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Sep 21, 2013
09/13

by
A. Kievsky

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Using modern nucleon-nucleon interactions in the description of the $A=3,4$ nuclear systems the $\chi^2$ per datum results to be much bigger than one. In particular it is not possible to reproduce the three- and four-nucleon binding energies and the $n-d$ scattering length simultaneously. This is one manifestation of the necessity of including a three-nucleon force in the nuclear Hamiltonian. In this paper we perform an analysis of some, widely used, three-nucleon force models. We analyze their...

Source: http://arxiv.org/abs/1011.2075v1

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Sep 22, 2013
09/13

by
A. Kievsky

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Two different aspects of the description of three- and four-nucleon systems are addressed. The use of bound state like wave functions to describe scattering states in $N-d$ collisions at low energies and the effects of some of the widely used three-nucleon force models in selected polarization observables in the three- and four-nucleon systems are discussed.

Source: http://arxiv.org/abs/1103.4263v1

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Sep 20, 2013
09/13

by
A. Kievsky

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Using modern nucleon-nucleon interactions in the description of the $A=3,4$ nuclei, it is not possible to reproduce both the three- and four-nucleon binding energies simultaneously. This is one manifestation of the necessity of including a three-nucleon force in the nuclear Hamiltonian. Several models of the three-nucleon force exist and are applied in the description of light nuclei. However, as it is discussed here, a simultaneous description of the three- and four-body binding energies and...

Source: http://arxiv.org/abs/1002.1254v1

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Jul 22, 2013
07/13

by
P. Barletta; A. Kievsky

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This paper investigates the possible use of the Hyperspherical Adiabatic basis in the description of scattering states of a three-body system. In particular, we analyze a 1+2 collision process below the three-body breakup. The convergence patterns for the observables of interest are analyzed by comparison to a unitary equivalent Hyperspherical Harmonic expansion. Furthermore, we compare and discuss two different possible choices for describing the asymptotic configurations of the system,...

Source: http://arxiv.org/abs/0807.2333v1

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6.0

Jun 28, 2018
06/18

by
A. Kievsky; M. Gattobigio

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We discuss weakly bound states of a few-fermion system having spin-isospin symmetry. This corresponds to the nuclear physics case in which the singlet, $a_0$, and triplet, $a_1$, $n-p$ scattering lengths are large with respect to the range of the nuclear interaction. The ratio of the two is about $a_0/a_1\approx-4.31$. This value defines a plane in which $a_0$ and $a_1$ can be varied up to the unitary limit, $1/a_0=0$ and $1/a_1=0$, maintaining its ratio fixed. Using a spin dependant potential...

Topics: Condensed Matter, Quantum Gases, Nuclear Theory

Source: http://arxiv.org/abs/1509.02059

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Sep 23, 2013
09/13

by
A. Kievsky; M. Gattobigio

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We investigate universal behavior in elastic atom-dimer scattering below the dimer breakup threshold calculating the atom-dimer effective-range function $ak\cot\delta$. Using the He-He system as a reference, we solve the Schr\"odinger equation for a family of potentials having different values of the two-body scattering length $a$ and we compare our results to the universal zero-range form deduced by Efimov, $ak\cot\delta=c_1(ka)+c_2(ka)\cot[s_0\ln(\kappa_*a)+\phi(ka)]$, for selected...

Source: http://arxiv.org/abs/1212.3457v2

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2.0

Jun 28, 2018
06/18

by
A. Kievsky; M. Gattobigio

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The structure of few-fermion systems having $1/2$ spin-isospin symmetry is studied using potential models. The strength and range of the two-body potentials are fixed to describe low energy observables in the angular momentum $L=0$ state and spin $S=0,1$ channels of the two-body system. Successively the strength of the potentials are varied in order to explore energy regions in which the two-body scattering lengths are close to the unitary limit. This study is motivated by the fact that in the...

