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M. J. Vicente-Vacas

Publications and source records attributed to M. J. Vicente-Vacas.

22 records · Page 2Linked to original sources

Neutron and proton spectra from the decay of $Λ$ hypernuclei

We have determined the spectra of neutrons and protons following the decay of $Λ$ hypernuclei through the one- and two-nucleon induced mechanisms. The momentum distributions of the primary nucleons are calculated and a Monte Carlo simulation is used to account for final state interactions. From the spectra we calculate the number of neutrons ($N_n$) and protons ($N_p$) per $Λ$ decay and show how the measurement of these quantities, particularly $N_p$, can lead to a determination of $Γ_n / Γ_p$, the ratio of neutron to proton induced $Λ$ decay. We also show that the consideration of the two-nucleon induced channel has a repercussion in the results, widening the band of allowed values of $Γ_n / Γ_p$ with respect to what is obtained neglecting this channel.

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Meson Exchange Currents in Pion Double Charge Exchange at High Energies

In this letter we study the high energy behavior of the forward differential cross section for the $^{18}O(π^+,π^-)^{18}Ne$ double charge exchange reaction. We have evaluated the sequential and the meson exchange current mechanisms. The meson exchange current contribution shows a very weak energy dependence and becomes relevant at incident pion kinetic energies above 600 MeV.

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Double Pion Photoproduction in Nuclei

The inclusive A(gamma,pi+ pi-)X reaction is studied theoretically. A sizeable enhancement of the cross section is found, in comparison with the scaling of the deuteron cross section (sigma_deuteron * A/2). This enhancement is due to the modifications in the nuclear medium of the gamma N ----> pi pi N amplitude and the pion dispersion relation. The enhancement is found to be bigger than the one already observed in the (pi,pi pi) reaction in nuclei.

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Inclusive Pion Double Charge Exchange above 0.5 GeV

A cascade model has been developed to study pion induced multichannel reactions (quasielastic, SCX, DCX, absorption and pion production) at pion energies above 0.5 GeV. Special attention has been paid to pion double charge exchange. Pion production is a determinant feature in the high energy pion nucleus reactions, and the DCX signal not related to pion production is sizeable only at forward angles and for high energy outgoing pions. The contribution to DCX of the conventional mechanism, with two quasielastic SCX steps decreases very fast as a function of the energy and reaches very low values at energies above 0.7 GeV. This opens the opportunity of having sizeable contributions of exotic mechanisms that are negligible at the delta resonance energies.

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