0000000000095716
AUTHOR
Vicente Vento Torres
Gluonic components of the pion and the transition form factor gamma*gamma* -> pi(0)
We propose an effective lagrangian for the coupling of the neutral pion with gluons whose strength is determined by a low energy theorem. We calculate the contribution of the gluonic components arising from this interaction to the pion transition form factor γ∗γ∗→π0 using the instanton liquid model to describe the QCD vacuum. We find that this contribution is large and might explain the anomalous behavior of the form factor at large virtuality of one of the photons, a feature which was recently discovered by the BaBar Collaboration.
Topological confinement in QCD2
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
Instantons and the delta I = 1/2 rule
The instanton induced interaction leads to a significant enhancement of the A0 weak amplitude determining the ΔI=1/2 rule, through the contribution of operators with dimension d=9, as we show in the weak K→ππ decay.
Dificultades en la enseñanza/aprendizaje de la física cuántica
Abstract We have elaborated a questionnaire about some selected basic concepts on Modern Physics, We have then analysed the students comprehension level on Quantum Physics before they follow this matter in the 3er year of Physics studies. Once this course has been completed. the evolution of the previous misconceptions is studied. We conclude that a teaching which considers previous misconceptions results in a sensitive improvement. However, we also detect the persistence of a few misconceptions acquired during the non-university teaching.
Quark Antisymmetrization Effects in Nuclear Physics
We analyze the observability of quark phenomena in nuclei by studying the effects of the antisymmetrization principle at the quark level in nuclear observables. We discuss the physics associated with one body quark observables and in particular pay special attention to the so called maximal Pauli blocking scenarios. We comment about the calculation of two body quark observables showing results of the Coulomb energy for a two nucleon system with deuteron quantum numbers.
DIS structure functions and the double-spin asymmetry in rho(0) electroproduction within a Regge approach
The proton, neutron and deuteron structure functions F2(x,Q2) and g1(x,Q2), measured at intermediate Q2, are analyzed within a Regge approach. This analysis serves to fix the parameters of this scheme which are then used to calculate, in a unified Regge approach, the properties of ρ0 meson electroproduction on the proton and the deuteron. In this way, the double-spin asymmetry observed at HERMES in ρ0 electroproduction on the proton, can be related to the anomalous behavior of the flavor-singlet part of the spin-dependent structure function g1(x,Q2) at small x.
Dynamical confinement in bosonized 2-dimensional QCD
In the bosonized version of two dimensional theories non 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 confinement appears as the dynamical collapse of the topology associated with its non trivial boundary conditions.
Single spin asymmetry parameter from deeply virtual compton scattering of hadrons up to twist - three accuracy. 1. Pion case
The study of deeply virtual Compton scattering (DVCS) has shown that electromagnetic gauge invariance requires, to leading order, not only twist-two but additional twist-three contributions. We apply this analysis and, using the Ellis-Furmanski-Petronzio factorization scheme, compute the single- (electron) spin asymmetry arising in the collision of longitudinally polarized electrons with hadrons up to twist-3 accuracy. In order to simplify the kinematics we restrict the actual calculation to pions in the chiral limit. The process is described in terms of the generalized parton distribution functions which we obtain within a bag model framework.