In this work we investigate neutron stars (NS) in $f(mathtt{R,L_m})$ theory of gravity for the case $f(mathtt{R,L_m}) = mathtt{R} + mathtt{L_m} + sigmamathtt{R}mathtt{L_m}$, where $mathtt{R}$ is the Ricci scalar and $mathtt{L_m}$ the Lagrangian matter density. In the term $sigmamathtt{R}mathtt{L_m}$, $sigma$ represents the coupling between the gravitational and particles fields. For the first time the hydrostatic equilibrium equations in the theory are solved considering realistic equations of state and NS masses and radii obtained are subject to joint constrains from massive pulsars, the gravitational wave event GW170817 and from the PSR J0030+0451 mass-radius from NASAs Neutron Star Interior Composition Explorer (${it NICER}$) data. We show that in this theory of gravity, the mass-radius results can accommodate massive pulsars, while the general theory of relativity can hardly do it. The theory also can explain the observed NS within the radius region constrained by the GW170817 and PSR J0030+0451 observations for masses around $1.4~M_{odot}$.
We develop a four-body model for the inclusive breakup of two-fragment halo projectiles colliding with two-fragment targets. In the case of a short lived projectiles, such as halo nuclei, on a deuteron target, the model allows the extraction of the neutron capture cross section of such projectiles. We supply examples.
In this paper we investigate the Exotic Charmonium (EC) production in $gamma gamma$ interactions present in proton-proton, proton-nucleus and nucleus-nucleus collisions at the CERN Large Hadron Collider (LHC) energies as well as for the proposed energies of the Future Circular Collider (FCC). Our results demonstrate that the experimental study of these processes is feasible and can be used to constrain the theoretical decay widths and shed some light on the configuration of the considered multiquark states.
The purpose of this paper is to develop an alternative theory of deuteron stripping to resonance states based on the surface integral formalism of Kadyrov et al. [Ann. Phys. 324, 1516 (2009)] and continuum-discretized coupled channels (CDCC). First we demonstrate how the surface integral formalism works in the three-body model and then we consider a more realistic problem in which a composite structure of target nuclei is taken via optical potentials. We explore different choices of channel wave functions and transition operators and show that a conventional CDCC volume matrix element can be written in terms of a surface-integral matrix element, which is peripheral, and an auxiliary matrix element, which determines the contribution of the nuclear interior over the variable $r_{nA}$. This auxiliary matrix element appears due to the inconsistency in treating of the $n-A$ potential: this potential should be real in the final state to support bound states or resonance scattering and complex in the initial state to describe $n-A$ scattering. Our main result is formulation of the theory of the stripping to resonance states using the prior form of the surface integral formalism and CDCC method. It is demonstrated that the conventional CDCC volume matrix element coincides with the surface matrix element, which converges for the stripping to the resonance state. Also the surface representation (over the variable $r_{nA}$ of the stripping matrix element enhances the peripheral part of the amplitude although the internal contribution doesnt disappear and increases with increase of the deuteron energy. We present calculations corroborating our findings for both stripping to the bound state and the resonance.
One-nucleon removal reactions at or above the Fermi energy are important tools to explore the single-particle structure of exotic nuclei. Experimental data must be compared with calculations to extract structure information, evaluate correlation effects in nuclei or determine reaction rates for nuclear astrophysics. However, there is insufficient knowledge to calculate accurately the cross sections for these reactions. We evaluate the contributions of the final state interaction (FSI) and of the medium modifications of the nucleon-nucleon interactions and obtain the shapes and magnitudes of momentum distributions. Such effects have been often neglected in the literature. Calculations for reactions at energies 35 - 1000 MeV/nucleon are reported and compared to published data. For consistency, the state-of-the-art eikonal method for stripping and diffraction dissociation is used. We find that the two effects are important and their relative contributions vary with the energy and with the atomic and mass number of the projectile involved. These two often neglected effects modify considerably the one-nucleon removal cross sections. As expected, the effect are largest at lower energies, around 50 MeV/nucleon and on heavy targets.
The continuum-discretized coupled-channels (CDCC) method is used to study the breakup of weakly-bound nuclei at intermediate energies collisions. For large impact parameters, the Eikonal CDCC (E-CDCC) method was applied. The effects of Lorentz contraction on the nuclear and Coulomb potentials have been investigated in details. Such effects tend to increase cross sections appreciably. We also show that, for loosely-bound nuclei, the contribution of the so-called close field is small and can be neglected.
