Solution of the Faddeev-Yakubovsky equations using realistic NN and 3N interaction

We solve the Faddeev-Yakubovsky equations for 3N and 4N bound states based on the most modern realistic nucleon-nucleon interactions. We include different realistic 3N forces. It is shown that all 3N force models can remove the underbinding of the triton and alpha-particle which one obtains with existing NN interactions. The agreement of theoretical predictions and the experimental binding energy is quite good and there is little room left for the action of four-nucleon forces in the alpha-particle. The effect of 3N forces on the wave function is investigated.Comment: 4 pages, to appear in the proceedings of the "European Few-Body Conference", Evora 200

Benchmark Calculations for the Triton Binding Energy for Modern NN Forces and the pi-pi Exchange Three-Nucleon Force

We present high precision benchmark calculations for the triton binding energy using the most recent, phase equivalent realistic nucleon-nucleon (NN) potentials and the Tuscon-Melbourne pi-pi three-nucleon force (3NF). That 3NF is included with partial waves up to a total two-body angular momentum of j_max=6. It is shown that the inclusion of the 3NF slows down the convergence in the partial waves and j_max=5 is needed in order to achieve converged results within a few keV. We adjust the cut-off parameter Lambda in the form factors of the Tuscon-Melbourne 3NF separately for the different NN potentials to the triton binding energy. This provides a set of phenomenological three-nucleon Hamiltonians which can be tested in three-nucleon scattering and systems with A>3. A connection between the probability to find two nucleons at short distances in the triton and the effect of that 3NF on the triton binding energy is pointed out.Comment: 18 pages REVTeX, 3 figure

Quantum Computer Using Coupled Quantum Dot Molecules

We propose a method for implementation of a quantum computer using artificial molecules. The artificial molecule consists of two coupled quantum dots stacked along z direction and one single electron. One-qubit and two-qubit gates are constructed by one molecule and two coupled molecules, respectively.The ground state and the first excited state of the molecule are used to encode the |0> and |1> states of a qubit. The qubit is manipulated by a resonant electromagnetic wave that is applied directly to the qubit through a microstrip line. The coupling between two qubits in a quantum controlled NOT gate is switched on (off) by floating (grounding) the metal film electrodes. We study the operations of the gates by using a box-shaped quantum dot model and numerically solving a time-dependent Schridinger equation, and demonstrate that the quantum gates can perform the quantum computation. The operating speed of the gates is about one operation per 4ps. The reading operation of the output of the quantum computer can be performed by detecting the polarization of the qubits.Comment: 18 pages, 7 figures, submitted to Jpn. J. Appl. Phys, please send your e-mail to Nan-Jian Wu <[email protected]

A New Look into the Partial Wave Decomposition of Three-Nucleon Forces

We demonstrate that the partial wave decomposition of three-nucleon forces used up to now in momentum space has to be necessarily unstable at high partial waves. This does not affect the applications performed up to now, which were restricted to low partial waves. We present a new way to perform the partial wave decomposition which is free of that defect. This is exemplified for the most often used $2\pi$-exchange Tuscon-Melbourne three-nucleon force. For the lower partial waves the results of the old method are reproduced.Comment: 38 pages in REVTeX, 4 figures in PiCTe

Modern NN Force Predictions for the Total ND Cross Section up to 300 MeV

For several modern nucleon-nucleon potentials state-of-the-art Faddeev calculations are carried out for the $nd$ total cross section between 10 and 300 MeV projectile energy and compared to new high precision measurements. The agreement between theory and data is rather good, with exception at the higher energies where a 10% discrepancy builds up. In addition the convergence of the multiple scattering series incorporated in the Faddeev scheme is studied numerically with the result, that rescattering corrections remain important. Based on this multiple scattering series the high energy limit of the total $nd$ cross section is also investigated analytically. In contrast to the naive expectation that the total $nd$ cross section is the sum of the $np$ and $nn$ total cross sections we find additional effects resulting from the rescattering processes, which have different signs and different behavior as function of the energy. A shadowing effect in the high energy limit only occurs for energies higher than 300 MeV. The expressions in the high energy limit have qualitatively a similar behavior as the exactly calculated expressions, but can be expected to be valid quantitatively only at much higher energies.Comment: 22 pages, 5 figure

On the usefulness of the spectral function concept

The usefulness of the spectral function S in the process 3He(e,e'N) has been investigated in a kinematical regime constrained by the conditions that the three-nucleon center-of-mass energy is less than 150 MeV and the magnitude of the three-momentum transfer smaller than 600 MeV/c. Results based on a full treatment of the final state interaction are compared to the spectral function approximation. In the case of proton knockout in the direction of the photon kinematical conditions have been identified where both response functions, RL and RT, can be well approximated by S. These conditions occur for certain low missing momenta and missing energies but not in all cases. So care is required. In case of neutron knockout only RT is a candidate for an approximate treatment by S. In the case of RL the concept of using S is not valid in the studied kinematical regime. This does not exclude the possibility that beyond that regime it might be useful. Possible applications using S for the extraction of electromagnetic form factors of the nucleons are pointed out.Comment: 27 pages, 25 fugure

Proton polarizations in polarized 3He studied with the \vec{3He} (\vec{e},e' p)d and \vec{3He} (\vec{e},e' p)pn processes

We study within the Faddeev framework the \vec{3He} (\vec{e},e' p)d as well as the \vec{3He} (\vec{e},e' p)pn and \vec{3He} (\vec{e},e' n)pp reactions in order to extract information on the proton and neutron polarization in polarized 3He. We achieve clear analytical insight for simplified dynamical assumptions and define conditions for experimental access to important 3He properties. In addition we point to the possibility to measure the electromagnetic proton form factors in the process \vec{3He} (\vec{e},e' p)d which would test the dynamical picture and put limits on medium corrections of the form factors.Comment: 38 pages, 22 figure