Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session 2WDA: Fundamental Physics at Low Energy III |
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Chair: David Hertzog, University of Washington Room: Hilton Kohala 3 |
Tuesday, October 23, 2018 2:00PM - 2:30PM |
2WDA.00001: The Hadronic Weak Interaction: Results, Opportunities and Challenges. Invited Speaker: David Bowman I give the results of two new experiments: the directional gamma asymmetry from polarized neutrons capturing on parahydrogen and the directional asymmetry of protons from the reaction of polarized neutrons with $^3$He. These and other parity violating (PV) asymmetries result from the weak interaction of nucleons, the hadronic weak interaction (HWI). In principal PV asymmetries are directly calculable from the standard model, but the difficulties of quantum chromodynamics put direct calculation beyond reach. I discuss two models which describe the HWI in terms of nuclear degrees of freedom: the meson exchange model introduced by Desplanques, Donoghue and Holstein and pionless effective field theory as developed by Schindler, Springer and Vanasse. The parameters of these models can be categorized according to expansions in 1/N$_c$, the number of colors. I discuss the results of efforts to extract the parameters of these models from available data and compare with the predictions of 1/N$_c$ expansions. There is qualitative agreement can be obtained my applying reasonable theoretical constraints that reduce the number of degrees of freedom. I argue that in order to make further progress experimental and theoretical work in exactly calculable systems is necessary. I discuss possible experiments in two and few-body systems. |
Tuesday, October 23, 2018 2:30PM - 3:00PM |
2WDA.00002: Discrete symmetry in compound nuclei Invited Speaker: Masaaki Kitaguchi We are discussing new approach to search for the time reversal symmetry violation, which is different from EDM experiments. The large enhancement of parity violation of the weak interaction contained in the nuclear interaction was discovered for some nuclei in the 1980's. The enhancement was explained as the result of the entrance channel interference between neighboring partial wave amplitudes. The enhancement of T-violation is also predicted with the same mechanism. The advantage to apply the mechanism is that takes T-odd effects due to the final-state interaction is expected to be negligibly small as the neutron propagation through the target material can be described by the neutron optics. The enhancement can be estimated by measuring the angular correlation terms of (n, γ) reaction according to s-p mixing theory with statistical treatments in the compound nuclei. We are continuing measurements of the (n, γ) reactions of the candidate nuclei at J-PARC. Intense pulsed neutrons and high energy-resolution germanium detectors enables us to measure the partial neutron width only with the γ-rays corresponding to the well-known spin-states in order to extract the enhancement factor. The T-violation search experiment requires the polarized neutron beam, the polarized nuclear target, and epithermal neutron detector. The research and development for the T-violation search experiment has also started. In the presentation, we will discuss the feasibility of the experiment at J-PARC. |
Tuesday, October 23, 2018 3:00PM - 3:30PM |
2WDA.00003: Hadronic light-by-light contributions to muon g-2 Invited Speaker: Christoph Lehner Anticipating the experimental improvements of Fermilab E989 and JPARC E34, an improvement of theory uncertainty for the hadronic contributions to the anomalous magnetic moment is needed. I will review the current status of theory calculations of the hadronic light-by-light contributions to the muon g-2. I will focus on first-principles methods such as the dispersive and lattice approaches.
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Tuesday, October 23, 2018 3:30PM - 4:00PM |
2WDA.00004: COFFEE BREAK
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