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1. HSTPROMO Internal Proper-motion Kinematics of Dwarf Spheroidal Galaxies. I. Velocity Anisotropy and Dark Matter Cusp Slope of Draco

   https://doi.org/10.3847/1538-4357/ad571c  

   Vitral, Eduardo; van_der_Marel, Roeland_P; Sohn, Sangmo_Tony; Libralato, Mattia; del_Pino, Andrés; Watkins, Laura_L; Bellini, Andrea; Walker, Matthew_G; Besla, Gurtina; Pawlowski, Marcel_S; et al (July 2024, The Astrophysical Journal)

   Abstract We analyze four epochs of Hubble Space Telescope imaging over 18 yr for the Draco dwarf spheroidal galaxy. We measure precise proper motions for hundreds of stars and combine these with existing line-of-sight (LOS) velocities. This provides the first radially resolved 3D velocity dispersion profiles for any dwarf galaxy. These constrain the intrinsic velocity anisotropy and resolve the mass–anisotropy degeneracy. We solve the Jeans equations in oblate axisymmetric geometry to infer the mass profile. We find the velocity dispersion to be radially anisotropic along the symmetry axis and tangentially anisotropic in the equatorial plane, with a globally averaged value $\overline{{\beta }_{\mathrm{B}}}=-{0.20}_{-0.53}^{+0.28}$, (where 1 – ${\beta }_{\mathrm{B}}\equiv 〈v_{\tan }^2〉/〈v_{\mathrm{rad}}^2〉$in 3D). The logarithmic dark matter (DM) density slope over the observed radial range, Γ_dark, is $-{0.83}_{-0.37}^{+0.32}$, consistent with the inner cusp predicted in ΛCDM cosmology. As expected given Draco’s low mass and ancient star formation history, it does not appear to have been dissolved by baryonic processes. We rule out cores larger than 487, 717, and 942 pc at 1σ, 2σ, and 3σconfidence, respectively, thus imposing important constraints on the self-interacting DM cross section. Spherical models yield biased estimates for both the velocity anisotropy and the inferred slope. The circular velocity at our outermost data point (900 pc) is ${24.19}_{-2.97}^{+6.31}\mathrm{km}{\mathrm{s}}^{-1}$. We infer a dynamical distance of ${75.37}_{-4.00}^{+4.73}$kpc and show that Draco has a modest LOS rotation, with $\left(v/\sigma \right)=0.22\pm 0.09$. Our results provide a new stringent test of the so-called “cusp–core” problem that can be readily extended to other dwarfs. 

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2. Observation of a pseudoscalar excess at the top quark pair production threshold

   https://doi.org/10.1088/1361-6633/adf7d3  

   Collaboration, The_CMS (August 2025, Reports on Progress in Physics)

   Abstract A search for resonances in top quark pair ( $\mathrm{t}\bar{\mathrm{t}}$) production in final states with two charged leptons and multiple jets is presented, based on proton–proton collision data collected by the CMS experiment at the CERN LHC at $\sqrt{s}=13\text{TeV}$, corresponding to 138 fb⁻¹. The analysis explores the invariant mass of the $\mathrm{t}\bar{\mathrm{t}}$system and two angular observables that provide direct access to the correlation of top quark and antiquark spins. A significant excess of events is observed near the kinematic $\mathrm{t}\bar{\mathrm{t}}$threshold compared to the non-resonant production predicted by fixed-order perturbative quantum chromodynamics (pQCD). The observed enhancement is consistent with the production of a color-singlet pseudoscalar ( ${}^1{\text{S}}_0^{\left[1\right]}$) quasi-bound toponium state, as predicted by non-relativistic quantum chromodynamics. Using a simplified model for ${}^1{\text{S}}_0^{\left[1\right]}$toponium, the cross section of the excess above the pQCD prediction is measured to be $8.8{}_{-1.4}^{+1.2}\text{pb}$. 

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3. Raman study of layered breathing kagome lattice semiconductor Nb ₃ Cl ₈

   https://doi.org/10.1088/2053-1583/acfa10  

   Jeff, Dylan A; Gonzalez, Favian; Harrison, Kamal; Zhao, Yuzhou; Fernando, Tharindu; Regmi, Sabin; Liu, Zhaoyu; Gutierrez, Humberto R; Neupane, Madhab; Yang, Jihui; et al (September 2023, 2D Materials)

   Abstract Niobium chloride (Nb₃Cl₈) is a layered two-dimensional semiconducting material with many exotic properties including a breathing kagome lattice, a topological flat band in its band structure, and a crystal structure that undergoes a structural and magnetic phase transition at temperatures below 90 K. Despite being a remarkable material with fascinating new physics, the understanding of its phonon properties is at its infancy. In this study, we investigate the phonon dynamics of Nb₃Cl₈in bulk and few layer flakes using polarized Raman spectroscopy and density-functional theory (DFT) analysis to determine the material’s vibrational modes, as well as their symmetrical representations and atomic displacements. We experimentally resolved 12 phonon modes, five of which areA_1gmodes while the remaining seven areE_gmodes, which is in strong agreement with our DFT calculation. Layer-dependent results suggest that the Raman peak positions are mostly insensitive to changes in layer thickness, while peak intensity and full width at half maximum are affected. Raman measurements as a function of excitation wavelength (473–785 nm) show a significant increase of the peak intensities when using a 473 nm excitation source, suggesting a near resonant condition. Temperature-dependent Raman experiments carried out above and below the transition temperature did not show any change in the symmetries of the phonon modes, suggesting that the structural phase transition is likely from the high temperatureP $\overline{\text{3}m}$1 phase to the low-temperatureR $\overline{3m}$phase. Magneto-Raman measurements carried out at 140 and 2 K between −2 and 2 T show that the Raman modes are not magnetically coupled. Overall, our study presented here significantly advances the fundamental understanding of layered Nb₃Cl₈material which can be further exploited for future applications. 

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4. Braid group action and quasi-split affine 𝚤quantum groups I

   https://doi.org/10.1090/ert/657  

   Lu, Ming; Wang, Weiqiang; Zhang, Weinan (October 2023, Representation Theory of the American Mathematical Society)

   This is the first of our papers on quasi-split affine quantum symmetric pairs $(\stackrel{~<\#comment/>}{\mathbf{U}}\left(\stackrel{^<\#comment/>}{\mathfrak{g}}\right),{\stackrel{~<\#comment/>}{\mathbf{U}}}^{\mathrm{ı<\#comment/>}})$, focusing on the real rank one case, i.e., $\mathfrak{g}={\mathfrak{s}\mathfrak{l}}_3$equipped with a diagram involution. We construct explicitly a relative braid group action of type $A_2^{\left(2\right)}$on the affine $\mathrm{ı<\#comment/>}$quantum group ${\stackrel{~<\#comment/>}{\mathbf{U}}}^{\mathrm{ı<\#comment/>}}$. Real and imaginary root vectors for ${\stackrel{~<\#comment/>}{\mathbf{U}}}^{\mathrm{ı<\#comment/>}}$are constructed, and a Drinfeld type presentation of ${\stackrel{~<\#comment/>}{\mathbf{U}}}^{\mathrm{ı<\#comment/>}}$is then established. This provides a new basic ingredient for the Drinfeld type presentation of higher rank quasi-split affine $\mathrm{ı<\#comment/>}$quantum groups in the sequels. 

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5. Electron impact excitation of allowed and forbidden transitions between fine-structure levels in Ti III

   https://doi.org/10.1088/1361-6595/ad95b8  

   Wang, Yang; Cao, Qiu-Yao; Zhu, Xi-Ming; Du, Chun-Meng; Bartschat, Klaus (November 2024, Plasma Sources Science and Technology)

   Abstract Introduction: We present an extensive theoretical investigation of the electron impact excitation of doubly-ionized titanium (Ti III) to meet the needs of spectral analysis and plasma modeling. OBJECTIVES: The main objective of this work is to extend the currently scarce database of both structure and collision data for Ti III. METHODS: The calculation was performed in the close-coupling approximation using theB-splineR-matrix method. The multi-configuration Hartree–Fock method in combination withB-spline configuration interaction expansions and the non-orthogonal orbitals technique is employed for accurate descriptions of the target wave functions and adequate accounts of the various interactions between the target states. Relativistic effects are treated at the semi-relativistic Breit-Pauli approximation level. RESULTS: The present close-coupling expansion includes 138 fine-structure levels of Ti III belonging to the $3d^2$, $4s^2$, $4s4p$, $3d4l$( $l=0-3$), $3d5l$( $l=0-3$), $3d6s$, and $3d6p$configurations. Comprehensive sets of radiative and electron collisional data are reported for all of the possible transitions between the 138 fine-structure levels. Thermally averaged collision strengths are determined using a Maxwellian distribution for a wide range of temperatures from ${10}^2$K to ${10}^5$K. The accuracy of the calculated radiative parameters is validated by comparing with available values from the NIST database and previous literature. CONCLUSION: Given the lack of sufficient currently available experimental and theoretical data, the electron impact excitation cross sections of the Ti III fine-structure levels presented here are systematic, extensive, and internally consistent, thus making them suitable for many modeling applications. 

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