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 H14: Cosmology |
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Sponsoring Units: DAP Chair: Michael Rashkovetskyi, Center for Astrophysics | Harvard & Smithsonian Room: Marquette V - 2nd Floor |
Sunday, April 16, 2023 1:30PM - 1:42PM |
H14.00001: Utilizing a newly revealed symmetry of observables with fundamental constant variation to resolve the Hubble Tension. Kylar Greene, Francis-Yan Cyr-Racine
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Sunday, April 16, 2023 1:42PM - 1:54PM |
H14.00002: The Hubble tension and the magnetic universe. Levon Pogosian The Hubble tension hints at a missing ingredient in our model describing the universe around the epoch of recombination. A stochastic magnetic fields, if present in the plasma prior to last scattering, would induce baryon inhomogeneities and speed up the recombination process. As a consequence, the sound horizon at last scattering would be smaller, potentially helping to relieve the Hubble tension. Intriguingly, the strength of the magnetic field required to alleviate the Hubble tension happens to be of the right order of magnitude to also explain the observed magnetic fields in galaxies, clusters of galaxies and the intergalactic space. I will review this proposal and provide an update on its current status. |
Sunday, April 16, 2023 1:54PM - 2:06PM |
H14.00003: The Big-Bang Nucleosynthesis within the Scale-Invariant Vacuum (SIV) paradigm Vesselin G Gueorguiev, Andre Maeder We will present our results on the study of the Li7 problem for testing the Scale-Invariant Vacuum (SIV) paradigm with high-precision Primordial Nucleosynthesis simulations using the PRIMAT'21 code that utilizes partially decoupled neutrinos during the Big-Bang Nucleosynthesis. Possible connections of the SIV cosmology to the Dark Matter and Early Dark Energy phenomena will be highlighted. |
Sunday, April 16, 2023 2:06PM - 2:18PM |
H14.00004: Was Entropy Conserved between BBN and Recombination? Alex Sobotka, Adrienne L Erickcek, Tristan L Smith The production of entropy after big bang nucleosynthesis (BBN) is a popular extension to the |
Sunday, April 16, 2023 2:18PM - 2:30PM |
H14.00005: Sterile Neutrino Decays During the Weak Decoupling Era Chad Kishimoto
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Sunday, April 16, 2023 2:30PM - 2:42PM |
H14.00006: Can Alternative Gravity Explain Galaxies which Appear to have No Dark Matter James G O'Brien, William M Kerin, Thomas Chiarelli Alternative gravity has long been shown to provide analysis and descriptions of rotation curve physics without the need for dark matter. Recently, numerous authors have made claims of galaxies whose rotation curves can be fit without dark matter. Although interesting enough, these galaxies can serve to provide new tests of the validity of alternative and standard gravity. To this end, we focus on two major theories, namely conformal weyl gravity and modified newtonian dynamics, both of which have had tremendous success in fitting galactic rotation curves without using any dark matter. The Tully Fisher relation and the Radial Acceleration rule will be explored in these galaxies to serve as tests for the parameters that generate no dark matter in standard gravity and allow us to see if alternative gravity that requires no dark matter by fiat can provide reasonable predictions for the data. |
Sunday, April 16, 2023 2:42PM - 2:54PM Author not Attending |
H14.00007: Cosmological tests of theories of varying fine-structure constant. Daniel Grin, Ethan Baker, Hurum Maksora Tohfa, Jens Chluba, Jack Crump In some extensions of the standard model of particle physics, the values of the fundamental coupling constants actually vary in space and time. Some recent observations of QSO hint at the possible time and spatial variation of the fine structure constant. We analyzed the Bekenstein-Sandvik-Barrow-Magueijo (BSBM) model which posits the existence of a cosmological scalar field and allows the field and the fine structure constant to evolve with the expansion of the universe. Using Principal Component Analysis of the CMB, we impose new constraints to these models. We also explore the relationship between the matter density and electromagnetic energy of the nucleus in these models, a key theoretical quantity that is degenerate with limits to the energy scale of new physics in these models, highlighting assumptions and limitations of past analyses. We assess the impact of the use of energy non-conserving equations in past modeling of this theory, and also explore the additional impact of dark energy constraints on such models. |
Sunday, April 16, 2023 2:54PM - 3:06PM |
H14.00008: Matter-antimatter asymmetry from preon aggregation in the early universe Richard B Holmes A universe consisting of protons, neutrons, and electrons with electrical neutrality is consistent with an equal number of c and c_bar preons, assuming the rishon preon theory of Shupe and Harari [1, 2]. Similarly, a universe consisting of antiprotons, antineutrons, and positrons with electrical neutrality is consistent with an equal number of c and c_bar preons. Hence, any combination of such matter-antimatter compositions is also consistent with an equal number of c and c_bar preons and overall electrical neutrality. It is proposed that the difference observed in baryon-antibaryon number density relative to photon number density, ~ 5x10-10, is due to allocation of preons between matter and antimatter during preon aggregation into normal matter. Two approaches are considered: (1) an allocation at times corresponding to the Planck temperature and (2) an allocation at times corresponding to quark and nucleon formation. Both approaches give the correct magnitude of the asymmetry assuming out-of-equilibrium freeze-out and a slight and allowed C-asymmetry in preon bonding in a self-consistent quantum field theory [3]. Sakharov’s baryon non-conservation condition is evidently not required with these approaches, because they assume another level of matter (preons) which is present before quark and lepton formation. Thus, preons can provide an elementary explanation of matter-antimatter asymmetry. |
Sunday, April 16, 2023 3:06PM - 3:18PM |
H14.00009: Cosmological singularities in non-standard backgrounds Oem Trivedi The universe's late-time acceleration has prompted a great deal of research into cosmological singularities. Recent work has seen a proper classification of such singularities into strong and weak based on their strength, with weak singularities including the sudden, w, and big freeze singularities and strong singularities including the big rip singularity. So I'd be discussing a variety of new findings in this regard in various exotic cosmologies in this talk. To begin, we consider RS-II Braneworld-based scalar field dark energy models and demonstrate the presence of finite time singularities in these regimes from a dynamical system perspective, using the Goriely-Hyde singularity analysis method. This approach is general in the sense that it is not restricted to any specific class of potentials or any constrained parameter region for the brane tension, and it is valid for both Quintessence and Phantom dark energy regimes. We show that finite time singularities can exist in these models for a limited set of initial conditions, and that this result holds regardless of whether the swampland dS conjecture is taken into account, and we also classify the physical nature of these singularities. I then discuss about the occurence of type V singularities in non- GR based cosmological backgrounds, namely ones of the RS-II, f(R) and Chern-Simons type and show that type V singularities occur in almost the same conditions in all these scenarios as they do in the usual GR based cosmology. However, I then discuss that if we consider inhomogenous equations of state for matter than the occurence conditions of these singularities changes considerably ( for f(R) gravity, these could be totally removed too). Finally, we discuss singularities in an asymptotically safe cosmology where I show that one can have Type I - Type IV singularities in such a cosmology for various versions of the equation of state and that the singularities can occur both in finite and infinite time. The conditions in which these singularities occur is significantly different than how they occur in the standard cosmology, with the formulations being even more involved. |
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