We present measurements of the b-bbar production cross section and angular correlations using the D0 detector at the Fermilab Tevatron p-pbar Collider operating at sqrt(s) = 1.8 TeV. The b quark production cross section for |y(b)|6 GeV/c is extracted from single muon and dimuon data samples. The results agree in shape with the next-to-leading order QCD calculation of heavy flavor production but are greater than the central values of these predictions. The angular correlations between b and bbar quarks, measured from the azimuthal opening angle between their decay muons, also agree in shape with the next-to-leading order QCD prediction.Comment: 22 pages, 4 figures, minor text changes and updated cross sections, Submitted to PL

We report a measurement of the top quark mass using six candidate events for the process $p\overline{p}\to t\overline{t}+\overrightarrow{X}{l}^{+}\nu {\mathrm{bl}}^{-}\overline{\nu }\overline{b}+X$, observed in the D0 experiment at the Fermilab $p\overline{p}$ collider. Using maximum likelihood fits to the dynamics of the decays, we measure a mass for the top quark of $m_t=168.4\mathrm{}\pm 12.3\left(\mathrm{stat}\right)\pm 3.6\left(\mathrm{syst}\right)\hspace{0.5em}\mathrm{Gev}$. We combine this result with our previous measurement in the $t\overline{t}\to l+\mathrm{jets}$ channel to obtain $m_t=172.1\mathrm{}\pm 7.1\hspace{0.5em}\mathrm{GeV}$ as the best value of the mass of the top quark measured by D0.

We determine the top quark mass $m_t$ using $t\overline{t}$ pairs produced in the DØ detector by $\sqrt{s}=1.8\mathrm{}\mathrm{TeV}$ $p\overline{p}$ collisions in a $125{\mathrm{pb}}^{-1}$ exposure at the Fermilab Tevatron. We make a two constraint fit to $m_t$ in $t\overline{t}\to {\mathrm{bW}}^{+}\overline{b}{W}^{-}$ final states with one W boson decaying to $q\overline{q}$ and the other to $e\nu$ or $\mu \nu .$ Likelihood fits to the data yield $m_t(l+\mathrm{jets})=173.3\mathrm{}\pm 5.6\mathrm{}\left(\mathrm{stat}\right)\mathrm{}\pm \mathrm{}5.5\mathrm{}\left(\mathrm{syst}\right)\mathrm{\hspace{0.5em}}\mathrm{GeV}{/c}^2.$ When this result is combined with an analysis of events in which both W bosons decay into leptons, we obtain $m_t=172.1\mathrm{}\pm 5.2\mathrm{}\left(\mathrm{stat}\right)\pm 4.9\mathrm{}\left(\mathrm{syst}\right)\mathrm{\hspace{0.5em}}\mathrm{GeV}{/c}^2.$ An alternate analysis, using three constraint fits to fixed top quark masses, gives $m_t(l+\mathrm{jets})=176.0\mathrm{}\pm 7.9\mathrm{}\left(\mathrm{stat}\right)\pm 4.8\mathrm{}\left(\mathrm{syst}\right)\mathrm{\hspace{0.5em}}\mathrm{GeV}{/c}^2,$ consistent with the above result. Studies of kinematic distributions of the top quark candidates are also presented. 14.65.Ha, 13.85.Ni, 13.85.Qk

We measure the top quark mass $m_t$ using $t\overline{t}$ pairs produced in the D0 detector by $\sqrt{s}=1.8\mathrm{}\mathrm{TeV}p\overline{p}$ collisions in a $125{\mathrm{pb}}^{-1\mathrm{}}$ exposure at the Fermilab Tevatron. We make a two constraint fit to $m_t$ in $t\overline{t}\to {\mathrm{bW}}^{+}\overline{b}{W}^{-}$ final states with one W decaying to $q\overline{q}$ and the other to $e\nu$ or $\mu \nu$. Events are binned in fit mass versus a measure of probability for events to be signal rather than background. Likelihood fits to the data yield $m_t=173.3\mathrm{}\pm 5.6\left(\mathrm{stat}\right)\pm 6.2\left(\mathrm{syst}\right)\mathrm{GeV}{/c}^2$.

The rapid developments in nanostructured materials and nanotechnology is starting to have a profound impact in many applications of the biomedical areas, including biomolecules, tissue engineering, and detection of biomarkers, cancer diagnosis, cancer therapy, and bioimaging. Nanotechnology applications hinge frequently on the availability in well-characterized size distributions for gold nanoparticles. In this work we implemented a methodology in order to determine gold nanoparticles size by using the UV-Vis spectra and the multivariate analysis with the principal components' analysis method. The sample size of gold nanoparticles used for correlation of this methodology were previously known (5, 10, 15, 20, 30, 40, 50, 60, and 80 nm), they were supplied by Sigma Aldrich and Ted Pella Inc. All GNPs were measurement with a spectrometer Shimadzu UV-VIS 1800 Rayleigh model over the range from 400 to 700 nm. The UV-VIS spectra was compared with the implemented methodology in order to show excellent behavior and similitude in results, which one suggests this is an outstanding usefully tool to determine the gold nanoparticle diameter.