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F. Cano

Publications and source records attributed to F. Cano.

At least 19 recordsLinked to original sources
arXiv2018

Truncated Local Uniformization of Formal Integrable Differential Forms

We prove the existence of Local Uniformization for rational codimension one foliations along rational rank one valuations, in any ambient dimension. This result is consequence of the Truncated Local Uniformization of integrable formal differential $1$-forms, that we also state and prove in the paper. Thanks to the truncated approach, we perform a classical inductive procedure, based both in the control of the Newton Polygon and in the possibility of avoiding accumulations of values, given by the existence of suitable Tschirnhausen transformations.

math.AG↗
arXiv2012

Infinitesimal Poincaré-Bendixson Problem in dimension three

We describe the sets of accumulation of secants for orbits of real analytic vector fields in dimension three having the origin as only ω-limit point. It is a kind of infinitesimal Poincaré-Bendixson problem in dimension three. These sets have structure of cyclic graph when the singularities are isolated under one blow-up. In the case of hyperbolic reduction of singularities with conditions of type Morse-Smale, we prove that the accumulation set is at most a single polycycle isomorphic to {\mathbb S}^1.

math.DS↗
arXiv2010

Deep Electroproduction of Photons and Mesons on the Deuteron

We study deeply virtual Compton scattering and deep exclusive meson electroproduction on a deuteron target. We model the Generalized Quark Distributions in the deuteron by using the impulse approximation for the lowest Fock-space state on the light-cone. We study the properties of the resulting GPDs, and verify that sum rules violations are quite small in the impulse approximation. Numerical predictions are given for the unpolarized cross sections and polarization asymmetries for the kinematical regimes relevant for JLab experiments and for HERMES at HERA. We conclude that the signal of coherent scattering on the deuteron is comparable to the one on the proton at least for low momentum transfer, providing support to the feasibility of the experiments. The short distance structure of the deuteron may thus be scrutinized in the near future.

hep-ph↗
arXiv2003

Real and Virtual Compton Scattering in a Regge Approach

We study Real and Deeply Virtual Compton Scattering in a model based on Regge trajectories and two-gluon exchange. In the kinematic regime of current experiments, the hadronic component of the outgoing real photon plays a major role. We analyze the spin structure of Compton scattering at large momentum transfer and give predictions for several spin asymmetries. In the DVCS channel, a fairly good agreement is obtained for the recently measured beam spin and charge asymmetries.

hep-ph↗
arXiv2002

Deeply Virtual Compton Scattering on Spin-1 Nuclei

We consider the Generalized Parton Distributions for spin-1 nuclei in general and on the deuteron in particular. We use the impulse approximation to obtain a convolution model for them. Sum rules are used to check the validity of the approach and to estimate the importance of higher Fock-space states in the deuteron. Numerical predictions for the Beam Spin Asymmetry in deeply virtual Compton scattering are presented.

hep-ph↗
arXiv2002

Deeply Virtual Compton Scattering on the Deuteron

We study deeply virtual Compton scattering (DVCS) on a deuteron target. We model the Generalized Quark Distributions in the deuteron by using the impulse approximation for the lowest Fock-space state. Numerical predictions are given for the unpolarized cross sections for the kinematical regimes relevant for JLab and HERMES at HERA. Differential cross sections show the same pattern as for the proton case and at low values of t they are of comparable size.

hep-ph↗
arXiv2001

Compton scattering, vector meson photoproduction and the partonic structure of the nucleon

At moderate and large momentum transfer, high energy vector meson photoproduction and Compton scattering can be consistently explained by mechanisms based on interactions and exchanges of constituent quarks and gluons. This opens an original window on the partonic structure of hadronic matter by emphasizing the role of quark correlations, quark exchange as implemented through saturating Regge trajectories and non-perturbative effects in the gluon propagator, which provides us with a bridge with lattice calculations. Compton scattering is directly related to vector meson photoproduction and enlarges the data set.

hep-ph↗
arXiv2001

Electromagnetic Form Factors of the Nucleon in a Relativistic Quark Pair Creation Model

We study the effects of the | qqq q\bar{q} > component of the hadronic wave function on the description of the electromagnetic structure of the nucleon. Starting with a qqq baryonic wave function which describes the baryonic and mesonic low energy spectrum, the extra q\bar{q} pair is generated through a relativistic version of the 3P_0 model. It is shown that this model leads to a renormalization of the quark mass that allows one to construct a conserved electromagnetic current. We conclude that these dynamical relativistic corrections play an important role in reproducing the Q2 dependence of the electromagnetic form factors at low Q^2.

