Transport properties of a meson gas

We present recent results on a systematic method to calculate transport coefficients for a meson gas (in particular, we analyze a pion gas) at low temperatures in the context of Chiral Perturbation Theory. Our method is based on the study of Feynman diagrams with a power counting which takes into account collisions in the plasma by means of a non-zero particle width. In this way, we obtain results compatible with analysis of Kinetic Theory with just the leading order diagram. We show the behavior with temperature of electrical and thermal conductivities and shear and bulk viscosities, and we discuss the fundamental role played by unitarity. We obtain that bulk viscosity is negligible against shear viscosity near the chiral phase transition. Relations between the different transport coefficients and bounds on them based on different theoretical approximations are also discussed. We also comment on some applications to heavy-ion collisions.Comment: 4 pages, 4 figures, IJMPE style. Contribution to the International Workshop X Hadron Physics (2007), Florianopolis, Brazil. Accepted for publication in IJMPE; 1 typo correcte

Bulk viscosity and the conformal anomaly in the pion gas

We calculate the bulk viscosity of the massive pion gas within Unitarized Chiral Perturbation Theory. We obtain a low temperature peak arising from explicit conformal breaking due to the pion mass and another peak near the critical temperature, dominated by the conformal anomaly through gluon condensate terms. The correlation between bulk viscosity and conformal breaking supports a recent QCD proposal. We discuss the role of resonances, heavier states and large-$N_c$ counting.Comment: Revised version accepted in Phys.Rev.Lett. 4 pages, 3 figure

Transport coefficients in Chiral Perturbation Theory

We present recent results on the calculation of transport coefficients for a pion gas at zero chemical potential in Chiral Perturbation Theory using Linear Response Theory. More precisely, we show the behavior of DC conductivity and shear viscosity at low temperatures. To compute transport coefficients, the standard power counting of ChPT has to be modified. The effects derived from imposing unitarity are also analyzed. As physical applications in Relativistic Heavy Ion Collisions, we show the relation of the DC conductivity to soft-photon production and phenomenological effects related to a nonzero shear viscosity. In addition, our values for the shear viscosity to entropy ratio satisfy the KSS bound.Comment: 3 pages, 6 figures, EPJA style. Talk given at the QNP06 conference in Madrid, and accepted for publication in EPJ

Shaping the identity of novice academics: strategies for support professional development

Studies on professional development and the construction of teaching identities in Higher Education point to the need to review the induction process for novice academics and to establish programmes that support their inclusion in the university. This article analyses such a programme, focusing on strategies used to construct an academic teaching identity. The results allowed participants to feel included, to construct rational guidelines for teaching, and to construct clear scenarios for understanding their tasks within the institution.However,theresultsalso highlight the need to integrate the research side intothe programme, thus helping them to construct a global academic identity that integrates the teaching self and the investigating self.IkasGura Research Group which is funded by the UPV/EHU (GIU 14/08) and, at the same time is part of the Training and Research Unit “Education, Culture and Society (UFI 11/54)

Pion scattering poles and chiral symmetry restoration

Using unitarized Chiral Perturbation Theory methods, we perform a detailed analysis of the $\pi\pi$ scattering poles $f_0(600)$ and $\rho(770)$ behaviour when medium effects such as temperature or density drive the system towards Chiral Symmetry Restoration. In the analysis of real poles below threshold, we show that it is crucial to extend properly the unitarized amplitudes so that they match the perturbative Adler zeros. Our results do not show threshold enhancement effects at finite temperature in the $f_0(600)$ channel, which remains as a pole of broad nature. We also implement T=0 finite density effects related to chiral symmetry restoration, by varying the pole position with the pion decay constant. Although this approach takes into account only a limited class of contributions, we reproduce the expected finite density restoration behaviour, which drives the poles towards the real axis, producing threshold enhancement and $\pi\pi$ bound states. We compare our results with several model approaches and discuss the experimental consequences, both in Relativistic Heavy Ion Collisions and in $\pi\to \pi\pi$ and $\gamma\to \pi\pi$ reactions in nuclei.Comment: 17 pages, 9 figures, final version to appear in Phys.Rev.D, added comments and reference

Analysis and interpretation of the spatial distribution of flags of Spain and religious symbols on the balconies of the municipality of Seville

In recent years Spanish flags have been hanged on balconies of private homes in different Spanish cities, reaching its peak at the end of 2017 during the tensest days of the institutional crisis in Catalonia. This paper identifies the spatial patterns of the distribution of Spanish flags and religious symbols on the balconies of the municipality of Seville, analyzing their relationship between the electoral results of the last elections to the Andalusian Parliament and other socioeconomic variables. The results indicate a strong correlation with the ideology of the voters, identifying positive correlations with respect to the vote to the PP and Vox, and negative with respect to the vote to Adelante Andalucía and PSOE

Scale, digitizing effort and fractality of the shoreline

En este trabajo se analizan las interrelaciones entre escala, esfuerzo digitalizador y dimensión fractal en los procesos de digitalización de diferentes tipos de línea de costa en siete sectores costeros diferentes. A partir de ortoimágenes con una resolución espacial de 0,5 metros, se digitalizaron 25 tramos costeros diferentes a cinco escalas distintas, de 1:10.000 a 1:1.500, identificando la longitud de cada uno de los tramos obtenidos y el número de vértices. Se calculó la dimensión fractal de cada uno de los tramos digitalizados a cada escala, analizando esta variable con la longitud y el número de vértices. Los resultados indican que algunos tramos costeros de gran complejidad (marismas y costas rocosas) presentan una estructura fractal. En estos casos es posible predecir la longitud total de línea de costa a gran escala a partir de la longitud de líneas de costa a menor escala.The aim of this work is to analyse the interrelations between scale, digitizing effort and fractal dimension in the digitization processes of different types of shoreline in seven coastal sectors. From orthoimages with a spatial resolution of 0.5 meters, 25 different coastal segments were digitized at five different scales, ranging from 1: 10,000 to 1: 1,500. The length of each of the obtained segments and their number of vertices were calculated. The fractal dimension of each of the digitized sections was calculated at each scale, analyzing this variable with the length and number of vertices. The results show that some very complex coastal sectors (tidal marshes and rocky coasts) have a fractal structure. In these cases it is possible to predict the total length of large-scale coastline from the length obtained digitizing at a smaller scale