Excitons and biexcitons in symmetric electron-hole bilayers

Symmetric electron-hole bilayer systems have been studied at zero temperature using the diffusion quantum Monte Carlo method. A flexible trial wave function is used that can describe fluid, excitonic and biexcitonic phases. We calculate condensate fractions and pair correlation functions for a large number of densities rs and layer separations d. At small d we find a one-component fluid phase, an excitonic fluid phase, and a biexcitonic fluid phase, and the transitions among them appear to be continuous. At d = 0, excitons appear to survive down to about rs = 0.5 a.u., and biexcitons form at rs > 2.5 a.u.Comment: 5 pages, 4 figure

The Inverse Amplitude Method and Adler Zeros

The Inverse Amplitude Method is a powerful unitarization technique to enlarge the energy applicability region of Effective Lagrangians. It has been widely used to describe resonances from Chiral Perturbation Theory as well as for the Strongly Interacting Symmetry Breaking Sector. In this work we show how it can be slightly modified to account also for the sub-threshold region, incorporating correctly the Adler zeros required by chiral symmetry and eliminating spurious poles. These improvements produce negligible effects on the physical region.Comment: 17 pages, 4 figure

Chiral extrapolation of light resonances from one and two-loop unitarized Chiral Perturbation Theory versus lattice results

We study the pion mass dependence of the rho(770) and f_0(600) masses and widths from one and two-loop unitarized Chiral Perturbation Theory. We show the consistency of one-loop calculations with lattice results for the M_rho, f_pi and the isospin 2 scattering length a_20.Then, we develop and apply the modified Inverse Amplitude Method formalism for two-loop ChPT. In contrast to the f_0(600), the rho(770) is rather sensitive to the two-loop ChPT parameters --our main source of systematic uncertainty. We thus provide two-loop unitarized fits constrained by lattice information on M_rho, f_pi, by the qqbar leading 1/N_c behavior of the rho and by existing estimates of low energy constants. These fits yield relatively stable predictions up to m_pi\simeq 300-350 MeV for the rho coupling and width as well as for all the f_0(600) parameters. We confirm, to two-loops, the weak m_pi dependence of the rho coupling and the KSRF relation, and the existence of two virtual f_0(600) poles for sufficiently high m_pi. At two loops one of these poles becomes a bound state when m_pi is somewhat larger than 300 MeV.Comment: 15 pages, to appear in Phys. Rev.

El nivel IXb de Ekain (Deba, Gipuzkoa, Región Cantábrica): Una ocupación efímera del Auriñaciense Antiguo

El yacimiento de Ekain, excavado en la década de los 70, tiene una larga secuencia paleolítica. El nivel IXb había sido atribuido al Auriñaciense, pero el escaso tamaño del conjunto ha impedido que forme parte sustancial de las síntesis sobre este tecnocomplejo. En este trabajo realizamos un completo análisis de la industria lítica, con especial énfasis en los remontados. Este análisis nos ha permitido constatar que se trata de un conjunto sincrónico, del Auriñaciense Antiguo, formado por un escaso número de ocupaciones efímeras en las que la principal actividad fue la fabricación de laminillas. Estos resultados enriquecen la visión sobre este tecnocomplejo concreto en el Cantábrico Oriental

La expresión erótica en la literatura hispánica

En este texto se analizan algunos procedimientos poéticos del discurso erótico mediante la lectura de varios textos de la literatura hispánica. Esta lectura se desarrollará a través de la imagen del viaje erótico. La imagen del viaje como travesía amorosa es un motivo recurrente en la literatura de todos los tiempos. Se definen, previamente, tres nociones muy cercanas, “sexualidad, erotismo y amor”, y se distingue entre lenguaje pornográfico y lenguaje erótico. También se hace un resumen histórico de las circunstancias que han rodeado la aparición del lenguaje erótico en Occidente.This paper explores some poetic procedures of the erotic discourse through the reading of several texts in Hispanic literature. This analysis will be articulated through the image of an erotic journey. The image of the travel as a love journey is very common in the history of literature. First of all, three closely connected concepts are defined: “sexuality, eroticism and love”. A historical distinction between pornographic and erotic language will then be made. Finally, a historical summary of the circumstances surrounding the emergence of erotic language in the West will also be made.peerReviewe