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 CG: Mini-Symposium on Fundamental Symmetries (Many-body Systems) I |
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Chair: Yasuhiro Sakemi, University of Tokyo Room: Hilton King's 3 |
Wednesday, October 24, 2018 7:00PM - 7:30PM |
CG.00001: Fundamental Symmetry Studies with Atoms and Nuclei Invited Speaker: Timothy Chupp Over recent decades experiment and theory have established the Standard Model of elementary particle interactions and developed a framework for precise calculations. In spite of this success, strong evidence that the Standard Model is incomplete is provided by three specific shortcomings: 1) we do not understand the origin of matter, that is how the early universe evolved to provide more matter than antimatter; 2) we do not know what constitutes the dark matter that comprises most of the mass of the observable universe; 3) we have not specified the quantum mechanics of neutrinos. Fundamental symmetry studies with many body atoms and nuclei contribute crucially to the endeavor of establishing a New Standard Model through the search for new phenomena such as the electric dipole moment (EDM) of atoms and molecules and precision measurements of parameters that may overconstrain and thus challenge Standard Model predictions. The experiments are challenging as they probe new physics complementary to collider searches. Interpreting experimental results to determine or constrain new-physics parameters presents manifold challenges to nuclear and hadronic theory as well. This overview will focus on the common theme of talks in the symposium and what we can learn in the broader context of challenges. |
Wednesday, October 24, 2018 7:30PM - 7:45PM |
CG.00002: The nuclear electric dipole moment Nodoka Yamanaka The electric dipole moment (EDM) of light nuclei is a very sensitive probe of CP violation beyond the standard model which may be measured in future experiment using storage rings. |
Wednesday, October 24, 2018 7:45PM - 8:00PM |
CG.00003: A new measurement of the permanent electric dipole moment of $^{129}$Xe using $^{3}$He comagnetometery and SQUID detection Natasha Sachdeva, Earl Babcock, Martin Burghoff, Timothy Edward Chupp, Skyler Degenkolb, Isaac Fan, Peter Fierlinger, Eva Krageloh, Wolfgang Killian, Florian Kuchler, Silvia Knappe-Gr{\"u}neberg, Tianhao Liu, Michael Marino, Jonas Meinel, Zahir Salhi, Jaideep Singh, Stefan Stuiber, Lutz Trahms, Jens Voigt Permanent electric dipole moment (EDM) measurements of $^{129}$Xe, along with other diamagnetic systems and the neutron, constrain beyond-the-standard-model hadronic CP-violating parameters. In the HeXeEDM experiment, a new technique is used to measure the EDM of $^{129}$Xe with a $^3$He comagnetometer. $^3$He and $^{129}$Xe are polarized using spin-exchange optical pumping, transferred to a measurement cell and transported into a magnetically shielded room. The free precession of both species is detected with SQUID magnetometers in the presence of an applied $2.7-3.3~$kV/cm electric field and a $2.6~\mathrm{\mu T}$ magnetic field. Comagnetometer imperfections are compensated for in combinations of four or eight high-voltage polarity segments. The latest result will be reported. |
Wednesday, October 24, 2018 8:00PM - 8:15PM |
CG.00004: Large-scale shell-model calculation and nuclear Schiff moment of 199Hg Kota Yanase, Koji Higashiyama, Eri Teruya, Naotaka Yoshinaga Nuclear Schiff moments contribute to the atomic electric dipole moments (EDM) of diamagnetic atoms such as mercury. The atomic EDM of 199Hg has been tried to be measured, and the strictest limits on some CP-violating mechanisms have been found. On the other hand, it has been difficult to prepare the nuclear wavefunction and calculate the nuclear Schiff moment accurately, for example, in large-scale shell-model calculations. We have performed large-scale shell-model calculations in neighboring regions on the nuclear chart [1,2]. In this study we establish an effective interaction which can systematically reproduce nuclear energy spectra, electromagnetic transition rates, and electromagnetic moments of the nuclei around 199Hg. Then we calculate the nuclear Schiff moment of 199Hg with the effective interaction developed. [1] E. Teruya, K. Higashiyama, and N. Yoshinaga, “Large-scale shell-model calculations of nuclei around mass 210”, Phys. Rev. C 93, 064327 (2016). [2] K. Yanase, E. Teruya, K. Higashiyama, and N. Yoshinaga, “Shell-model study of Pb, Bi, Po, At, Rn, and Fr isotopes with masses from 210 to 217”, Phys. Rev. C (Accepted 15 June 2018). |
Wednesday, October 24, 2018 8:15PM - 8:30PM |
CG.00005: Time reversal violation in radiative beta decay: experimental progress John A Behr, Tine Valencic, James C McNeil, Melissa J Anholm, Alexandre Gorelov, Dan G. Melconian, Gerald Gwinner, Danny Ashery Some explanations for the excess of matter over antimatter in the universe involve sources of time reversal violation (TRV) in addition to the one known in the standard model of particle physics. We are beginning a search for TRV in a correlation between the momenta of the beta, neutrino, and the radiative gamma sometimes emitted in nuclear beta decay. Correlations involving three (out of four) momenta are sensitive to certain types of TRV physics to which observables involving spin, such as electric dipole moments and spin-polarized beta decay correlations, are less directly sensitive. TRV experiments have been done in radiative kaon decay, but not in systems involving the first generation of quarks. A class of low-energy scale physics models [Gardner and He, Phys. Rev. D 87 116012 (2013)] produces TRV effects by a cross-term with the vector current beta decay of the neutron, tritium, or some positron-decaying isotopes, and such effects grow with lepton momentum and Z. We will present progress towards measuring the TRV asymmetry in radiative beta decay of laser-trapped $^{38m}$K, adding compact gamma-ray detection to TRIUMF's neutral atom trap (TRINAT) for $\beta$-$\nu$ correlations. |
