Newtonian gravity and resonance on de-Sitter branes

A dS brane on the boundary between two five-dimensional spacetimes is determined. We consider asymmetric scenarios with AdS${}_5$ vacua at each side of the dS brane; and as a result, a resonant mode inside of the spectrum of the gravitational fluctuations is found. We analyze the deviations to the Newton potential generated by the gravitational excitations, finding that, for scenarios with large values of the cosmological constants, the contribution of the resonant mode is exponentially suppressed. However, when one of the vacua is null, the resonant mode belongs to the light states set of the gravitational fluctuations and five-dimensional gravity is recovered on the dS brane.Comment: 6 pages, 2 figure

The Value of Literary Journalism: Searching for Truths Through An Objective/Subjective Dialectic

Literary Journalism is a hybrid genre that combines literary devices with advanced journalistic techniques to create nonfiction narratives. The distinctive qualities of literary journalism, working in addition to so-called objective approaches of conventional journalism, provide the reader with an alternative observation of specific social phenomena. In the introduction, issues revolving around the genre will be discussed followed by the introduction of the objective/subjective dialectic thus formulating my thesis that insists combining the two approaches allows the reader to see truth beyond ideology. The three chapters that follow offer readings of three key and representative works of literary journalism. The Armies of the Night by Norman Mailer discusses the author’s experience at a 1967 Vietnam War protest, American Ground by William Langewiesche provides a fresh look at an American tragedy, and Into Thin Air by Jon Krakauer questions the ambitions of mankind in the classic enigmatic battle versus nature

Close to the edge: hierarchy in a double braneworld

We show that the hierarchy between the Planck and the weak scales can follow from the tendency of gravitons and fermions to localize at different edges of a thick double wall embedded in an $AdS_5$ spacetime without reflection symmetry. This double wall is a stable BPS thick-wall solution with two sub-walls located at its edges; fermions are coupled to the scalar field through Yukawa interactions, but the the lack of reflection symmetry forces them to be localized in one of the sub-walls. We show that the graviton zero-mode wavefunction is suppressed in the fermion edge by an exponential function of the distance between the sub-walls, and that the massive modes decouple so that Newtonian gravity is recuperated.Comment: Some typos corrected, references adde

Gauge field localization on brane worlds

We consider the effects of spacetime curvature and brane thickness on the localization of gauge fields on a brane via kinetic terms induced by localized fermions. We find that in a warped geometry with and infinitely thin brane, both the infrared and the ultraviolet behavior of the electromagnetic propagator are affected, providing a more stringent bound on the brane's tension than that coming from the requirement of four-dimensional gravity on the brane. On the other hand, for a thick wall in a flat spacetime, where the fermions are localized by means of a Yukawa coupling, we find that 4-dimensional electromagnetism is recovered in a region bounded from above by the same critical distance appearing in the thin case, but also from below by a new scale related to the brane's thickness and the electromagnetic couplings.Comment: 7 page

Respuestas del ciclo del carbono del suelo al cambio global y su predicción mediante la modelización de vínculos entre procesos bióticos y abióticos clave en los ecosistemas terrestres

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Ecología. Fecha de lectura: 19-05-202