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[show abstract]
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ABSTRACT: We compare results from the traditional partial wave treatment of deuteron
electro-disintegration with a new approach that uses three dimensional
formalism. The new framework for the two-nucleon (2N) system using a complete
set of isospin - spin states made it possible to construct simple
implementations that employ a very general operator form of the current
operator and 2N states.
06/2012;
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[show abstract]
[hide abstract]
ABSTRACT: 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.
06/2012;
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[show abstract]
[hide abstract]
ABSTRACT: Recently a formalism for a direct treatment of the Faddeev equation for the
three-nucleon bound state in three dimensions has been proposed. It relies on
an operator representation of the Faddeev component in the momentum space and
leads to a finite set of coupled equations for scalar functions which depend
only on three variables. In this paper we provide further elements of this
formalism and show the first numerical results for chiral NNLO nuclear forces.
06/2012;
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[hide abstract]
ABSTRACT: We solved the Faddeev equation in a Poincaré invariant model of the three-nucleon system. Two-body interactions are generated
so that when they are added to the two-nucleon invariant mass operator (rest energy) the two-nucleon S matrix is identical to the experimental S matrix modeled with a given nucleon–nucleon interaction. Cluster properties of the three-nucleon S-matrix determine how these
two-nucleon interactions are embedded in the three-nucleon mass operator. Differences in the predictions of the relativistic
and corresponding non-relativistic models for elastic and breakup processes are investigated. Of special interest are effects
of relativity on the elastic scattering angular distribution and total cross sections, the lowering of the A
y
maximum in elastic nucleon-deuteron (Nd) scattering below ≈25MeV caused by the Wigner spin rotations and the significant
changes of the breakup cross sections in certain regions of the phase-space.
Few-Body Systems 05/2012; 49(1):61-64. · 1.44 Impact Factor
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[hide abstract]
ABSTRACT: The Wolfenstein parameters are for the first time obtained analytically in terms of observables. It is shown that a set of
ten nucleon–nucleon (NN) observables, which contains polarization observables together with the differential cross section,
determines uniquely the solution for Wolfenstein parameters except for a common insignificant phase. Using such analytical
solutions one expects to get more accurate theoretical parameters for the potential models by χ
2 fitting to the resulting Wolfenstein parameter data than the standard manner of a phase-shift analysis. An example of fixing
a unique set of physical solutions for the Wolfenstein parameters from a set of 16 solutions based on nine observables alone
and adding one more observable is illustrated using pseudo data generated by the CD Bonn potential.
Few-Body Systems 05/2012; 50(1):231-234. · 1.44 Impact Factor
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S. Kuroita,
K. Sagara,
Y. Eguchi,
K. Yashima,
T. Shishido,
T. Yabe,
M. Dozono,
Y. Yamada,
T. Wakasa,
T. Noro,
H. Matsubara,
J. Zenihiro,
A. Tamii,
H. Okamura,
K. Hatanaka,
T. Saito,
Y. Maeda, H. Kamada,
Y. Tameshige
[show abstract]
[hide abstract]
ABSTRACT: In our previous inclusive experiment on 2H(p, p)pn at 247MeV, the measured cross section at forward angles is about twice larger than 3N calculation with ππ 3NF. Therefore, we have made an exclusive experiment on 2H(p, p
1
p
2)n at the same energy. The preliminary data suggest that the cross section was enhanced at forward angle of θ
1 and θ
2.
Few-Body Systems 04/2012; 50(1):287-289. · 1.44 Impact Factor
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E. Stephan,
St. Kistryn,
N. Kalantar-Nayestanaki,
A. Biegun,
K. Bodek,
I. Ciepał,
A. Deltuva,
M. Eslami-Kalantari,
A. C. Fonseca,
I. Gasparić, [......],
H. Mardanpour,
J. Messchendorp,
A. Micherdzińska,
H. Moeini,
A. Nogga,
A. Ramazani-Moghaddam-Arani,
R. Skibiński,
R. Sworst,
H. Witała,
J. Zejma
[show abstract]
[hide abstract]
ABSTRACT: High precision data for vector and tensor analyzing powers of the 1H([(d)\vec],pp)n{^1{\rm {H}}(\vec{\rm{d}},\rm{{pp}})\rm{n}} breakup reaction at 130 and 100MeV deuteron beam energies have been measured in a large fraction of the phase space. They
are compared to the theoretical predictions based on various approaches to describe the three nucleon (3N) system dynamics.
