Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session T66: Frontiers in Fundamental Physics IRecordings Available

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Chair: David Singh, University of Missouri Room: Hyatt Regency Hotel Grant Park D 
Thursday, March 17, 2022 11:30AM  11:42AM 
T66.00001: Numerical Studies of OneDimensional Gratings of Heliconical Liquid Crystals Sha Liu, QiHuo Wei Numerical Studies of OneDimensional Gratings of Heliconical Liquid Crystals 
Thursday, March 17, 2022 11:42AM  11:54AM 
T66.00002: Length scale formation and the localization in the Landau levels of quasicrystals Junmo Jeon, Moon Jip Park, SungBin Lee The quasicrystals have motivated extensive studies of quantum phenomena such as critical states. Nevertheless, the Landau levels of quasicrystals have been barely understood because of the complication of tilings without periodic length scales. Thus, it has been thought that the system cannot possess any universal features of the Landau levels. Contrary to these assertions, we discuss new quantum phenomena in quasicrystals where electrons localization behavior is distinct in short and large length scales under magnetic fields. In short length scales, electrons are completely localized forming islands with a certain radius, however, in large length scales, such localized islands are extensively distributed and interfere with each other under field control. In the twodimensional rhombic quasicrystals with rotational symmetries, we derive exact flux conditions and the localization length for such electron localization. Furthermore, macroscopically degenerate zeroenergy Landau levels are present due to the chiral symmetry of the rhombic tilings. This gives an important message that the critical state can be completely removable under a magnetic field and the emergence of such quantum states can be applied to control the fractality of electron wave functions in quasicrystals. 
Thursday, March 17, 2022 11:54AM  12:06PM 
T66.00003: Emptiness Formation in Polytropic Quantum Liquids HsiuChung Yeh, Dimitri M Gangardt, Alex Kamenev We study large deviations in interacting quantum liquids with the polytropic equation of state P(ρ) ∼ ρ^{γ} , where ρ is density and P is pressure. By solving hydrodynamic equations in imaginary time we evaluate the instanton action and calculate the emptiness formation probability (EFP), the probability that no particle resides in a macroscopic interval of a given size. Analytic solutions are found for a certain infinite sequence of rational polytropic indexes γ and the result can be analytically continued to any value of γ ≥ 1. Our findings agree with (and significantly expand on) previously known analytical and numerical results for EFP in quantum liquids. We also discuss interesting universal spacetime features of the instanton solution. 
Thursday, March 17, 2022 12:06PM  12:18PM 
T66.00004: Theoretical Investigation of Resonance Energy Transfer Using Discrete and Continuous Donor and Acceptor Models Yeonjun Jeong, Marc R Bourgeois, Charles Cherqui, Suyog Padgaonkar, Paul T Brown, Kobra N Avanaki, Rafael LópezArteaga, Shawn IrgenGioro, Yue Wu, Vinod K Sangwan, Marc C Hersam, Emily A Weiss, George C Schatz Resonance energy transfer (RET) is the transport of electronic energy from an excited atom or molecule to another. Besides being an essential process in photosynthesis, RET presents useful applications such as spectroscopic nanoruler and photosensitization of semiconductors. In this study, we investigate the ways to harness high RET rates using various models. First, we consider systems that consist of a single donoracceptor pair and a metal nanoparticle (NP) to identify the geometrical factors that maximize RET rates when the donoracceptor pair is coupled to the plasmonenhanced nearfield. It is demonstrated that conversely, rate information can be used to obtain geometrical information of nanophotonic systems. Then, it is shown that RET involving multiple donors may invoke collective mechanisms that give rise to higher RET efficiency, exemplified by activation of surface lattice resonance (SLR) modes and energy transfer among the donors. Finally, energy transfer from a medium consisting of donors as a fourlevel system to a medium of acceptors as a twolevel system is described by solving integral equations involving polarization and electric field. 
Thursday, March 17, 2022 12:18PM  12:30PM 
T66.00005: Bootstrap bounds on conformal field theories with LiebSchultzMattis anomalies Ryan A Lanzetta, Lukasz Fidkowski We put bounds on 1+1d conformal field theories (CFTs) that saturate certain mixed anomalies arising in spin chains subject to the LiebSchultzMattis (LSM) theorem using conformal bootstrap techniques. To do this, we will present a new hybrid bootstrap approach, which augments modular bootstrap by additionally imposing crossing symmetry on correlation functions of certain symmetry defect operators. The hybrid bootstrap accounts for a more complete picture of 't Hooft anomalies of discrete symmetries in 1+1d CFTs than modular bootstrap alone and still gives universal bounds on local operators. In particular, we will present universal bounds on charged operators, some of which are only possible with our hybrid approach. Our bounds exhibit distinctive kinks, some of which are approximately saturated by known theories such as the su(3) level 1 WZW model, and others which are unexplained. 
