Bulletin of the American Physical Society
APS April Meeting 2018
Volume 63, Number 4
Saturday–Tuesday, April 14–17, 2018; Columbus, Ohio
Session K14: Precision Measurements and Tests of Fundamental Physics |
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Sponsoring Units: GPMFC Chair: Susan Gardner, University of Kentucky Room: A226 |
Sunday, April 15, 2018 3:30PM - 3:42PM |
K14.00001: Lorentz and CPT Violation in Precision Experiments Yunhua Ding, V. Alan Kostelecky The Lorentz and CPT invariances of relativity are fundamental in physics. However, tiny violation of these invariances could emerge in an underlying unified theory such as strings. This talk focuses on possible experimental effects for Lorentz and CPT violation. In particular, observable signals in measurements from precision experiments involving confined particles and antiparticles will be discussed. Existing measurements are used to extract new and improved bounds on numerous coefficients for Lorentz and CPT violation, and prospects for future experiments are described. [Preview Abstract] |
Sunday, April 15, 2018 3:42PM - 3:54PM |
K14.00002: Status of the "Proton Radius Puzzle" Randolf Pohl The Proton Radius Puzzle [1] is the 5 sigma discrepancy between the proton rms charge radius measured in muonic hydrogen [2] on the one hand, and in regular hydrogen and elastic electron scattering on the other [3]. I will report on several new measurements in muonic and electronic atoms, which have recently started to shed light on the discrepancy. These include measurements in muonic deuterium [4], helium-3 and helium-4, as well as a new measurement in regular hydrogen [5]. In the outlook, I will present ongoing and planned measurements of the CREMA Collaboration targeting the (magnetic) Zemach radius of the proton [6], and the charge radii of other light nuclei. [1] R. Pohl et al., Annu. Rev. Nucl. Part. Sci. 63, 175 (2013) [2] A. Antognini et al., (CREMA Collab.), Science 339, 417 (2013) [3] P. Mohr et al. (CODATA-2014), Rev. Mod. Phys. 88, 035009 (2016) [4] R. Pohl et al., (CREMA Collab.), Science 353, 669 (2016) [5] A. Beyer et al., Science 358, 79 (2017) [6] R. Pohl et al., J. Phys. Soc. Japan Conf. Proc. 18, 011021 (2017) [Preview Abstract] |
Sunday, April 15, 2018 3:54PM - 4:06PM |
K14.00003: Multi-Mode Apparatus to Resolve the Discrepancy Concerning Big G Ian Guerrero, Grace Mattingly, Hilde Isachsen, S.R. Bastin, Charles Hoyle, Ricardo Decca Although the Newtonian gravitational constant, $G$, is arguably one of the most important constants in physics, it is also the one known with the least precision. Modern measurements have high uncertainties and are in disagreement by as much as 0.05 percent, nearly 40 times the uncertainty of the most precise measurement. To address these problems a collaboration between Indiana University-Purdue University Indianapolis (IUPUI), Syracuse University (SU), and Humboldt State University (HSU) will build an experiment designed to lower uncertainties and understand discrepancies between modern measurements. In order to determine $G$, the experiment will follow the work done by Gundlach and Merkowitz, measuring the angular acceleration of a torsion pendulum due to a set of attractor masses. Additionally, multiple measurements will be made using different methods, but within the same apparatus. This approach will provide a means to understand possible systematic errors due to varying methods in previous experiments. In this talk the methods for determining G will be discussed, emphasizing improvements on the metrological aspects. An update on the status of the experimental setup will be presented. [Preview Abstract] |
Sunday, April 15, 2018 4:06PM - 4:18PM |
K14.00004: New source and test masses for G experiments and their metrology Kofi Assumin-Gyimah There are serious inconsistencies in our current knowledge of the universal gravitational constant, $G$ despite a long history of measurements. The scatter in the measured values could be an indication of the incompleteness of general relativity, the current accepted description of gravity, or due to underestimated biases in the metrology of small forces. The metrology of test and source masses, typically made of high density metals, is of prime importance. There are however, some inherent limitations in the previous evaluations of systematic uncertainties associated with them. We propose to address these by developing high density transparent materials such as $PbWO_{4}$, for use in the next generation of experiments. This is motivated by the fact that density variation in glass and single crystals are significantly smaller than in metals and can be measured nondestructively. Consequently, we will develop a laser interferometer for the measurement of the internal density gradients of these masses. All components of the interferometer have been purchased and assembled in the Medium Energy Physics Lab at MSU. Preliminary measurements have begun and we will show some results from a 2x2x12 cm$^3$ $PbWO_{4}$ sample.\\ [Preview Abstract] |
Sunday, April 15, 2018 4:18PM - 4:30PM |
