Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session Q15: Particle & Fields Theory II |
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Sponsoring Units: DPF Chair: Francisco Ponce, Stanford University Room: Sheraton Plaza Court 4 |
Monday, April 15, 2019 10:45AM - 10:57AM |
Q15.00001: Construction and applications of Lorentz-violating nonabelian gauge field theories Zonghao Li, V Alan Kostelecky Lorentz violation can emerge in certain theoretical schemes unifying General Relativity and the Standard Model, and it is a popular candidate for modifications to low-energy physics. The Standard-Model Extension (SME) is a comprehensive framework for describing Lorentz violation in the context of realistic effective field theory. All minimal SME operators are known, but the explicit construction of possible nonminimal operators of arbitrary mass dimension has been an open issue. In this talk, we present a method to construct arbitrary gauge-invariant Lorentz-violating operators in nonabelian field theories. Applied to quantum electrodynamics and quantum chromodynamics, the method establishes the Lagrange densities for Lorentz-violating QED and QCD. We study implications of these theories for experiments involving light-by-light scattering and deep inelastic scattering, and we use existing data to obtain first bounds on certain nonminimal SME coefficients. |
Monday, April 15, 2019 10:57AM - 11:09AM |
Q15.00002: Sources for Biconformal gravity Walter Davis Muhwezi Biconformal gravity is a 2n-dimensional conformal gauge theory with a curvature linear action that has been shown to reproduce scale invariant general relativity on the cotangent bundle of n-dimensional space time. We explore Yang-Mills sources for biconformal gravity. The questions we seek to clarify are whether the augmented field equations reduce the Yang-Mills sector to n-dimensional Yang-Mills theory and yield the appropriate energy-momentum tensor as the gravitational source. |
Monday, April 15, 2019 11:09AM - 11:21AM |
Q15.00003: Lattice N=4 three-dimensional super-Yang-Mills Joel Giedt, Arthur Lipstein, Paul Martin We describe our recent work on the lattice formulation of N=4 three-dimensional super-Yang-Mills. Our formulation was based on the Donaldson-Witten twist, but we have also been studying the formulation based on the Blau-Thompson twist by Joseph. We find in the latter case there is a single counterterm necessary to restore supersymmetry in the continuum limit, and that this counterterm |
Monday, April 15, 2019 11:21AM - 11:33AM |
Q15.00004: Quantum Mechanics of a Single Photon and the question of its Localizability in Space Hassan Babaei, Ali Mostafazadeh We use the dynamical Maxwell equations to determine the space of state vectors of a single photon. We endow this space with a relativistically invariant positive-definite inner product to make it into a Hilbert space. We identify the Hamiltonian operator with the generator of time translations, construct momentum and helicity operators, and introduce a chirality (direction-of-time) operator. Next, we construct a position operator that has commuting components. These also commute with the helicity and chirality operators. We obtain the eigenstates of the position operator, which we identify with the localized states of the photon, and use them to determine photon’s position wave function. The position wave function for the localized states has a delta-function singularity at a single point in space, but their electromagnetic fields diverge on a particular plane containing this plane. This behavior turns out to be related to an implicit freedom in the choice of the position operator. Each choice for the position operator determines the plane at which the electromagnetic fields of a given localized state diverge. |
Monday, April 15, 2019 11:33AM - 11:45AM |
Q15.00005: Anomalous Electron Velocity and Zitterbewegung Basil S Davis Dirac's Relativistic Wave Equation implies an electron velocity equal to the velocity of light of magnitude c, in apparent violation of Relativity. This theoretical result has been largely considered as a mathematical curiosity with little physical relevance. In this paper it is shown that a velocity c can be observed for an electron that is in a superposition of positive and negative energy states - called a zitterbewegung state. But this velocity c is attainable only by electron spin and electron charge, and not by electron mass. A zitterbewegung state is experimentally realizable when the electron is accelerated with sufficient energy so that its spatial wave function is confined within about a Compton wavelength h/mc. Such high energies are now available through the technology of plasma electron acceleration employed in plasma wakefield accelerators and laser-driven wakefield accelerators. Plasma acceleration conceived 30 years ago has been successfully accomplished within the past decade. Whereas spintronic analogues to zitterbewegung have been implemented, genuine electron zitterbewegung is only now realizable. It is therefore possible to observe electron spin and electron charge moving at the speed of light. |
Monday, April 15, 2019 11:45AM - 11:57AM |
Q15.00006: A Hypergeometric Resummation Algorithm for the resummation of Divergent series in Quantum field Theory Abouzeid M Shalaby In Phys. Rev. D 96, 025015 (2017), we used the effective potential to discuss the PT-symmetric if3 field theory. In PRL 115, 143001 (2015), a new precise as well as simple resummation technique has been introduced. We modified that resummation algorithm in arXiv:1811.10998 to extrapolate its accuracy to strong couplings. As the hypergeometric resummation and the effective potential are both non-perturbative techniques, in this talk we stress how can the results of the effective potential can predict the strong coupling behavior of the PT-symmetric if3 field theory and thus predict exactly the first two parameters of the hypergeomtric function 2F1 used to resum the divergent series of the ground state energy. This resummation algorithm is thus very suitable to rsum divergent series in quantum field theory as it uses only the first two terms in the perturbation series to predict the other two parameters. Accordingly, the algorithm results in accurate results for the whole range of the coupling space and expected to be suitable for problems where higher orders loop calculations are time consuming like QCD.
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Monday, April 15, 2019 11:57AM - 12:09PM |
Q15.00007: Non-perturbative techniques in strongly coupled field theories Margaret Carrington Non-perturbative techniques are needed to study strongly coupled systems. One powerful approach is the n-particle irreducible effective action. The method provides a systematic expansion for which the truncation occurs at the level of the action. The standard renormalization procedure can be modified at the 2PI level by introducing multiple sets of counterterms, but counterterms cannot be used at higher orders. We have developed a method based on a renormalization group approach which allows us to construct a renormalized theory at any order in the nPI approximation. We present results from a calculation using a scalar theory with quartic coupling in 4 dimensions, at the 4 loop level. Both the 2PI and 4PI theories can be renormalized using one bare coupling constant and one bare mass, which are introduced at the level of the Lagrangian. |
Monday, April 15, 2019 12:09PM - 12:21PM |
Q15.00008: ABSTRACT WITHDRAWN
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Monday, April 15, 2019 12:21PM - 12:33PM |
Q15.00009: Lorentz violation, scalar fields, and Finsler geometry Benjamin r Edwards, V Alan Kostelecky The quadratic scalar field theory incorporating general violations of Lorentz symmetry is presented, and the classical relativistic point-particle lagrangian yielding the corresponding dispersion relation is obtained. Point-particle motions in the presence of Lorentz violation are associated with a Finsler geometry. A method to extract these Finsler spaces is described, and some of their properties are studied. |
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