The excited hadron spectrum in lattice QCD using a new method of estimating quark propagation

Progress in determining the spectrum of excited baryons and mesons in lattice QCD is described. Large sets of carefully-designed hadron operators have been studied and their effectiveness in facilitating the extraction of excited-state energies is demonstrated. A new method of stochastically estimating the low-lying effects of quark propagation is proposed which will allow reliable determinations of temporal correlations of single-hadron and multi-hadron operators.Comment: 5 pages, 4 figures, talk given at Hadron 2009, Tallahassee, Florida, December 1, 200

Nucleon, Δ\Delta and Ω\Omega excited states in Nf=2+1N_f=2+1 lattice QCD

The energies of the excited states of the Nucleon, $\Delta$ and $\Omega$ are computed in lattice QCD, using two light quarks and one strange quark on anisotropic lattices. The calculation is performed at three values of the light quark mass, corresponding to pion masses $m_{\pi}$ = 392(4), 438(3) and 521(3) MeV. We employ the variational method with a large basis of interpolating operators enabling six energies in each irreducible representation of the lattice to be distinguished clearly. We compare our calculation with the low-lying experimental spectrum, with which we find reasonable agreement in the pattern of states. The need to include operators that couple to the expected multi-hadron states in the spectrum is clearly identified.Comment: Revised for publication. References added, Table VI expanded to add strange baryon multiparticle thresholds and multiparticle thresholds added to Figs. 4, 5 and 6. 15 pages, 6 figure

First results from 2+1 dynamical quark flavors on an anisotropic lattice: light-hadron spectroscopy and setting the strange-quark mass

We present the first light-hadron spectroscopy on a set of $N_f=2+1$ dynamical, anisotropic lattices. A convenient set of coordinates that parameterize the two-dimensional plane of light and strange-quark masses is introduced. These coordinates are used to extrapolate data obtained at the simulated values of the quark masses to the physical light and strange-quark point. A measurement of the Sommer scale on these ensembles is made, and the performance of the hybrid Monte Carlo algorithm used for generating the ensembles is estimated.Comment: 24 pages. Hadron Spectrum Collaboratio

Improved Measurement of Branching Fractions for pipi Transitions among Upsilon(nS)States

Using samples of (5.93 +/- 0.10) x 10^6 Upsilon(3S) decays and (9.11 +/- 0.14) x 10^6 Upsilon(2S) decays collected with the CLEO detector, we report improved measurements of the branching fractions for the following five transitions: B(Upsilon(3S)-->Upsilon(1S) pi^+ pi^-) = (4.46 +/- 0.01 +/- 0.13)%, B(Upsilon(2S)-->Upsilon(1S) pi^+ pi^-) = (18.02 +/- 0.02 +/- 0.61)%, B(Upsilon(3S)-->Upsilon(1S) pi^0 pi^0) = (2.24 +/- 0.09 +/- 0.11)%, B(Upsilon(2S)-->Upsilon(1S) pi^0 pi^0) = (8.43 +/- 0.16 +/- 0.42)% and B(Upsilon(3S)-->Upsilon(2S) pi^0 pi^0) = (1.82 +/- 0.09 +/- 0.12)%. In each case the first uncertainty reported is statistical, while the second is systematic.Comment: 11 pages, available at http://www.lns.cornell.edu/public/CLNS/, Accepted for Publication in Phys. Rev.

On the existence and uniqueness of first best tolls in networks with multiple user classes and elastic demand

System optimal (SO) or first best pricing is examined in networks with multiple user classes and elastic demand, where different user classes have a different average value of value of time (VOT). Different flows (and first best tolls) are obtained depending on whether the SO characterisation is in units of generalised time or money. The standard first best tolls for time unit system optimum are unsatisfactory, due to the fact that link tolls are differentiated across users. The standard first best tolls for the money unit system optimum may seem to be practicable, but the objective function of the money unit system optimum is nonconvex, leading to possible multiple optima (and non-unique first best tolls). Since these standard first best tolls are unsatisfactory, we look to finding common money tolls which drive user equilibrium flows to time unit SO flows. Such tolls are known to exist in the fixed demand case, but we prove that such tolls do not exist in the elastic demand case. Although common money tolls do not exist which drive the solution to the exact time system optimal flows, tolls do exist which can push the system close to time system optimum (TSO) flows

Visual self-localization with tiny images

Abstract. Self-localization of mobile robots is often performed visually, whereby the resolution of the images influences a lot the computation time. In this paper, we examine how a reduction of the image resolution affects localization accuracy. We downscale the images, preserving their aspect ratio, up to a tiny resolution of 15×11 and 20×15 pixels. Our results are based on extensive tests on different datasets that have been recorded indoors by a small differential drive robot and outdoors by a flying quadrocopter. Four well-known global image features and a pixelwise image comparison method are compared under realistic conditions such as illumination changes and translations. Our results show that even when reducing the image resolution down to the tiny resolutions above, accurate localization is achievable. In this way, we can speed up the localization process considerably.