Thursday, March 17, 2022 12:30PM  12:42PM 
T66.00006: Static and Dynamics Evolution of Chargecarriers in Shape Engineered Metal Halide Perovskite Nanocrystals SANTU K BERA, Suman Bera, Narayan Pradhan, K V Adarsh Metal halide perovskites (MHPs) nanocrystals (NCs) with their unique structure and exotic properties, emerged as promising and potential material for highly efficient and low costing photovoltaics and optoelectronic applications. For their wide and diverse applications, it is desirable to engineer and tune their properties, which is achieved previously via cationanion exchange, doping and variation in size. Herein we study the photophysics of CsPbBr_{3 }NCs by engineering their shape from usual cubic to rhombicdodecahedrons and rhombicuboctahedron by steady state and time resolved spectroscopy. In our analysis we observe a remarkably contrasting behaviour of dynamic BursteinMoss effect (BME) and amplified spontaneous emission (ASE). The BME is observed in the cubic and rhombicdodecahedrons NCs with shift 24 and 20 meV respectively, on the other hand ASE appeared only in rhombicuboctahedron NCs. Further it is observed that secondorder decay is the major channel for carrier recombination with the rate of 3.68×10^{10}, 3.65×10^{10} and 2.03×10^{10} cm^{3} s^{1} in cubic, rhombicdodecahedrons and rhombicuboctahedron. These results offer insights into intrinsic photophysics in MHPs with direct implications for photovoltaic and optoelectronic applications by engineering shape of NCs. 
Thursday, March 17, 2022 12:42PM  12:54PM 
T66.00007: Universal empirical and theoretical for an updated compilation of K xray production cross sections by protons Gregory Lapicki, Department of Physics, East Carolina University, Greenville NC 27858, USA Gregory Lapicki The relevance of xray production cross sections (XRPCS) and the related ionization cross sections (ISC) in many research areas has been described at length and analyzed in detail [1]. Xray emission cross sections by ion impact are a relevant input in many areas such as studies of track structure in biological matter. Particle Induced Xray Emission (PIXE) strongly requires trustworthy databases for XRPCS and/or reliable predictions of innershell ionization theories as periodically evaluated in Monte Carlo Geant4 simulations [2]. To check if theories are accurate across the periodic table of elements and a large range of projectile energies, equally comprehensive databases are essential and a universal fit for them is desired. 
Thursday, March 17, 2022 12:54PM  1:06PM 
T66.00008: Identification of Higgs boson events from the background by machine learning. OuraniaMaria GlezakouElbert, Savannah Thais Almost a decade since its detection in the Large Hadron Collider, the Higgs boson remains a key component in the confirmation of the standard model (SM) of particle physics. Current experimental efforts to determine the Higgs boson decay channels, predicted by the SM, rely on the accurate identification of Higgs boson events from a noisy background. Machine learning methods have emerged as new ways to accurately classify rare events present in large datasets. This study compares three supervised classification models in their ability to accurately and efficiently identify signal events: (i) boosted decision trees, (ii) support vector machine, and (iii) neural networks. With an accuracy of 83.88%, F1score of 81.72% and a training time of 8.4 seconds using the simulated dataset from the 2014 ATLAS Higgs boson Machine Learning Challenge, a histogram gradient boosted decision tree was determined to be the most effective classification model for identifying Higgs boson events. The worst performing algorithm was the support vector machine with the lowest accuracy at 80.35%, F1score of 77.12%, and the second lowest training time of 50 minutes. 
