2,956 research outputs found
On the widths and binding energies of nuclear states and the role of multi-nucleon interactions
We report on our recent self-consistent calculations of nuclear
quasi-bound states using optical potentials derived from chirally
motivated meson-baryon coupled channels models [1,2]. The single-nucleon
potentials were supplemented by a phenomenological multi-nucleon
interaction term introduced to achieve good fits to atom data. We
demonstrate a substantial impact of the multi-nucleon absorption on the
widths of nuclear states. If such states ever exist in nuclear many-body
systems, their widths are excessively large to allow observation.Comment: 9 pages, 5 figures, proceedings of the EXA2017 conference, Vienna,
Austria, September 11 - 15, 201
Description of Heavy Quark Systems by means of Energy Dependent Potentials
We apply, for the first time, an energy dependent Schrodinger equation to
describe static properties of heavy quark systems, i.e. charmonium and
bottonium. We show that a good description of the eigenstates and reasonable
values for the widths can be obtained. Values of the radii and of the density
at the origin are also given. We compare the results to those deduced with a
Schrodinger equation implemented with potentials used so far. We note that the
energy dependence of the confining potential provides a natural mechanism for
the saturation of the spectra. Our results introduce a new class of potentials
for the description of heavy quark systems.Comment: 3 page
Bernoulli potential at a superconductor surface
The electrostatic Bernoulli potential measured at the surface of a
superconductor via Kelvin capacitive coupling is shown to be independent of the
pairing mechanism. This contrasts with the Bernoulli potential in the bulk
where contributions due to pairing dominate close to .Comment: 2 page
Metallic properties of magnesium point contacts
We present an experimental and theoretical study of the conductance and
stability of Mg atomic-sized contacts. Using Mechanically Controllable Break
Junctions (MCBJ), we have observed that the room temperature conductance
histograms exhibit a series of peaks, which suggests the existence of a shell
effect. Its periodicity, however, cannot be simply explained in terms of either
an atomic or electronic shell effect. We have also found that at room
temperature, contacts of the diameter of a single atom are absent. A possible
interpretation could be the occurrence of a metal-to-insulator transition as
the contact radius is reduced, in analogy with what it is known in the context
of Mg clusters. However, our first principle calculations show that while an
infinite linear chain can be insulating, Mg wires with larger atomic
coordinations, as in realistic atomic contacts, are alwaysmetallic. Finally, at
liquid helium temperature our measurements show that the conductance histogram
is dominated by a pronounced peak at the quantum of conductance. This is in
good agreement with our calculations based on a tight-binding model that
indicate that the conductance of a Mg one-atom contact is dominated by a single
fully open conduction channel.Comment: 14 pages, 5 figure
Ground states and excited states of hypernuclei in Relativistic Mean Field approach
Hypernuclei have been studied within the framework of Relativistic Mean Field
theory. The force FSU Gold has been extended to include hyperons. The effective
hyperon-nucleon and nucleon-nucleon interactions have been obtained by fitting
experimental energies in a number of hypernuclei over a wide range of mass.
Calculations successfully describe various features including hyperon
separation energy and single particle spectra of single-\Lambda hypernuclei
throughout the periodic table. We also extend this formalism to double-\Lambda
hypernuclei.Comment: 16 pages,3 figure
Eta-mesic nuclei
In this contribution we report on theoretical studies of nuclear
quasi-bound states in few- and many-body systems performed recently by the
Jerusalem-Prague Collaboration [1-5]. Underlying energy-dependent
interactions are derived from coupled-channel models that incorporate the
resonance. The role of self-consistent treatment of the strong
energy dependence of subthreshold amplitudes is discussed. Quite large
downward energy shift together with rapid decrease of the amplitudes
below threshold result in relatively small binding energies and widths of the
calculated nuclear bound states. We argue that the subthreshold behavior
of scattering amplitudes is crucial to conclude whether nuclear
states exist, in which nuclei the meson could be bound and if the
corresponding widths are small enough to allow detection of these
nuclear states in experiment.Comment: 7 pages, 5 figures; presented at HADRON2017, Sept. 25-29, 2017,
Salamanca (Spain); prepared for Proceedings of Scienc
- …