31 research outputs found
Embedding nuclear physics inside the unitary window
The large values of the singlet and triplet scattering lengths locate the
two-nucleon system close to the unitary limit, the limit in which these two
values diverge. As a consequence, the system shows a continuous scale
invariance which strongly constrains the values of the observables, a
well-known fact already noticed a long time ago. The three-nucleon system shows
a discrete scale invariance that can be observed by correlations of the triton
binding energy with other observables as the doublet nucleon-deuteron
scattering length or the alpha-particle binding energy. The low-energy dynamics
of these systems is universal; it does not depend on the details of the
particular way in which the nucleons interact. Instead, it depends on a few
control parameters, the large values of the scattering lengths and the triton
binding energy. Using a potential model with variable strength set to give
values to the control parameters, we study the spectrum of nuclei
in the region between the unitary limit and their physical values. In
particular, we analyze how the binding energies emerge from the unitary limit
forming the observed levels
Nuclear matter saturation with chiral three-nucleon interactions fitted to light nuclei properties
The energy per particle of symmetric nuclear matter and pure neutron matter is calculated using the many-body Brueckner-Hartree-Fock approach and employing the Chiral Next-to-next-to-next-to leading order (N3LO) nucleon-nucleon (NN) potential, supplemented with various parametrizations of the Chiral Next-to-next-to leading order (N2LO) three-nucleon interaction. Such combination is able to reproduce several observables of the physics of light nuclei for suitable choices of the parameters entering in the three-nucleon interaction. We find that some of these parametrizations provide a satisfactory saturation point of symmetric nuclear matter and values of the symmetry energy and its slope parameter L in very good agreement with those extracted from various nuclear experimental data. Thus, our results represent a significant step toward a unified description of few- and many-body nuclear systems starting from two- and three-nucleon interactions based on the symmetries of QCD
Nuclear matter calculations with chiral interactions
We calculate the energy per particle of symmetric nuclearmatter and pure neutronmatter using the many-body Brueckner-Hartree-Fock approach and employing the Chiral Next-To-next-To-next-To leading order (N3LO) nucleon-nucleon (NN) potential, supplemented with various parametrizations of the Chiral Next-To-next-To leading order (N2LO) three-nucleon force. Such combination is able to reproduce several observables of the physics of light nuclei for suitable choices of the parameters entering in the three-nucleon interaction. We find that some of these parametrizations, provide also reasonable values for the observables of nuclear matter at the saturation point
Local chiral potentials and the structure of light nuclei
We present fully local versions of the minimally non-local nucleon-nucleon
potentials constructed in a previous paper [M.\ Piarulli {\it et al.}, Phys.\
Rev.\ C {\bf 91}, 024003 (2015)], and use them in hypersperical-harmonics and
quantum Monte Carlo calculations of ground and excited states of H, He,
He, He, and Li nuclei. The long-range part of these local
potentials includes one- and two-pion exchange contributions without and with
-isobars in the intermediate states up to order ( denotes
generically the low momentum scale) in the chiral expansion, while the
short-range part consists of contact interactions up to order . The
low-energy constants multiplying these contact interactions are fitted to the
2013 Granada database in two different ranges of laboratory energies, either
0--125 MeV or 0--200 MeV, and to the deuteron binding energy and singlet
scattering length. Fits to these data are performed for three models
characterized by long- and short-range cutoffs, and
respectively, ranging from fm down to
fm. The long-range (short-range) cutoff regularizes the one- and
two-pion exchange (contact) part of the potential.Comment: 29 pages, 3 figure
New trends in few-body systems: a 30th anniversary collection
Few-Body Systems refer to a multidisciplinary subject of research in different sectors of physics in which the number of degrees of freedom governing the dynamics is sufficiently low to allow a description with controlled approximations. Examples can be found in atomic, nuclear and subnuclear physics as well as in some aspects of condensed matter. This issue, celebrating the 30th Anniversary of the Journal, contains two review articles, one in exotic hadrons and one in antikaon-nucleon systems, as well as a selection of original articles on experimental and theoretical physics in which modern problems in few-body systems are discussed. Specific arguments, presented by world expert leaders, are very extensive and include the three and four-nucleon system, short-range correlations, universal behavior in few-boson systems, perspectives on the origin of hadron masses, scattering problems and studies using electromagnetic probes. This issue gives an overview of actual problems in Few-Body Systems
Nuclear matter properties from local chiral interactions with Delta isobar intermediate states
Using two-nucleon and three-nucleon interactions derived in the framework of chiral perturbation theory (ChPT) with and without the explicit Δ isobar contributions, we calculate the energy per particle of symmetric nuclear matter and pure neutron matter in the framework of the microscopic Brueckner-Hartree-Fock approach. In particular, we present for the first time nuclear matter calculations using the new fully local in coordinate-space two-nucleon interaction at the next-to-next-to-next-to-leading-order (N3LO) of ChPT with Δ isobar intermediate states (N3LOΔ) recently developed by Piarulli et al. [arXiv:1606.06335]. We find that using this N3LOΔ potential, supplemented with a local N2LO three-nucleon interaction with explicit Δ isobar degrees of freedom, it is possible to obtain a satisfactory saturation point of symmetric nuclear matter. For this combination of two- and three-nucleon interactions we also calculate the nuclear symmetry energy and we compare our results with the empirical constraints on this quantity obtained using the excitation energies to isobaric analog states in nuclei and using experimental data on the neutron skin thickness of heavy nuclei, finding a very good agreement in all the considered nucleonic density range. In addition, we find that the explicit inclusion of Δ isobars diminishes the strength of the three-nucleon interactions needed to get a good saturation point of symmetric nuclear matter. We also compare the results of our calculations with those obtained by other research groups using chiral nuclear interactions with different many-body methods, finding in many cases a very satisfactory agreement