K14.00005: Short-range Tests of Gravitational Physics C.D. Hoyle, Z.D. Comden, N.K. Dunkley, N. Hernandez, H. Isachsen, J.S. Johnson, G.D. Martinez, A.E. Sanchez, J.G. Stillman Scenarios attempting to unify the Standard Model and General Relativity often include features that violate the Weak Equivalence Principle (WEP) and/or gravitational Inverse-Square Law (ISL). A violation of either the WEP or ISL at any length scale would bring into question our fundamental understanding of gravity. Motivated by these considerations, undergraduates and faculty at Humboldt State University are operating an experiment to probe gravitational physics below the 50-micron length scale. The experiment employs a torsion pendulum with equal masses of different material arranged as a ``composition dipole.'' We measure the twist of the torsion pendulum as an attractor mass is oscillated nearby in a parallel-plate configuration, providing a time varying torque on the pendulum. The size and distance dependence of the torque variation provide a means to search for any deviation from the WEP or ISL at untested distance scales. This talk will focus on the analysis of preliminary data and future experimental prospects. [Preview Abstract] |
Sunday, April 15, 2018 4:30PM - 4:42PM |
K14.00006: An experimental search for exotic spin-dependent interactions with a spin-exchange relaxation-free magnetometer Young Jin Kim, Ping-Han Chu, Igor Savukov Many theoretical extensions of the Standard Model of particle physics propose new fundamental bosons such as the axion and axionlike particles, which are prominent dark matter candidates. The exotic particles are very light and can mediate new macroscopic interactions between fermions with an interaction range from micrometers to centimeters. We propose a novel experimental approach to probe the exotic spin-dependent interactions using a spin-exchange relaxation-free (SERF) magnetometer, as both a source of polarized electrons and a detector. The SERF magnetometer is the most sensitive cryogen-free magnetic sensor reaching femtotesla sensitivity, and it contains a large number of alkali atoms in a vapor cell as the source of almost 100 {\%} optically polarized electrons. This approach aims to detect magnetic-field like effects from the exotic interactions between the SERF polarized electrons and atoms of a solid-state mass. Based on our analysis and preliminary studies, we estimate that this novel method can improve the previous experimental limits from a few existing experiments and set new limits on most interactions in the interaction range below 1 cm. [Preview Abstract] |
Sunday, April 15, 2018 4:42PM - 4:54PM |
K14.00007: A New Quantum Eraser Using Hyperentanglement Hyung Choi, Draven Houser, Dustin Swarm We propose a new type of quantum eraser using hyperentangled photon pairs. Whereas a typical quantum eraser makes use of photons that are entangled in a single quantum state, usually in polarization, our new quantum eraser exploits entanglements in both polarization and momentum states. In a typical quantum eraser one gains ``which-path" information of one photon by changing the polarization measurement of the other. This results in ``erasing" the interference pattern previously obtained through indistinguishability of paths. In our new quantum eraser we gain information about the momentum state of one photon by changing the polarization of the other photon in one of its momentum states. The knowledge of the momentum state then ``erases" the interference pattern previously obtained in the coincident counts of the photon pairs. This new quantum eraser may readily be implemented using photon pairs produced by Type-I Parametric Down Conversion. To achieve extra entanglement in momentum states, we simply subject them to pass through two distinguishable sets of pinholes and then recombine them before they reach polarization detectors. [Preview Abstract] |
Sunday, April 15, 2018 4:54PM - 5:06PM |
K14.00008: On a Mirror Structure of Matter Fields Rasulkhozha S. Sharafiddinov Spontaneous mirror symmetry violation is carried out in nature as the transition between the usual left (right)-handed and the mirror right (left)-handed spaces, where the same particle has the different lifetimes. As a consequence, all the equations of motion for the unified field theory of elementary particles include the mass, energy and momentum as the matrices expressing the ideas of the left- and right-handed neutrinos are of long- and short-lived objects, respectively. These ideas require in principle to go away from the chiral definitions of the structure of matter fields taking into account that the Dirac matrices come forward in the Weyl presentation as the matrices having an exact mathematical formulation but not allowing to follow the logic of a true nature of mirror symmetry including the dynamical origination of its spontaneous violation. Therefore, from the point of view of the mass, energy and momentum matrices, each of the structural contradictions between the spontaneous mirror symmetry violation and the chiral presentation of the Weyl must be interpreted as an indication to the absence in nature of a place for chirality. [Preview Abstract] |
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