DFAMN - Artículoshttp://hdl.handle.net/10481/314212020-03-29T04:08:13Z2020-03-29T04:08:13ZDouble parton distribution of valence quarks in the pion in chiral quark modelsBroniowski, WojciechRuiz Arriola, Enriquehttp://hdl.handle.net/10481/599662020-03-03T12:32:45ZDouble parton distribution of valence quarks in the pion in chiral quark models
Broniowski, Wojciech; Ruiz Arriola, Enrique
The valence double parton distribution of the pion is analyzed in the framework of chiral quark models,
where in the chiral limit factorization between the longitudinal and transverse degrees of freedom occurs.
This feature leads, at the quark-model scale, to a particularly simple distribution of the form
D (x1, x2, q) = δ (1 − x1 − x2)F(q), where x1,2 are the longitudinal momentum fractions carried by the
valence quark and antiquark and q is their relative transverse momentum. For q = 0 this result complies
immediately with the Gaunt-Sterling sum rules. The Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP)
evolution to higher scales is carried out in terms of the Mellin moments. We then explore its role on the
longitudinal correlation quantified with the ratio of the double distribution to the product of single
distributions, D (x1, x2, q = 0) / D(x1) D(x2). We point out that the ratios of moments (xn1
xm2)/(xn1)(xm2) are
independent of the evolution, providing particularly suitable measures to be tested in the upcoming lattice
simulations. The transverse form factor F(q) and its Fourier conjugate in the relative transverse coordinate
b are obtained in variants of the Nambu–Jona-Lasinio model with the spectral and Pauli-Villars
regularizations. The results are valid in the soft-momentum domain. Interestingly, with the spectral
regularization of the model, the effective cross section for the double parton scattering of pions is exactly
equal to the geometric cross section, σeff = π(b2), and yields about 20 mb.
Realistic spectral function model for charged-current quasielastic-like neutrino and antineutrino scattering cross sections on 12CIvanov, M. V.Antonov, A. N.Megías, G. D.Caballero, J. A.Barbaro, M. B.Amaro Soriano, José EnriqueRuiz Simo, I.Donnlly, T. W.Udías, J. M.http://hdl.handle.net/10481/594482020-02-05T11:47:24ZRealistic spectral function model for charged-current quasielastic-like neutrino and antineutrino scattering cross sections on 12C
Ivanov, M. V.; Antonov, A. N.; Megías, G. D.; Caballero, J. A.; Barbaro, M. B.; Amaro Soriano, José Enrique; Ruiz Simo, I.; Donnlly, T. W.; Udías, J. M.
A detailed study of charged current quasielastic neutrino and antineutrino scattering cross sections on a 12C
target with no pions in the final state is presented. The initial nucleus is described by means of a realistic spectral
function S(p, E) in which nucleon-nucleon correlations are implemented by using natural orbitals through
the Jastrow method. The roles played by these correlations and by final-state interactions are analyzed and
discussed. The model also includes the contribution of weak two-body currents in the two-particle two-hole
sector, evaluated within a fully relativistic Fermi gas. The theoretical predictions are compared with a large
set of experimental data for double-differential, single-differential, and total integrated cross sections measured
by the MiniBooNE, MINERνA, and T2K experiments. Good agreement with experimental data is found over
the whole range of neutrino energies. The results are also in global good agreement with the predictions of
the superscaling approach, which is based on the analysis of electron-nucleus scattering data, with only a few
differences seen at specific kinematics.
