Bulletin of the American Physical Society
APS April Meeting 2023
Volume 68, Number 6
Minneapolis, Minnesota (Apr 15-18)
Virtual (Apr 24-26); Time Zone: Central Time
Session B08: Quantum Cosmology and Quantum Field Theory in Curved Spacetimes |
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Sponsoring Units: DGRAV Chair: Gautam Satishchandran, Princeton University Room: Symphony III - 2nd Floor |
Saturday, April 15, 2023 10:45AM - 10:57AM |
B08.00001: Reheating with Effective Potentials Sanjib Katuwal, Richard P Woodard, Shun-Pei Miao We consider reheating for a charged inflaton which is minimally coupled to electromagnetism. The evolution of such an inflaton induces a time-dependent mass for the photon. We show how the massive photon propagator can be expressed as a spatial Fourier mode sum involving three different sorts of mode functions, just like the constant mass case. We develop accurate analytic approximations for these mode functions, and use them to approximate the effective force exerted on the inflaton 0-mode. This effective force allows one to simply compute the evolution of the inflaton 0-mode and to follow the progress of reheating. |
Saturday, April 15, 2023 10:57AM - 11:09AM |
B08.00002: Producing primordial fluctuations with quadratic curvature terms Mauricio Gamonal, Eugenio Bianchi We study cosmological perturbations in an effective theory of gravity described by a linear combination of the scalar curvature R, R2, and the Weyl tensor squared. Higher-order time derivatives induced by the Weyl-squared term are treated self-consistently by applying reduction of order, so only physically relevant solutions are considered. Deviations from the predictions of Starobinsky inflation to the tensor and scalar primordial power spectra are also discussed. |
Saturday, April 15, 2023 11:09AM - 11:21AM |
B08.00003: Gravity of Gluonic Fluctuations Kristian Mackewicz, Craig J Hogan We analyze the classical linear gravitational effect of an idealized pion-like dynamical system: a gluonic bubble model where uniform gluonic stress-energy with equation of state p= - ρ c^2 fills a sphere bounded by a thin sheet comprising the quarks' rest mass. In one orbit of a system of total mass M, quarks of mass m |
Saturday, April 15, 2023 11:21AM - 11:33AM |
B08.00004: IR-finite Scattering theory in QFT Kartik Prabhu The traditional S-matrix amplitudes approach to scattering of massless fields in QFT is ill-defined due to IR-divergences, which are intimately tied to the classical memory effect. In the quantum theory, states with different memories live in different inequivalent Hilbert spaces. Any non-trivial scatterring process generates nontrivial memory and hence maps between in and out states living in these different Hilbert spaces leading to the IR divergences in the traditional approach. I will outline an approach to scattering theory in QFT, using the notion of algebraic states from QFT in curved spacetimes without reference to any preferred Hilbert space. In the case where no massless fields are present, this approach reporduces the traditional S-matrix formulation. For massless fields, I will consider the case of QED coupled to a fixed external classical source current. Even though the traditional approach gives IR-divergent amplitdues, the scattering process is well-defined and IR-finite in the sense of algebraic states. I discuss generalizations to QED with quantum sources and gravity. |
Saturday, April 15, 2023 11:33AM - 11:45AM |
B08.00005: Mutual information in interacting quantum field theories away from equilibrium Brenden M Bowen, Albert R Farah, Spasen Chaykov, Nishant Agarwal Momentum modes of an interacting quantum field theory (QFT) are generically entangled. On the other hand, the notion of decoupling in effective field theory, whereby degrees of freedom well beyond relevant energies do not play a significant role in the system’s behavior, suggests that well-separated modes must not affect each other’s evolution. It has been shown in previous work that the mutual information between two momentum modes of an interacting scalar QFT in Minkowski spacetime in its ground state indeed decays with mode separation, consistent with decoupling. I will first discuss the advantages of using mutual information over entanglement entropy or general Renyi entropies as a measure of correlations between degrees of freedom with a shared environment. I will next discuss the calculation of mutual information away from equilibrium and present results on time-dependent mutual information for different interacting QFTs initialized in the ground state of the free theory at an arbitrary initial time. I will show that mutual information in this out-of-equilibrium case also decays with mode separation and limits to the equilibrium result at late times. Lastly, I will generalize the results to interacting QFTs in de Sitter spacetime and discuss how background dynamics and the presence of a physical horizon affect decoupling. |
