arXiv subjects
Publications and source records attributed to F. Fernández.
We present a nonrelativistic coupled-channel calculation of the deuteron structure including Delta Delta and NN^*(1440) channels, besides the standard NN S and D-wave components. All the necessary building blocks to perform the calculation have been obtained from the same underlying quark model. The calculated NN^*(1440) probabilities find support in the explanation given to different deuteron reactions.
A $NN\to NN^{\ast}(1440)$ transition potential, based on an effective quark-quark interaction and a constituent quark cluster model for baryons, is derived in the Born-Oppenheimer approach. The potential shows significant differences with respect to those obtained by a direct scaling of the nucleon-nucleon interaction. From its asymptotic behavior we extract the values of $πNN^{\ast}(1440)$ and $σNN^{\ast}(1440)$ coupling constants in a particular coupling scheme
By means of a $NN \to NN^*(1440)$ transition potential derived in a parameter-free way from a quark model, we determined simultaneously the $πNN^*(1440)$ and $σNN^*(1440)$ coupling constants.
Hard-photon (E$_γ>$ 30 MeV) emission from second-chance nucleon-nucleon Bremsstrahlung collisions in intermediate energy heavy-ion reactions is studied employing a realistic thermal model. Photon spectra and yields measured in several nucleus-nucleus reactions are consistent with an emission from hot nuclear systems with temperatures $T\approx$ 4 - 7 MeV. The corresponding caloric curve in the region of excitation energies $ε^\star\approx$ 3{\it A} - 8{\it A} MeV shows lower values of $T$ than those expected for a Fermi fluid.
We study the possible existence of nonstrange dibaryons and tribaryons by solving the bound-state problem of the two- and three-body systems composed of nucleons and deltas. The two-body systems are $NN$, $NΔ$, and $ΔΔ$, while the three-body systems are $NNN$, $NNΔ$, $NΔΔ$, and $ΔΔΔ$. We use as input the nonlocal $NN$, $NΔ$, and $ΔΔ$ potentials derived from the chiral quark cluster model by means of the resonating group method. We compare with previous results obtained from the local version based on the Born-Oppenheimer approximation.
The three-nucleon bound state problem is studied employing a nucleon-nucleon potential obtained from a basic quark-quark interaction in a five-channel Faddeev calculation. The obtained triton binding energy is comparable to those predicted by conventional models of the $NN$ force.
We present a calculation of the deuteron wave function including $NN$, $ΔΔ$, and $NN^*$(1440) channels. All the transition potentials, as well as the direct $NN$ potential, have been obtained from the same underlying quark model using standard techniques available in the literature. The calculated weights for the different channels are in agreement with previous theoretical estimations.
The three-nucleon bound state problem is studied employing nucleon-nucleon potentials derived from a basic quark-quark interaction. We analyze the effects of the nonlocalities generated by the quark model. The calculated triton binding energies indicate that quark-model nonlocalities can yield additional binding in the order of few hundred keV.
We derive a $NN^*$(1440) potential from a non-relativistic quark-quark interaction and a chiral quark cluster model for the baryons. By making use of the Born-Oppenheimer approximation we examine the most important features of this interaction in comparison to those obtained from meson-exchange models.