The TRAPSENSOR facility: an open-ring 7 tesla Penning trap for laserbased precision experimentsGutiérrez, ManuelBerrocal, JoaquínCornejo, Juan ManuelDomínguez, Franciscodel Pozo, JesúsArrazola, Íñigohttp://hdl.handle.net/10481/594042020-02-04T11:12:44ZThe TRAPSENSOR facility: an open-ring 7 tesla Penning trap for laserbased precision experiments
Gutiérrez, Manuel; Berrocal, Joaquín; Cornejo, Juan Manuel; Domínguez, Francisco; del Pozo, Jesús; Arrazola, Íñigo
APenning-trap facility for high-precision mass spectrometry based on a novel detection method has
been built. This method consists in measuring motional frequencies of singly-charged ions trapped in
strong magnetic fields through the fluorescence photons from laser-cooled 40Ca+ ions, to overcome
limitations faced in electronic single-ion detection techniques. The key element of this facility is an
open-ring Penning trap coupled upstream to a preparation Penning trap similar to those used at
Radioactive Ion Beam facilities. Here we present a full characterization of the trap and demonstrate
motional frequency measurements of trapped ions stored by applying external radiofrequency fields
in resonance with the ions’ eigenmotions, in combination with time-of-flight identification. The
infrastructure developed to observe the fluorescence photons from 40Ca+, comprising the 12 laser
beams and the optical system to register the image in a high-sensitive CCD sensor, has been proved by
taking images of the trapped and cooled 40Ca+ ions. This demonstrates the functionality of the
proposed laser-based mass-spectrometry technique, providing a unique platform for precision
experiments with implications in different fields of physics.
Spectral-shift and scattering-equivalent Hamiltonians on a coarse momentum gridGómez Rocha, MaríaRuiz Arriola, Enriquehttp://hdl.handle.net/10481/591012020-01-24T08:31:51ZSpectral-shift and scattering-equivalent Hamiltonians on a coarse momentum grid
Gómez Rocha, María; Ruiz Arriola, Enrique
The solution of the scattering problem based on the Lippmann-Schwinger equation requires in many cases a discretization of the spectrum in the continuum which does not respect the unitary equivalence of the S-matrix on the finite grid. We present a new prescription for the calculation of phase shifts based on the shift that is produced in the spectrum of a Chebyshev-angle variable. This is analogous to the energy shift that is produced in the energy levels of a scattering process in a box, when an interaction is introduced. Our formulation holds for any momentum grid and preserves the unitary equivalence of the scattering problem on the finite momentum grid. We illustrate this procedure numerically considering the non-relativistic NN case for 1S0 and 3S1 channels. Our spectral shift formula provides much more accurate results than the previous ones and turns out to be at least as competitive as the standard procedures for calculating phase shifts.
Neutron radiobiology studies with a pure cold neutron beamPedrosa-Rivera, MaríaRuiz-Magaña, María JoséPorras Sánchez, José IgnacioPraena Rodríguez, Antonio JavierTorres-Sánchez, P.Sabariego, M. P.Ruiz Ruiz, María Carmenhttp://hdl.handle.net/10481/587572020-01-15T08:55:39ZNeutron radiobiology studies with a pure cold neutron beam
Pedrosa-Rivera, María; Ruiz-Magaña, María José; Porras Sánchez, José Ignacio; Praena Rodríguez, Antonio Javier; Torres-Sánchez, P.; Sabariego, M. P.; Ruiz Ruiz, María Carmen
Data on the radiobiological effects of thermal neutrons are usually obtained from irradiations in a mixed field of
neutrons of different energies and gamma rays or from conversion of proton data with similar energies to those
created in the neutron capture on nitrogen. Experimental data from irradiations in a pure thermal or cold
neutron beam can help to find new values for neutron relative biological effectiveness (RBE) factors, which are
useful for BNCT (Boron Neutron Capture Therapy) and radiation protection applications. We present a new
experimental setup for radiobiological studies at a cold neutron beam at Institut Laue-Langevin, a beam without
fast neutron component and almost no gamma ray contribution. After the irradiation, survival assays are performed
to obtain the survival curves. Finally, comparing with a reference photon irradiation, the thermal
neutron RBE factors can be calculated. The methodology is outlined at the example of A375 melanoma cells for
which new radiobiological data were obtained.