More Like this

1. Discovery of an intermediate nematic state in a bilayer kagome metal ScV6Sn6

   https://doi.org/10.1038/s41467-025-63294-5  

   Farhang, Camron; Meier, William R; Lu, Weihang; Li, Jiangxu; Wu, Yudong; Mozaffari, Shirin; Madhogaria, Richa P; Zhang, Yang; Mandrus, David; Xia, Jing (August 2025, Nature Communications)

   Abstract Nematicity, spontaneous breaking of rotational symmetry, is a ubiquitous phenomenon in correlated quantum matter. Here we show a phase transition in high-quality ScV₆Sn₆bilayer kagome metal at a temperature$${T}^{*}$$ $T^{*}$ , occurring seven Kelvins below the charge density wave transition at$${T}_{{CDW}}$$ $T_{CDW}$ , as indicated by thermodynamic, transport, and optical measurements. This emerging intermediate phase does not exhibit spontaneous time-reversal-symmetry breaking, as evidenced by zero-field Sagnac interferometry. However, it displays a strong, spontaneous in-plane anisotropy between$${T}^{*}$$ $T^{*}$ and$${T}_{{CDW}}$$ $T_{CDW}$ , revealed by transport and optical polarization rotation measurements. A pronounced depolarization effect detected by the Sagnac interferometer further confirms its nematic nature. Unlike AV₃Sb₅, this phase, alongside the recently discovered intra-unit cell nematic order at lower temperatures, presents a diverse landscape of nematicities at multiple length and temperature scales. Our findings highlight ScV₆Sn₆as a prime candidate for realizing symmetry-breaking phases driven by charge density competition, kagome physics, and Van Hove singularities. 

   more » « less
2. Observation of momentum-dependent charge density wave gap in a layered antiferromagnet GdTe3

   https://doi.org/10.1038/s41598-023-44851-8  

   Regmi, Sabin; Bin Elius, Iftakhar; Sakhya, Anup Pradhan; Jeff, Dylan; Sprague, Milo; Mondal, Mazharul Islam; Jarrett, Damani; Valadez, Nathan; Agosto, Alexis; Romanova, Tetiana; et al (December 2023, Scientific Reports)

   Abstract Charge density wave (CDW) ordering has been an important topic of study for a long time owing to its connection with other exotic phases such as superconductivity and magnetism. The$$R{\textrm{Te}}_{3}$$ $R{\text{Te}}_3$ (R= rare-earth elements) family of materials provides a fertile ground to study the dynamics of CDW in van der Waals layered materials, and the presence of magnetism in these materials allows to explore the interplay among CDW and long range magnetic ordering. Here, we have carried out a high-resolution angle-resolved photoemission spectroscopy (ARPES) study of a CDW material$${\textrm{Gd}}{\textrm{Te}}_{3}$$ $\text{Gd}{\text{Te}}_3$ , which is antiferromagnetic below$$\sim \mathrm {12~K}$$ $\sim 12K$ , along with thermodynamic, electrical transport, magnetic, and Raman measurements. Our ARPES data show a two-fold symmetric Fermi surface with both gapped and ungapped regions indicative of the partial nesting. The gap is momentum dependent, maximum along$${\overline{\Gamma }}-\mathrm{\overline{Z}}$$ $\overline{\Gamma }-\overline{Z}$ and gradually decreases going towards$${\overline{\Gamma }}-\mathrm{\overline{X}}$$ $\overline{\Gamma }-\overline{X}$ . Our study provides a platform to study the dynamics of CDW and its interaction with other physical orders in two- and three-dimensions. 

   more » « less
3. More accurate $$ \sigma \left(\mathcal{GG}\to h\right),\Gamma \left(h\to \mathcal{GG},\mathcal{AA},\overline{\Psi}\Psi \right) $$ and Higgs width results via the geoSMEFT

   https://doi.org/10.1007/JHEP01(2024)170  

   Martin, Adam; Trott, Michael (January 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> We develop Standard Model Effective Field Theory (SMEFT) predictions ofσ($$ \mathcal{GG} $$ $\mathrm{GG}$ →h), Γ(h→$$ \mathcal{GG} $$ $\mathrm{GG}$ ), Γ(h→$$ \mathcal{AA} $$ $\mathrm{AA}$ ) to incorporate full two loop Standard Model results at the amplitude level, in conjunction with dimension eight SMEFT corrections. We simultaneously report consistent Γ(h→$$ \overline{\Psi}\Psi $$ $\overline{\Psi }\Psi$ ) results including leading QCD corrections and dimension eight SMEFT corrections. This extends the predictions of the former processes Γ, σto a full set of corrections at$$ \mathcal{O}\left({\overline{v}}_T^2/{\varLambda}^2{\left(16{\pi}^2\right)}^2\right) $$ $O\left({\overline{v}}_T^2/{\Lambda }^2{\left(16{\pi }^2\right)}^2\right)$ and$$ \mathcal{O}\left({\overline{v}}_T^4/{\Lambda}^4\right) $$ $O\left({\overline{v}}_T^4/{\Lambda }^4\right)$ , where$$ {\overline{v}}_T $$ ${\overline{v}}_T$ is the electroweak scale vacuum expectation value and Λ is the cut off scale of the SMEFT. Throughout, cross consistency between the operator and loop expansions is maintained by the use of the geometric SMEFT formalism. For Γ(h→$$ \overline{\Psi}\Psi $$ $\overline{\Psi }\Psi$ ), we include results at$$ \mathcal{O}\left({\overline{v}}_T^2/{\Lambda}^2\left(16{\pi}^2\right)\right) $$ $O\left({\overline{v}}_T^2/{\Lambda }^2\left(16{\pi }^2\right)\right)$ in the limit where subleadingm_Ψ→ 0 corrections are neglected. We clarify how gauge invariant SMEFT renormalization counterterms combine with the Standard Model counter terms in higher order SMEFT calculations when the Background Field Method is used. We also update the prediction of the total Higgs width in the SMEFT to consistently include some of these higher order perturbative effects. 

