Bulletin of the American Physical Society
78th Annual Meeting of the Southeastern Section of the APS
Volume 56, Number 9
Wednesday–Saturday, October 19–22, 2011; Roanoke, Virginia
Session EA: Physics at Jefferson Lab |
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Chair: Romulus Godang, University of South Alabama Room: Crystal Ballroom A |
Thursday, October 20, 2011 3:45PM - 4:15PM |
EA.00001: Qweak: A Precision Standard Model Test at Jefferson Lab Invited Speaker: The Qweak collaboration is currently performing the first precision measurement of the proton's neutral weak charge at Jefferson Lab. The Standard Model gives a firm prediction for the weak charge; any deviation from that can be interpreted as new physics beyond the Standard Model. This precision, low energy measurement is sensitive to new physics signatures at energy scales up to 2 TeV. The experiment measures the parity-violating asymmetry in the scattering of longitudinally polarized electrons on the proton at low momentum transfer. An overview of the motivation and experimental approach will be presented, along with an update on the current status. [Preview Abstract] |
Thursday, October 20, 2011 4:15PM - 4:45PM |
EA.00002: Hadron Spectroscopy at Jefferson Lab: Search for new States of Hadronic Matter Invited Speaker: Hadrons are complex systems of confined quarks and gluons and exhibit the characteristic spectra of excited states. Quantum Chromodynamics (QCD) is only poorly understood in this non-perturbative regime. It is one of the key issues in hadronic physics to identify the relevant degrees of freedom giving rise to the observed mass spectra and the effective forces between them. Current efforts of the CLAS Collaboration at Jefferson Lab focus on the search for new baryon resonances utilizing polarized beams and targets. A further particular interesting question in hadron spectrosocpy concerns the role of glue and how this is related to the confinement in QCD. I will briefly discuss the efforts of the GlueX Collaboration to search for new forms of hadronic matter beyond simple quark-antiquark systems. [Preview Abstract] |
Thursday, October 20, 2011 4:45PM - 5:15PM |
EA.00003: High Precision Measurement of the $\pi ^{0}$ Radiative Decay Width Invited Speaker: As the lightest particle in the hadron spectrum, the $\pi ^{0}$ plays an important role in understanding the fundamental symmetries of QCD. The $\pi ^{0}\to \gamma \gamma $ decay provides a key process for test of the chiral anomaly, and at the same time a test of the Nambu-Goldstone nature of the $\pi ^{0}$ meson due to spontaneous chiral symmetry breaking. Theoretical activities over the last decade have resulted in high precision (1{\%} level) predictions for the decay amplitude of the $\pi ^{0}$ into two photons. The experimental measurement of this parameter with a comparable precision will be critical to test these important QCD predictions. The PrimEx collaboration at Jefferson Lab has developed and performed new experiments to measure the $\pi ^{0}$ radiative decay width via the Primakoff effect. A new level of experimental precision has been achieved by implementing the high intensity and high resolution photon tagging facility and by developing a novel, high resolution, electromagnetic hybrid calorimeter (HYCAL). A recently published result from the first experimental data (PrimEx-I) with a 2.8{\%} total uncertainty is a factor of 2.5 more precise than the current Particle Data Group average. The second experiment (PrimEx-II) was carried out in fall 2010 with the final goal of 1.4{\%} precision. The result of PrimEx-I and the status of PrimEx-II will be presented. [Preview Abstract] |
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