Mixed Meson Masses with Domain-Wall Valence and Staggered Sea Fermions

Mixed action lattice calculations allow for an additive lattice spacing dependent mass renormalization of mesons composed of one sea and one valence quark, regardless of the type of fermion discretization methods used in the valence and sea sectors. The value of the mass renormalization depends upon the lattice actions used. This mixed meson mass shift is an important lattice artifact to determine for mixed action calculations; because it modifies the pion mass, it plays a central role in the low energy dynamics of all hadronic correlation functions. We determine the leading order, $\mathcal{O}(a^2)$, and next to leading order, $\mathcal{O}(a^2 m_\pi^2)$, additive mass shift of \textit{valence-sea} mesons for a mixed lattice action with domain-wall valence fermions and rooted staggered sea fermions, relevant to the majority of current large scale mixed action lattice efforts. We find that on the asqtad improved coarse MILC lattices, this additive mass shift is well parameterized in lattice units by $\Delta(am)^2 = 0.034(2) -0.06(2) (a m_\pi)^2$, which in physical units, using $a=0.125$ fm, corresponds to $\Delta(m)^2 = (291\pm 8 \textrm{MeV})^2 -0.06(2) m_\pi^2$. In terms of the mixed action effective field theory parameters, the corresponding mass shift is given by $a^2 \Delta_\mathrm{Mix} = (316 \pm 4 \textrm{MeV})^2$ at leading order plus next-to-leading order corrections including the necessary chiral logarithms for this mixed action calculation, determined in this work. Within the precision of our calculation, one can not distinguish between the full next-to-leading order effective field theory analysis of this additive mixed meson mass shift and the parameterization given above.Comment: 28 pages, 3 figures, 5 table

The K+K+ Scattering Length from Lattice QCD

The K+K+ scattering length is calculated in fully-dynamical lattice QCD with domain-wall valence quarks on the MILC asqtad-improved gauge configurations with rooted staggered sea quarks. Three-flavor mixed-action chiral perturbation theory at next-to-leading order, which includes the leading effects of the finite lattice spacing, is used to extrapolate the results of the lattice calculation to the physical value of m_{K+}/f_{K+}. We find m_{K+} a_{K+K+} = -0.352 +- 0.016, where the statistical and systematic errors have been combined in quadrature.Comment: 17 pages, 12 figures. NPLQCD collaboratio

The Gell-Mann -- Okubo mass relation among baryons from fully-dynamical mixed-action lattice QCD

We explore the Gell-Mann--Okubo mass relation among the octet baryons using fully-dynamical, mixed-action (domain-wall on rooted-staggered) lattice QCD calculations at a lattice spacing of b ~ 0.125 fm and pion masses of m_pi ~ 290 MeV, 350 MeV, 490 MeV and 590 MeV. Deviations from the Gell-Mann--Okubo mass relation are found to be small at each quark mass.Comment: 10 pages, 7 figure

Injective choosability of subcubic planar graphs with girth 6

An injective coloring of a graph G is an assignment of colors to the vertices of G so that any two vertices with a common neighbor have distinct colors. A graph G is injectively k-choosable if for any list assignment L, where |L(v)| ≥ k for all v ∈ V(G), G has an injective L-coloring. Injective colorings have applications in the theory of error-correcting codes and are closely related to other notions of colorability. In this paper, we show that subcubic planar graphs with girth at least 6 are injectively 5-choosable. This strengthens the result of Lužar, Škrekovski, and Tancer that subcubic planar graphs with girth at least 7 are injectively 5-colorable. Our result also improves several other results in particular cases

The Low-Energy Theorem of Pion Photoproduction in Soliton Models of the Nucleon

We derive an analytic expression for the Kroll-Ruderman amplitude up to the order 1/N_C for general Skyrme-type models of the nucleon. Due to the degeneracy of intermediate N- and Delta-states we find deviations from the standard low-energy theorem for the photoproduction of neutral pions.Comment: 17 pages, LATEX, SI-93-TP3S

Brass Blast with special guest Georgia Brass Band

Kennesaw State University School of Music presents Brass Blast with special guest, Georgia Brass Band.https://digitalcommons.kennesaw.edu/musicprograms/1375/thumbnail.jp