Low-momentum effective interaction in the three-dimensional approach

The formulation of the low-momentum effective interaction in the model space Lee-Suzuki and the renormalization group methods is implemented in the three-dimensional approach. In this approach the low-momentum effective interaction V_{low k} has been formulated as a function of the magnitude of momentum vectors and the angle between them. As an application the spin-isospin independent Malfliet-Tjon potential has been used into the model space Lee-Suzuki method and it has been shown that the low-momentum effective interaction V_{low k} reproduces the same two-body observables obtained by the bare potential V_{NN}.Comment: 15 pages, 5 eps figure

Neutron-19C scattering: Emergence of universal properties in a finite range potential

AbstractThe low-energy properties of the elastic s-wave scattering for the n-19C are studied near the critical condition for the occurrence of an excited Efimov state in n–n-18C. It is established to which extent the universal scaling laws, strictly valid in the zero-range limit, survive when finite range potentials are considered. By fixing the two-neutrons separation energy in 20C with available experimental data, it is studied the scaling of the real (δ0R) and imaginary parts of the s-wave phase-shift with the variation of the n-18C binding energy. We obtain some universal characteristics given by the pole-position of kcot⁡(δ0R) and effective-range parameters. By increasing the n-18C binding energy, it was verified that the excited state of 20C goes to a virtual state, resembling the neutron–deuteron behavior in the triton. It is confirmed that the analytical structure of the unitary cut is not affected by the range of the potential or mass asymmetry of the three-body system

A Spin-Isospin Dependent 3N Scattering Formalism in a 3D Faddeev Scheme

We have introduced a spin-isospin dependent three-dimensional approach for formulation of the three-nucleon scattering. Faddeev equation is expressed in terms of vector Jacobi momenta and spin-isospin quantum numbers of each nucleon. Our formalism is based on connecting the transition amplitude $T$ to momentum-helicity representations of the two-body $t$-matrix and the deuteron wave function. Finally the expressions for nucleon-deuteron elastic scattering and full breakup process amplitudes are presented.Comment: 17 page

Triton photodisintegration in three-dimensional approach

Two- and three- particles photodisintegration of the triton is investigated in a three-dimensional (3D) Faddeev approach. For this purpose the Jacobi momentum vectors for three particles system and spin-isospin quantum numbers of the individual nucleons are considered. Based on this picture the three-nucleon Faddeev integral equations with the two-nucleon interaction are formulated without employing the partial wave decomposition. The single nucleon current as well as $\pi-$ and $\rho-$ like exchange currents are used in an appropriate form to be employed in 3D approach. The exchange currents are derived from AV18 NN force. The two-body t-matrix, Deuteron and Triton wave functions are calculated in the 3D approach by using AV18 potential. Benchmarks are presented to compare the total cross section for the two- and three- particles photodisintegration in the range of $E_{\gamma}<30 MeV$. The 3D Faddeev approach shows promising results

Universality in Four-Boson Systems

We report recent advances on the study of universal weakly bound four-boson states from the solutions of the Faddeev-Yakubovsky equations with zero-range two-body interactions. In particular, we present the correlation between the energies of successive tetramers between two neighbor Efimov trimers and compare it to recent finite range potential model calculations. We provide further results on the large momentum structure of the tetramer wave function, where the four-body scale, introduced in the regularization procedure of the bound state equations in momentum space, is clearly manifested. The results we are presenting confirm a previous conjecture on a four-body scaling behavior, which is independent of the three-body one. We show that the correlation between the positions of two successive resonant four-boson recombination peaks are consistent with recent data, as well as with recent calculations close to the unitary limit. Systematic deviations suggest the relevance of range corrections.Comment: Accepted for publication in special issue of Few-Body Systems devoted to the Sixth Workshop on the Critical Stability of Quantum Few-Body Systems, October 2011, Erice, Sicily, Ital

Different Methods for the Two-Nucleon T-Matrix in the Operator Form

We compare three methods to calculate the nucleon-nucleon t-matrix based on the three-dimensional formulation of J. Golak et al., Phys. Rev. C 81, 034006, (2010). In the first place we solve a system of complex linear inhomogeneous equations directly for the t-matrix. Our second method is based on iterations and a variant of the Lanczos algorithm. In the third case we obtain the t-matrix in two steps, solving a system of real linear equations for the k-matrix expansion coefficients and then solving an on-shell equation, which connects the scalar coefficients of the k- and t-matrices. A very good agreement among the three methods is demonstrated for selected nucleon-nucleon scattering observables using a chiral next-to-next-to-leading-order neutron-proton potential. We also apply our three-dimensional framework to the demanding problem of proton-proton scattering, using a corresponding version of the nucleon-nucleon potential and supplementing it with the (screened) Coulomb force, taken also in the three-dimensional form. We show converged results for two different screening functions and find a very good agreement with other methods dealing with proton-proton scattering.Comment: 18 pages, 10 figures (54 eps files

Molecular dynamic and in vitro evaluation of chitosan/tripolyphosphate nanoparticles as an insulin delivery system at two different pH values

Understanding the atomic interaction mechanism between chitosan and insulin at different pH levels is essential in the design of chitosan-based drug-delivery systems. In the present study, insulin-loaded nanoparticles were prepared via ionic gelation of tripolyphosphate (TPP) and chitosan with 76 ± 5.5 encapsulation efficiency. Our results showed that the nanoparticles were spherical with a size of 254 nm. Furthermore, the in vitro release profile of insulin was evaluated for two different pH levels. The release of insulin from nanoparticles after 48 h at pH 4.0 was 92, compared to 56 at pH 7.4. The kinetics of the release were best fitted by the Weibull equation, which described a burst release in the first five hours followed by a sustained insulin release for up to 48 h. Moreover, we designed a long single chain chitosan (128 kDa)/TPP nanoparticles in real size for the first time and studied the system behavior in acidic and neutral environments using molecular dynamic simulation for 40 nanoseconds (ns). Our results showed that chitosan chains opened more with higher root-mean-square deviation (RMSD) values at pH 4.0 than at pH 7.4. Also, RMSD plots for insulin and TPP molecules showed that insulin molecules diffused away from chitosan chains, and that TPP were randomly dispersed further away from the chitosan chain in an acidic medium than in a neutral one. The in silico studies were in agreement with our in vitro data. Thus self-assembled chitosan/TPP nanoparticles show promise as a means to release protein drugs in acidic environments. Communicated by Ramaswamy H. Sarma. © 2021 Informa UK Limited, trading as Taylor & Francis Group

Erratum to “Neutron–19C scattering: Emergence of universal properties in a finite range potential” [Phys. Lett. B 764 (2017) 196]

Numerical results for the function (1−EK/E0)kcot⁡δ0R, as given in Phys. Lett. B 764 (2017) 196, are revised. Fig. 2 and Tables 2 and 3 should be replaced by the following corresponding figure and tables. The conclusions of the original paper remain unchanged. Keywords: Halo nuclei, Scattering theory, Efimov physics, Faddeev equatio