nucl-th↗
arXiv2001

Quark correlations and gluon propagators in elastic vector meson production

We study the behavior of the differential cross section for vector meson photoproduction at large momentum transfer in the two-gluon exchange model. We focus on the treatment of two-quark correlation function in the proton and on gluon propagators with a dynamically generated mass. We find that only the large t region is sensitive to the particular details of these inputs.

hep-ph↗
arXiv2001

Generalized parton distributions in the deuteron

We introduce generalized quark and gluon distributions in the deuteron, which can be measured in exclusive processes like deeply virtual Compton scattering and meson electroproduction. We discuss the basic properties of these distributions, and point out how they probe the interplay of nucleon and parton degrees of freedom in the deuteron wave function.

hep-ph↗
arXiv2000

Probing Relativistic Spin Effects in the Nucleon by Means of Drell-Yan Processes

Significant differences between transverse and longitudinal polarized parton distributions are found at low energies within a light-front covariant quark model of the nucleon. These differences are due to relativistic spin effects introduced by the Melosh rotations and survive evolution to higher $Q^2$ scales. A specific observable related to double-spin asymmetries in lepton pair production in polarized hadron-hadron collisions is defined. The possibility of assessing the relevance of these relativistic spin effects in future experiments at RHIC and HERA--$\vec{N}$ is discussed.

hep-ph↗
arXiv2000

Meson exchange and nucleon polarizabilities in the quark model

Modifications to the nucleon electric polarizability induced by pion and sigma exchange in the q-q potentials are studied by means of sum rule techniques within a non-relativistic quark model. Contributions from meson exchange interactions are found to be small and in general reduce the quark core polarizability for a number of hybrid and one-boson-exchange q-q models. These results can be explained by the constraints that the baryonic spectrum impose on the short range behavior of the mesonic interactions.

nucl-th↗
arXiv2000

An Analysis of the Asymptotic Limit of Gluon Shadowing

We examine the gluon distributions in nuclei in the asymptotic region defined by $Q^2 \to \infty$, $x \to 0$. An analysis using the Double Asymptotic Scaling variables of Ball and Forte is proposed. New scaling relations are predicted which can help disentangling the different mechanisms of low $x$ perturbative QCD evolution in nuclei.

hep-ph↗
arXiv2000

Orbital Angular Momentum Parton Distributions in Light-Front Dynamics

We study the quark angular momentum distribution in the nucleon within a light-front covariant quark model. Special emphasis is put into the orbital angular momentum: a quantity which is very sensitive to the relativistic treatment of the spin in a light-front dynamical approach. Discrepancies with the predictions of the low-energy traditional quark models where relativistic spin effects are neglected, are visible also after perturbative evolution to higher momentum scales. Orbital angular momentum distributions and their contribution to the spin sum rule are calculated for different phenomenological mass operators and compared with the results of the MIT bag model.

hep-ph↗
arXiv1999

Describing the nucleon and its form factors at high q**2

The nucleon form factors are calculated using a non-relativistic description in terms of constituent quarks. The emphasis is put on the reliability of present numerical methods used to solve the three-body problem in order to correctly reproduce the expected asymptotic behavior of form factors. Nucleon wave functions obtained in the hyperspherical formalism or employing Faddeev equations have been considered. While a q**(-8) behavior is expected at high q for a quark-quark force behaving like 1/r at short distances, it is found that the hypercentral approximation in the hyperspherical formalism (K=0) leads to a q**(-7) behavior. An infinite set of waves is required to get the correct behavior. Solutions of the Faddeev equations lead to the q**(-8) behavior. The amplitude of the corresponding term however depends on the number of partial waves retained in the Faddeev amplitude. The convergence to the asymptotic behavior has also been studied. Sizeable departures are observed in some cases at squared momentum transfers as high as 50 (GeV/c)**2. It is not clear whether these departures are of the order 1/q or 1/q**2 log q relatively to the dominant contribution and whether the bad convergence results from truncations in the calculations. From a comparison with the most complete Faddeev results, a q**2 validity range is obtained for the calculation made in the hyperspherical formalism or in the Faddeev approach with the minimum number of amplitudes.

nucl-th↗
arXiv1999

Polarized Parton Distributions in Light-Front Dynamics

We present a consistent calculation of the structure functions within a light-front constituent quark model of the nucleon. Relativistic effects and the relevance of the covariance constraints are analyzed for polarized parton distributions. Various models, which differ in their gluonic structure at the hadronic scale, are investigated. The results of the full covariant calculation are compared with those of a non-relativistic approximation to show the structure and magnitude of the differences. It is also shown how measurements of transversity in doubly polarized Drell-Yan lepton pair production are a clearcut sign of covariance requirements for the spin.

hep-ph↗