11,967 research outputs found
Relativistic quantum motion of spin-0 particles under the influence of non-inertial effects in the cosmic string space-time
We study solutions for the Klein-Gordon equation with vector and scalar
potentials of the Coulomb types under the influence of non-inertial effects in
the space-time of topological defects. We also investigate a quantum particle
described by the Klein-Gordon oscillator in the background space-time generated
by a string. An important result obtained is that the non-inertial effects
restrict the physical region of the space-time where the particle can be
placed. In addition, we show that these potentials can form bound states for
the relativistic wave equation equation in this kind of background.Comment: arXiv admin note: text overlap with arXiv:1608.0669
Klein-Gordon oscillator in a topologically nontrivial space-time
In this study, we analyze solutions of the wave equation for scalar particles
in a space-time with nontrivial topology. Solutions for the Klein--Gordon
oscillator are found considering two configurations of this space-time. In the
first one, it is assumed the space where the metric is
written in the usual inertial frame of reference. In the second case, we
consider a rotating reference frame adapted to the circle S1. We obtained
compact expressions for the energy spectrum and for the particles wave
functions in both configurations. Additionally, we show that the energy
spectrum of the solution associated to the rotating system has an additional
term that breaks the symmetry around
Ages and metallicities of star clusters: new calibrations and diagnostic diagrams from visible integrated spectra
We present homogeneous scales of ages and metallicities for star clusters
from very young objects, through intermediate-age ones up to the oldest known
clusters. All the selected clusters have integrated spectra in the visible
range, as well as reliable determinations of their ages and metallicities. From
these spectra equivalent widths (EWs) of KCaII, Gband(CH) and MgI metallic, and
Hdelta, Hgamma and Hbeta Balmer lines have been measured homogeneously. The
analysis of these EWs shows that the EW sums of the metallic and Balmer H
lines, separately, are good indicators of cluster age for objects younger than
10 Gyr, and that the former is also sensitive to cluster metallicity for ages
greater than 10 Gyr. We propose an iterative procedure for estimating cluster
ages by employing two new diagnostic diagrams and age calibrations based on the
above EW sums. For clusters older than 10 Gyr, we also provide a calibration to
derive their overall metal contents.Comment: 9 pages, 4 figures, accepted by A&
Mass distribution and structural parameters of Small Magellanic Cloud star clusters
In this work, we estimate, for the first time, the total masses and mass function (MF) slopes of a sample of 29 young and intermediate-age Small Magellanic Cloud (SMC) clusters from CCD Washington photometry. We also derive age, interstellar reddening and structural parameters for most of the studied clusters by employing a statistical method to remove the unavoidable field star contamination. Only these 29 clusters out of 68 originally analysed cluster candidates present stellar overdensities and coherent distribution in their colour–magnitude diagrams compatible with the existence of a genuine star cluster. We employed simple stellar population models to derive general equations for estimating the cluster mass based only on its age and integrated light in the B, V, I, C and T1 filter. These equations were tested against mass values computed from luminosity functions, showing an excellent agreement. The sample contains clusters with ages between 60 Myr and 3 Gyr and masses between 300 and 3000 M ⊙ distributed between ∼0_{.}^{\circ}5 and ∼2° from the SMC optical centre. We determined MF slopes for 24 clusters, of which 19 have slopes compatible with that of Kroupa's initial mass function (α = 2.3 ± 0.7), considering the uncertainties. The remaining clusters – H86-188, H86-190, K47, K63 and NGC 242 – showed flatter MFs. Additionally, only clusters with masses lower than ∼1000 M ⊙ and flatter MF were found within ∼0$ $_{.}^{\circ}6 from the SMC rotational centre.Fil: Maia, F.F.S.. Universidade Federal do Minas Gerais; BrasilFil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Santos Jr., João F. C.. Universidade Federal do Minas Gerais; Brasi
Analytical BPS Maxwell-Higgs vortices
We have established a prescription for the calculation of analytical vortex
solutions in the context of generalized Maxwell-Higgs models whose overall
dynamics is controlled by two positive functions of the scalar field. We have
also determined a natural constraint between these functions and the Higgs
potential allowing the existence of axially symmetric
Bogomol'nyi-Prasad-Sommerfield (BPS) solutions possessing finite energy.
Furthermore, when the generalizing functions are chosen suitably, the
nonstandard BPS equations can be solved exactly. We have studied some examples,
comparing them with the usual Abrikosov-Nielsen-Olesen (ANO) solution. The
overall conclusion is that the analytical self-dual vortices are well-behaved
in all relevant sectors, strongly supporting the generalized models they belong
themselves. In particular, our results mimic well-known properties of the usual
(numerical) configurations, as localized energy density, while contributing to
the understanding of topological solitons and their description by means of
analytical methods.Comment: 8 pages, 4 figure
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