Effects of drop and film viscosity on drop impacts onto thin films

While drop-film impacts have been studied extensively in the past, little thought has been given towards separating the effects of the drop fluid properties from those of the film. Distinguishing between the behaviors resulting from characteristics of each independently could provide insight into the underlying physical phenomena with a clarity that is unavailable when the drop and the film consist of identical liquids. In this study, the viscosity is the central parameter varied in both drop and film liquid. Using water, aqueous glycerol mixtures, and Fluoroinert FC-72, a range of kinematic viscosity covering 3 orders of magnitude (4 × 10-7 - 6.5 × 10 -4 m2/s) is examined; a smaller range of surface tension (0.024-0.072 N/m) is covered, as well. Drop impacts occur over a range of Weber numbers from 20 to 3000 and Reynolds numbers from 20 to 14000. Impact outcomes categorized are both formation of a crown and splashing from the crown. Criteria for each impact outcome are presented in light of both film and drop properties; certain outcomes are found to depend more strongly on either the properties of the drop or the film individually. Crown formation appears to relate more strongly to the film's properties, whereas crown splashing has some dependence on the drop properties. Existing splashing correlations are examined in light of the separation of properties. © 2013 by Begell House, Inc

Experimental determination of multipartite entanglement with incomplete information

Multipartite entanglement is very poorly understood despite all the theoretical and experimental advances of the last decades. Preparation, manipulation and identification of this resource is crucial for both practical and fundamental reasons. However, the difficulty in the practical manipulation and the complexity of the data generated by measurements on these systems increase rapidly with the number of parties. Therefore, we would like to experimentally address the problem of how much information about multipartite entanglement we can access with incomplete measurements. In particular, it was shown that some types of pure multipartite entangled states can be witnessed without measuring the correlations [M. Walter et al., Science 340, 1205 (2013)] between parties, which is strongly demanding experimentally. We explore this method using an optical setup that permits the preparation and the complete tomographic reconstruction of many inequivalent classes of three- and four-partite entangled states, and compare complete versus incomplete information. We show that the method is useful in practice, even for non-pure states or non ideal measurement conditions.Comment: 12 pages, 7 figures. Close to published versio

Universality in the Electroproduction of Vector Mesons

We study universality in the electroproduction of vector mesons using a unified nonperturbative approach which has already proved to reproduce extremely well the available experimental data. In this framework, after the extraction of factors that are specific of each vector meson, we arrive at a reduced integrated elastic cross section which is universal. Our calculations suggest a finite infrared behavior for the strong coupling constant.Comment: 22 pages, 10 figure

Recent studies of top quark properties and decays at hadron colliders

The top quark is the heaviest known elementary particle. Observed for the first time in 1995 at the Tevatron by the CDF and D0 experiments, it has become object of several studies aimed at fully characterize its properties and decays. Precise determinations of top quark characteristics verify the internal consistency of the standard model and are sensitive to new physics phenomena. With the advent of the large top quark production rates generated at the LHC, top quark studies have reached unprecedented statistical precision. This review summarizes the recent measurements of top quark properties and studies of its decays performed at the LHC and Tevatron.Comment: 13 pages, 4 figures, 5 tables, Presented at Flavor Physics and CP Violation (FPCP 2012), Hefei, China, May 21-25, 201

Quark mixings as a test of a new symmetry of quark Yukawa couplings

Based on the hierarchy exhibited by quarks masses at low energies, we assume that Yukawa couplings of up and down quarks are related by $Y_u\propto Y_d^2$ at grand unification scales. This ansatz gives rise to a symmetrical CKM matrix at the grand unification (GU) scale. Using three specific models as illustrative examples for the evolution down to low energies, we obtain the entries and asymmetries of the CKM matrix which are in very good agreement with their measured values. This indicates that the small asymmetry of the CKM matrix at low energies may be the effect of the renormalization group evolution only.Comment: LaTeX file, 10 pages including 1 tabl

Experimental investigation of dynamical invariants in bipartite entanglement

The non-conservation of entanglement, when two or more particles interact, sets it apart from other dynamical quantities like energy and momentum. It does not allow the interpretation of the subtle dynamics of entanglement as a flow of this quantity between the constituents of the system. Here we show that adding a third party to a two-particle system may lead to a conservation law that relates the quantities characterizing the bipartite entanglement between each of the parties and the other two. We provide an experimental demonstration of this idea using entangled photons, and generalize it to N-partite GHZ states

Stability of Ca-montmorillonite hydrates: A computer simulation study

Classic simulations are used to study interlayer structure, swelling curves, and stability of Ca-montmorillonite hydrates. For this purpose, NPzzT$ and MuPzzT ensembles are sampled for ground level and given burial conditions. For ground level conditions, a double layer hydrate having 15.0 A of basal spacing is the predominant state for relative vapor pressures (p/po) ranging in 0.6-1.0. A triple hydrate counting on 17.9 A of interlaminar distance was also found stable for p/po=1.0. For low vapor pressures, the system may produce a less hydrated but still double layer state with 13.5 A or even a single layer hydrate with 12.2 A of interlaminar distance. This depends on the established initial conditions. On the other hand, the effect of burial conditions is two sided. It was found that it enhances dehydration for all vapor pressures except for saturation, where swelling is promoted.Comment: 8 pages, 9 figure

White dwarf constraints on a varying GG

A secular variation of $G$ modifies the structure and evolutionary time scales of white dwarfs. Using an state-of-the-art stellar evolutionary code, an up-to-date pulsational code, and a detailed population synthesis code we demonstrate that the effects of a running $G$ are obvious both in the properties of individual white dwarfs, and in those of the white dwarf populations in clusters. Specifically, we show that the white dwarf evolutionary sequences depend on both the value of $\dot G/G$, and on the value of $G$ when the white dwarf was born. We show as well that the pulsational properties of variable white dwarfs can be used to constrain $\dot G/G$. Finally, we also show that the ensemble properties of of white dwarfs in clusters can also be used to set upper bounds to $\dot G/G$. Precisely, the tightest bound --- $\dot G/G \sim -1.8 10^{-12}$ yr$^{-1}$ --- is obtained studying the population of the old, metal-rich, well populated, open cluster NGC 6791. Less stringent upper limits can be obtained comparing the theoretical results obtained taking into account the effects of a running $G$ with the measured rates of change of the periods of two well studied pulsating white dwarfs, G117--B15A and R548. Using these white dwarfs we obtain $\dot G/G\sim -1.8\times 10^{-10}$ yr$^{-1}$, and $\dot G/G\sim -1.3\times 10^{-10}$ yr$^{-1}$, respectively, which although less restrictive than the previous bound, can be improved measuring the rate of change of the period of massive white dwarfs.Comment: 6 pages, 3 figures. To be published in the proceedings of the conference "Varying fundamental constants and dynamical dark energy" (8 - 13 July 2013, Sexten Center for Astrophysics

A clean signal for a top-like isosinglet fermion at the Large Hadron Collider

We predict a clean signal at the Large Hadron Collider ($\sqrt s)$=14 TeV for a scenario where there is a top-like, charge +2/3 vectorlike isosinglet fermion. Such a quark, via mixing with the standard model top, can undergo decays via both flavour-changing Z-boson coupling and flavour-changing Yukawa interactions. We concentrate on the latter channel, and study the situation where, following its pair-production, the heavy quark pair gives rise to two tops and two Higgs boson. We show that the case where each Higgs decays in the $b\bar{b}$ channel, there can be a rather distinct and background-free signal that can unveil the existence of the vectorlike isosinglet quark of this kind.Comment: 14 pages, 5 figures, 4 table