Topics: Quantum Gases, Nuclear Theory, Condensed Matter

Source: http://arxiv.org/abs/1511.09184

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9.0

Jun 28, 2018
06/18

by
A. Kievsky; M. Gattobigio

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Using potential models we analyze range corrections to the universal law dictated by the Efimov theory of three bosons. In the case of finite-range interactions we have observed that, at first order, it is necessary to supplement the theory with one finite-range parameter, $\Gamma_n^3$, for each specific $n$-level [Kievsky and Gattobigio, Phys. Rev. A {\bf 87}, 052719 (2013)]. The value of $\Gamma_n^3$ depends on the way the potentials is changed to tune the scattering length toward the unitary...

Topics: Nuclear Theory, Quantum Gases, Condensed Matter

Source: http://arxiv.org/abs/1507.03402

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Sep 20, 2013
09/13

by
M. Gattobigio; A. Kievsky; M. Viviani

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In this work we show results for light nuclear systems and small clusters of helium atoms using the hyperspherical harmonics basis. We use the basis without previous symmetrization or antisymmetrization of the state. After the diagonalization of the Hamiltonian matrix, the eigenvectors have well defined symmetry under particle permutation and the identification of the physical states is possible. We show results for systems composed up to six particles. As an example of a fermionic system, we...

Source: http://arxiv.org/abs/1205.4319v1

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Sep 18, 2013
09/13

by
M. Gattobigio; A. Kievsky; M. Viviani

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We study small clusters of bosons, $A=2,3,4,5,6$, characterized by a resonant interaction. Firstly, we use a soft-gaussian interaction that reproduces the values of the dimer binding energy and the atom-atom scattering length obtained with LM2M2 potential, a widely used $^4$He-$^4$He interaction. We change the intensity of the potential to explore the clusters' spectra in different regions with large positive and large negative values of the two-body scattering length and we report the...

Source: http://arxiv.org/abs/1211.6637v1

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Sep 18, 2013
09/13

by
L. Girlanda; A. Kievsky; M. Viviani

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We obtain a minimal form of the two-derivative three-nucleon contact Lagrangian, by imposing all constraints deriving from discrete symmetries, Fierz identities and Poincare' covariance. The resulting interaction, depending on 10 unknown low-energy constants, leads to a three-nucleon potential which we give in a local form in configuration space. We also consider the leading (no-derivative) four-nucleon interaction and show that there exists only one independent operator.

Source: http://arxiv.org/abs/1102.4799v2

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Sep 19, 2013
09/13

by
M. Viviani; A. Kievsky; S. Rosati

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The Kohn variational principle is formulated for calculating elastic proton-deuteron scattering amplitudes at energies above the deuteron breakup threshold. The use of such a principle with an expansion of the wave function on the (correlated) hyperspherical harmonic basis is discussed.

Source: http://arxiv.org/abs/nucl-th/0102048v1

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Sep 21, 2013
09/13

by
M. Gattobigio; A. Kievsky; M. Viviani

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In this work we investigate small clusters of helium atoms using the hyperspherical harmonic basis. We consider systems with $A=2,3,4,5,6$ atoms with an inter-particle potential which does not present a strong repulsion at short distances. We use an attractive gaussian potential that reproduces the values of the dimer binding energy, the atom-atom scattering length, and the effective range obtained with one of the widely used He-He interactions, the LM2M2 potential. In systems with more than...

Source: http://arxiv.org/abs/1106.3853v2

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Sep 22, 2013
09/13

by
M. Lombardi; P. Barletta; A. Kievsky

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The advantage of using a Discrete Variable Representation (DVR) is that the Hamiltonian of two interacting particles can be constructed in a very simple form. However the DVR Hamiltonian is approximate and, as a consequence, the results cannot be considered as variational ones. We will show that the variational character of the results can be restored by performing a reduced number of integrals. In practice, for a variational description of the lowest n bound states only n(n+1)/2 integrals are...

Source: http://arxiv.org/abs/physics/0403071v2

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34

Sep 18, 2013
09/13

by
A. Kievsky; S. Rosati; M. Viviani

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Coulomb effects in the neutron-deuteron and proton-deuteron polarization-transfer coefficients $K_y^{y'}$, $K_z^{x'}$, $K_y^{x'x'-y'y'}$ and $K_y^{z'z'}$ are studied at energies above the deuteron breakup threshold. Theoretical predictions for these observables are evaluated in the framework of the Kohn Variational Principle using correlated basis functions to expand the three-nucleon scattering wave function. The two-nucleon Argonne $v_{18}$ and the three-nucleon Urbana IX potentials are...

