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1. A Rapid Ionization Change in the Nebular-phase Spectra of the Type Ia SN 2011fe

   https://doi.org/10.3847/2041-8213/ac4fbd  

   Tucker, M. A.; Ashall, C.; Shappee, B. J.; Kochanek, C. S.; Stanek, K. Z.; Garnavich, P. (February 2022, The Astrophysical Journal Letters)

   Abstract We present three new spectra of the nearby Type Ia supernova (SN Ia) 2011fe covering ≈480–850 days after maximum light and show that the ejecta undergoes a rapid ionization shift at ∼500 days after explosion. The prominent Feiiiemission lines at ≈4600 Å are replaced with Fei+Feiiblends at ∼4400 Å and ∼5400 Å. The ≈7300 Å feature, which is produced by [Feii]+[Niii] at ≲400 days after explosion, is replaced by broad (≈±15,000 km s⁻¹) symmetric [Caii] emission. Models predict this ionization transition occurring ∼100 days later than what is observed, which we attribute to clumping in the ejecta. Finally, we use the nebular-phase spectra to test several proposed progenitor scenarios for SN 2011fe. Nondetections of H and He exclude nearby nondegenerate companions, [Oi] nondetections disfavor the violent merger of two white dwarfs, and the symmetric emission-line profiles favor a symmetric explosion. 

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2. Application of Convolutional Neural Networks to Predict Magnetic Fields’ Directions in Turbulent Clouds

   https://doi.org/10.3847/1538-4357/aca66c  

   Xu, Duo; Law, Chi-Yan; Tan, Jonathan C (January 2023, The Astrophysical Journal)

   Abstract We adopt the deep learning methodcasi-3d(convolutional approach to structure identification-3D) to infer the orientation of magnetic fields in sub-/trans-Alfvénic turbulent clouds from molecular line emission. We carry out magnetohydrodynamic simulations with different magnetic field strengths and use these to generate synthetic observations. We apply the 3D radiation transfer coderadmc-3dto model¹²CO and¹³CO (J = 1−0) line emission from the simulated clouds and then train acasi-3dmodel on these line emission data cubes to predict magnetic field morphology at the pixel level. The trainedcasi-3dmodel is able to infer magnetic field directions with a low error (≲10° for sub-Alfvénic samples and ≲30° for trans-Alfvénic samples). We further test the performance ofcasi-3don a real sub-/trans- Alfvénic region in Taurus. Thecasi-3dprediction is consistent with the magnetic field direction inferred from Planck dust polarization measurements. We use our developed methods to produce a new magnetic field map of Taurus that has a three times higher angular resolution than the Planck map. 

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3. Codimension one defects in free scalar field theory

   https://doi.org/10.1007/JHEP06(2025)065  

   Kim, Seolhwa; Kraus, Per; Sun, Zhengdi (June 2025, Journal of High Energy Physics)

   A<sc>bstract</sc> We study various aspects of codimension one defects in free scalar field theory, with particular emphasis on line defects in two-dimensions. These defects are generically non-conformal, but include conformal and topological defects as special cases. Our analysis is based on the interplay between two complementary descriptions, the first involving matching conditions imposed on fields and their derivatives across the defect, and the second on the resummation of perturbation theory in terms of renormalized defect couplings. Using either description as appropriate we compute a variety of observables: correlators of fields in the presence of such defects; the defect anomalous dimension; multiple defects and their fusion; canonical quantization and instabilities; ring shaped defects with application to the g-theorem and the entanglement entropy of accelerating defects; defects on the torus and Cardy formulas for the asymptotic density of states of the defect Hilbert space; and quenches produced by spacelike defects. The simplicity of the model allows for explicit computation of all these quantities, and provides a starting point for more complicated theories involving interactions. 

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4. Moduli spaces in CFT: bootstrap equation in a perturbative example

   https://doi.org/10.1007/JHEP12(2024)144  

   Cuomo, Gabriel; Rastelli, Leonardo; Sharon, Adar (December 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> Conformal field theories that exhibit spontaneous breaking of conformal symmetry (a moduli space of vacua) must satisfy a set of bootstrap constraints, involving the usual data (scaling dimensions and OPE coefficients) as well as new data such as the spectrum of asymptotic states in the broken vacuum and form factors. The simplest bootstrap equation arises by expanding a two-point function of local operators in two channels, at short distance using the OPE and at large distance using the EFT in the broken vacuum. We illustrate this equation in what is arguably the simplest perturbative model that exhibits conformal symmetry breaking, namely the real ABC model ind= 4 −ϵdimensions. We investigate the convergence properties of the bootstrap equation and check explicitly many of the non-trivial relations that it imposes on theory data. 

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5. Fully stabilized Minkowski vacua in the 26 Landau-Ginzburg model

   https://doi.org/10.1007/JHEP10(2024)095  

   Rajaguru, Muthusamy; Sengupta, Anindya; Wrase, Timm (October 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> We study moduli stabilization via fluxes in the 2⁶Landau-Ginzburg model. Fluxes not only give masses to scalar fields but can also induce higher order couplings that stabilize massless fields. We investigate this for several different flux choices in the 2⁶model and find two examples that are inconsistent with the Refined Tadpole Conjecture. We also present, to our knowledge, the first 4d$$ \mathcal{N} $$ $N$= 1 Minkowski solution in string theory without any flat direction. 

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