Search results for "UNESCO::FÍSICA::Nucleónica::Física de partículas"
showing 10 items of 14 documents
Topological confinement in QCD2
1994
In two dimensional SU(N) theories confinement can be understood as a topological property of the vacuum. In the bosonized version of two dimensional theories no trivial boundary conditions (topology) play a crucial role. They are inevitable if one wants to describe non singlet states. In abelian bosonization, color is the charge of a topological current in terms of a non-linear meson field. We show that cofinement appears as the dynamical collapse of the topology associated with its non trivial boundary conditions. Vento Torres, Vicente, Vicente.Vento@ific.uv.es
Composite scalars and dark matter from four-fermion interactions
2022
Parte I: Emergencia de masas en el Modelo Estándar El bosón de Higgs es un campo escalar del Modelo Estándar (SM, por sus siglas en inglés) de partı́culas elementales que cumple dos funciones muy importantes. Por un lado permite construir una teorı́a renormalizable. El potencial escalar contiene un término de masa y un término cuadrático en el campo de Higgs, los cuales son ajus- tados en base a mediciones experimentales y haciéndolos compatible con la aparición de una ruptura espontánea de la simetrı́a SU (2) L × U (1) Y del SM. Y por otra parte ayuda a explicar la masa de todos los fermiones en el esquema de la teorı́a cuántica de campos, al poseer interacciones de tipo Yukawa que son aju…
HADES experiment: di-lepton spectroscopy in p + p (2.2 GeV) and C+C (1 and 2 A GeV) collisions
2006
The HADES (High Acceptance Di-Electron Spectrometer) is a tool designed for lepton pair (e+e−) spectroscopy in pion, proton and heavy ion induced reactions in the 1–2AGeV energy range. One of the goals of the HADES experiment is to study in-medium modifications of hadron properties like effective masses, decay widths, electromagnetic form factors etc. Such effects can be probed with vector mesons ( ρ,ω,ɸ ) decaying into e+e− channel. The identification of vector mesons by means of a HADES spectrometer is based on invariant mass reconstruction of e+e− pairs. The combined information from all spectrometer sub-detectors is used to reconstruct the di-lepton signal. The recent results from 2.2Ge…
Coherent neutrino scattering
2009
We present a microscopic model for coherent pion production off nuclei induced by neutrinos. This model is built upon a model for single nucleon processes that goes beyond the usual Delta dominance by including non resonant background contributions. We include nuclear medium effects: medium corrections to Delta$ properties and outgoing pion absortion via an optical potential. This results in major modifications to cross sections for low energy experiments when compared with phenomenological models like Rein-Sehgal's.
Lifetime measurements of excited states in neutron-rich nuclei around 48 Ca
2009
The lifetimes of the first excited states of the N = 30 isotones 50Ca and 51Sc and the Z = 18 isotopes 44−46Ar isotopes have been determined using a novel technique that combines the Recoil Distance Doppler Shift method with the CLARA-PRISMA spectrometers in multinucleon transfer reactions. The results allow determinination of the effective charges above 48Ca and test the strength of the N = 28 magic number when moving away from the stability line. Gadea Raga, Andrés, Gadea.Andres@ific.uv.es ; Algora, Alejandro, Alejandro.Algora@ific.uv.es ; Rubio Barroso, Berta, Berta.Rubio@ific.uv.es
β-Delayed and isomer spectroscopy of neutron-rich Ta and W isotopes
2009
Decays of neutron-rich A ~ 190 nuclei have been studied following projectile fragmentation of a 208Pb beam on a 9Be target at the GSI Fragment Separator. Gamma-ray decays from previously reported isomeric states in 188Ta, 190W and 192, 193Re were used as internal calibrations for the particle identification analysis, together with the identification of previously unreported isomeric decays in 189Ta and 191W. The current work also identifies β-delayed γ rays following the decay of 188Ta to 188W for the first time. Algora, Alejandro, Alejandro.Algora@ific.uv.es ; Molina Palacios, Francisco Manuel, Francisco.Molina@ific.uv.es; Rubio Barroso, Berta, Berta.Rubio@ific.uv.es
βDelayed γRay spectroscopy of heavy neutron rich nuclei “south” of lead
2009
Relativistic projectile fragmentation of a 208Pb primary beam has been used to produce neutron-rich nuclei with proton-holes relative to the Z = 82 shell closure, i.e., “south” of Pb. βDelayed γRay spectroscopy allows to investigate the structural properties of such nuclei with A ~ 195 → 205. The current work presents transitions de-exciting excited states in 204Au, which are the first spectroscopic information on this N = 125 isotone. Agramunt Ros, Jorge, Jorge.Agramunt@ific.uv.es ; Algora, Alejandro, Alejandro.Algora@ific.uv.es ; Molina Palacios, Francisco Manuel, Francisco.Molina@ific.uv.es ; Rubio Barroso, Berta, Berta.Rubio@ific.uv.es
Population of neutron-rich nuclei around 48ca with deep inelastic collisions
2009
The deep inelastic reaction 48Ca+64Ni at 6 MeV/A has been studied using the CLARA–PRISMA setup. Angular distributions for pure elastic scattering and total cross-sections of the most relevant transfer channels have been measured. The experimental results are compared with predictions from a semiclassical model, showing good agreement for the presently analyzed few neutrons transfer channels. The decay of the most intense reaction products has also been studied, giving indications of the population of states with very short lifetimes. Gadea Raga, Andrés, Gadea.Andres@ific.uv.es
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…
Open problems in the physics of neutrino interactions with nucleons and nuclei
2020
Along this thesis we address the interaction of neutrinos with nucleons and nuclei, in different scenarios. In first place, we critically analyze a proposal to explain the excess of events in the mini experiment, developed Masip et al. (JHEP 1301, 106 (2013)) and based in a model proposed by Gninenko (Phys. Rev. D83, 015015 (2011)). In this model we have a heavy neutrino, with a mass around 50 GeV, which would be produced in the interaction between the incoming light neutrino and the detector material. Then this heavy neutrino would decay emitting a light neutrino and a photon. The Cherenkov detectors are unable to distinguish a photon signal from an electron one, for this reason this model…