Source: http://arxiv.org/abs/nucl-th/0105079v1

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2.0

Jun 30, 2018
06/18

by
E. Garrido; A. Kievsky; M. Viviani

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General expressions for the breakup cross sections in the lab frame for $1+2$ reactions are given in terms of the hyperspherical adiabatic basis. The three-body wave function is expanded in this basis and the corresponding hyperradial functions are obtained by solving a set of second order differential equations. The ${\cal S}$-matrix is computed by using two recently derived integral relations. Even though the method is shown to be well suited to describe $1+2$ processes, there are...

Topic: Nuclear Theory

Source: http://arxiv.org/abs/1407.0172

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Sep 22, 2013
09/13

by
M. Viviani; S. Rosati; A. Kievsky

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The Kohn variational principle and the (correlated) Hyperspherical Harmonics technique are applied to study the n-3H and p-3He scattering at zero energy. Predictions for the singlet and triplet scattering lengths are obtained for non-relativistic nuclear Hamiltonians including two- and three-body potentials. The calculated n-3H total cross section agrees well with the measured value, while some small discrepancy is found for the coherent scattering length. For the p-3He channel, the calculated...

Source: http://arxiv.org/abs/nucl-th/9807059v1

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Sep 23, 2013
09/13

by
M. Viviani; A. Kievsky; S. Rosati

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The problem of calculating the four--nucleon bound state properties for the case of realistic two- and three-body nuclear potentials is studied using the hyperspherical harmonic (HH) approach. A careful analysis of the convergence of different classes of HH functions has been performed. A restricted basis is chosen to allow for accurate estimates of the binding energy and other properties of the 4He ground state. Results for various modern two-nucleon and two- plus three-nucleon interactions...

Source: http://arxiv.org/abs/nucl-th/0408019v1

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33

Sep 22, 2013
09/13

by
A. Kievsky; E. Pace; G. Salme`

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An approach for the description of the final state interaction in the evaluation of inclusive electromagnetic responses of a polarized Helium-3 target, is briefly illustrated. Preliminary results of calculations, where the final state interaction is fully taken into account for the two-body break-up channel, are compared with experimental data, showing a very encouraging improvement with respect to the plane wave impulse approximation results.

Source: http://arxiv.org/abs/nucl-th/0501060v1

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Sep 24, 2013
09/13

by
A. Kievsky; M. Viviani; S. Rosati

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Differential and total breakup cross sections as well as vector and tensor analyzing powers for p-d scattering are studied for energies above the deuteron breakup threshold up to E(lab)=28 MeV. The p-d scattering wave function is expanded in terms of the correlated hyperspherical harmonic basis and the elastic S-matrix is obtained using the Kohn variational principle in its complex form. The effects of the Coulomb interaction, which are expected to be important in this energy range, have been...

Source: http://arxiv.org/abs/nucl-th/0103058v1

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Sep 22, 2013
09/13

by
M. Viviani; A. Kievsky; A. Rinat

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We compute cross sections for inclusive scattering of high energy electrons on 4He, based on the two lowest orders of the Gersch-Rodriguez-Smith (GRS) series. The required one- and two-particle density matrices are obtained from non-relativistic 4He wave functions using realistic models for the nucleon-nucleon and three-nucleon interaction. Predictions for E=3.6 GeV agree well with the NE3 SLAC-Virginia data.

Source: http://arxiv.org/abs/nucl-th/0111049v1

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Sep 19, 2013
09/13

by
M. Gattobigio; A. Kievsky; M. Viviani

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The use of the hyperspherical harmonic (HH) basis in the description of bound states in an $A$-body system composed by identical particles is normally preceded by a symmetrization procedure in which the statistic of the system is taken into account. This preliminary step is not strictly necessary; the direct use of the HH basis is possible, even if the basis has not a well defined behavior under particle permutations. In fact, after the diagonalization of the Hamiltonian matrix, the...

