University of Warsaw

About: University of Warsaw is a education organization based out in Warsaw, Poland. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 20832 authors who have published 56617 publications receiving 1185084 citations. The organization is also known as: Uniwersytet Warszawski & Warsaw University.

Coupled-cluster method for multideterminantal reference states

Abstract: A general coupled-cluster method valid for arbitrary multideterminantal reference states is formulated. The resulting cluster expansion for the wave function is a generalization of that introduced by Silverstone and Sinano\ifmmode \check{g}\else \v{g}\fi{}lu and applied by Sinano\ifmmode \check{g}\else \v{g}\fi{}lu and collaborators. The connected nature of the cluster operators and the effective interaction is proven in the case when the reference space is complete, i.e., is invariant under unitary transformations of partly occupied orbitals. For incomplete reference spaces the disconnected terms appearing in the effective interaction are properly generated by the coupled-cluster theory. Approximate schemes for solving coupled-cluster equations are proposed and their relation with perturbation theory is briefly discussed.

Planck 2013 results. XI. All-sky model of thermal dust emission

Abstract: This paper presents an all-sky model of dust emission from the Planck 857, 545 and 353 GHz, and IRAS 100 micron data. Using a modified black-body fit to the data we present all-sky maps of the dust optical depth, temperature, and spectral index over the 353-3000 GHz range. This model is a tight representation of the data at 5 arcmin. It shows variations of the order of 30 % compared with the widely-used model of Finkbeiner, Davis, and Schlegel. The Planck data allow us to estimate the dust temperature uniformly over the whole sky, providing an improved estimate of the dust optical depth compared to previous all-sky dust model, especially in high-contrast molecular regions. An increase of the dust opacity at 353 GHz, tau_353/N_H, from the diffuse to the denser interstellar medium (ISM) is reported. It is associated with a decrease in the observed dust temperature, T_obs, that could be due at least in part to the increased dust opacity. We also report an excess of dust emission at HI column densities lower than 10^20 cm^-2 that could be the signature of dust in the warm ionized medium. In the diffuse ISM at high Galactic latitude, we report an anti-correlation between tau_353/N_H and T_obs while the dust specific luminosity, i.e., the total dust emission integrated over frequency (the radiance) per hydrogen atom, stays about constant. The implication is that in the diffuse high-latitude ISM tau_353 is not as reliable a tracer of dust column density as we conclude it is in molecular clouds where the correlation of tau_353 with dust extinction estimated using colour excess measurements on stars is strong. To estimate Galactic E(B-V) in extragalactic fields at high latitude we develop a new method based on the thermal dust radiance, instead of the dust optical depth, calibrated to E(B-V) using reddening measurements of quasars deduced from Sloan Digital Sky Survey data.

An eclipsing-binary distance to the Large Magellanic Cloud accurate to two per cent

Abstract: Observations of eight long-period, late-type eclipsing-binary systems composed of cool, giant stars are used to determine a distance to the Large Magellanic Cloud accurate to 2.2 per cent, providing a base for a determination of the Hubble constant to an accuracy of 3 per cent. The physical properties of stars in eclipsing binary systems can be accurately determined thanks to the intimate interactions between the two bodies, and by monitoring the fluctuating light from such systems it is possible to obtain accurate extragalactic distance measurement. This technique has now been used to determine the most accurate distance estimate yet for the Large Magellanic Cloud (LMC), our nearest-neighbour galaxy. The data from eight long-period, late-type eclipsing systems particularly suitable for this calibration technique suggest that the LMC is around 49.97 kiloparsecs from us, to an accuracy of 2.2%. The distance to the LMC is a key element in determining the Hubble constant, an important measure of the rate of expansion of the Universe. In the era of precision cosmology, it is essential to determine the Hubble constant to an accuracy of three per cent or better1,2. At present, its uncertainty is dominated by the uncertainty in the distance to the Large Magellanic Cloud (LMC), which, being our second-closest galaxy, serves as the best anchor point for the cosmic distance scale2,3. Observations of eclipsing binaries offer a unique opportunity to measure stellar parameters and distances precisely and accurately4,5. The eclipsing-binary method was previously applied to the LMC6,7, but the accuracy of the distance results was lessened by the need to model the bright, early-type systems used in those studies. Here we report determinations of the distances to eight long-period, late-type eclipsing systems in the LMC, composed of cool, giant stars. For these systems, we can accurately measure both the linear and the angular sizes of their components and avoid the most important problems related to the hot, early-type systems. The LMC distance that we derive from these systems (49.97 ± 0.19 (statistical) ± 1.11 (systematic) kiloparsecs) is accurate to 2.2 per cent and provides a firm base for a 3-per-cent determination of the Hubble constant, with prospects for improvement to 2 per cent in the future.

Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes

Abstract: This revision of the classification of eukaryotes follows that of Adl et al., 2012 [J. Euk. Microbiol. 59(5)] and retains an emphasis on protists. Changes since have improved the resolution of many ...

Determination of jet energy calibration and transverse momentum resolution in CMS

Abstract: Measurements of the jet energy calibration and transverse momentum resolution in CMS are presented, performed with a data sample collected in proton-proton collisions at a centre-of-mass energy of 7TeV, corresponding to an integrated luminosity of 36pb−1. The transverse momentum balance in dijet and γ/Z+jets events is used to measure the jet energy response in the CMS detector, as well as the transverse momentum resolution. The results are presented for three different methods to reconstruct jets: a calorimeter-based approach, the ``Jet-Plus-Track'' approach, which improves the measurement of calorimeter jets by exploiting the associated tracks, and the ``Particle Flow'' approach, which attempts to reconstruct individually each particle in the event, prior to the jet clustering, based on information from all relevant subdetectors