Electric resistivity of multi-walled carbon nanotubes at high temperatures

The electric resistivity of a clean multi-walled carbon nanotube (MWNT) mat sample was studied at temperatures T between 300 and 1900 K. We found that the resistivity ρ decreases monotonously with increasing temperature without showing any sign of turn up. Our results can be well fitted with a power law of T^−α within the framework of one dimensional Luttinger liquid theory with α = 0.13 or with a simple thermally activated inter shell hopping model.     

Pigments characterization of polychrome vases production at Lipára: New insights by noninvasive spectroscopic methods

One of the most impressive Sicilian pottery production is attributed to the so‐called Lipari Painter and his followers, whose vessels—found in the archeological site of Lipari (Aeolian Island, Sicily)—are decorated with characteristic blue, red, and white figures. From the archeological point of view, these artworks keep open many questions concerning dating, production technique, and cultural background. In this context, new data on the manufacture procedures and on the raw materials used for the pigments may contribute to a deeper comprehension of this early Hellenistic vase tradition. The preciousness of the vessels, exhibited at the Archeological Museum of Lipari, imposed the use of in situ nondestructive methods to address new insights on the nature of the colored layers. Thus, analyses by Raman and X‐ray fluorescence spectroscopy have been performed with portable instruments on a selection of vessels certainly attributed to Lipari Painter and to some others of his followers. The results of this study testify the use of different pigments: kaolin and gypsum, probably supplied locally, for white layers; Egyptian blue for blue hues; red ochre for brown‐reddish hues; and cinnabar for pink and red‐purple nuances. The identification of both Egyptian blue and cinnabar opens an interesting discussion about dating and circulation of the raw materials.     

Search for new physics in photon-lepton events in pp collisions at sqrt[s] = 1.8 TeV

We present the results of a search in pp collisions at sqrt[s] = 1.8 TeV for anomalous production of events containing a photon and a lepton (e or mu), both with large transverse energy, using 86 pb(-1) of data collected with the Collider Detector at Fermilab during the 1994-1995 collider run at the Fermilab Tevatron. The presence of large missing transverse energy (E(T)), additional photons, or additional leptons in these events is also analyzed. The results are consistent with standard model expectations, with the possible exception of photon-lepton events with large E(T), for which the observed total is 16 events and the expected mean total is 7.6+/-0.7 events.     

Quantum computational gates with radiation free couplings

We examine a generic three level mechanism of quantum computation in which all fundamental single and double qubit quantum logic gates are operating under the effect of adiabatically controllable static (radiation free) bias couplings between the states. Under the time evolution imposed by these bias couplings the quantum state cycles between the two degenerate levels in the ground state and the quantum gates are realized by changing Hamiltonian at certain time intervals when the system collapses to a two state subspace. We propose a physical implementation of the mechanism using Aharonov-Bohm persistent-current loops in crossed electric and magnetic fields, with the output of the loop read out by using a quantum Hall effect aided mechanism. Received 26 March 2002 / Received in final form 8 July 2002 Published online 19 November 2002     

Solvent effects on the UV (n --> pi*) and NMR (13C and 17O) spectra of acetone in aqueous solution. An integrated car-parrinello and DFT/PCM approach

The accurate reproduction of ultraviolet and nuclear magnetic resonance spectra of acetone in aqueous solution is used as a test of an integrated computational tool rooted in the density functional theory, the polarizable continuum model, and the Car-Parrinello dynamics. The analysis and solution of several conceptual and practical issues results in a robust and effective approach, which also can be used by nonspecialists and provides a general and powerful complement to experimental techniques.     

Observation of the narrow state X(3872)-->J/psipi+pi- in pp collisions at sqaure root of s=1.96 TeV

We report the observation of a narrow state decaying into J/psipi+pi- and produced in 220 pb(-1) of p p-bar collisions at =1.96 Tesqaure root of sV in the CDF II experiment. We observe 730+/-90 decays. The mass is measured to be 3871.3+/-0.7(stat)+/-0.4(syst) MeV/c2, with an observed width consistent with the detector resolution. This is in agreement with the recent observation by the Belle Collaboration of the X(3872) meson.     

Accurate vibrational spectra and magnetic properties of organic free radicals: the case of H2CN

We present the structural, magnetic, and vibrational properties of H2CN computed using a second-order perturbative approach in which equilibrium values and harmonic frequencies evaluated at the coupled-cluster level are combined with anharmonic and vibrational averaging contributions obtained by hybrid Hartree-Fock/Kohn-Sham methods. Our computations lead to remarkably accurate results and suggest some revision of the experimental vibrational assignments.     

Search for anomalous kinematics in tt dilepton events at CDF II

We report on a search for anomalous kinematics of tt dilepton events in pp collisions at square root of s=1.96 TeV using 193 pb(-1) of data collected with the CDF II detector. We developed a new a priori technique designed to isolate the subset in a data sample revealing the largest deviation from standard model (SM) expectations and to quantify the significance of this departure. In the four-variable space considered, no particular subset shows a significant discrepancy, and we find that the probability of obtaining a data sample less consistent with the SM than what is observed is 1.0%-4.5%.     

First measurements of inclusive W and Z cross sections from run II of the fermilab tevatron collider

We report the first measurements of inclusive W and Z cross sections times leptonic branching ratios for pp collisions at square root[s]=1.96 TeV, based on their decays to electrons and muons. The data correspond to an integrated luminosity of 72 pb(-1) recorded with the CDF detector at the Fermilab Tevatron. We test e-mu universality in W decays, and we measure the ratio of leptonic W and Z rates from which the leptonic branching fraction B(W-->lnu) can be extracted as well as an indirect value for the total width of the W and the Cabibbo-Kobayashi-Maskawa matrix element, |V(cs)|.