Source: http://arxiv.org/abs/1009.3426v1

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27

Sep 18, 2013
09/13

by
A. Kievsky; S. Rosati; M. Viviani

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The complex Kohn variational principle and the (correlated) hyperspherical harmonics method are applied to study the proton-deuteron elastic scattering at energies above the deuteron breakup threshold. Results for the elastic cross section and various elastic polarization observables have been obtained by fully taking into account the long-range effect of the Coulomb interaction and using a realistic nucleon-nucleon interaction model. Detailed comparison between the theoretical predictions and...

Source: http://arxiv.org/abs/nucl-th/9901007v2

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Sep 22, 2013
09/13

by
A. Kievsky; M. Viviani; L. E. Marcucci

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The electromagnetic potential consisting in the Coulomb plus the magnetic moment interactions between two nucleons is studied in nucleon-deuteron scattering. For states in which the relative N-d angular momentum L has low values the three--nucleon problem has been solved using the correlated hyperspherical harmonic expansion basis. For states in which the angular momentum L has large values, explicit formulae for the nucleon-deuteron magnetic moment interaction are derived and used to calculate...

Source: http://arxiv.org/abs/nucl-th/0309066v1

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30

Sep 23, 2013
09/13

by
A. Kievsky; M. Viviani; L. E. Marcucci

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Bound-state-like wave functions are used to determine the scattering matrix corresponding to low energy $N-d$ and $p-^3$He collisions. To this end, the coupled channel form of the integral relations derived from the Kohn variational principle is used. The construction of degenerate bound-state-like wave functions belonging to the continuum spectrum of the Hamiltonian is discussed. Examples are shown using realistic nucleon-nucleon forces.

Source: http://arxiv.org/abs/1109.3976v1

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3.0

Jun 30, 2018
06/18

by
A. Kievsky; N. K. Timofeyuk; M. Gattobigio

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We present the analysis of the $N$-boson spectrum computed using a soft two-body potential the strength of which has been varied in order to cover an extended range of positive and negative values of the two-body scattering length $a$ close to the unitary limit. The spectrum shows a tree structure of two states, one shallow and one deep, attached to the ground-state of the system with one less particle. It is governed by an unique universal function, $\Delta(\xi)$, already known in the case of...

Topics: Physics, Quantum Physics, Quantum Gases, Atomic and Molecular Clusters, Chemical Physics, Nuclear...

Source: http://arxiv.org/abs/1405.2371

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3.0

Jun 30, 2018
06/18

by
A. Kievsky; M. Gattobigio; N. K. Timofeyuk

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It is well-known that three-boson systems show the Efimov effect when the two-body scattering length $a$ is large with respect to the range of the two-body interaction. This effect is a manifestation of a discrete scaling invariance (DSI). In this work we study DSI in the $N$-body system by analysing the spectrum of $N$ identical bosons obtained with a pairwise gaussian interaction close to the unitary limit. We consider different universal ratios such as $E_N^0/E_3^0$ and $E_N^1/E_N^0$, with...

Topics: Quantum Gases, Nuclear Theory, Condensed Matter

Source: http://arxiv.org/abs/1404.7337

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27

Sep 22, 2013
09/13

by
A. Kievsky; C. R. Brune; M. Viviani

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The total cross section for p-d breakup is studied in terms of the elastic S-matrix through the unitary condition. Calculations using the complex Kohn variational method along with the Pair Correlated Hyperspherical Harmonic basis are presented. The results have been restricted to energies below Ep=30 MeV where Coulomb effects are expected to be sizable and are compared to the existing data. Two different measurements have been found in the literature: 40 years ago, Gibbons and Macklin (1959);...

Source: http://arxiv.org/abs/nucl-th/0003054v1

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45

Sep 18, 2013
09/13

by
A. Kievsky; E. Pace; G. Salme`; M. Viviani

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The investigation of the electromagnetic inclusive responses of polarized $^{3}$He within the plane wave impulse approximation is briefly reported. A particular emphasys is put on the extraction, from the inclusive responses at the quasielastic peak, of the neutron form factors from feasible experiments.

