Bulletin of the American Physical Society
84th Annual Meeting of the APS Southeastern Section
Volume 62, Number 13
Thursday–Saturday, November 16–18, 2017; Milledgeville, Georgia
Session G1: Precision Tests of Low Energy QCD |
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Chair: Liping Gan, University of North Carolina Wilmington Room: MSU Building University Banquet Room A |
Friday, November 17, 2017 1:30PM - 2:00PM |
G1.00001: Low Energy Tests of QCD Invited Speaker: Jose Goity This talk will present a summary of key tests of QCD at low energy. These include decays that test the axial anomalies, and symmetry breaking corrections to those decays, the scattering lengths in $\pi-\pi$ scattering and $\pi-N$ scattering, and the $\sigma$ terms. Features of violations of SU(3) symmetry in baryons are also discussed. [Preview Abstract] |
Friday, November 17, 2017 2:00PM - 2:30PM |
G1.00002: PrimEx II Results: Precision Measurement of the Neutral Pion Lifetime Invited Speaker: Ilya Larin The PrimEx experiments in Hall B at Jefferson lab were aimed to perform a precision measurement of the $\pi^{\mathrm{0}}\to \gamma \gamma $ decay width via Primakoff effect. A combination of a state-of-the-art high resolution lead tungstate hybrid electromagnetic calorimeter and a tagged photon beam offered a great advantage in reducing experimental uncertainties. The published result from the first (PrimEx I) experiment has 2.8{\%} accuracy. The second (PrimEx II) experiment with several times more statistics than the PrimEx I and an improved systematics was aimed to achieve a better than 2.0{\%} precision. An updated PrimEx II result will be presented. [Preview Abstract] |
Friday, November 17, 2017 2:30PM - 3:00PM |
G1.00003: A Precision Measurement of the $\eta$ Radiative Decay Width via the Primakoff Effect Invited Speaker: Alexander Somov The GlueX detector in the experimental Hall-D at Jefferson Lab provides a unique capability to perform a measurement of the $\eta \to \gamma \gamma$ decay width via the Primakoff effect with the precision significantly better than all existing collider and Primakoff results. The experiment will measure differential cross sections of $\eta$ mesons at forward angles on a liquid hydrogen and ${}^{4}{\rm He}$ targets using a beam of tagged photons, which will be used for the extraction of the decay width. The measurement is essential for the determination of the fundamental properties such as the ratios of the light quark masses and the $\eta$-$\eta^\prime$ mixing angle, and will provide an important test of chiral symmetry breaking in QCD. The experimental results will also allow to significantly reduce uncertainties on partial widths of all other $\eta$ decays. We will give an overview of the PrimEx-D physics program and experimental setup. [Preview Abstract] |
Friday, November 17, 2017 3:00PM - 3:30PM |
G1.00004: Measuring the Charged Pion Polarizability in the $\gamma\gamma\rightarrow\pi^{+{}}\pi^{-{}}$ Reaction Invited Speaker: David Lawrence A new measurement of the charged pion polarizability $\alpha_{\pi}-\beta_{\pi}$ is approved to run at Jefferson Lab using the GlueX detector in experimental Hall D. The charged pion polarizability ranks among the most important tests of low-energy QCD presently unresolved by experiment. Analogous to precision measurements of $\pi^{0}\rightarrow\gamma\gamma$ that test the intrinsic odd-parity (anomalous) sector of QCD, the pion polarizability tests the intrinsic even-parity sector of QCD. The $\gamma\gamma\rightarrow\pi^{+{}}\pi^{-{}}$ cross section will be accessed via the Primakoff mechanism on a nuclear target. The linearly polarized photon source in Hall D will allow the separation of the Primakoff cross section from coherent $\rho^{0}(770)$ production. An additional detector will also need to be constructed to help distinguish $\pi^{+{}}\pi^{-{}}$ and $\mu^{+{}}\mu^{-{}}$ events. An update on the status of the experiment will be given. [Preview Abstract] |
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