La Caldera de hundimiento de Vallehermoso Isla de La Gomera (Canarias).

Durante la realización del Proyecto MAGNA a escala 1:25.000 de la isla de La Gomera (Islas Canarias), se ha identificado una caldera de colapso en el área de Vallehermoso (hojas 73-81 Agulo y 73-82 Hermigua). La caldera presenta una forma casi circular con un diámetro de 2.4 Km aproximadamente. Su génesis puede, en principio, ser atribuida a un brusco y repentino vaciado de una cámara magmática sálica, dando lugar al hundimiento del techo. Este magma sálico es el responsable de la formación traqui-fonolítica (cone-sheets). La caldera está delimitada por fracturas escalonadas con desarrollo de importantes brechastectónicas y rellenada por tobas y brechas piroclásticas (¿ignimbríticas?) y por abundantes facies diferentes de debris-avalanche. Posteriormente al hundimiento, en las zonas de borde de la caldera, se han desarrollado intrusiones sálicas con morfología de pitones, domos, etc. Su novedad geológica dentro del marco de la isla de La Gomera, nos ha impulsado a redactar esta nota previa, que posteriormente, será seguida de una publicación más detallada

Edades radiométricas de los edificios miocenos de Fuerteventura (Islas Canarias).

Se han realizado once nuevas dataciones K-Ar de las coladas básicas (basaltos, nefelinitas) y sálicas (traquitas) de los tres edificios principales subaéreos (Tetir o Norte, Gran Tarajal o Central y Jandía o Sur) que constituyen la Fase miocena de la isla. Se precisa algo más la cronoestratigrafía relativa entre ellos, así como la correspondiente a los tramos que los integran

Nuevas edades K-Ar de las rocas volcánicas de la isla de Tenerife

Six new isotopic age determinations were established in volcanic rocks of Tenerife. These data belong to different units of the main volcanic edifices and the results allow us to get a more accurate knowledge of the eruptive history of the island. One of these ages corresponds to a trachyandesitic flow of the Upper Unit of the Anaga Old Edifice (Old Basaltic Series) and the result, 3,38 ±0,19 Ma matches with the age interval established by previous authors for this unit (3,70 - 3,28 Ma). Three ages belong to units of the Cañadas Edifice and the results are 1,59 ± 0,19 Ma, 2,94 ± 0,15 Ma and 4,0 ± 0,2 Ma. This shows that the felsic volcanic activity started in the very early stages of the Cañadas Edifice evolution and it shows also that there are a partial overlap with the youngest episodes of the Old Tenerife Edifices. The age determination on a phonolitic plug that intrudes on basaltic flows of the Dorsal Edifice gives a result of 1,16 ± 0,09 Ma. The last age data of this work belongs to a mafic phonolite flow of a peripherial volcano (Taco Mountain). The result, 0,55 ± 0,06 Ma reinforces the evidence of felsic-intermediate volcanic activity in several peripherial volcanoes contemporary with the Cañadas Edifice lifespan

Search for TeV-scale gravity signatures in high-mass final states with leptons and jets with the ATLAS detector at sqrt [ s ] = 13TeV

A search for physics beyond the Standard Model, in final states with at least one high transverse momentum charged lepton (electron or muon) and two additional high transverse momentum leptons or jets, is performed using 3.2 fb−1 of proton–proton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2015 at √s = 13 TeV. The upper end of the distribution of the scalar sum of the transverse momenta of leptons and jets is sensitive to the production of high-mass objects. No excess of events beyond Standard Model predictions is observed. Exclusion limits are set for models of microscopic black holes with two to six extra dimensions

Search for dark matter produced in association with a hadronically decaying vector boson in pp collisions at sqrt (s) = 13 TeV with the ATLAS detector

A search is presented for dark matter produced in association with a hadronically decaying W or Z boson using 3.2 fb−1 of pp collisions at View the MathML sources=13 TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet compatible with a W or Z boson and with large missing transverse momentum are analysed. The data are consistent with the Standard Model predictions and are interpreted in terms of both an effective field theory and a simplified model containing dark matter

Measurement of the cross section for isolated-photon plus jet production in pp collisions at √s=13 TeV using the ATLAS detector

