4,239 research outputs found
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
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