Saturday, April 15, 2023 11:45AM - 11:57AM |
B08.00006: The Average Null Energy Condition for Classical Dirac Fields Robert J Weinbaum Assessing whether known matter fields satisfy or violate energy conditions is of central importance — both for theoretical results in general relativity, and for restricting the class of physically allowed spacetimes, such as traversable wormholes. Though it is understood that quantum fields violate all pointwise energy conditions, there is hope that the averaged version of the null energy condition (ANEC) may hold true generically. |
Saturday, April 15, 2023 11:57AM - 12:09PM |
B08.00007: Pseudo-Gravity at Quantum Scales: Role of Quantum Potentials in Spacetime Geometry Shantikumar Nair The principle of equivalence upon which general relativity is based was extended to the case of quantum potential-driven electrodynamics. It was shown that accelerations can be defined as the gradient of the quantum potential and these accelerations can be locally erased by geometrization of spacetime using a general relativity-based approach. The paper develops spacetime metrics based on the quantum potential for the case of the ground state of the hydrogen atom and show that geodesic accelerations and forces calculated from this metric matched local accelerations and electromagnetic forces that the electron is subjected to. Further, time was found to be contracted, and space expanded, and mass increased, from the perspective of a remote observer, in the presence of the quantum potential. Spacetime perturbations were significant when electrons were confined into a volume having a radius of 10-15 m. Calculations suggested opportunities for experimental validation of predicted spacetime curvatures in the atom. The spacetime transformation at quantum scales was found to be consistent with the uncertainty principle. It was possible to show that a modified Einstein equation asymptotically approached the electrostatic Poisson equation in the Newtonian limit. |
Saturday, April 15, 2023 12:09PM - 12:21PM |
B08.00008: An extension of General Relativity Frank S Hafner A full scale fifth spacetime dimension provides an extension of general relativity, thus the Universe expands along two degrees of freedom, parallel and normal to light. Our eyes see parallel expansion. Normal expansion is the unwinding of spacetime as Universe mass density decreases. Near Universe inception, there was near infinite mass density causing near infinite spacetime curvature. As density decreased, so did spacetime curvature. A tetherball shows this – the ball moving around the pole is the curved path of light. The ball moving away from the pole one pole circumference per revolution represents normal expansion. The eye perceives two dimensions, but motion on the human scale provides the illusion of a three-dimensional view. The universe does not have human scale motion. Slower observations are needed for visualization in the mind of the fifth spacetime dimension - primarily the illusion of the effects of dark energy. There is a semipermeable interface between Minkowski space and the fifth spacetime dimension. Quasi-tunneling of wave/particles and gravity into the fifth dimension creates potential explanations for little understood phenomena - dark matter, ultra-high energy gamma rays, and maybe a means for superluminal travel… The slightest momentum in the fifth spacetime dimension may have prevented the early universe from sliding back into the Big Crunch. Each dimension is normal to the previous through the fifth spacetime dimension - all dimensions are the same in this respect. |
Saturday, April 15, 2023 12:21PM - 12:33PM |
B08.00009: Nature of the Curvature of Space-Time Rasulkhozha S Sharafiddinov At first sight, a graviton as the united gauge boson [1] may be described by a vector (axial-vector) field, but this is not quite so. The point is that the vectors (axial vectors) constitute the plane surface. The same corresponding individual force of a Newton or Coulomb nature does not influence |
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