Color-flavor locked strange matter and strangelets at finite temperature

It is possible that a system composed of up, down and strange quarks consists the true ground state of nuclear matter at high densities and low temperatures. This exotic plasma, called strange quark matter (SQM), seems to be even more favorable energetically if quarks are in a superconducting state, the so-called color-flavor locked state. Here are presented calculations made on the basis of the MIT bag model considering the influence of finite temperature on the allowed parameters characterizing the system for stability of bulk SQM (the so-called stability windows) and also for strangelets, small lumps of SQM, both in the color-flavor locking scenario. We compare these results with the unpaired SQM and also briefly discuss some astrophysical implications of them. Also, the issue of strangelet's electric charge is discussed. The effects of dynamical screening, though important for non-paired SQM strangelets, are not relevant when considering pairing among all three flavor and colors of quarks.Comment: 17 pp. 15 figs., to appear in Phys. Rev.

Trapping of strangelets in the geomagnetic field

Strangelets coming from the interstellar medium (ISM) are an interesting target to experiments searching for evidence of this hypothetic state of hadronic matter. We entertain the possibility of a {\it trapped} strangelet population, quite analogous to ordinary nuclei and electron belts. For a population of strangelets to be trapped by the geomagnetic field, these incoming particles would have to fulfill certain conditions, namely having magnetic rigidities above the geomagnetic cutoff and below a certain threshold for adiabatic motion to hold. We show in this work that, for fully ionized strangelets, there is a narrow window for stable trapping. An estimate of the stationary population is presented and the dominant loss mechanisms discussed. It is shown that the population would be substantially enhanced with respect to the ISM flux (up to two orders of magnitude) due to quasi-stable trapping.Comment: 10 pp., 5 figure

New Colloidal Lithographic Nanopatterns Fabricated by Combining Pre-Heating and Reactive Ion Etching

We report a low-cost and simple method for fabrication of nonspherical colloidal lithographic nanopatterns with a long-range order by preheating and oxygen reactive ion etching of monolayer and double-layer polystyrene spheres. This strategy allows excellent control of size and morphology of the colloidal particles and expands the applications of the colloidal patterns as templates for preparing ordered functional nanostructure arrays. For the first time, various unique nanostructures with long-range order, including network structures with tunable neck length and width, hexagonal-shaped, and rectangular-shaped arrays as well as size tunable nanohole arrays, were fabricated by this route. Promising potentials of such unique periodic nanostructures in various fields, such as photonic crystals, catalysts, templates for deposition, and masks for etching, are naturally expected

Thermodynamic limit and semi--intensive quantities

The properties of statistical ensembles with abelian charges close to the thermodynamic limit are discussed. The finite volume corrections to the probability distributions and particle density moments are calculated. Results are obtained for statistical ensembles with both exact and average charge conservation. A new class of variables (semi--intensive variables) which differ in the thermodynamic limit depending on how charge conservation is implemented in the system is introduced. The thermodynamic limit behavior of these variables is calculated through the next to leading order finite volume corrections to the corresponding probability density distributions.Comment: 11 pages, 2 figures In v2 figures are added and corresponding editorial changes are done. Paper will be published in Journal of Physics

Ascending aortic aneurysm and aortic valve dysfunction in bicuspid aortic valve disease

BACKGROUND: The relationship of aortic valve dysfunction and ascending aortic aneurysm is unclear in adults with bicuspid aortic valve disease. METHODS: We retrospectively studied 134 consecutive out-patients (98 men, 36 women aged 43+/-18years) with bicuspid aortic valve disease. To investigate the relationship of ascending aortic aneurysm and aortic valve dysfunction we exclusively considered severe pathologies that required treatment by surgical or percutaneous intervention. RESULTS: Of 134 patients, 39 had aortic valve dysfunction without concomitant ascending aortic aneurysm which had been treated previously with isolated valve surgery or percutaneous valvuloplasty comprising 25 patients with aortic stenosis (19%) and 14 patients with aortic regurgitation (10%). Conversely, 26 patients had ascending aortic aneurysm which had been treated previously with aortic surgery (19%). Of these, ascending aortic aneurysm was associated with severe aortic stenosis in 13 patients and with severe aortic regurgitation in 7 patients, whereas aneurysm was unrelated to severe aortic valve dysfunction in the remaining 6 patients including 2 without any degree of aortic valve dysfunction. The maximal aortic diameters were similar at the time of aortic surgery irrespective of presence of severe aortic valve dysfunction (P=.527). Other characteristics of patients with ascending aortic aneurysm were also similar irrespective of presence or type of aortic valve dysfunction. CONCLUSION: The majority of patients with bicuspid aortic valve disease exhibit ascending aortic aneurysm in conjunction with severe aortic valve dysfunction. However, in our study 6 of 134 (5%) of persons with bicuspid aortic valve disease developed ascending aortic aneurysm without aortic valve dysfunction

