Ca II Triplet Spectroscopy of Small Magellanic Cloud Red Giants. III. Abundances and Velocities for a Sample of 14 Clusters

We obtained spectra of red giants in 15 Small Magellanic Cloud (SMC) clusters in the region of the CaII lines with FORS2 on the Very Large Telescope (VLT). We determined the mean metallicity and radial velocity with mean errors of 0.05 dex and 2.6 km/s, respectively, from a mean of 6.5 members per cluster. One cluster (B113) was too young for a reliable metallicity determination and was excluded from the sample. We combined the sample studied here with 15 clusters previously studied by us using the same technique, and with 7 clusters whose metallicities determined by other authors are on a scale similar to ours. This compilation of 36 clusters is the largest SMC cluster sample currently available with accurate and homogeneously determined metallicities. We found a high probability that the metallicity distribution is bimodal, with potential peaks at -1.1 and -0.8 dex. Our data show no strong evidence of a metallicity gradient in the SMC clusters, somewhat at odds with recent evidence from CaT spectra of a large sample of field stars Dobbie et al. (2014). This may be revealing possible differences in the chemical history of clusters and field stars. Our clusters show a significant dispersion of metallicities, whatever age is considered, which could be reflecting the lack of a unique AMR in this galaxy. None of the chemical evolution models currently available in the literature satisfactorily represents the global chemical enrichment processes of SMC clusters.Comment: 49 pages, 15 figures. Accepted for publication in A

Flavour violation at the LHC: type-I versus type-II seesaw in minimal supergravity

We reconsider the role that the possible detection of lepton flavour violating (LFV) decays of supersymmetric particles at the Large Hadron Collider (LHC) can play in helping reconstruct the underlying neutrino mass generation mechanism within the simplest high-scale minimal supergravity (mSUGRA) seesaw schemes. We study in detail the LFV scalar tau decays at the LHC, assuming that the observed neutrino masses arise either through the pure type-I or the simpler type-II seesaw mechanism. We perform a scan over the mSUGRA parameter space in order to identify regions where lepton flavour violating decays of $\chi^0_2$ can be maximized, while respecting current low-energy constraints, such as those coming from the bounds on Br($\mu \to e \gamma$). We estimate the cross section for $\chi^0_2 \to \chi^0_1 + \tau + \mu$. Though insufficient for a full reconstruction of the seesaw, the search for LFV decays of supersymmetric states at the LHC brings complementary information to that coming from low energy neutrino oscillation experiments and LFV searches.Comment: 20 pages, 13 figures; minor changes; 4 references added, final version for publicatio

Non-Abelian Discrete Symmetries and Neutrino Masses: Two Examples

Two recent examples of non-Abelian discrete symmetries (S_3 and A_4) in understanding neutrino masses and mixing are discussed.Comment: 16 pages, no figure, invited contribution to NJP focus issue on neutrino

Multiple stellar populations in three rich Large Magellanic Cloud star clusters

We present deep colour-magnitude diagrams for three rich intermediate-age star clusters in the Large Magellanic Cloud, constructed from archival ACS F435W and F814W imaging. All three clusters exhibit clear evidence for peculiar main-sequence turn-offs. NGC 1846 and 1806 each possess two distinct turn-off branches, while the turn-off for NGC 1783 shows a much larger spread in colour than can be explained by the photometric uncertainties. We demonstrate that although all three clusters contain significant populations of unresolved binary stars, these cannot be the underlying cause of the observed turn-off morphologies. The simplest explanation is that each cluster is composed of at least two different stellar populations with very similar metal abundances but ages separated by up to ~300 Myr. The origin of these unusual properties remains unidentified; however, the fact that at least three massive clusters containing multiple stellar populations are now known in the LMC suggests a potentially significant formation channel.Comment: To appear in ApJ Letters, replaced with accepted versio

Scaling laws for the 2d 8-state Potts model with Fixed Boundary Conditions

We study the effects of frozen boundaries in a Monte Carlo simulation near a first order phase transition. Recent theoretical analysis of the dynamics of first order phase transitions has enabled to state the scaling laws governing the critical regime of the transition. We check these new scaling laws performing a Monte Carlo simulation of the 2d, 8-state spin Potts model. In particular, our results support a pseudo-critical beta finite-size scaling of the form beta(infinity) + a/L + b/L^2, instead of beta(infinity) + c/L^d + d/L^{2d}. Moreover, our value for the latent heat is 0.294(11), which does not coincide with the latent heat analytically derived for the same model if periodic boundary conditions are assumed, which is 0.486358...Comment: 10 pages, 3 postscript figure

The Gaia-ESO Survey: Detailed Abundances in the Metal-poor Globular Cluster NGC 4372

We present the abundance analysis for a sample of 7 red giant branch stars in the metal-poor globular cluster NGC 4372 based on UVES spectra acquired as part of the Gaia-ESO Survey. This is the first extensive study of this cluster from high resolution spectroscopy. We derive abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, Fe, Cr, Ni, Y, Ba, and La. We find a metallicity of [Fe/H] = -2.19 $\pm$ 0.03 and find no evidence for a metallicity spread. This metallicity makes NGC 4372 one of the most metal-poor galactic globular clusters. We also find an {\alpha}-enhancement typical of halo globular clusters at this metallicity. Significant spreads are observed in the abundances of light elements. In particular we find a Na-O anti-correlation. Abundances of O are relatively high compared with other globular clusters. This could indicate that NGC 4372 was formed in an environment with high O for its metallicity. A Mg-Al spread is also present which spans a range of more than 0.5 dex in Al abundances. Na is correlated with Al and Mg abundances at a lower significance level. This pattern suggests that the Mg-Al burning cycle is active. This behavior can also be seen in giant stars of other massive, metal-poor clusters. A relation between light and heavy s-process elements has been identified.Comment: 14 pages, 14 figures, accepted for publication in A&