The dynamics of isolated-photon production in association with a jet in proton–proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb−1. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti- algorithm with radius parameter and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photon–jet invariant mass and the scattering angle in the photon–jet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements

A search for resonances decaying into a Higgs boson and a new particle X in the XH → qqbb final state with the ATLAS detector

A search for heavy resonances decaying into a Higgs boson (H) and a new particle (X) is reported, utilizing 36.1 fb−1 of proton–proton collision data at collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle X is assumed to decay to a pair of light quarks, and the fully hadronic final state is analysed. The search considers the regime of high XH resonance masses, where the X and H bosons are both highly Lorentz-boosted and are each reconstructed using a single jet with large radius parameter. A two-dimensional phase space of XH mass versus X mass is scanned for evidence of a signal, over a range of XH resonance mass values between 1 TeV and 4 TeV, and for X particles with masses from 50 GeV to 1000 GeV. All search results are consistent with the expectations for the background due to Standard Model processes, and 95% CL upper limits are set, as a function of XH and X masses, on the production cross-section of the resonance

Measurement of the top quark mass in the tt→ dilepton channel from √s = 8 TeV ATLAS data

The top quark mass is measured in the tt¯ → dilepton channel (lepton = e,μ) using ATLAS data recorded in the year 2012 at the LHC. The data were taken at a proton proton centre-of-mass energy of √s = 8 TeV and correspond to an integrated luminosity of about 20.2 fb−1. Exploiting the template method, and using the distribution of invariant masses of lepton–b-jet pairs, the top quark mass is measured to be mtop = 172.99±0.41 (stat) ±0.74 (syst) GeV, with a total uncertainty of 0.84 GeV. Finally, a combination with previous ATLAS mtop measurements from √s = 7 TeV data in the tt¯ → dilepton and tt¯ → lepton + jets channels results in mtop = 172.84±0.34 (stat)±0.61 (syst) GeV, with a total uncertainty of 0.70 GeV

Combination of searches for Higgs boson pairs in pp collisions at \sqrts = 13 TeV with the ATLAS detector

This letter presents a combination of searches for Higgs boson pair production using up to 36.1 fb(-1) of proton-proton collision data at a centre-of-mass energy root s = 13 TeV recorded with the ATLAS detector at the LHC. The combination is performed using six analyses searching for Higgs boson pairs decaying into the b (b) over barb (b) over bar, b (b) over barW(+)W(-), b (b) over bar tau(+)tau(-), W+W-W+W-, b (b) over bar gamma gamma and W+W-gamma gamma final states. Results are presented for non-resonant and resonant Higgs boson pair production modes. No statistically significant excess in data above the Standard Model predictions is found. The combined observed (expected) limit at 95% confidence level on the non-resonant Higgs boson pair production cross-section is 6.9 (10) times the predicted Standard Model cross-section. Limits are also set on the ratio (kappa(lambda)) of the Higgs boson self-coupling to its Standard Model value. This ratio is constrained at 95% confidence level in observation (expectation) to -5.0 &lt; kappa(lambda) &lt; 12.0 (-5.8 &lt; kappa(lambda) &lt; 12.0). In addition, limits are set on the production of narrow scalar resonances and spin-2 Kaluza-Klein Randall-Sundrum gravitons. Exclusion regions are also provided in the parameter space of the habemus Minimal Supersymmetric Standard Model and the Electroweak Singlet Model. For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2019.135103</p

Searches for lepton-flavour-violating decays of the Higgs boson in s=13\sqrt{s}=13 TeV pp\mathit{pp} collisions with the ATLAS detector

This Letter presents direct searches for lepton flavour violation in Higgs boson decays, H → eτ and H → μτ , performed with the ATLAS detector at the LHC. The searches are based on a data sample of proton–proton collisions at a centre-of-mass energy √s = 13 TeV, corresponding to an integrated luminosity of 36.1 fb−1. No significant excess is observed above the expected background from Standard Model processes. The observed (median expected) 95% confidence-level upper limits on the leptonflavour-violating branching ratios are 0.47% (0.34+0.13−0.10%) and 0.28% (0.37+0.14−0.10%) for H → eτ and H → μτ , respectively.publishedVersio