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1. Excited state analysis in the quasi-PDF matrix elements

   https://doi.org/10.22323/1.334.0097  

   Li, Ruizi; Yang, Yi-Bo; Lin, Huey-Wen (May 2019, The 36th Annual International Symposium on Lattice Field Theory (LATTICE2018))

   We study and demonstrate the ground-state extrapolation of the unpolarized and polarized nucleon quark quasi-PDF matrix elements in a highly boosted hadron frame on the lattice. The calculation is done using the Wilson clover quark on a MILC’s dynamical Nf = 2+1+1 highly improved staggered quarks (HISQ) ensemble with one step hypercubic smearing, and with the lattice spacing a∼0.09 fm and pion mass 310 MeV. Applying the Gaussian momentum-smeared quark sources and comparing various fits in 1-, 2-, and 3-state fitting models, we show that excited state contributions can be under control in the lattice calculation of the nucleon quark quasi-PDF matrix elements. 

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2. Gluon Parton Distribution of the Pion from Lattice QCD

   Zhouyou Fan, Huey-Wen Lin (January 2021, Physics letters)

   null (Ed.)

   We present the first determination of the x-dependent pion gluon distribution from lattice QCD using the pseudo-PDF approach. We use lattice ensembles with 2+1+1 flavors of highly improved staggered quarks (HISQ), generated by MILC Collaboration, at two lattice spacings a≈0.12 and 0.15~fm and three pion masses Mπ≈220, 310 and 690 MeV. We use clover fermions for the valence action and momentum smearing to achieve pion boost momentum up to 2.29 GeV. We find that the dependence of the pion gluon parton distribution on lattice spacing and pion mass is mild. We compare our results from the lightest pion mass ensemble with the determination by JAM and xFitter global fits. 

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3. Hadronic vacuum polarization of the muon on 2+1+1-flavor HISQ ensembles: an update.

   https://doi.org/10.22323/1.396.0526  

   Lahert, Shaun; DeTar, Carleton; El-Khadra, Aida X; Gámiz, Elvira; Gottlieb, Steven; Kronfeld, Andreas; Neil, Ethan; Peterson, Curtis T.; Van de Water, Ruth (May 2022, The 38th International Symposium on Lattice Field Theory (LATTICE2021))

   We give an update on the status of the Fermilab Lattice-HPQCD-MILC calculation of the con- tribution to the muon’s anomolous magnetic moment from the light-quark, connected hadronic vacuum polarization. We present preliminary, blinded results in the intermediate window for this contribution a^ll_{\mu W}. The calculation is performed on Nf = 2 + 1 + 1 highly-improved staggered quark (HISQ) ensembles from the MILC collaboration with physical pion mass at four lattice spacings between 0.15 fm and 0.06 fm. We also present preliminary results for a study of the two- pion contributions to the vector-current correlation function performed on the 0.15 fm ensemble contribution, 𝑎𝑙𝑙 . The calculation is performed on the 0.15 fm ensemble where we see a factor of four improvement over traditional noise reduction techniques. 

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4. Distinct spin–lattice and spin–phonon interactions in monolayer magnetic CrI ₃

   https://doi.org/10.1039/c8cp03599g  

   Webster, Lucas; Liang, Liangbo; Yan, Jia-An (January 2018, Physical Chemistry Chemical Physics)

   We apply the density-functional theory to study various phases (including non-magnetic (NM), anti-ferromagnetic (AFM), and ferromagnetic (FM)) in monolayer magnetic chromium triiodide (CrI 3 ), a recently fabricated 2D magnetic material. It is found that: (1) the introduction of magnetism in monolayer CrI 3 gives rise to metal-to-semiconductor transition; (2) the electronic band topologies as well as the nature of direct and indirect band gaps in either AFM or FM phases exhibit delicate dependence on the magnetic ordering and spin–orbit coupling; and (3) the phonon modes involving Cr atoms are particularly sensitive to the magnetic ordering, highlighting distinct spin–lattice and spin–phonon coupling in this magnet. First-principles simulations of the Raman spectra demonstrate that both frequencies and intensities of the Raman peaks strongly depend on the magnetic ordering. The polarization dependent A 1g modes at 77 cm −1 and 130 cm −1 along with the E g mode at about 50 cm −1 in the FM phase may offer a useful fingerprint to characterize this material. Our results not only provide a detailed guiding map for experimental characterization of CrI 3 , but also reveal how the evolution of magnetism can be tracked by its lattice dynamics and Raman response. 

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5. QCD Predictions for Physical Multimeson Scattering Amplitudes

   https://doi.org/10.1103/6nql-yrhw  

   Dawid, Sebastian M; Draper, Zachary T; Hanlon, Andrew D; Hörz, Ben; Morningstar, Colin; Romero-López, Fernando; Sharpe, Stephen R; Skinner, Sarah (July 2025, Physical Review Letters)

   We use lattice QCD calculations of the finite-volume spectra of systems of two and three mesons to determine, for the first time, three-particle scattering amplitudes with physical quark masses. Our results are for combinations of π+ and K+, at a lattice spacing a=0.063 fm, and in the isospin-symmetric limit. We also obtain accurate results for maximal-isospin two-meson amplitudes, with those for ${\pi }^{+}{K}^{+}$and $2K^{+}$being the first determinations at the physical point. Dense lattice spectra are obtained using the stochastic Laplacian-Heaviside method, and the analysis leading to scattering amplitudes is done using the relativistic finite-volume formalism. Results are compared to chiral perturbation theory and to phenomenological fits to experimental data, finding good agreement. 

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