Heavy-Light Semileptonic Decays in Staggered Chiral Perturbation Theory

We calculate the form factors for the semileptonic decays of heavy-light pseudoscalar mesons in partially quenched staggered chiral perturbation theory (\schpt), working to leading order in $1/m_Q$, where $m_Q$ is the heavy quark mass. We take the light meson in the final state to be a pseudoscalar corresponding to the exact chiral symmetry of staggered quarks. The treatment assumes the validity of the standard prescription for representing the staggered ``fourth root trick'' within \schpt by insertions of factors of 1/4 for each sea quark loop. Our calculation is based on an existing partially quenched continuum chiral perturbation theory calculation with degenerate sea quarks by Becirevic, Prelovsek and Zupan, which we generalize to the staggered (and non-degenerate) case. As a by-product, we obtain the continuum partially quenched results with non-degenerate sea quarks. We analyze the effects of non-leading chiral terms, and find a relation among the coefficients governing the analytic valence mass dependence at this order. Our results are useful in analyzing lattice computations of form factors $B\to\pi$ and $D\to K$ when the light quarks are simulated with the staggered action.Comment: 53 pages, 8 figures, v2: Minor correction to the section on finite volume effects, and typos fixed. Version to be published in Phys. Rev.

The QCD spectrum with three quark flavors

We present results from a lattice hadron spectrum calculation using three flavors of dynamical quarks - two light and one strange, and quenched simulations for comparison. These simulations were done using a one-loop Symanzik improved gauge action and an improved Kogut-Susskind quark action. The lattice spacings, and hence also the physical volumes, were tuned to be the same in all the runs to better expose differences due to flavor number. Lattice spacings were tuned using the static quark potential, so as a byproduct we obtain updated results for the effect of sea quarks on the static quark potential. We find indications that the full QCD meson spectrum is in better agreement with experiment than the quenched spectrum. For the 0++ (a0) meson we see a coupling to two pseudoscalar mesons, or a meson decay on the lattice.Comment: 38 pages, 20 figures, uses epsf. 5/29/01 revision responds to referee's Comments, changes pion fits and tables, and corrects Fig. 10 and some minor error

Quantum Stochastic Processes: A Case Study

We present a detailed study of a simple quantum stochastic process, the quantum phase space Brownian motion, which we obtain as the Markovian limit of a simple model of open quantum system. We show that this physical description of the process allows us to specify and to construct the dilation of the quantum dynamical maps, including conditional quantum expectations. The quantum phase space Brownian motion possesses many properties similar to that of the classical Brownian motion, notably its increments are independent and identically distributed. Possible applications to dissipative phenomena in the quantum Hall effect are suggested.Comment: 35 pages, 1 figure

Quadratic cavity soliton optical frequency combs

We theoretically investigate the formation of frequency combs in a dispersive second-harmonic generation cavity system, and predict the existence of quadratic cavity solitons in the absence of a temporal walk-off

Charmonia enhancement in quark-gluon plasma with improved description of c-quarks phase-distribution

We present a dynamical model of heavy quark evolution in the quark-gluon plasma (QGP) based on the Fokker-Planck equation. We then apply this model to the case of central ultra-relativistic nucleus-nucleus collisions performed at RHIC and estimate the component of $J/\psi$ production (integrated and differential) stemming from c-$\bar{c}$ pairs that are initially uncorrelated.Comment: contribution presented at SQM0

The Nature of the Low-Metallicity ISM in the Dwarf Galaxy NGC 1569

We are modeling the spectra of dwarf galaxies from infrared to submillimeter wavelengths to understand the nature of the various dust components in low-metallicity environments, which may be comparable to the ISM of galaxies in their early evolutionary state. The overall nature of the dust in these environments appears to differ from those of higher metallicity starbursting systems. Here, we present a study of one of our sample of dwarf galaxies, NGC 1569, which is a nearby, well-studied starbursting dwarf. Using ISOCAM, IRAS, ISOPHOT and SCUBA data with the Desert et al. (1990) model, we find consistency with little contribution from PAHs and Very Small Grains and a relative abundance of bigger colder grains, which dominate the FIR and submillimeter wavelengths. We are compelled to use 4 dust components, adding a very cold dust component, to reproduce the submillimetre excess of our observations.Comment: 4 pages, 4 postscript figures. Proceedings of "Infrared and Submillimeter Astronomy. An International Colloquium to Honor the Memory of Guy Serra" (2002

The Anatomy of Subjective Well-Being

Subjective Well-Being has increasingly been studied by several economists. This paper fits in that literature but takes into account that there are different aspects of life such as health, financial situation, and job. We call them domains. In this paper, we consider Subjective Well-Being as a composite of various domain satisfactions (DS). We postulate a two -layer model where individual Subjective Well-Being is explained by individual subjective domain satisfactions with respect to job, finance, health, leisure, housing, and environment. We distinguish between long -term and short - term effects. Next, we explain domain satisfactions and Subjective Well-Being by objectively measurable variables such as income. We estimate a model for the GS and DS equations with individual random effects and fix time effects.Subjective Well-Being, satisfaction measurement, qualitative regressors, health satisfaction, job satisfaction

A precise determination of T_c in QCD from scaling

Existing lattice data on the QCD phase transition are analyzed in renormalized perturbation theory. In quenched QCD it is found that T_c scales for lattices with only 3 time slices, and that T_c/Lambda_msbar=1.15 \pm 0.05. A preliminary estimate in QCD with two flavours of dynamical quarks shows that this ratio depends on the quark mass. For realistic quark masses we estimate T_c/Lambda_msbar=0.49 \pm 0.02. We also investigate the equation of state in quenched QCD at 1-loop order in renormalised perturbation theory.Comment: 7 pages, 5 eps figures; improved error analysis yields smaller errors on T_

Management of Agitation During the COVID-19 Pandemic

The coronavirus disease 2019 (COVID-19) pandemic caused by the coronavirus SARS-CoV-2 has radically altered delivery of care in emergency settings. Unprecedented hardship due to ongoing fears of exposure and threats to personal safety, along with societal measures enacted to curb disease transmission, have had broad psychosocial impact on patients and healthcare workers alike. These changes can significantly affect diagnosing and managing behavioral emergencies such as agitation in the emergency department. On behalf of the American Association for Emergency Psychiatry, we highlight unique considerations for patients with severe behavioral symptoms and staff members managing symptoms of agitation during COVID-19. Early detection and treatment of agitation, precautions to minimize staff hazards, coordination with security personnel and psychiatric services, and avoidance of coercive strategies that cause respiratory depression will help mitigate heightened risks to safety caused by this outbreak

Testing improved actions for dynamical Kogut-Susskind quarks

We extend tests of "Naik" and "fat link" improvements of the Kogut-Susskind quark action to full QCD simulations, and verify that the improvements previously demonstrated in the quenched approximation apply also to dynamical quark simulations. We extend the study of flavor symmetry improvement to the complete set of pions, and find that the nonlocal pions are significantly heavier than the local non-Goldstone pion. These results can be used to estimate the lattice spacing necessary for realistic simulations with this action.Comment: 16 pages, LaTeX, PostScript figures include