American Physical Society

About: American Physical Society is a nonprofit organization based out in College Park, Maryland, United States. It is known for research contribution in the topics: Quantum chromodynamics & Quark. The organization has 107 authors who have published 391 publications receiving 14126 citations. The organization is also known as: APS.

Leptonic decay constants fDs and fD in three flavor lattice QCD

Abstract: We determine the leptonic decay constants f D s and f D in three flavor unquenched lattice QCD. We use O ( a 2 ) -improved sraggered light quarks and O ( a ) -improved charm quarks in the Fermilab heavy quark formalism. Our preliminary results, based upon an analysis at a single lattice spacing, are f D s = 263 −9 +5 ± 24 MeV and f D = 225 −13 +11 ± 21 MeV . In each case, the first reported error is statistical while the second is the combined systematic uncertainty.

The Equation of State for QCD with 2+1 Flavors of Quarks

Abstract: We report results for the interaction measure, pressure and energy density for nonzero temperature QCD with 2+1 flavors of improved staggered quarks. In our simulations we use a Symanzik improved gauge action and the Asqtad $O(a^2)$ improved staggered quark action for lattices with temporal extent $N_t=4$ and 6. The heavy quark mass $m_s$ is fixed at approximately the physical strange quark mass and the two degenerate light quarks have masses $m_{ud} =0.1m_s$ or $0.2m_s$. The calculation of the thermodynamic observables employs the integral method where energy density and pressure are obtained by integration over the interaction measure.

Symanzik flow on HISQ ensembles

Abstract: =a, originally proposed bythe BMW collaboration, is computed using Symanzik flow at four lattice spacings ranging from0.15 to 0.06 fm. With a Taylor series ansatz, the results are simultaneously extrapolated to thecontinuum and interpolated to physical quark masses. We give a preliminary determination of thescale w

Quantum-dot lasers fabricated with self-assembled microcrystals

Abstract: This paper describes improvements that have been achieved in the optical properties of self-assembled InGaAs quantum dots and the high performance of quantum-dot lasers that incorporate these improvements. We found that spectra broadening was reduced and emission efficiency was improved by alternately supplying small amounts of InAs and GaAs on GaAs substrates to grow quantum dots using both metalorganic vapor phase epitaxy and molecular beam epitaxy. The narrow spectra and high emission efficiency improve the practical performance of dot lasers. A threshold current of 5.4 mA, a current density of 160 A/cm 2, and an output power of 110 mW were achieved in continuous wave operation at 25 ̊C.

Progress on four flavor QCD with the HISQ action

Abstract: We describe recent progress on generation of gauge configurations using the Highly Improved Staggered Quark (HISQ) action that was designed by the HPQCD/UKQCD collaboration. The HISQ action requires two levels of smearing with a reunitarization of the links before the second smearing. We describe how we deal with the occurrence of occasional large forces arising from the reunitarization step. The MILC collaboration is currently generating ensembles with approximate lattice spacings of 0.15, 0.12, 0.09, and 0.06 fm, with the strange and charm quark masses close to their physical values and the mass of the light quarks m_l set to 0.2 m_s. We present recent results for pion taste splittings, light hadron masses, the static potential, the eta_c dispersion relation and the topological susceptibility.