Theoretical predictions describe very well the vector analyzing power data, with no need to include any three-nucleon force
effects for these observables. Tensor analyzing powers can be also very well reproduced by calculations in most of the studied
region, but locally certain discrepancies are observed. At 130MeV for A
xy
such discrepancies usually appear, or are enhanced, when model 3N forces are included. Predicted effects of 3NFs are much
lower at 100MeV and at this energy equally good consistency between the data and the calculations is obtained with or without
3NFs.
Few-Body Systems 04/2012; 50(1):283-285. · 1.44 Impact Factor
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E. Stephan,
St. Kistryn,
A. Biegun,
K. Bodek,
I. Ciepał,
A. Deltuva,
E. Epelbaum,
A. C. Fonseca,
J. Golak,
N. Kalantar-Nayestanaki, [......],
B. Kłos,
A. Kozela,
M. Mahjour-Shafiei,
A. Micherdzińska,
A. Nogga,
R. Skibiński,
R. Sworst,
H. Witała,
J. Zejma,
W. Zipper
[show abstract]
[hide abstract]
ABSTRACT: High-precision tensor analyzing power T20 data of the 1H (d,pp)n reaction at 130MeV beam energy have been determined for 81 kinematical configurations. They are compared to theoretical
predictions based on various approaches to describe the dynamics of the three-nucleon (3N) system. The calculations are performed
using modern realistic nucleon-nucleon potentials combined with three-nucleon force (3NF) models or with an effective 3NF
resulting from the explicit treatment of the D \Delta -isobar in coupled-channels (CC) calculations. Alternatively, the framework of chiral perturbation theory is used to generate
consistent two-nucleon and three-nucleon potentials at the currently numerically attainable order. Results of the CC calculations
with the D \Delta degrees of freedom and including long-range Coulomb force are also shown. In general all predictions are consistent with
each other and describe the experimental T20 results quite well. In a few configurations small inconsistencies between the data and the results of all approaches are
observed. Predicted effects of the 3NF are not big and in most cases do not lead to an improved description of the data. The
Coulomb force effects are also small in size and often opposite to the effects of TM99 3NF.
European Physical Journal A 04/2012; 42(1):13-24. · 2.19 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: A recently developed procedure for a partial-wave decomposition of a three-nucleon force is applied to the p \pi -p \pi , p \pi -r \rho and r \rho -r \rho components of the Tucson-Melbourne three-nucleon potential. The resulting matrix elements for the p \pi -p \pi and p \pi -r \rho components are compared with the values obtained using the standard approach to the partial-wave decomposition, in which
the p \pi -r \rho expressions for the matrix elements are also derived and presented. Several numerical tests and results for the triton binding
energy and the correlation function prove the reliability and efficiency of the new method.
European Physical Journal A 04/2012; 47(4):1-16. · 2.19 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We review the construction and applications of exactly Poincaré invariant quantum mechanical models of few-degree of freedom
systems. We discuss the construction of dynamical representations of the Poincaré group on few-particle Hilbert spaces, the
relation to quantum field theory, the formulation of cluster properties, and practical considerations related to the construction
of realistic interactions and the solution of the dynamical equations. Selected applications illustrate the utility of this
approach.
Few-Body Systems 04/2012; 49(1):129-147. · 1.44 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: The direct treatment of the Faddeev equation for the three-boson system in 3 dimensions is generalized to nucleons. The one
Faddeev equation for identical bosons is replaced by a strictly finite set of coupled equations for scalar functions which
depend only on 3 variables. The spin-momentum dependence occurring as scalar products in 2N and 3N forces accompanied by scalar
functions is supplemented by a corresponding expansion of the Faddeev amplitudes. After removing the spin degrees of freedom
by suitable operations only scalar expressions depending on momenta remain. The corresponding steps are performed for the
deuteron leading to two coupled equations.
