Isobaric single charge-exchange reactions, changing nuclear charges by one unit but leaving the mass partitions unaffected, have been for the first time investigated by peripheral collisions of $^{112}$Sn ions accelerated up to 1textit{A} GeV at the
GSI facilities. The high-resolving power of the FRS spectrometer allows us to obtain $(p, n)$-type isobaric charge-exchange cross sections with an uncertainty of $3.5%$ and to separate quasi-elastic and inelastic components in the missing-energy spectra of the ejectiles. The inelastic component is associated to the excitation of the $Delta$(1232) isobar resonance and the emission of pions in s-wave both in the target and projectile nucleus, while the quasi-elastic contribution is associated to the nuclear spin-isospin response of nucleon-hole excitations. An apparent shift of the $Delta$-resonance peak of $sim$63 MeV is observed when comparing the missing-energy spectra obtained from the measurements with proton and carbon targets. A detailed analysis, performed with a theoretical model for the reactions, indicates that this observation can be simply interpreted as a change in the relative magnitude between the contribution of the excitation of the resonance in the target and in the projectile.
We present an extension of a previous work where, assuming a simple free bosonic gas supplemented with a relativistic meand field model to describe the pure nucleonic part of the EoS, we studied the consequences that the first non-trivial hexaquark $
d^*$(2380) could have on the properties of neutron stars. Compared to that exploratory work we employ a standard non-linear Walecka model including additional terms that describe the interaction of the $d^*(2380)$ di-baryon with the other particles of the system through the exchange of $sigma$- and $omega$-meson fields. Our results have show that the presence of the $d^*(2380)$ leads to maximum masses compatible with the recent observations of $sim 2$M$_odot$ millisecond pulsars if the interaction of the $d^*(2380)$ is slightly repulsive or the $d^*(2380)$ does not interacts at all. An attractive interaction makes the equation of state too soft to be able to support a $2$M$_odot$ neutron star whereas an extremely repulsive one induces the collapse of the neutron star into a black hole as soon as the $d^*(2380)$ appears.
A systematic study of the microscopic and thermodynamical properties of pure neutron matter at finite temperature within the Self-Consistent Greens Function approach is performed. The model dependence of these results is analyzed by both comparing th
e results obtained with two different microscopic interactions, the CD-BONN and the Argonne V18 potentials, and by analyzing the results obtained with other approaches, such as the Brueckner--Hartree--Fock approximation, the variational approach and the virial expansion.