Multiplicity Distributions in Canonical and Microcanonical Statistical Ensembles

The aim of this paper is to introduce a new technique for calculation of observables, in particular multiplicity distributions, in various statistical ensembles at finite volume. The method is based on Fourier analysis of the grand canonical partition function. Taylor expansion of the generating function is used to separate contributions to the partition function in their power in volume. We employ Laplace's asymptotic expansion to show that any equilibrium distribution of multiplicity, charge, energy, etc. tends to a multivariate normal distribution in the thermodynamic limit. Gram-Charlier expansion allows additionally for calculation of finite volume corrections. Analytical formulas are presented for inclusion of resonance decay and finite acceptance effects directly into the system partition function. This paper consolidates and extends previously published results of current investigation into properties of statistical ensembles.Comment: 53 pages, 7 figure

Bose-Einstein correlations of pion pairs in central Pb+Pb collisions at CERN SPS energies

Measurements of Bose-Einstein correlations of pion pairs in central Pb+Pb collisions were performed with the NA49 detector at the CERN SPS for beam energies of 20A, 30A, 40A, 80A, and 158A GeV. Correlation functions were measured in the longitudinally co-moving ``out-side-long'' reference frame as a function of rapidity and transverse momentum in the forward hemisphere of the reaction. Radius and correlation strength parameters were obtained from fits of a Gaussian parametrization. The results show a decrease of the radius parameters with increasing transverse momentum characteristic of strong radial flow in the pion source. No striking dependence on pion-pair rapidity or beam energy is observed. Static and dynamic properties of the pion source are obtained from simultaneous fits with a blast-wave model to radius parameters and midrapidity transverse momentum spectra. Predictions of hydrodynamic and microscopic models of Pb+Pb collisions are discussed.Comment: 22 pages, 23 figure

Measurement of event-by-event transverse momentum and multiplicity fluctuations using strongly intensive measures Δ[PT,N]\Delta[P_T, N] and Σ[PT,N]\Sigma[P_T, N] in nucleus-nucleus collisions at the CERN Super Proton Synchrotron

Results from the NA49 experiment at the CERN SPS are presented on event-by-event transverse momentum and multiplicity fluctuations of charged particles, produced at forward rapidities in central Pb+Pb interactions at beam momenta 20$A$, 30$A$, 40$A$, 80$A$, and 158$A$ GeV/c, as well as in systems of different size ($p+p$, C+C, Si+Si, and Pb+Pb) at 158$A$ GeV/c. This publication extends the previous NA49 measurements of the strongly intensive measure $\Phi_{p_T}$ by a study of the recently proposed strongly intensive measures of fluctuations $\Delta[P_T, N]$ and $\Sigma[P_T, N]$. In the explored kinematic region transverse momentum and multiplicity fluctuations show no significant energy dependence in the SPS energy range. However, a remarkable system size dependence is observed for both $\Delta[P_T, N]$ and $\Sigma[P_T, N]$, with the largest values measured in peripheral Pb+Pb interactions. The results are compared with NA61/SHINE measurements in $p+p$ collisions, as well as with predictions of the UrQMD and EPOS models.Comment: 12 pages, 14 figures, to be submitted to PR

High p_T Spectra of Identified Particles Produced in Pb+Pb Collisions at 158A GeV Beam Energy

Results of the NA49 collaboration on the production of hadrons with large transverse momentum in Pb+Pb collisions at 158A GeV beam energy are presented. A range up to p_T = 4 GeV/c is covered. The nuclear modification factor R_CP is extracted for pions, kaons and protons, and the baryon to meson ratios p/pi+, pbar/pi- and Lambda/K^0_s are studied. All results are compared to other measurements at SPS and RHIC and to theoretical calculations.Comment: Submitted to J. Phys. G (Proceedings of the 9th International Conference on Strangeness in Quark Matter, Los Angeles, USA, March 26-31, 2006). 5 pages, 3 figure

Strangeness production at SPS energies

We present a summary of measurements of strange particles performed by the experiment NA49 in central and minimum bias Pb+Pb collisions in the beam energy range 20A - 158A GeV. New results on Xi production in central Pb+Pb collisions and on Lambda, Xi production in minimum bias collisions are shown. Transverse mass spectra and rapidity distributions of strange particles at different energies are compared. The energy dependence of the particle yields and ratios is discussed. NA49 measurements of the Lambda and Xi enhancement factors are shown for the first time.Comment: Submitted to J. Phys. G (Proceedings of the 9th International Conference on Strangeness in Quark Matter, Los Angeles, USA, March 26-31, 2006). 9 pages, 9 figure