Thursday, March 17, 2022 1:06PM  1:18PM 
T66.00009: ThreeDimensional Real Space Invariants: Theory and Applications Yuanfeng Xu, Luis Elcoro, Guowei Li, Zhida Song, Nicolas Regnault, Qun Yang, Yan Sun, Stuart S Parkin, Claudia Felser, Andrei B Bernevig In this work, we have developed the threedimensional real space invariants (3D RSIs) for all the 1,651 Shubnikov space groups (SSGs) with spinorbit coupling (SOC), including the 230 paramagnetic space groups (SGs) and the 1,421 magnetic space groups (MSGs), and provide the expressions of all the RSIs in the Bilbao Crystallographic Server. The 3D RSIs have allowed for the identification of a special set of 3D topologically trivial insulators which we call Obstructed Atomic Insulators (OAIs), and electrides which we call obstructed metals. Using the theoretical formulation of RSIs, we have performed the high throughput scanning of the Topological Quantum Chemistry database materials and found more than 3300 OAIs. and 5000 obstructed metals. Furthermore, we analyze the potential applications of OAIs and obstructed metals in catalysis and superconductivities. 
Thursday, March 17, 2022 1:18PM  1:30PM 
T66.00010: Lorentz transformations and Clifford algebra as real and imaginary components respectively of δ(δz+δzδz)=0 Joel D Maker Dirac had to postulate his Clifford algebra γ s inside the relativistic energy E^{2} equation to create his linear equation. In contrast here we get both special relativity and the Clifford algebra from the single equation δ(δz+δzδz)=0 since it splits into the real component Minkowski metric (Lorentz transformations) and imaginary component Clifford algebra. But it also gives 4D and the operator formalism and so first derivatives. We thereby get the Dirac equations for the electron e and neutrino v. In addition in this formulation the e,v composite is the Standard electroweak Model and the 3e composite gives the rest of particle physics. 
Thursday, March 17, 2022 1:30PM  1:42PM 
T66.00011: Discovery of Millisecond Pulsars in Globular Clusters Tasha Gautam

Thursday, March 17, 2022 1:42PM  1:54PM 
T66.00012: Multicomponent multiscatter capture of dark matter Caleb M Levy, Cosmin Ilie In recent years, the usefulness of astrophysical objects as dark matter probes has become increasingly evident. The potentially observable signatures of DM gravitationally trapped inside a compact astrophysical object have been used to forecast stringent constraints on the nucleondark matter interaction crosssection. Currently, the probes of interest are: at high redshifts, Population III stars that form in isolation, or in small numbers, in very dense DM minihalos at z=1540, and, in our own Milky Way, neutron stars, white dwarfs, brown dwarfs, exoplanets, etc. None of those objects are truly singlecomponent, and, as such, capture rates calculated with the common assumption made in the literature of singlecomponent capture, i.e. capture of DM by multiple scatterings with one single type of nucleus inside the object, are not accurate. In this work, we present an extension of this formalism to multicomponent objects and apply it to Pop III stars, investigating the role of He on the capture rate. As expected, we find that the inclusion of helium leads to an enhancement of the overall capture rate, improving the potential of Pop III stars as Dark Matter probes. 
Thursday, March 17, 2022 1:54PM  2:06PM 
T66.00013: Dark Sound Benedict J Fraser The Axion is a candidate particle for dark matter in our universe, and it is currently a pressing topic to develop new detection methods for this particle. Owing to its high occupancy number, the Axion can display properties of a BoseEinstein condensate. In particular, selfinteractions and gravity produce a sound mode (``Dark Sound") in the system, whose dynamics allows us to probe with new frequency regimes at detectors. We present our analysis and numerical estimates of detection parameters. 
Thursday, March 17, 2022 2:06PM  2:18PM 
T66.00014: Search for the Expected Radiation due to Photoejection of an Inner Shell Electron Carl Franck, Philip Jacobson, Arthur Campello, Andrija Rasovic, Matthew Dykes Pratt et al have called attention to the unsettled observational status for the radiation (intraatomic bremstahllung, IAB) expected upon the photoejection of inner shell electrons. We tested for such radiation in the 3 to 7 keV band produced by photoelectrons from the K shell of a copper target upon absorption of an incident 46 keV photon. Exploting a prediction for the major background process: ordinary bremsstrahlung due to the encounter of the photoelectron with atoms other than that of its point of origin, we conclude that for our thinnest (40 nm) targets within statistical limits we observe no IAB radiation. In this manner, contemporary theory is ruled out by over 5 sigmas. Assuming no particular secondary process the intensity of observed IAB radiation is 4 sigmas below expectations. We conclude that in contrast to the sister nuclear process of internal bremsstrahlung observed upon beta decay, our understanding of intratomic bremsstrahlung remains lacking. 
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