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Alfredo Iorio, Boris Ivetić, Salvatore Mignemi, Pablo Pais
Fri Feb 03 2023 09:53:06 (1 day)
# 1.
We discuss here how, when higher-order effects in the parameter $\frac{\ell}{\hbar} |\vec{p}|$, related to the lattice spacing $\ell$, are considered, pristine graphene, and other Dirac materials, can be used as tabletop systems where generalized commutation relations are naturally realized. Such generalized algebras of quantization, which lead to generalized versions of the Heisenberg uncertainty principle, are under intense scrutiny these days, as they could manifest a fundamental length scale of spacetime. Despite the efforts and the many intriguing results, there are no experimental signatures of any generalized uncertainty principle (GUP). Therefore, our results here, which tell how to use tabletop physical systems to test certain GUPs in analog experiments, should be of interest to practitioners of quantum gravity. We identify three different energy regimes that we call “layers”, where the physics is still of a Dirac type but within precisely described limits. The higher the energy, the more sensitive the Dirac system becomes to the effects of the lattice. Here such lattice plays the role of a discrete space where the Dirac quasi-particles live. With the goals just illustrated, we had to identify the mapping between the high-energy coordinates, $X^i$, and the low-energy ones, $x^i$, i.e., those measured in the lab. We then obtained three generalized Heisenberg algebras. For two of them we have the noticeable result that $X^i = x^i$, and for the third one we obtained an improvement with respect to an earlier work: the generalized coordinates expressed in terms of the standard phase space variables, $X^i(x,p)$, and higher order terms.
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physics.hist-ph updates on arXiv.org
by
Jonathan Agil, Rémy Battesti, Carlo Rizzo
Fri Feb 03 2023 09:53:06 (1 day)
# 2.
The nature of light, the existence of magnetism, the physical meaning of a vacuum are problems so deeply related to philosophy that they have been discussed for thousands of years. In this paper, we concentrate ourselves on a question that concerns the three of them: does light speed in a vacuum change when a magnetic field is present? The experimental answer to this fundamental question has not yet been given even if it has been stated in modern terms for more than a century. To fully understand the importance of such a question in physics, we review the main facts and concepts from the historical point of view.
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M. Fabbrichesi, R. Floreanini, E. Gabrielli, L. Marzola
Fri Feb 03 2023 09:53:05 (1 day)
# 3.
Quantum entanglement of weak interaction gauge bosons produced at colliders can be explored by computing the corresponding polarization density matrix. To this end, we consider the Higgs boson decays $H\to W W^*$ and $H\to Z Z^*$, in which $W^*$ and $Z^*$ are off-shell states, and the $WW$, $WZ$ and $ZZ$ di-boson production in proton collisions. The polarization density matrix of the di-boson state is determined by the amplitude of the production process and can be experimentally reconstructed from the angular distribution of the momenta of the charged leptons into which the gauge boson decays. We show that a suitable instance of the Bell inequality is violated in the Higgs boson decays to a degree that can be tested with high accuracy at the LHC already with present data. The same Bell inequality is violated in the production of $WW$ and $ZZ$ boson pairs for invariant masses above 900 GeV and scattering angles close to $\pi/2$ in the center of mass frame. In this case high luminosity LHC data are needed to detect violations of the Bell inequality with sufficient accuracy. We also analyze the prospects for detecting Bell inequality violations in di-boson final states at future $e^+e^-$ and muon colliders. A further observable that provides a lower bound on the amount of polarization entanglement in the di-boson system is computed for each of the examined processes. The analytic expressions for the polarization density matrices are presented in full in an Appendix. We also provide the unitary matrices required in the optimization procedure necessary in testing the Bell inequalities.
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Purba Mukherjee, Gabriel Rodrigues, Carlos Bengaly
Fri Feb 03 2023 09:53:03 (1 day)
# 4.
The fundamental constants in Nature play a crucial role in the understanding of physical phenomena. Hence, it is of paramount importance to measure them with exquisite precision and to examine whether they present any variability across cosmic time, as a means to test the standard model of Cosmology, as well as fundamental physics. We revisit a consistency test of the speed of light variability proposed by Cai {\it et al.} using the latest cosmological observations, viz., Pantheon compilation of Type Ia Supernova luminosity distances (SN), cosmic chronometers from differential galaxy ages (CC), and measurements of both radial and transverse modes of baryonic acoustic oscillations ($r$-BAO and $a$-BAO) respectively. Such a test has the advantage of being independent of any assumption on the cosmic curvature – which can be degenerated with some variable speed of light models – as well as any dark energy model. We deploy the well-known Gaussian Processes to reconstruct cosmic distances and ages in the $0<z<2$ redshift range. Moreover, we examine the impact of cosmological priors on our analysis, such as the Hubble constant, supernova absolute magnitude, and the sound horizon scale. We find null evidence for the speed of light variability hypothesis for most choices of priors and data-set combinations, except for a mild deviation from it (at $\sim 2\sigma$ confidence level) at $z>1$ when the $a$-BAO data are included for some priors and reconstruction kernel cases. Still, we ascribe no statistical significance to this result for the incompleteness of this data set at such higher redshifts.
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E. Minguzzi
Fri Feb 03 2023 09:53:00 (1 day)
# 5.
In applied mechanics Reye’s law (1860) establishes, via energy arguments, that the mass of the debris produced by dry friction in the contact of rigid bodies is proportional to the work done by friction forces. This result has long been used for the determination of the distribution of pressure in the contact of rigid bodies, and hence for the design of brakes. In this work I show that, when bodies losing mass due to friction are treated, as they should, as variable mass systems, a relationship analogous to the relativistic mass formula is recovered. This result suggests that mathematical structures typical of relativistic physics could have been discovered prior to 1905, without making any reference to electromagnetism, group theory or the speed of light. Also this result could point to the existence of a physical theory depending on two constants, the speed of light (Reye’s constant) and a universal frictional deceleration with respect to an absolute frame. The limit of the theory for vanishing friction would give Special Relativity, as the absolute frame would become unobservable, while the limit for the speed of light going to infinity would lead to Aristotelian mechanics, i.e. a classical mechanics type theory presenting universal friction. Finally, I present a reference frame transformation that displays these features and I apply the theory to some open cosmological problems.
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PhilSci-Archive: No conditions. Results ordered -Date Deposited.
Fri Feb 03 2023 07:40:29 (1 day)
# 6.
Vaughan, Martin P (2020) The Concept of Entropic Time: A Preliminary Discussion. [Preprint]
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Thu Feb 02 2023 13:55:04 (1 day)
# 7.
Weinert, Friedel (2023) Reichenbach’s ‘Causal’ Theory of Time: A Re-Assessment. [Preprint]
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Tue Jan 31 2023 03:58:52 (4 days)
# 8.
Fraser, James D. (2021) The Twin Origins of Renormalization Group Concepts. Studies in History and Philosophy of Science, 89. pp. 114-128. ISSN 00393681
