The eta transition form factor from space- and time-like experimental data

The $\eta$ transition form factor is analysed for the first time in both space- and time-like regions at low and intermediate energies in a model-independent approach through the use of rational approximants. The $\eta\rightarrow e^+e^-\gamma$ experimental data provided by the A2 Collaboration in the very low energy region of the dilelectron invariant mass distribution allows for the extraction of the most precise up-to-date slope and curvature parameters of the form factors as well as their values at zero and infinity. The impact of these new results on the mixing parameters of the $\eta$-$\eta^\prime$ system, together with the role played by renormalisation dependent effects, and on the determination of the $VP\gamma$ couplings from $V\to P\gamma$ and $P\to V\gamma$ radiative decays are also discussed.Comment: 16 pages, 17 figures; v2: additional comments, references added; mathces published version in EPJ

Greens function for time-harmonic elastodynamics in a half-space with hysteretic damping

Se presenta una solución analítica para la respuesta de un semiespacio tridimensional homogéneo con una carga puntual armónica en el tiempo. Esta expresión es de gran importancia debido a que se puede emplear como solución fundamental en el Método de los Elementos de Contorno para la resolución de problemas elastodinámicos tridimensionales de semiespacios. Las expresiones se han validado comparando los resultados con otros empleados en el Método de Elementos de Contorno en los que es necesaria la discretización de la superficie del semiespacio. También se ha comparado con otras soluciones para el semiespacio en 2.5D y con resultados experimentales obtenidos de referencias bibliográficas. Por último, se estudia el comportamiento asintótico de la solución para diferentes estados comparando los resultados con soluciones fundamentales existentes.This paper presents an analytical solution for the steady-state response of a homogeneous three-dimensional half-space subject to a time-harmonic point load. This expresion is of great importance in the formulation of three-dimensional elastodynamic problems in a half-space by means of boundary element methods which can be employed as a Fundamental Solution. The expressions are validated comparing the results with those obtained with the boundary element method solution, where the free surface is discretized. The solution is further compared to that of a 2.5D half-space, and with experimental results available in the literature. The asymptotic behaviour of the solution is explored for different limits of the distance, frequency and wave number, and the ensuing limits are compared to existing fundamental solutions.Peer Reviewe

Steady-state signatures of radiation trapping by cold multilevel atoms

In this paper, we use steady-state measurements to obtain evidence of radiation trapping in an optically thick a cloud of cold rubidium atoms. We investigate the fluorescence properties of our sample, pumped on opened transitions. The intensity of fluorescence exhibits a non trivial dependence on the optical thickness of the media. A simplified model, based on rate equations self-consistently coupled to a diffusive model of light transport, is used to explain the experimental observations in terms of incoherent radiation trapping on one spectral line. Measurements of atomic populations and fluorescence spectrum qualitatively agree with this interpretation.Comment: 8 pages, 5 figure

Die ältesten schriftlichen Belege für den Gott Seth

The present paper addresses the alkali activation of Portland cements containing blast furnace slag (20 and 30% of the cement by weight) with a view to the possible use of these materials in oil well construction. The hydration studies conducted showed that in cement/slag blends, the sodium silicate activating solution partially inhibited the dissolution of the silicate phases in the Portland cement, retarding cement hydration and reducing the precipitation of reaction products. Due to such partial inhibition, the cement/slag blends had significantly lower mechanical strength than Portland cements hydrated with water. 29Si and 27Al MAS NMR and BSE/EDX studies, in turn, showed that the C-S-H gel forming in the alkali-activated cement/slag pastes contained Al in tetrahedral positions and low Ca/Si ratios.En el presente trabajo se ha estudiado la activación alcalina de cementos Pórtland con incorporación de escoria de horno alto (20% y 30% con respecto al peso de cemento) para su posible aplicación en la construcción de pozos petrolíferos. Los estudios de hidratación realizados indican que en mezclas cemento/escoria, la disolución activadora de silicato sódico inhibe parcialmente la disolución de las fases silicato del cemento Pórtland originando un retraso de su hidratación así como la menor precipitación de productos de reacción. Dicha parcial inhibición de los procesos reactivos en las mezclas cemento/escoria originan resistencias mecánicas significativamente inferiores a las pastas de cemento Portland hidratadas con agua. Finalmente, los estudios de 29Si y 27Al RMN MAS y BSE/EDX indican que el gel C-S-H formado en pastas de mezcla cemento/escoria activadas alcalinamente presenta Al en posiciones tetraédricas y bajas relaciones Ca/Si

A combined study of hadronic D+→K−π+π+D^+\to K^-\pi^+\pi^+ and Ds+→K+K+π−D_s^+\to K^+K^+\pi^- decays by means of the analysis of semileptonic D+→K−π+ℓ+νℓD^+\to K^-\pi^+ \ell^+\nu_\ell decays

We perform a combined study of the two hadronic decays $D^+\to K^-\pi^+\pi^+$ and $D_s^+\to K^+K^+\pi^-$ using a detailed analysis of the semileptonic decays $D^+\to K^-\pi^+ \ell^+\nu_\ell$ ($\ell=e, \mu$) thanks to the high-statistics dataset provided by the BESIII Collaboration. We propose simple and suitable amplitude parametrizations of the studied reactions that shall be of interest to experimentalists for upcoming analyses. These new parametrizations are based on the na\"ive factorization hypothesis and the description of the resulting matrix elements in terms of well-known hadronic form factors, with special emphasis on the $K\pi$ scalar and vector cases. Such form factors account for two-body final state interactions which fulfill analyticity, unitarity and chiral symmetry constraints. As a result of our study, we find that the $P$-wave contribution fits nicely within the na\"ive-factorization approach, whereas the $S$-wave contribution requires complex Wilson coefficients that hint for possibly genuine three-body non-factorizable effects. Our hypothesis is further supported by the examination of $D_s^+\to K^+K^+\pi^-$ decays, where we achieve a description in overall good agreement with data.Comment: 23 pages, 8 figures; version accepted for publication in Phys.Rev.