Wednesday, October 24, 2018 8:30PM - 8:45PM |
CG.00006: A new approach to high-precision measurements of the electron EDM using francium atoms Hiroki Nagahama, Tomohiro Hayamizu, Naoya Ozawa, Jun Tsutsumi, Kazuo Tanaka, Kenichi Harada, Aiko Uchiyama, Masatoshi Itoh, Takeshi Inoue, Hirokazu Kawamura, Yasuhiro Sakemi Searching for the permanent electric dipole moment (EDM) of a particle leads to new physics beyond the standard model of particle physics. It is known that the electron EDM is enhanced in heavy paramagnetic atoms; for instance, francium (Fr) atoms, which can be produced by a fusion reaction between oxygen and gold. The electron structure of Fr atoms allows laser-cooling as well as trapping in an optical lattice where high-precision measurements of the electron EDM take place. The number of Fr atoms in an optical lattice is directly related to the precision of the measurements. Therefore, it is important to prepare a large number of Fr atoms in a magneto-optical trap (MOT) prior to transferring them to an optical lattice. Based on the results of trapping Fr atoms with an MOT at Tohoku University’s CYRIC facility, I will present updates on the development of an innovative new experimental apparatus being constructed at RIKEN’s RIBF facility. This new apparatus is designed to realize the largest number of Fr atoms ever trapped with an MOT. |
Wednesday, October 24, 2018 8:45PM - 9:00PM |
CG.00007: Searching for Hadronic CP Violation in Deformed 173Yb with Polyatomic Molecules Nicholas Hutzler, Arian Jadbabaie, Nickolas Pilgram The fact that the universe is made entirely out of matter, and contains no free anti-matter, has no physical explanation. While we cannot currently say what process created the matter in the universe, we know that it must violate CP symmetry, and will induce CP-violating electromagnetic moments in regular matter. We can search for signatures of these electromagnetic moments via precision measurements in polar molecules, whose extremely large internal electromagnetic fields can significantly amplify these moments. These effects would arise from physics beyond the Standard Model, which enables tabletop searches for new, symmetry-violating particles and forces. With modern, quantum science techniques to control polar molecules, these searches can currently reach into the TeV scale, and offer a route to the PeV scale through advanced cooling and trapping techniques. I will discuss a new experiment being developed at Caltech to use polyatomic 173YbOH to search for hadronic CP violation via the nuclear magnetic quadrupole moment of the deformed 173Yb nucleus, which is sensitive to a wide variety of CP-violating sources beyond the Standard Model. |
Wednesday, October 24, 2018 9:00PM - 9:15PM |
CG.00008: Dropping Antimatter: Measuring the Gravitational Free-fall of Antihydrogen as a Test of Einstein’s Equivalence Principle with the ALPHA-g Experiment at CERN Makoto Fujiwara ALPHA-g is a new initiative by the ALPHA Collaboration at CERN. Its goal is to investigate the gravitational behaviour of antihydrogen, the simplest neutral antimatter atoms. Studying gravity in any system is challenging because of its extreme weakness, compared to other fundamental forces in Nature. Gravitational studies of antimatter are particularly challenging, due to its scarcity, and it has prevented thus far any direct measurement of antimatter gravity; no one has ever seen antimatter fall. However, dramatic developments in the past two decades in our ability to synthesize, confine and control antihydrogen, have now made it conceivable to devise an experiment to make a precision measurement of gravity with antimatter. In this talk, I will give an over view of ALPHA-g, and discuss the status of the experiment which is currently under construction with aggressive schedule, aiming at performing first commissioning measurements this fall at CERN. |
Wednesday, October 24, 2018 9:15PM - 9:30PM |
CG.00009: Progress Towards a Measurement of the Fierz Interference in 37K Beta Decay Melissa Anholm, Benjamin B Fenker, John A Behr, Dan Melconian, Danny Ashery, Iuliana Cohen, Alexandre Gorelov, Gerald Gwinner, James C McNeil The TRIUMF Neutral Atom Trap provides a unique environment for precision tests of the standard model. By observing the decay products emerging from a small cloud of cold, spin-polarized 37K, angular correlations can be constructed to measure, eg, the beta asymmetry coefficient [PRL 120, 062502]. This measurement can be generalized to consider scalar and tensor currents, which give rise to the Fierz interference (b_Fierz). While b_Fierz is zero under the standard model, a non-zero b_Fierz would introduce a new beta energy dependence. By constructing the beta asymmetry with the super-ratio technique, many systematic effects cancel out at leading order, while the resulting combination of data remains sensitive to b_Fierz. Because the sensitivity to b_Fierz under this construction scales with the size of the asymmetry parameter, 37K provides significantly better sensitivity than either 19Ne or the free neutron. The collected data carries sufficient statistical weight to determine b_Fierz to within 0.04 of its true value, and an investigation into systematic effects is ongoing. |
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