   more » « less
4. Elliptic anisotropy measurement of the f0(980) hadron in proton-lead collisions and evidence for its quark-antiquark composition

   https://doi.org/10.1038/s41467-025-56200-6  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Hussain, P S; Jeitler, M; et al (December 2025, Nature Communications)

   Abstract Despite the f₀(980) hadron having been discovered half a century ago, the question about its quark content has not been settled: it might be an ordinary quark-antiquark ($${{\rm{q}}}\overline{{{\rm{q}}}}$$ $q\overline{q}$ ) meson, a tetraquark ($${{\rm{q}}}\overline{{{\rm{q}}}}{{\rm{q}}}\overline{{{\rm{q}}}}$$ $q\overline{q}q\overline{q}$ ) exotic state, a kaon-antikaon ($${{\rm{K}}}\overline{{{\rm{K}}}}$$ $K\overline{K}$ ) molecule, or a quark-antiquark-gluon ($${{\rm{q}}}\overline{{{\rm{q}}}}{{\rm{g}}}$$ $q\overline{q}g$ ) hybrid. This paper reports strong evidence that the f₀(980) state is an ordinary$${{\rm{q}}}\overline{{{\rm{q}}}}$$ $q\overline{q}$ meson, inferred from the scaling of elliptic anisotropies (v₂) with the number of constituent quarks (n_q), as empirically established using conventional hadrons in relativistic heavy ion collisions. The f₀(980) state is reconstructed via its dominant decay channel f₀(980) →π⁺π⁻, in proton-lead collisions recorded by the CMS experiment at the LHC, and itsv₂is measured as a function of transverse momentum (p_T). It is found that then_q= 2 ($${{\rm{q}}}\overline{{{\rm{q}}}}$$ $q\overline{q}$ state) hypothesis is favored overn_q= 4 ($${{\rm{q}}}\overline{{{\rm{q}}}}{{\rm{q}}}\overline{{{\rm{q}}}}$$ $q\overline{q}q\overline{q}$ or$${{\rm{K}}}\overline{{{\rm{K}}}}$$ $K\overline{K}$ states) by 7.7, 6.3, or 3.1 standard deviations in thep_T< 10, 8, or 6 GeV/cranges, respectively, and overn_q= 3 ($${{\rm{q}}}\overline{{{\rm{q}}}}{{\rm{g}}}$$ $q\overline{q}g$ hybrid state) by 3.5 standard deviations in thep_T< 8 GeV/crange. This result represents the first determination of the quark content of the f₀(980) state, made possible by using a novel approach, and paves the way for similar studies of other exotic hadron candidates. 

   more » « less
5. Nonnegative Ricci curvature, nilpotency, and Hausdorff dimension

   https://doi.org/10.1007/s00208-026-03378-9  

   Pan, Jiayin (January 2026, Mathematische Annalen)

   Abstract LetMbe an open (complete and non-compact) manifold with$$\textrm{Ric}\ge 0$$ $\text{Ric}\ge 0$ and escape rate not 1/2. It is known that under these conditions, the fundamental group$$\pi _1(M)$$ ${\pi }_1\left(M\right)$ has a finitely generated torsion-free nilpotent subgroup$$\mathcal {N}$$ $N$ of finite index, as long as$$\pi _1(M)$$ ${\pi }_1\left(M\right)$ is an infinite group. We show that the nilpotency step of$$\mathcal {N}$$ $N$ must be reflected in the asymptotic geometry of the universal cover$$\widetilde{M}$$ $\tilde{M}$ , in terms of the Hausdorff dimension of an isometric$$\mathbb {R}$$ $R$ -orbit: there exist an asymptotic cone (Y, y) of$$\widetilde{M}$$ $\tilde{M}$ and a closed$$\mathbb {R}$$ $R$ -subgroupLof the isometry group ofYsuch that its orbitLyhas Hausdorff dimension at least the nilpotency step of$$\mathcal {N}$$ $N$ . This resolves a question raised by Wei and the author (see Pan and Wei in Geom Funct Anal 32:676–685, 2022, Remark 1.7 and Pan in Geom Topol 28:1409–1436, 2024, Conjecture 0.2). 

   more » « less