Source: http://arxiv.org/abs/nucl-th/9710074v1

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44

Sep 22, 2013
09/13

by
M. Gattobigio; A. Kievsky; M. Viviani; P. Barletta

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The hyperspherical harmonic basis is used to describe bound states in an $A$--body system. The approach presented here is based on the representation of the potential energy in terms of hyperspherical harmonic functions. Using this representation, the matrix elements between the basis elements are simple, and the potential energy is presented in a compact form, well suited for numerical implementation. The basis is neither symmetrized nor antisymmetrized, as required in the case of identical...

Source: http://arxiv.org/abs/0811.4259v2

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48

Sep 22, 2013
09/13

by
A. Kievsky; E. Pace; G. Salme`; M. Viviani

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The electromagnetic inclusive responses of polarized $^{3}$He and $^{3}$H are thoroughly investigated at the quasielastic peak for squared momentum transfers up to $2 (GeV/c)^2$, within the plane wave impulse approximation. Great emphasys is put on the effects in the bound-state due to different two- and three-body nuclear forces, and to the Coulomb interaction as well. A careful analysis of the polarized responses allows to select possible experiments for minimizing the model dependence in the...

Source: http://arxiv.org/abs/nucl-th/9704050v1

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2.0

Jun 29, 2018
06/18

by
A. Kievsky; M. Viviani; M. Gattobigio; L. Girlanda

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In chiral effective field theory the leading order (LO) nucleon-nucleon potential includes two contact terms, in the two spin channels $S=0,1$, and the one-pion-exchange potential. When the pion degrees of freedom are integrated out, as in the pionless effective field theory, the LO potential includes two contact terms only. In the three-nucleon system, the pionless theory includes a three-nucleon contact term interaction at LO whereas the chiral effective theory does not. Accordingly arbitrary...

Topics: Condensed Matter, Quantum Gases, Nuclear Theory

Source: http://arxiv.org/abs/1610.09858

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30

Sep 23, 2013
09/13

by
E. Pace; G. Salme`; S. Scopetta; A. Kievsky

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The possibility of a reliable extraction of the neutron deep inelastic structure function, $F_2^n(x)$, for $ x < 0.85$ from joint measurements of deep inelastic structure functions of deuteron, $^{3}He$ and $^{3}H$ is investigated. The model dependence in this extraction, linked to the possible different interactions between nucleons in nuclei, is shown to be weak, if the nuclear structure effects are properly taken into account. A combined analysis of the deep inelastic structure functions...

Source: http://arxiv.org/abs/nucl-th/0109005v1

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63

Sep 17, 2013
09/13

by
F. Baroncini; A. Kievsky; E. Pace; G. Salme`

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This contribution briefly illustrates preliminary calculations of the electromagnetic form factors of $^3$He and $^3$H, obtained within the Light-front Relativistic Hamiltonian Dynamics, adopting i) a Poincar\'e covariant current operator, without dynamical two-body currents, and ii) realistic nuclear bound states with $S$, $P$ and $D$ waves. The kinematical region of few $(GeV/c)^2$, relevant for forthcoming TJLAB experiments, has been investigated, obtaining possible signatures of...

Source: http://arxiv.org/abs/0807.4809v1

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43

Sep 20, 2013
09/13

by
A. Kievsky; M. Viviani; L. Girlanda; L. E. Marcucci

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Using modern nucleon-nucleon interactions in the description of the $A=3,4$ nuclei, it is not possible to reproduce both the three- and four-nucleon binding energies simultaneously. This is one manifestation of the necessity of including a three-nucleon force in the nuclear Hamiltonian. In this paper we will perform a comparative study of some, widely used, three-nucleon force models. We will analyze their capability to describe the aforementioned binding energies as well as the $n-d$ doublet...

Source: http://arxiv.org/abs/1002.1601v1

3
3.0

Jun 28, 2018
06/18

by
L. E. Marcucci; G. Mangano; A. Kievsky; M. Viviani

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The astrophysical $S$-factor for the radiative capture $d(p,\gamma)^3$He in the energy-range of interest for Big Bang Nucleosynthesis (BBN) is calculated using an {\it ab-initio} approach. The nuclear Hamiltonian retains both two- and three-nucleon interactions - the Argonne $v_{18}$ and the Urbana IX, respectively. Both one- and many-body contributions to the nuclear current operator are included. The former retain for the first time, besides the $1/m$ leading order contribution ($m$ is the...

