D meson semileptonic form factors in Nf=3 QCD with M\"obius domain-wall quarks

We present our calculation of D \to pi and D \to K semileptonic form factors in Nf = 2+1 lattice QCD. We simulate three lattice cutoffs 1/a \sim 2.5, 3.6 and 4.5 GeV with pion masses as low as 230 MeV. The M\"obius domain-wall action is employed for both light and charm quarks. We present our results for the vector and scalar form factors and discuss their dependence on the lattice spacing, light quark masses and momentum transfer.Comment: 8 pages, 5 figures, talk presented at the 35th International Symposium on Lattice Field Theory (Lattice 2017), 18-24 June 2017, Granada, Spai

Optical observation of quasiperiodic Heisenberg antiferromagnets in two dimensions

We calculate magnetic Raman spectra of Heisenberg antiferromagnets on the two-dimensional Penrose lattice. We follow the Shastry-Shraiman formulation of Raman scattering in a strongly correlated Hubbard system and obtain the second- and fourth-order effective Raman operators. The second-order Raman intensity comes from the E2 mode, and it is invariant under an arbitrary rotation of polarization vectors. The fourth-order Raman intensities consist of A1 and A2, as well as E2, modes and therefore yield strong polarization dependence. In particular, the A2 mode intensity directly detects the dynamical spin-chirality fluctuations. Employing linearly and circularly polarized lights, we can separately extract every irreducible representation from the observations. We further discuss effects of magnon-magnon interactions on the magnetic Raman scattering. Our theory provides a reasonable explanation for the two-magnon scattering process.Comment: 7 pages, 5 figure

Topological susceptibility in 2+1-flavor QCD with chiral fermions

We compute the topological susceptibility $\chi_t$ of 2+1-flavor lattice QCD with dynamical M\"obius domain-wall fermions, whose residual mass is kept at 1 MeV or smaller. In our analysis, we focus on the fluctuation of the topological charge density in a "slab" sub-volume of the simulated lattice, as proposed by Bietenholz et al. The quark mass dependence of our results agrees well with the prediction of the chiral perturbation theory, from which the chiral condensate is extracted. Combining the results for the pion mass $M_\pi$ and decay constant $F_\pi$, we obtain $\chi_t$ = 0.227(02)(11)$M_\pi^2 F_\pi^2$ at the physical point, where the first error is statistical and the second is systematic.Comment: 8 pages, 3 figures, talk given at the 35th International Symposium on Lattice Field Theory, 18-24 June 2017, Granada, Spai