54AM |
CC.00005: Photoproduction of ππ Resonances at GlueX Jonathan Zarling The spectrum of excited $\rho$ mesons has long been a topic of interest. Recently, studies of the charmonium spectrum have revealed an apparent overabundance of vector mesons. In addition, lattice QCD calculations predict hybrid mesons with vector quantum numbers. This has generated a renewed interest in study of vector mesons composed of light quarks, where one might hope to draw parallels with charmonium and search for hybrid mesons. The GlueX experiment at Jefferson Lab, utilizing a linearly polarized photon beam near 9 GeV, is poised to improve knowledge of the spectrum of excited light vector mesons. In particular, we propose to study the reactions γ p→ $π^{+} π^{-}$ p and γ p→ $π^{0} π^{0} p$. While the vector mesons are expected to dominate the $π^{+} π^{-}$ channel, the $π^{0} π^{0}$ channel can be used to constrain the tensor and scalar components of the pi pi production. Together these should allow an exploration of $\pi\pi$ resonances, including excited $\rho$ mesons. [Preview Abstract] |
Friday, October 14, 2016 9:54AM - 10:06AM |
CC.00006: ABSTRACT WITHDRAWN |
Friday, October 14, 2016 10:06AM - 10:18AM |
CC.00007: Analysis of the $\eta(548)~\rightarrow~\pi^+~\pi^-~\pi^0$ and $\eta^\prime(958)~\rightarrow~\pi^+~\pi^-~\eta$ channels using a 8-9 GeV tagged photon beam for the GlueX Experiment Tegan Beattie, Zisis Papandreou, Justin Stevens The primary goal of the GlueX experiment is to conduct a definitive mapping of states in the light meson sector with an emphasis on searching for exotic hybrid mesons as evidence of gluonic excitations. The experiment, housed in the Hall-D facility at Jefferson Lab following its accelerator upgrade to 12 GeV, is now entering the physics data taking phase. The $\eta(548)$ and $\eta^\prime(958)$ mesons are two of the richest unflavoured light mesons readily available at GlueX energies for studying resonances. Many other light mesons have decay channels involving the $\eta$ mesons with significant branching ratios, and $\pi\eta$/$\pi\eta^\prime$ resonances are among the top contenders for possibly-accessible exotic and hybrid resonances which GlueX aims to study. As such, the ability to reconstruct pure $\eta$/$\eta^\prime$ samples and analyze their decays is of utmost importance for understanding future work on more complicated analyses. Preliminary analysis results from commissioning data will be presented. [Preview Abstract] |
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