Topics: Cosmology and Nongalactic Astrophysics, Astrophysics, Nuclear Theory

Source: http://arxiv.org/abs/1510.07877

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40

Sep 22, 2013
09/13

by
A. Kievsky; M. Viviani; L. E. Marcucci; S. Rosati

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N-d elastic scattering is studied at different energies using one of the modern NN interactions, the Argonne v_{18} which explicitly includes the magnetic moment interaction between two nucleons. This interaction, which has been often neglected in the description of the few-nucleon continuum, produces sizable modifications in some elastic observables. Its effects, as well as those produced by the Coulomb potential, are analyzed as a function of energy. The magnetic moment interaction produces...

Source: http://arxiv.org/abs/nucl-th/0309029v1

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4.0

Jun 29, 2018
06/18

by
R. Álvarez-Rodríguez; A. Deltuva. M. Gattobigio; A. Kievsky

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Two-, three-, and four-boson systems are studied close to the unitary limit using potential models constructed to reproduce the minimal information given by the two-body scattering length $a$ and the two-body binding energy or virtual state energy $E_2$. The particular path used to reach the unitary limit is given by varying the potential strength. In this way the energy spectrum in the three- and four-boson systems is computed. The lowest energy states show finite-range effects absorbed in the...

Topics: Condensed Matter, Quantum Gases, Nuclear Theory

Source: http://arxiv.org/abs/1603.05878

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32

Sep 22, 2013
09/13

by
M. Viviani; L. Girlanda; A. Kievsky; L. E. Marcucci

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The effect of the inclusion of different models of three nucleon (3N) forces in p-3He elastic scattering at low energies is studied. Two models have been considered: one derived from effective field theory at next-to-next-to-leading order and one derived from a more phenomenological point of view -- the so-called Illinois model. The four nucleon scattering observables are calculated using the Kohn variational principle and the hyperspherical harmonic technique and the results are compared with...

Source: http://arxiv.org/abs/1210.5890v1

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33

Sep 19, 2013
09/13

by
A. Kievsky; L. E. Marcucci; S. Rosati; M. Viviani

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Few days ago V.D. Efros submitted a preprint to nucl-th containing criticisms of our recent research activity on bound and scattering states of A=3, 4 nucleons. As a consequence, we are forced to examine the essence of the controversy and of the comments contained in that preprint. These are the motivations of the present paper.

Source: http://arxiv.org/abs/nucl-th/9804073v1

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Sep 22, 2013
09/13

by
M. Viviani; A. Kievsky; L. Girlanda; L. E. Marcucci

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The Kohn variational principle and the hyperspherical harmonics technique are applied to study n-3H elastic scattering at low energies. In this contribution the first results obtained using a non-local realistic interaction derived from the chiral perturbation theory are reported. They are found to be in good agreement with those obtained solving the Faddeev-Yakubovsky equations. The calculated total and differential cross sections are compared with the available experimental data. The effect...

Source: http://arxiv.org/abs/0812.3547v1

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66

Sep 22, 2013
09/13

by
A. Kievsky; E. Garrido; C. Romero-Redondo; P. Barletta

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The helium trimer is studied using two- and three-body soft-core potentials. Realistic helium-helium potentials present an extremely strong short-range repulsion and support a single, very shallow, bound state. The description of systems with more than two helium atoms is difficult due to the very large cancellation between kinetic and potential energy. We analyze the possibility of describing the three helium system in the ultracold regime using a gaussian representation of a widely used...

Source: http://arxiv.org/abs/1101.1719v1

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28

Sep 18, 2013
09/13

by
E. Garrido; C. Romero-Redondo; A. Kievsky; M. Viviani

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The integral relations formalism introduced in \cite{bar09,rom11}, and designed to describe 1+$N$ reactions, is extended here to collision energies above the threshold for the target breakup. These two relations are completely general, and in this work they are used together with the adiabatic expansion method for the description of 1+2 reactions. The neutron-deuteron breakup, for which benchmark calculations are available, is taken as a test of the method. The s-wave collision between the...

