Neutrino structure functions in the QCD dipole picture

In this contribution we present an exploratory QCD analysis of the neutrino structure functions in charged current DIS using the color dipole formalism. The corresponding dipole cross sections are taken from recent phenomenological and theoretical studies in deep inelastic inclusive production, including nuclear shadowing corrections. The theoretical predictions are compared to the available experimental results in the small-x region.Comment: 4 pages, 2 figures. To appear in the proceedings of the XXXVI International Symposium on Multiparticle Dynamics. September 02-08, 2006 Paraty, Rio de Janeiro, Brazi

On a link between a species survival time in an evolution model and the Bessel distributions

We consider a stochastic model for species evolution. A new species is born at rate lambda and a species dies at rate mu. A random number, sampled from a given distribution F, is associated with each new species at the time of birth. Every time there is a death event, the species that is killed is the one with the smallest fitness. We consider the (random) survival time of a species with a given fitness f. We show that the survival time distribution depends crucially on whether ff_c where f_c is a critical fitness that is computed explicitly.Comment: 13 page

Truncated BFKL Series and Hadronic Collisions

A truncated BFKL series is studied and applied to hadronic processes. The proton-(anti)proton cross sections are described with good agreement with data and in a way consistent with the unitarity bound. The elastic scattering amplitude is calculated at momentum transfer $t$ different from zero, introducing two distinct ansatze for the proton impact factor. The elastic differential cross section is obtained at small $t$ approximation and compared with the data.Comment: 17pp, 6 figures, uses jhep.cls. Some text modifications, 2 figures added. Version to appear in Physical Review

A stochastic model of evolution

We propose a stochastic model for evolution. Births and deaths of species occur with constant probabilities. Each new species is associated with a fitness sampled from the uniform distribution on [0,1]. Every time there is a death event then the type that is killed is the one with the smallest fitness. We show that there is a sharp phase transition when the birth probability is larger than the death probability. The set of species with fitness higher than a certain critical value approach an uniform distribution. On the other hand all the species with fitness less than the critical disappear after a finite (random) time.Comment: 6 pages, 1 figure, TeX, Added references, To appear in Markov Processes and Related Field

Quasi-Dirac neutrinos and solar neutrino data

We present an analysis of the solar neutrino data in the context of a quasi-Dirac neutrino model in which the lepton mixing matrix is given at tree level by the tribimaximal matrix. When radiative corrections are taken into account, new effects in neutrino oscillations, as $\nu_e \to \nu_s$, appear. This oscillation is constrained by the solar neutrino data. In our analysis, we have found an allowed region for our two free parameters $\epsilon$ and $m_1$. The radiative correction, $\epsilon$, can vary approximately from $5\times 10^{-9}$ to $10^{-6}$ and the calculated fourth mass eigenstate, $m_4$, 0.01 eV to 0.2 eV at 2$\sigma$ level. These results are very similar to the ones presented in the literature.Comment: 24 pages, 7 figures and 2 tables. Results and conclusion unchanged. Version published in EPJC. Figures improve

Investigating diffractive W production in hadron-hadron collisions at high energies

We compute the hard diffractive hadroproduction of bosons W at high energies using Regge factorization and taking into account multiple Pomeron exchange corrections. The ratio of diffractive to non-diffractive W production agrees with the current Tevatron data and a prediction for the LHC is presented.Comment: 4 pages, 1 table. To appear in the proceedings of 10th International Workshop on Hadron Physics (X Hadron Physics), Florianopolis, Brazil, 26-31 Mar 200

FCNC in the minimal 3-3-1 model revisited

We show that in the minimal 3-3-1 model the flavor changing neutral currents (FCNCs) do not impose necessarily strong constraints on the mass of the $Z^\prime$ of the model if we also consider the neutral scalar contributions to such processes, like the neutral mesons mass difference and rare semileptonic decays. We first obtain numerical values for all the mixing matrices of the model i.e., the unitary matrices that rotate the left- and right-handed quarks in each charge sector which give the correct mass of all the quarks and the CKM mixing matrix. Then, we find that there is a range of parameters in which the neutral scalar contributions to these processes may interfere with those of the $Z^\prime$, implying this vector boson may be lighter than it has been thought.Comment: Extended version including the effect of a pseudoscalar. 37 pags. and 12 figures. New references added. Version matches the published versio