Determination of carboximetillysine in toasted and baked foods

La carboximetillisina (CML) es un indicador de etapas avanzadas de la reacción de Maillard. Su formación en los alimentos dependerá directamente de la composición de los mismos, pero también de la temperatura y tiempo de calentamiento al que se ven sometidos durante el procesado. Concretamente, se ve favorecida cuando el tratamiento térmico es más severo, de ahí que esté presente en alimentos tostados u horneados como los productos de panadería o bollería. En el presente trabajo se analizó el contenido de CML en 9 tipos de alimentos: pan integral, pan de molde tostado a diferentes tiempos, colines, torta de inés rosales, palmera, caracola, suizo y medianoche y galleta integral más o menos horneadas. La determinación de CML se realizó mediante cromatografía de gases acoplada a espectrometría de masas, previa reducción, hidrólisis y derivatización. Los valores de CML determinados en las muestras del estudio oscilaron entre 1,38 mg/100 g muestra (palitos no integrales) y 10,4 mg/100 g de muestra (galleta más tostada). El pan de molde mostró un incremento en el contenido de CML paralelo al tiempo de tostado, pasando de 6,31 mg/100 g sin tostar, a 6,44 mg/100g con 1 minuto de tostado y a 8,95 mg/100 g con 6 minutos de tostado. En conclusión, es importante conocer la cantidad de CML que contiene un alimento, para controlar su ingesta, especialmente en los sometidos a tostado u horneado, ya que, como se ha comprobado en este estudio, el contenido de CML incrementa paralelamente al tratamiento térmico.Carboximetillysine (CML) is an indicator of advanced stages of Maillard reaction. Its formation in foods depends on their composition but, moreover, on temperature and time of thermal treatment whom they are submitted during processed. Particularly, it is favored when thermal treatment is more severe, with the result that it is present in toasted or baked foods such as bakery products. In the present study, CML content in 9 different foods was analyzed: integral bread, sliced bread which was toasted at different times, breadsticks, “inés rosales” cake, heart-shaped pastry, flaky pastry, bun with sugar and bun and integral biscuit more or less baked. Determination of CML was carried out by GCMS, after reduction, hydrolysis and derivatization. CML values in studied samples ranged from 1.38 mg/100 g of sample (no integral breadsticks) to 10.4 mg/100 g of sample (more toasted biscuit). In sliced bread a relationship between CML content and time of toasting was observed, increasing from 6.31 mg/100 g without toasting to 6.44 mg/100 g with 1 min and to 8.95 mg/100 g with 6 min of toasting. In conclusion, it is important to know CML content in foods in order to control its intake, especially in toasted or baked foods since, as it has been tested in this study, CML content is related to the thermal treatment.Este trabajo ha sido realizado bajos los proyectos de investigación AGL 2006 12656/ALI, financiado por el Ministerio de Ciencia y Tecnología y P06 CTS 1900, financiado por la Junta de Andalucía

Numerical comparison of two approaches for the study of phase transitions in small systems

We compare two recently proposed methods for the characterization of phase transitions in small systems. The validity and usefulness of these approaches are studied for the case of the q=4 and q=5 Potts model, i.e. systems where a thermodynamic limit and exact results exist. Guided by this analysis we discuss then the helix-coil transition in polyalanine, an example of structural transitions in biological molecules.Comment: 16 pages and 7 figure

Minimal Supersymmetric Inverse Seesaw: Neutrino masses, lepton flavour violation and LHC phenomenology

We study neutrino masses in the framework of the supersymmetric inverse seesaw model. Different from the non-supersymmetric version a minimal realization with just one pair of singlets is sufficient to explain all neutrino data. We compute the neutrino mass matrix up to 1-loop order and show how neutrino data can be described in terms of the model parameters. We then calculate rates for lepton flavour violating (LFV) processes, such as $\mu \to e \gamma$, and chargino decays to singlet scalar neutrinos. The latter decays are potentially observable at the LHC and show a characteristic decay pattern dictated by the same parameters which generate the observed large neutrino angles.Comment: 26 pages, 4 figures; added explanatory comments, final version for publicatio

Infrared photometry and CaT spectroscopy of globular cluster M 28 (NGC 6626)

Recent studies show that the inner Galactic regions host genuine bulge globular clusters, but also halo intruders, complex remnants of primordial building blocks, and objects likely accreted during major merging events. In this study we focus on the properties of M 28, a very old and massive cluster currently located in the Galactic bulge. We analysed wide-field infrared photometry collected by the VVV survey, VVV proper motions, and intermediate-resolution spectra in the calcium triplet range for 113 targets in the cluster area. Our results in general confirm previous estimates of the cluster properties available in the literature. We find no evidence of differences in metallicity between cluster stars, setting an upper limit of Delta[Fe/H]<0.08 dex to any internal inhomogeneity. We confirm that M 28 is one of the oldest objects in the Galactic bulge (13-14 Gyr). From this result and the literature data, we find evidence of a weak age-metallicity relation among bulge globular clusters that suggests formation and chemical enrichment. In addition, wide-field density maps show that M 28 is tidally stressed and that it is losing mass into the general bulge field. Our study indicates that M 28 is a genuine bulge globular cluster, but its very old age and its mass loss suggest that this cluster could be the remnant of a larger structure, possibly a primeval bulge building block.Comment: Accepted for publication in Astronomy & Astrophysic