Source: http://arxiv.org/abs/1211.1802v1

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Sep 22, 2013
09/13

by
P. Barletta; A. Fabrocini; A. Kievsky; J. Navarro; A. Polls

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The He2-SF6 trimers, in their different He isotopic combinations, are studied both in the framework of the correlated Jastrow approach and of the Correlated Hyperspherical Harmonics expansion method. The energetics and structure of the He-SF6 dimers are analyzed, and the existence of a characteristic rotational band in the excitation spectrum is discussed, as well as the isotopic differences. The binding energies and the spatial properties of the trimers, in their ground and lowest lying...

Source: http://arxiv.org/abs/physics/0309103v1

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40

Sep 22, 2013
09/13

by
L. E. Marcucci; R. Schiavilla; M. Viviani; A. Kievsky; S. Rosati

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The astrophysical factor for the proton weak capture on 3He is calculated with correlated-hyperspherical-harmonics bound and continuum wave functions corresponding to a realistic Hamiltonian consisting of the Argonne v18 two-nucleon and Urbana-IX three-nucleon interactions. The nuclear weak charge and current operators have vector and axial-vector components, that include one- and many-body terms. All possible multipole transitions connecting any of the p-3He S- and P-wave channels to the 4He...

Source: http://arxiv.org/abs/nucl-th/0003065v1

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39

Sep 22, 2013
09/13

by
M. Viviani; L. Girlanda; A. Kievsky; L. E. Marcucci; S. Rosati

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The Kohn variational principle and the hyperspherical harmonic technique are applied to study p-3He elastic scattering at low energies. Preliminary results obtained using several interaction models are reported. The calculations are compared to a recent phase shift analysis performed at the Triangle University Nuclear Laboratory and to the available experimental data. Using a three-nucleon interaction derived from chiral perturbation theory at N2LO, we have found a noticeable reduction of the...

Source: http://arxiv.org/abs/1004.1306v1

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30

Sep 21, 2013
09/13

by
L. E. Marcucci; A. Kievsky; L. Girlanda; S. Rosati; M. Viviani

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The application of the hyperspherical harmonic approach to the case of the N-d scattering problem below deuteron breakup threshold is described. The nuclear Hamiltonian includes two- and three-nucleon interactions, in particular the Argonne v_{18}, the N3LO-Idaho, and the V_{low k} two-nucleon, and the Urbana IX and N2LO three-nucleon interactions. Some of these models are local, some are non-local. Also electromagnetic effects are included. Accurate calculations for many scattering observables...

Source: http://arxiv.org/abs/0905.3306v1

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34

Sep 18, 2013
09/13

by
L. E. Marcucci; M. Viviani; A. Kievsky; S. Rosati; R. Schiavilla

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Recent advances in the study of the p-d radiative and mu-3he weak capture processes are presented and discussed. The three-nucleon bound and scattering states are obtained using the correlated-hyperspherical-harmonics method, with realistic Hamiltonians consisting of the Argonne v14 or Argonne v18 two-nucleon and Tucson-Melbourne or Urbana IX three-nucleon interactions. The electromagnetic and weak transition operators include one- and two-body contributions. The theoretical accuracy achieved...

Source: http://arxiv.org/abs/nucl-th/0212009v1

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31

Sep 23, 2013
09/13

by
L. E. Marcucci; M. Viviani; R. Schiavilla; A. Kievsky; S. Rosati

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Recent advances in the study of pd radiative capture in a wide range of center-of-mass energy below and above deuteron breakup threshold are presented and discussed.

Source: http://arxiv.org/abs/nucl-th/0411083v1

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Sep 24, 2013
09/13

by
R. Schiavilla; O. Benhar; A. Kievsky; L. E. Marcucci; M. Viviani

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Polarization observables in the $^4$He$(\vec{e},e^\prime\vec{p})$$^3$H reaction are calculated using accurate three- and four-nucleon bound-state wave functions, a realistic model for the nuclear electromagnetic current operator, and a treatment of final-state-interactions with an optical potential. In contrast to earlier studies, no significant discrepancies are found between theory and experiment both for the ratio of transverse to longitudinal polarization transfers and for the induced...

Source: http://arxiv.org/abs/nucl-th/0412020v1