Bulletin of the American Physical Society
2023 APS April Meeting
Volume 68, Number 6
Minneapolis, Minnesota (Apr 1518)
Virtual (Apr 2426); Time Zone: Central Time
Session Q05: Particle Physcis in the CosmosInvited

Hide Abstracts 
Sponsoring Units: DPF DAP Chair: Priscilla Cushman, University of Minnesota Room: MG Salon E  3rd Floor 
Monday, April 17, 2023 3:45PM  4:21PM Withdrawn 
Q05.00001: Anisotropy of the Stochastic Gravitational Wave Background from Primordial Fluctuations Invited Speaker: Yuhsin Tsai Gravitational waves produced in the primordial universe should show up as anisotropic stochastic gravitational wave backgrounds (GWB), similar to the cosmic microwave background (CMB). The GWB can carry the adiabatic perturbations as the CMB, or it can exhibit different energy fluctuations with nonminimal inflationary and reheating processes. 
Monday, April 17, 2023 4:21PM  4:57PM 
Q05.00002: Coulomb's Choice: The Classical Equation of Quantized Gauge Theories Invited Speaker: Surjeet Rajendran The classical equations of motion of a quantum field theory are obtained by minimizing an action. When we apply this procedure to a gauge theory, there is an interesting issue. The variation of the classical action along a gauge direction is zero. Thus, one of the traditional classical equations that are obtained by such a variation does not actually exist. Alternately, the quantum theory is defined by gauge fixing the classical action. This gauge fixed action is slightly different from the classical action and it can be shown that this procedure also results in some classical equations not existing. The missing equations are the constraint equations of the gauge theory  Coulomb’s law in the case of electromagnetism and the time components of Einstein’s equations in the case of gravity. What does this imply? We show that even though the constraint equations are not obeyed, the time derivatives of the constraints are automatically satisfied by the quantum evolution. A quantum state that does not obey the constraint can be consistently time evolved. The time evolution of this quantum state would be identical to that of a classical state that contains some “dark” object i.e. dark charge in the case of electromagnetism and dark matter in the case of gravity. But, there is no new physics associated with this “dark” object  it is simply a choice of initial quantum state of the theory, leading to new cosmological observables. In this talk, I will describe these effects in the simple model of “minisuperspace” i.e. homogeneous quantum cosmology. As a consequence, we will show that one can obtain natural time evolution in quantum cosmology and that the time evolution of the quantum state of the universe need not be described by the Wheeler deWitt equation which requires the universe to be in an energy eigenstate thus forcing the quantum state of the universe to be timeless. 
Monday, April 17, 2023 4:57PM  5:33PM Withdrawn 
Q05.00003: TBD Invited Speaker: Rebecca Leane

Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2024 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700