Few-Body Systems 04/2012; 47(1):25-38. · 1.44 Impact Factor
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I. Ciepał,
St. Kistryn,
E. Stephan,
A. Biegun,
K. Bodek,
A. Deltuva,
E. Epelbaum,
M. Eslami-Kalantari,
A. Fonseca,
J. Golak, [......],
H. Sakai,
K. Sekiguchi,
I. Sitnik,
R. Siudak,
R. Skibiński,
R. Sworst,
J. Urban,
H. Witała,
A. Wrońska,
J. Zejma
[show abstract]
[hide abstract]
ABSTRACT: Set of vector analyzing power data of the d⃗p elastic scattering and 1H(d⃗, pp)n breakup reactions at 130-MeV deuteron beam energy has been measured in the domain of very forward polar angles. The results are compared with theoretical predictions originating from various approaches: realistic nucleon-nucleon (NN) potentials and the NN potentials combined with a three-nucleon force (3NF) model and with predictions based on the ChPT framework. In case of the breakup process, none of the theoretical calculations reveal sensitivity to any of the dynamical effects such as 3NF or Coulomb interaction and they describe the experimental data equally well. For the elastic scattering, the Coulomb correction appears not negligible at very small θdc.m.. The effect seems to be confirmed by the data.
Phys. Rev. C. 01/2012; 85(1).
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[show abstract]
[hide abstract]
ABSTRACT: Long-range contributions to the three-nucleon force that have been recently
worked out in chiral effective field theory at next-to-next-to-next-to-leading
order are for the first time included in the triton and the doublet
nucleon-deuteron scattering length calculations. The strengths of the two
short-range terms available at this order in the chiral expansion are
determined from the triton binding energy and the neutron-deuteron doublet
scattering length. The structure of the resulting three-nucleon force is
explored and effects for the two-nucleon correlation function in the triton are
investigated. Expectation values of the individual contributions to the
three-nucleon force in the triton are found to be in the range from a few 100
keV to about 1 MeV. Our study demonstrates that the very complicated operator
structure of the novel chiral three-nucleon forces can be successively
implemented in three-nucleon Faddeev calculations.
07/2011;
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[show abstract]
[hide abstract]
ABSTRACT: If one assumes a translationally invariant motion of the nucleons relative to
the c. m. position in single particle mean fields a correlated single particle
picture of the nuclear wave function emerges. A single particle product ansatz
leads for that Hamiltonian to nonlinear equations for the single particle wave
functions. In contrast to a standard not translationally invariant shell model
picture those single particle s-, p- etc states are coupled. The strength of
the resulting coupling is an open question. The Schroedinger equation for that
Hamiltonian can be solved by few- and many -body techniques, which will allow
to check the validity or non-validity of a single particle product ansatz.
Realistic nuclear wave functions exhibit repulsive 2-body short range
correlations. Therefore a translationally invariant single particle picture --
if useful at all -- can only be expected beyond those ranges. Since exact A = 3
and 4 nucleon ground state wave functions and beyond based on modern nuclear
forces are available, the translationally invariant shell model picture can be
optimized by an adjustment to the exact wave function and its validity or
non-validity decided.
06/2011;
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K Sekiguchi,
H Okamura,
N Sakamoto,
H Suzuki,
M. Dozono,
Y Maeda,
T Saito,
S Sakaguchi,
H Sakai,
M Sasano,
Y Shimizu,
T. Wakasa,
K. Yako,
H Witała,
W. Glöckle,
J. Golak, H Kamada,
A. Nogga
[show abstract]
[hide abstract]
ABSTRACT: A complete high precision set of deuteron analyzing powers for elastic
deuteron-proton ($dp$) scattering at 250 MeV/nucleon (MeV/N) has been measured.
