Search results for "FÍSICA NUCLEAR"
showing 10 items of 900 documents
Right-handed neutrino magnetic moments
2009
PACS numbers: 14.60.St, 13.15.+g, 13.35.Hb, 13.66.Hk
Implications of new generations on neutrino masses
2011
We explore the possible implications that new families, that are being searched for at the LHC, would have on neutrino masses. In particular, we have explored the possibility that the smallness of the observed neutrino masses is naturally understood in a modified version of the Standard Model (SM) with complete extra generations of fermions, i.e., that have right-handed neutrinos, in which neutrino masses are generated at two loops. With one extra family it is not possible to fit the observed spectrum of masses and mixings. However, the radiative mass generated provides an important constraint in these kind of models, so the neutrino masses do not exceed their cosmological bound. Within the…
Decay studies of the long-lived states in Tl-186
2020
9 pags., 12 figs., 3 tabs.
Can measurements of 2HDM parameters provide hints for high scale supersymmetry?
2018
Two-Higgs-doublet models (2HDMs) are minimal extensions of the Standard Model (SM) that may still be discovered at the LHC. The quartic couplings of their potentials can be determined from the measurement of the masses and branching ratios of their extended scalar sectors. We show that the evolution of these couplings through renormalization group equations can determine whether the observed 2HDM is a low energy manifestation of a more fundamental theory, as for instance, supersymmetry, which fixes the quartic couplings in terms of the gauge couplings. At leading order, the minimal supersymmetric extension of the SM (MSSM) dictates all the quartic couplings, which can be translated into a p…
The baryon number two system in the Chiral Soliton Model
2012
We study the interaction between two B = 1 states in a chiral soliton model where baryons are described as non-topological solitons. By using the hedgehog solution for the B = 1 states we construct three possible B = 2 configurations to analyze the role of the relative orientation of the hedgehog quills in the dynamics. The strong dependence of the intersoliton interaction on these relative orientations reveals that studies of dense hadronic matter using this model should take into account their implications.
The translationally-invariant coupled cluster method in coordinate space
2000
We study a formulation of the translationally-invariant coupled cluster method in coordinate space. Previous calculations in configuration space showed poor convergence, a problem that the new formulation is expected to remedy. This question is investigated for a system of bosons interacting through the Wigner part of the Afnan-Tang S3 interaction, where previous results exist.
Anomalies in b→s Transitions and Dark Matter
2018
Since 2013, the LHCb collaboration has reported on the measurement of several observables associated to $b \to s$ transitions, finding various deviations from their predicted values in the Standard Model. These include a set of deviations in branching ratios and angular observables, as well as in the observables $R_K$ and $R_{K^\ast}$, specially built to test the possible violation of Lepton Flavor Universality. Even though these tantalizing hints are not conclusive yet, the $b \to s$ anomalies have gained considerable attention in the flavor community. Here we review New Physics models that address these anomalies and explore their possible connection to the dark matter of the Universe. Af…
Search for Z0 decays to two leptons and a charged particle-antiparticle pair
1993
Based on a sample equivalent to 365 000 hadronic Z0 decays, the search in DELPHI data for pairs of leptons accompanied by a pair of charged particles is described. A total of 11 events were found in the electron channel, 9 in the muon channel and 7 in the tau channel. Results on lepton pairs with a radiated photon are also presented. The data from all channels are compatible with the expectations from standard processes. However, one event was found in the tau channel with an unusually high mass of the charged particle pair.
Neutrino Bremsstrahlung from electrons in neutron star crusts
2001
The process of v (v) over bar Bremsstrahlung via electron scattering off nuclei in the crust of a cooling neutron star is studied within the Random Phase Approximation. We show that the electromagnetic plasma screens the vector weak coupling of electrons with the neutrino field. This screening effect takes place in both the crystalline and liquid phase of the neutron star crust, when the momentum carried out by the neutrino pair is smaller than the inverse Debye screening distance of the electrons. This condition holds in the crust volume at temperatures and densities where the electron Bremsstrahlung dominates the neutrino production. As a result, the vector weak current contribution to th…
Canonical equivalence of a generic 2-D dilaton gravity model and a free field
1997
We show that a canonical transformation converts, up to a boundary term, a generic 2-D dilaton gravity model into a free field theory with a Minkowskian target space.