Combined study of hadronic D+→K−π+π+ and D+s→K+K+π− decays by means of the analysis of semileptonic D+→K−π+ℓ+νℓ decays

P. S.-P. thanks J. Nieves for discussions on semileptonic form factors. This work has been supported by the European Union’s Horizon 2020 Research and Innovation Program under Grants No. 754510 (EU, H2020-MSCA-COFUND2016) and No. 824093 (H2020- INFRAIA-2018-1), the Spanish Ministry of Science and Innovation under Grants No. PID2020–112965GB-I00 and No. PID2020–114767GB-I00, Junta de Andalucía under Grants No. POSTDOC_21_00136 and No. FQM-225, and the Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement de la Generalitat de Catalunya under Grant No. 2021 SGR 00649. IFAE is partially funded by the CERCA program of the Generalitat de Catalunya.We perform a combined study of the two hadronic decays D+→K−π+π+ and D+s→K+K+π− using a detailed analysis of the semileptonic decays D+→K−π+ℓ+νℓ (ℓ=e, μ) thanks to the high-statistics dataset provided by the BESIII Collaboration. We propose simple and suitable amplitude parametrizations of the studied reactions that shall be of interest to experimentalists for upcoming analyses. These new parametrizations are based on the naïve-factorization hypothesis and the description of the resulting matrix elements in terms of well-known hadronic form factors, with special emphasis on the Kπ scalar and vector cases. Such form factors account for two-body final-state interactions which fulfill analyticity, unitarity, and chiral symmetry constraints. As a result of our study, we find that the P-wave contribution fits nicely within the naïve-factorization approach, whereas the S-wave contribution requires complex Wilson coefficients that hint for possibly genuine three-body nonfactorizable effects. Our hypothesis is further supported by the examination of D+s→K+K+π− decays, where we achieve a description in overall good agreement with data.European Union’s Horizon 2020 Research and Innovation Program under Grant No. 754510 (EU, H2020-MSCA-COFUND2016)European Union’s Horizon 2020 Research and Innovation Program under Grant No. 824093 (H2020- INFRAIA-2018-1)Spanish Ministry of Science and Innovation under Grants No. PID2020–112965GB-I00 and No. PID2020–114767GB-I00Junta de Andalucía under Grants No. POSTDOC_21_00136 and No. FQM-225Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement de la Generalitat de Catalunya under Grant No. 2021 SGR 00649CERCA program of the Generalitat de Cataluny

A Survey of the Reef-Related Medusa (Cnidaria) Community in the Western Caribbean Sea

The species composition, distribution, and abundance of medusae collected during a 4-day plankton survey in a reef system of the Mexican Caribbean were studied. Highest mean medusae abundance was observed over the fore-reef zone and in daytime samples. Lowest abundances occurred in the reef lagoon and at dusk. Seventeen species were identified, with Liriope tetraphylla, Aglaura hemistoma, Cubaia aphrodite, and Sarsia prolifera being the most abundant. They belong to a group of medusae dominant along the world\u27s second largest barrier reef. Cluster analysis revealed primary (fore-reef) and secondary (reef lagoon, channel) oceanic groups, showing the strong oceanic influence along and across the reef system. Day-to-day variation in the reef medusan community seemed relatively unimportant. The community structure of the reef medusa fauna appeared to be quite uniform despite the expected migratory behavior of these predators, tidal exchange across the reef, introduction of oceanic species, and time of day. The species composition was most closely related to that of the Campeche Bank and oceanic Caribbean waters. Dominance of oceanic medusae within the reef lagoon was attributed to the narrowness of the continental shelf and the mesoscale hydrological features of the zone

A Survey of the Reef-Related Medusa (Cnidaria) Community in the Western Caribbean Sea

The species composition, distribution, and abundance of medusae collected during a 4-day plankton survey in a reef system of the Mexican Caribbean were studied. Highest mean medusae abundance was observed over the fore-reef zone and in daytime samples. Lowest abundances occurred in the reef lagoon and at dusk. Seventeen species were identified, with Liriope tetraphylla, Aglaura hemistoma, Cubaia aphrodite, and Sarsia prolifera being the most abundant. They belong to a group of medusae dominant along the world\u27s second largest barrier reef. Cluster analysis revealed primary (fore-reef) and secondary (reef lagoon, channel) oceanic groups, showing the strong oceanic influence along and across the reef system. Day-to-day variation in the reef medusan community seemed relatively unimportant. The community structure of the reef medusa fauna appeared to be quite uniform despite the expected migratory behavior of these predators, tidal exchange across the reef, introduction of oceanic species, and time of day. The species composition was most closely related to that of the Campeche Bank and oceanic Caribbean waters. Dominance of oceanic medusae within the reef lagoon was attributed to the narrowness of the continental shelf and the mesoscale hydrological features of the zone