Effect of a cylindrical thin-shell of matter on the electrostatic self-force on a charge

The electrostatic self-force on a point charge in cylindrical thin-shell space-times is interpreted as the sum of a $bulk$ field and a $shell$ field. The $bulk$ part corresponds to a field sourced by the test charge placed in a space-time without the shell. The $shell$ field accounts for the discontinuity of the extrinsic curvature ${\kappa^p}_q$. An equivalent electric problem is stated, in which the effect of the shell of matter on the field is reconstructed with the electric potential produced by a non-gravitating charge distribution of total image charge $Q$, to interpret the shell field in both the interior and exterior regions of the space-time. The self-force on a point charge $q$ in a locally flat geometry with a cylindrical thin-shell of matter is calculated. The charge is repelled from the shell if ${\kappa^{p}}_{p}=\kappa<0$ (ordinary matter) and attracted toward the shell if $\kappa>0$ (exotic matter). The total image charge is zero for exterior problems, while for interior problems $Q/q=-\kappa \, r_e$, with $r_e$ the external radius of the shell. The procedure is general and can be applied to interpret self-forces in other space-times with shells, e.g., for locally flat wormholes we found $Q_{\mp}^{wh}/q=-1/ (\kappa_{wh} r_{\pm})$.Comment: (15 pages, 6 figures; the work had been extended, corrected and reformulated from version v1 to v2, and minor misprints corrected from v2 to v3

Perturbative dynamics of thin-shell wormholes beyond general relativity: An alternative approach

Recent studies relating the approximations for the equations-of-state for thin shells and their consequent perturbative evolution are extended to thin-shell wormholes in theories beyond general relativity and more than four spacetime dimensions. The assumption of equations-of-state of the same form for static and slowly evolving shells appears as a strong restriction excluding the possibility of oscillatory evolutions. Then the new results considerably differ from previous ones obtained within the usual linearized approach.Fil: Rubín de Celis, Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Tomasini, Cecilia. Universidad de Buenos Aires; ArgentinaFil: Simeone, Claudio Mauricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin

Probing global aspects of a geometry by the self-force on a charge: Spherical thin-shell wormholes

The self-interaction for a static point charge in the space-time of a thin-shell wormhole constructed connecting two identical Schwarzschild geometries is calculated in a series expansion. The electrostatic self-force is evaluated numerically. It is found to be attractive towards the throat except for some values of the throat radius proximate to the value of the Schwarzschild horizon for which the force is repulsive or attractive depending on the position of the charge. The result differs from the self-force in the space-time of the Schwarzschild black hole, where it is always repulsive from the center. Although these wormhole and black hole geometries are locally indistinguishable, the different topologies of both backgrounds are manifested in the electrostatic field of a point charge.Comment: 17 pages, 4 figue

Felix Hänseler (1780-1841), a german-born spanish botanist and pharmacist who lived in Málaga at one time

La biografía botánica más completa y fiable de este destacado investigador hispano-alemán –más conocido por el apellido paterno de Haenseler o Henseler–, continúa siendo la publicada a mediados del siglo XIX en la revista científica berlinesa Botanische Zeitung (1846); que fue confeccionada conjuntamente por sus amigos y colegas Pablo Prolongo García (1806-1885) y Moritz Willkomm (1821-1895)1, cuya versión española presentaron Juan A. Devesa y Mª del Carmen Viera (2001). La gran importancia del personaje y de sus investigaciones naturalísticas multidisciplinares en la provincia de Málaga merecen ser revalorizadas. En este artículo partiremos de la referida publicación bio-bibliográfica de 1846 en la que integraremos la muy atomizada información disponible actualmente sobre nuestro biografiado, de quien en el contexto académico nacional únicamente hay una escueta referencia recogida en la Flora Ibéric

Self-force on an arbitrarily coupled scalar charge in cylindrical thin-shell spacetimes

We consider the arbitrarily coupled field and self-force of a static massless scalar charge in cylindrical spacetimes with one or two asymptotic regions, with the only matter content concentrated in a thin-shell characterized by the trace of the extrinsic curvature jump κ. The self-force is studied numerically and analytically in terms of the curvature coupling ξ. We found the critical values ξc(n)=n/(ρ(rs)κ), with n∈ N and ρ(rs) the metric’s profile function at the position of the shell, for which the scalar field is divergent in the background configuration. The pathological behavior is removed by restricting the coupling to a domain of stability. The coupling has a significant influence over the self-force at the vicinities of the shell, and we identified ξ= 1 / 4 as the value for which the scalar force changes sign at a neighborhood of rs; if κ(1 - 4 ξ) > 0 the shell acts repulsively as an effective potential barrier, while if κ(1 - 4 ξ) < 0 it attracts the charge as a potential well. The sign of the asymptotic self-force only depends on whether there is an angle deficit or not on the external region where the charge is placed; conical asymptotics produce a leading attractive force, while Minkowski regions produce a repulsive asymptotic self-force.Fil: Tomasini, Clara Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Rubín de Celis, Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Simeone, Claudio Mauricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentin