Constraints on Non-standard Top Quark Couplings

We study non-standard top quark couplings in the effective field theory approach. All nine dimension-six operators that generate anomalous couplings between the electroweak gauge bosons and the third-generation quarks are included. We calculate their contributions at tree level and one loop to all major precision electroweak observables. The calculations are compared with data to obtain constraints on eight of these operators.Comment: 26 pages, 2 figure

Effective Field Theory for Nonstandard Top Quark Couplings

We present an effective-field-theory calculation of the effect of a dimension-six operator involving the top quark on precision electroweak data via a top-quark loop. We demonstrate the renormalizability, in the modern sense, of the effective field theory. We use the oblique parameter U to bound the coefficient of the operator, and compare with the bound derived from top-quark decay.Comment: 10 pages, 3 figure

Effective Field Theory: A Modern Approach to Anomalous Couplings

We advocate an effective field theory approach to anomalous couplings. The effective field theory approach is the natural way to extend the standard model such that the gauge symmetries are respected. It is general enough to capture any physics beyond the standard model, yet also provides guidance as to the most likely place to see the effects of new physics. The effective field theory approach also clarifies that one need not be concerned with the violation of unitarity in scattering processes at high energy. We apply these ideas to pair production of electroweak vector bosons.Comment: 16 pages, 1 figur

El cerdo Pelón Mexicano: programa de conservación genética de una raza en peligro

Here is described the programme of genetic conservation of the Mexican Hair-less pig under development in the Yukatan State (Mexico). It consists of several actions on the characterization of the population and its management system, the in situ and ex situ conservation, and the coordination. The results obtained by the moment are summarized.Aquí se describe el programa de conservación genética del cerdo Pelón Mexicano en desarrollo en el Estado de Yukatan (México). Consiste en varias acciones sobre la caracterización de la población y de sus sistemas de explotación, la conservación in situ y ex situ y la coordinación. Se resumen los resultados obtenidos hasta el momento

A preference for a non-zero neutrino mass from cosmological data

We present results from the analysis of cosmic microwave background (CMB), large scale structure (galaxy redshift survey) and X-ray galaxy cluster (baryon fraction and X-ray luminosity function) data, assuming a geometrically flat cosmological model and allowing for tensor components and a non-negligible neutrino mass. From a combined analysis of all data, assuming three degenerate neutrinos species, we measure a contribution of neutrinos to the energy density of the universe, Omega_nu h^2=0.0059^{+0.0033}_{-0.0027} (68 per cent confidence limits), with zero falling on the 99 per cent confidence limit. This corresponds to ~4 per cent of the total mass density of the Universe and implies a species-summed neutrino mass \sum_i m_i =0.56^{+0.30}_{-0.26} eV, or m_nu~0.2 eV per neutrino. We examine possible sources of systematic uncertainty in the results. Combining the CMB, large scale structure and cluster baryon fraction data, we measure an amplitude of mass fluctuations on 8h^{-1} Mpc scales of sigma_8=0.74^{+0.12}_{-0.07}, which is consistent with measurements based on the X-ray luminosity function and other studies of the number density and evolution of galaxy clusters. This value is lower than that obtained when fixing a negligible neutrino mass (sigma_8=0.86^{+0.08}_{-0.07}). The combination of CMB, large scale structure and cluster baryon fraction data also leads to remarkably tight constraints on the Hubble constant, H_0=68.4^{+2.0}_{-1.4} km/s/Mpc, mean matter density, Omega_m =0.31\pm0.02 and physical baryon density, Omega_b h^2=0.024\pm0.001, of the Universe.Comment: Final version. MNRAS, in press (9 pages, 6 figures, 1 table). Includes small modification to the neutrino mass calculation and comment on quintessence. Conclusions unchange

Recolonization Process and Fish Assemblage Dynamics in the Guadiamar River (SW Spain) After the Aznalcóllar Mine Toxic Spill