The new data are presented together with data from previous measurements at 70,
100, 135 and 200 MeV/N. They are compared with the results of three-nucleon
(3N) Faddeev calculations based on modern nucleon-nucleon (NN) potentials alone
or combined with two models of three nucleon forces (3NFs): the
Tucson-Melbourne 99 (TM99) and Urbana IX. At 250 MeV/N large discrepancies
between pure NN models and data, which are not resolved by including 3NFs, were
found at c.m.\ backward angles of $\theta_{\rm c.m.}\gtrsim 120^\circ$ for
almost all the deuteron analyzing powers. These discrepancies are quite similar
to those found for the cross section at the same energy. We found small
relativistic effects that cannot resolve the discrepancies with the data
indicating that other, short-ranged 3NFs are required to obtain a proper
description of the data.
06/2011;
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[show abstract]
[hide abstract]
ABSTRACT: We extend our formulation of relativistic three-nucleon Faddeev equations to
include both pairwise interactions and a three-nucleon force. Exact Poincare
invariance is realized by adding interactions to the mass Casimir operator
(rest Hamiltonian) of the non-interacting system without changing the spin
Casimir operator. This is achieved by using interactions defined by
rotationally invariant kernels that are functions of internal momentum
variables and single-particle spins that undergo identical Wigner rotations. To
solve the resulting equations one needs matrix elements of the three-nucleon
force with these properties in a momentum-space partial-wave basis. We present
two methods to calculate matrix elements of three-nucleon forces with these
properties. For a number of examples we show that at higher energies, where
effects of relativity and of three-nucleon forces are non-negligible, a
consistent treatment of both is required to properly analyze the data.
01/2011;
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[show abstract]
[hide abstract]
ABSTRACT: We review the construction and applications of exactly Poincar\'e invariant
quantum mechanical models of few-degree of freedom systems. We discuss the
construction of dynamical representations of the Poincar\'e group on
few-particle Hilbert spaces, the relation to quantum field theory, the
formulation of cluster properties, and practical considerations related to the
construction of realistic interactions and the solution of the dynamical
equations. Selected applications illustrate the utility of this approach.
08/2010;
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[show abstract]
[hide abstract]
ABSTRACT: We study the four-nucleon force contribution to the binding energy of 4He in the framework of chiral nuclear interactions. The four-nucleon forces start to contribute in the next-to-next-to-next-to leading order. We discuss our power counting expectations for the size of the 4N contribution and then explicitly calculate it in first order perturbation theory. Our expectations agree with the results. Quantitatively, the contribution might be significant. This motivates further studies in more complex nuclei.
EPJ Web of Conferences. 01/2010;
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S. Kuroita,
K Sagara,
Y Eguchi,
K. Yashima,
T Yabe,
T Shishido,
M. Dozono,
Y Yamada,
T. Wakasa,
T Noro,
H Matsubara,
J. Zenihiro,
A. Tamii,
H Okamura,
K Hatanaka,
T Saito,
Y Maeda, H Kamada,
Y. Tameshige
[show abstract]
[hide abstract]
ABSTRACT: In our previous inclusive experiment on pd breakup at Ep = 247 MeV, we found experimental cross section is about twice larger than 3N calculation with ππ3NF at forward angle. Therefore we made exclusive measurement of 2H(p, p1 p2)n cross section at the same 247 MeV. Preliminary data indicate that the cross section enhancement appears at forward angles of θ1 and θ2. We made also inclusive experiment again and confirmed the previous data.
EPJ Web of Conferences. 01/2010;
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[show abstract]
[hide abstract]
ABSTRACT: We study the binding energy of the three-nucleon system in relativistic models that use two different relativistic treatments of the potential that are phase equivalent to realistic NN interactions. One is based on a unitary scale transformation that relates the non-relativistic center-of-mass Hamiltonian to the relativistic mass (rest energy) operator and the other uses a non-linear equation that relates the interaction in the relativistic mass operator to the non-relativistic interaction. In both cases Lorentz-boosted interactions are used in the relativistic Faddeev equation to solve for the three-nucleon binding energy. Using the same realistic NN potentials as input, the solution of the relativistic three-nucleon Faddeev equation for 3H shows slightly less binding energy than the corresponding nonrelativistic result. The effect of the Wigner spin rotation on the binding is very small.
EPJ Web of Conferences. 01/2010;
