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1. Non-Minimal Lorentz Violation in Macroscopic Matter

   https://doi.org/10.3390/sym12122026  

   Mewes, Matthew (December 2020, Symmetry)

   null (Ed.)

   The effects of Lorentz and CPT violations on macroscopic objects are explored. Effective composite coefficients for Lorentz violation are derived in terms of coefficients for electrons, protons, and neutrons in the Standard-Model Extension, including all minimal and non-minimal violations. The hamiltonian and modified Newton’s second law for a test body are derived. The framework is applied to free-fall and torsion-balance tests of the weak equivalence principle and to orbital motion. The effects on continuous media are studied, and the frequency shifts in acoustic resonators are calculated. 

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2. Free transport for convex potentials

   https://doi.org/10.53733/102  

   Dabrowski, Yoann; Guionnet, Alice; Shlyakhtenko, Dima (September 2021, New Zealand Journal of Mathematics)

   We construct non-commutative analogs of transport maps among free Gibbs state satisfying a certain convexity condition. Unlike previous constructions, our approach is non-perturbative in nature and thus can be used to construct transport maps between free Gibbs states associated to potentials which are far from quadratic, i.e., states which are far from the semicircle law. An essential technical ingredient in our approach is the extension of free stochastic analysis to non-commutative spaces of functions based on the Haagerup tensor product. 

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3. Hyperbolic Groups That Are Not Commensurably Co-Hopfian

   https://doi.org/10.1093/imrn/rnaa033  

   Stark, Emily; Woodhouse, Daniel J (April 2020, International Mathematics Research Notices)

   Abstract Sela proved that every torsion-free one-ended hyperbolic group is co-Hopfian. We prove that there exist torsion-free one-ended hyperbolic groups that are not commensurably co-Hopfian. In particular, we show that the fundamental group of every simple surface amalgam is not commensurably co-Hopfian. 

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4. A generalization of decomposition in orbifolds

   https://doi.org/10.1007/JHEP10(2021)134  

   Robbins, Daniel G.; Sharpe, Eric; Vandermeulen, Thomas (October 2021, Journal of High Energy Physics)

   A bstract This paper describes a generalization of decomposition in orbifolds. In general terms, decomposition states that two-dimensional orbifolds and gauge theories whose gauge groups have trivially-acting subgroups decompose into disjoint unions of theories. However, decomposition can be, at least naively, broken in orbifolds if the orbifold has discrete torsion in the trivially-acting subgroup. (Formally, this breaks finite global one-form symmetries.) Nevertheless, even in such cases, one still sees rudiments of decomposition. In this paper, we generalize decomposition in orbifolds to include such examples of discrete torsion, which we check in numerous examples. Our analysis includes as special cases (and in one sense generalizes) quantum symmetries of abelian orbifolds. 

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5. Elimination of the Blue Loops in the Evolution of Intermediate-mass Stars by the Neutrino Magnetic Moment and Large Extra Dimensions

   Mori, K.; Balantekin, A. Baha; Kajino, T.; Famiano, M.A. (August 2020, ArXivorg)

   For searching beyond Standard Model physics, stars are laboratories which complement terrestrial experiments. Massless neutrinos in the Standard Model of particle physics cannot have a magnetic moment, but massive neutrinos have a finite magnetic moment in the minimal extension of the Standard Model. Large extra dimensions are a possible solution of the hierarchy problem. Both of these provide additional energy loss channels in stellar interiors via the electromagnetic interaction and radiation into extra dimensions, respectively, and thus affect stellar evolution. We perform simulations of stellar evolution with such additional energy losses and find that they eliminate the blue loops in the evolution of intermediate-mass stars. The existence of Cepheid stars can be used to constrain the neutrino magnetic moment and large extra dimensions. In order for Cepheids to exist, the neutrino magnetic moment should be smaller than the range ∼ 2×10−10 to 4×10−11µB , where µB is the Bohr magneton, and the fundamental scale in the (4+2)-spacetime should be larger than ∼ 2 to 5 TeV, depending on the rate of the 12C(α, γ) 16O reaction. The fundamental scale also has strong dependence on the metallicity. This value of the magnetic moment is in the range explored in the reactor experiments, but higher than the limit inferred from globular clusters. Similarly the fundamental scale value we constrain corresponds to a size of the compactified dimensions comparable to those explored in the torsion balance experiments, but is smaller than the limits inferred from collider experiments and low-mass stars. 

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