Search results for "Partículas"
showing 10 items of 105 documents
Measurement of the flavour composition of dijet events in pp collisions at √s = 7 TeV with the ATLAS detector
2013
This paper describes a measurement of the flavour composition of dijet events produced in pp collisions at s√=7~TeVs=7~TeV using the ATLAS detector. The measurement uses the full 2010 data sample, corresponding to an integrated luminosity of 39 pb−1. Six possible combinations of light, charm and bottom jets are identified in the dijet events, where the jet flavour is defined by the presence of bottom, charm or solely light flavour hadrons in the jet. Kinematic variables, based on the properties of displaced decay vertices and optimised for jet flavour identification, are used in a multidimensional template fit to measure the fractions of these dijet flavour states as functions of the leadin…
Electron performance measurements with the ATLAS detector using the 2010 LHC proton-proton collision data
2012
Acknowledgements We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF, DNSRC and Lundbeck Foundation, Denmark; ARTEMIS, European Union; IN2P3-CNRS, CEA-DSM/IRFU, France; GNAS, Georgia; BMBF, DFG, HGF, MPG and AvH Foundation, Germany; GSRT, Greece; ISF, MINERVA, GIF, DIP and Benoziyo…
Universal features of the nuclear matrix elements governing the mass sector of the 0νββ decay
2005
In this work we report on manifest universal features found in the nuclear matrix elements which govern the mass sector of the neutrinoless double beta decay. The results are based on the analysis of the calculated matrix elements corresponding to the decays of 76Ge, 82Se, 100Mo, and 116Cd. The results suggest a dominance of few low-lying nuclear states of few multipoles in these matrix elements. Dedicated charge-exchange reactions could be used to probe these key states to determine experimentally the value of the nuclear matrix element.
The exposure of the hybrid detector of the Pierre Auger Observatory
2010
The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays. It consists of a surface array to measure secondary particles at ground level and a fluorescence detector to measure the development of air showers in the atmosphere above the array. The ‘‘hybrid” detection mode combines the information from the two subsystems. We describe the determination of the hybrid exposure for events observed by the fluorescence telescopes in coincidence with at least one water-Cherenkov detector of the surface array. A detailed knowledge of the time dependence of the detection operations is crucial for an accurate evaluation of the exposure. We discuss the relevance of monitoring data coll…
Characterization of the optical properties at the ANTARES site using the Optical Beacon system. Influence on the detector performance
2014
Neutrino Astronomy aims to scientifically exploit neutrinos as a new cosmic messenger to explore high energy astrophysical phenomena in the TeV-PeV energy range. The very low fluxes and the small interaction crosssection of neutrinos with matter require the construction of massive detectors. When the incoming neutrino direction can be reconstructed with a reasonable angular accuracy, the detector is dubbed "telescope", since the neutrinos, having no electric charge, point back to their source. In the Cherenkov technique, the observation of the neutrino is carried out through the detection of the Cherenkov light induced by the charged relativistic particles produced in the neutrino interacti…
Do Saharan Dust Days Carry a Risk of Hospitalization From Respiratory Diseases for Citizens of the Canary Islands (Spain)?
2021
Background: Saharan dust meets the Canary Islands at the beginning of its westward path across the North Atlantic, exceeding the European daily levels for PM10; for this reason, their two provincial capital cities, constitute optimal sites where to evaluate the health effects of this natural event. Objectives: To assess the short-term association between Saharan Dust Days (SDDs) and respiratory morbidity in the two capital cities. Methods: We carried out a time-series analysis with daily emergency hospital admissions due to all respiratory system diseases, chronic obstructive pulmonary disease (COPD) and asthma between 2001 and 2005, assessing the independent effect of SDDs, defined accordi…
Medium effects in DIS from polarized nuclear targets
2014
The behavior of the nucleon structure functions in lepton nuclei deep inelastic scattering, both polarized and unpolarized, due to nuclear structure effects is reanalyzed. The study is performed in two schemes: an x-rescaling approach, and one in which there is an increase of sea quark components in the in medium nucleon, related to the low energy N-N interaction. In view of a recent interesting experimental proposal to study the behavior of the proton spin structure functions in nuclei we proceed to compare these approaches in an effort to enlighten the possible phenomenological interest of such difficult experiment.
The pion distribution amplitude and the pion-photon transition form factor in a nonlocal chiral quark model
2014
We study the pion Distribution Amplitude (\pi DA) in the context of a nonlocal chiral quark model. The corresponding Lagrangian reproduces the phenomenological values of the pion mass and decay constant, as well as the momentum dependence of the quark propagator obtained in lattice calculations. It is found that the obtained \pi DA has two symmetric maxima, which arise from the new contributions generated by the nonlocal character of the interactions. This \pi DA is applied to leading order and next-to-leading order calculations of the pion-photon transition form factor. Implications of the results are discussed.
Light- and strange-quark mass dependence of the ρ(770) meson revisited
2020
Recent lattice data on $\pi\pi$-scattering phase shifts in the vector-isovector channel, pseudoscalar meson masses and decay constants for strange-quark masses smaller or equal to the physical value allow us to study the strangeness dependence of these observables for the first time. We perform a global analysis on two kind of lattice trajectories depending on whether the sum of quark masses or the strange-quark mass is kept fixed to the physical point. The quark mass dependence of these observables is extracted from unitarized coupled-channel one-loop Chiral Perturbation Theory. This analysis guides new predictions on the $\rho(770)$ meson properties over trajectories where the strange-qua…
Bistable spin-crossover nanoparticles showing magnetic thermal hysteresis near room temperature
2007
We have demonstrated that the reverse micelle technique can be applied to polymeric spin-crossover systems, such as [Fe(Htrz)2(trz)](BF4), to control the growth of the crystallites. Small nanoparticles of diameters around 10 nm and narrow size distribution were obtained. It is easy to envision that, by modifying the synthetic procedure, the size and critical temperatures of these nanoparticles can be tuned. On one hand, different ratios of solvent, water, and surfactants will lead to different micelle sizes, which will affect the particle size and, maybe, the magnetic properties. On the other hand, the critical temperatures can be lowered towards room temperature by changing the composition…