A QCD sum rule calculation of the X±(5568)→Bs0π±X^\pm(5568) \to B_{s}^0\pi^\pm decay width

To understand the nature of the $X(5568)$, recently observed in the mass spectrum of the $B_{s}^0\pi^\pm$ system by the D0 Collaboration, we have investigated, in a previous work, a scalar tetraquark (diquak-antidiquark) structure for it, within the two-point QCD sum rules method. The result found for its mass agrees well with the experimental value. Encouraged by this finding we now extend our calculations to obtain the decay width of $X(5568)$ to $B_{s}^0\pi^\pm$ using the three-point QCD sum rule. We obtain a value of (20.4\pm8.7)\MeV, which, on comparing with the experimental value of 21.9\pm6.4 (\mbox{sta})^{+5.0}_{-2.5}(\mbox{syst}) \MeV/c^2, reinforces the scalar four quark nature of $X(5568)$.Comment: Minor modifications made. Some new discussions and references adde

Monte Carlo Simulations of Ultrathin Magnetic Dots

In this work we study the thermodynamic properties of ultrathin ferromagnetic dots using Monte Carlo simulations. We investigate the vortex density as a function of the temperature and the vortex structure in monolayer dots with perpendicular anisotropy and long-range dipole interaction. The interplay between these two terms in the hamiltonian leads to an interesting behavior of the thermodynamic quantities as well as the vortex density.Comment: 10 figure

Hamiltonian thermodynamics of three-dimensional dilatonic black holes

The action for a class of three-dimensional dilaton-gravity theories with a cosmological constant can be recast in a Brans-Dicke type action, with its free $\omega$ parameter. These theories have static spherically symmetric black holes. Those with well formulated asymptotics are studied through a Hamiltonian formalism, and their thermodynamical properties are found out. The theories studied are general relativity ($\omega\to\infty$), a dimensionally reduced cylindrical four-dimensional general relativity theory ($\omega=0$), and a theory representing a class of theories ($\omega=-3$). The Hamiltonian formalism is setup in three dimensions through foliations on the right region of the Carter-Penrose diagram, with the bifurcation 1-sphere as the left boundary, and anti-de Sitter infinity as the right boundary. The metric functions on the foliated hypersurfaces are the canonical coordinates. The Hamiltonian action is written, the Hamiltonian being a sum of constraints. One finds a new action which yields an unconstrained theory with one pair of canonical coordinates $\{M,P_M\}$, $M$ being the mass parameter and $P_M$ its conjugate momenta The resulting Hamiltonian is a sum of boundary terms only. A quantization of the theory is performed. The Schr\"odinger evolution operator is constructed, the trace is taken, and the partition function of the canonical ensemble is obtained. The black hole entropies differ, in general, from the usual quarter of the horizon area due to the dilaton.Comment: 34 pages, 3 figures, references added, minor changes in the revised versio

Time dependent transformations in deformation quantization

We study the action of time dependent canonical and coordinate transformations in phase space quantum mechanics. We extend the covariant formulation of the theory by providing a formalism that is fully invariant under both standard and time dependent coordinate transformations. This result considerably enlarges the set of possible phase space representations of quantum mechanics and makes it possible to construct a causal representation for the distributional sector of Wigner quantum mechanics.Comment: 16 pages, to appear in the J. Math. Phy

Half Quantization

A general dynamical system composed by two coupled sectors is considered. The initial time configuration of one of these sectors is described by a set of classical data while the other is described by standard quantum data. These dynamical systems will be named half quantum. The aim of this paper is to derive the dynamical evolution of a general half quantum system from its full quantum formulation. The standard approach would be to use quantum mechanics to make predictions for the time evolution of the half quantum initial data. The main problem is how can quantum mechanics be applied to a dynamical system whose initial time configuration is not described by a set of fully quantum data. A solution to this problem is presented and used, as a guideline to obtain a general formulation of coupled classical-quantum dynamics. Finally, a quantization prescription mapping a given classical theory to the correspondent half quantum one is presented.Comment: 20 pages, LaTex file, Substantially revised versio

The impact of sound in people's behaviour in outdoor settings: A study using virtual reality and eye-tracking

This paper presents an analysis of space perception and how visual cues, such as landmarks and sound, are perceived and impact people's behaviour while exploring a given outdoor space. The primary goal of the research is to investigate how auditory sensations and visual stimuli influence people's behaviour in outdoor built environments. Our technique compares people's perception of the built environment in different conditions: the real world and a replicated virtual world. As a case study, a university campus was used, and four experimental conditions were designed. The study followed a between-subjects design, and the data collection included gaze data acquired from an eye-tracking device as well as self-reports. The study concludes that sound influences human behaviour in such settings. More specifically conclusions are that: i) human behaviour in virtual replications of the real space, including both visual and sound stimuli, is tendentially more similar to human behaviour in the real world than in simulations omitting sound; and ii) there is a difference in human behaviour when people explore the same virtually replicated outdoor space, by varying the presence of sound. This study is particularly useful for researchers working on the comparison between human behaviour in virtual and real environments, related to visual and sound stimuli.info:eu-repo/semantics/publishedVersio

X, Y and Z States

Many new states in the charmonium mass region were recently discovered by BaBar, Belle, CLEO-c, CDF, D0, BESIII, LHCb and CMS Collaborations. We use the QCD Sum Rule approach to study the possible structure of some of these states.Comment: Contribution for the proceedings of the "XII Quark Confinement and the Hadron Spectrum - CONF12" conferenc