The Guadiamar River (SW Iberian Peninsula) received a major toxic spill (6hm3) from a tailing pond in 1998 that defaunated 67km of the main stem. Following early mud removal works, the fish assemblage was annually monitored at four affected sampling sites and one located in the upstream non-affected reach of the Guadiamar River as reference. Fish abundance and assemblage structure were analysed. Principal response curve was applied to assess the recovery trends and to identify the most influential species. A non-metric multidimensional scaling ordination and permutational multivariate analysis of variance were applied to evaluate changes in fish assemblage structure between sites and years. Overall, the affected reaches harboured fish within 2years of the spill. Colonists arrived mainly from the upstream and downstream non-affected Guadiamar River reaches and, to a lesser extent, from three lateral tributaries. It is likely that the proximity, connectivity and environmental conditions of non-affected fish sources greatly influenced the recolonization process in each site. The structure of the fish community in the affected sites was initially similar to that in the unaffected reference stretch but changed dramatically with time, and each site followed its own trajectory. Currently, long-term threats such as mining leachates, urban sewage, agricultural pollution and exotic fish species expansion have probably exceeded the initial spill effect. This highlights the large effect of anthropogenic factors on freshwater ecosystem resilience, and the need to significantly reduce both pollution and exotic species if the affected reach of the Guadiamar River is to recover fully

Molecular survey of pyrethroid resistance mechanisms in Mexican field populations of Rhipicephalus (Boophilus) microplus

Susceptibility to synthetic pyrethroids (SP´s) and the role of two major resistance mechanisms were evaluated in Mexican Rhipicephalus microplus tick populations. Larval packet test (LPT), knock-down (kdr) PCR allele-specific assay (PASA) and esterase activity assays were conducted in tick populations for cypermethrin, flumethrin and deltamethrin. Esterase activity did not have a significant correlation with SP´s resistance. However a significant correlation (p < 0.01) was found between the presence of the sodium channel mutation, and resistance to SP´s as measured by PASA and LPT respectively. Just over half the populations (16/28) were cross-resistant to flumethrin, deltamethrin and cypermethrine, 21.4% of the samples (6/28) were susceptible to all of the three pyrethroids 10.7 of the samples (3/28) were resistant to flumethrin, 3.4 of the samples (1/28) were resistant to deltamethrin only and 7.1% (2/28) were resistant to flumethrin and deltamethrin. The presence of the kdr mutation correlates with resistance to the SP´s as a class. Target site insensitivity is the major mechanism of resistance to SP´s in Mexican R. microplus field strains, involving the presence of a sodium channel mutation, however, esterase-based, other mutations or combination of mechanisms can also occur

Search for strongly interacting massive particles generating trackless jets in proton-proton collisions at s = 13 TeV

A search for dark matter in the form of strongly interacting massive particles (SIMPs) using the CMS detector at the LHC is presented. The SIMPs would be produced in pairs that manifest themselves as pairs of jets without tracks. The energy fraction of jets carried by charged particles is used as a key discriminator to suppress efficiently the large multijet background, and the remaining background is estimated directly from data. The search is performed using proton-proton collision data corresponding to an integrated luminosity of 16.1 fb - 1 , collected with the CMS detector in 2016. No significant excess of events is observed above the expected background. For the simplified dark matter model under consideration, SIMPs with masses up to 100 GeV are excluded and further sensitivity is explored towards higher masses

Evidence for Top Quark Production in Nucleus-Nucleus Collisions

Peer reviewe

Search for dark matter produced in association with a Higgs boson decaying to a pair of bottom quarks in proton-proton collisions at root s=13TeV

A search for dark matter produced in association with a Higgs boson decaying to a pair of bottom quarks is performed in proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS detector at the LHC. The analyzed data sample corresponds to an integrated luminosity of 35.9 fb(-1). The signal is characterized by a large missing transverse momentum recoiling against a bottom quark-antiquark system that has a large Lorentz boost. The number of events observed in the data is consistent with the standard model background prediction. Results are interpreted in terms of limits both on parameters of the type-2 two-Higgs doublet model extended by an additional light pseudoscalar boson a (2HDM+a) and on parameters of a baryonic Z simplified model. The 2HDM+a model is tested experimentally for the first time. For the baryonic Z model, the presented results constitute the most stringent constraints to date.Peer reviewe