Few-Body Systems (FEW-BODY SYST )

Publisher: Springer Verlag


The journal is devoted to the publication of original research work both experimental and theoretical in the field of few-body systems. Conceptually such systems are understood as consisting of a small number of well-defined constituent structures. Investigations of the behaviour of these systems form the central subject matter of the journal. Systems for which an equivalent one-body description is available or can be designed and large systems for which specific many-body methods are needed are outside the scope of the journal. The focus of interest lies in the research methods properties and results characteristic of few-body systems. Particular examples of few-body systems are light nuclei light atoms small molecules but also celestial systems "elementary" particles (considered as systems of few constituents) or larger systems with a few-particle substructure. The principal aim of the journal is to bring together competent work from various fields of physics such as particle nuclear atomic molecular and condensed-matter physics and also from astrophysics astronomy mathematics and chemistry thereby fostering research done on related problems in different areas of natural sciences. While concentrating on few-body systems which can also be characterized as generally amenable to rigorous solutions the journal stresses interdisciplinarity through the exchange of ideas methods results experience and knowledge gathered in neighbouring fields. Beyond the publication of articles the journal as a forum for the community of scientists engaged in the study of few-body problems also provides for the rapid dissemination of actual scientific and practical information in separate News Sections; these include abstracts of recent preprints a calendar of conferences and meetings book reviews announcements etc. Though the emphasis is on regular research articles the journal publishes also papers in the form of letters rapid communications comments and from time to time reviews or progress reports.

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  • Website
    Few-Body Systems website
  • Other titles
    Few-body systems (Online), Acta physica Austriaca new series
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    Document, Periodical, Internet resource
  • Document type
    Internet Resource, Computer File, Journal / Magazine / Newspaper

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Springer Verlag

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    • Author's pre-print on pre-print servers such as arXiv.org
    • Author's post-print on author's personal website immediately
    • Author's post-print on any open access repository after 12 months after publication
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    • Published source must be acknowledged
    • Must link to publisher version
    • Set phrase to accompany link to published version (see policy)
    • Articles in some journals can be made Open Access on payment of additional charge
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Publications in this journal

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    ABSTRACT: We sketch an all order proof of cancellation of infrared (IR) divergences in light front quantum electrodynamics using a coherent state formalism. In this talk, it has been shown that the true IR divergences in fermion self energy are eliminated to all orders in a light-front time-ordered perturbative calculation if one uses coherent state basis instead of the usual Fock basis to calculate the Hamiltonian matrix elements.
    Few-Body Systems 12/2014;
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    ABSTRACT: In this paper, we study the Dirac equation with spin and pseudospin symmetry by the quadratic algebra approach for the 4-dimensional harmonic oscillator. By realization of the quadratic algebras in the deformed oscillator algebra, we obtain the relativistic energy spectrum. Also, by regarding the generalized Kustaanheimo–Stiefel transformation, we obtain the relativistic energy spectrum for the charge-dyon system with the U(1) monopole.
    Few-Body Systems 12/2014;
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    ABSTRACT: The analysis of semi-inclusive deep inelastic electron scattering off polarized $^3$He at finite momentum transfers, aimed at the extraction of the quark transverse-momentum distributions in the neutron, requires the use of a distorted spin-dependent spectral function for $^3$He, which takes care of the final state interaction effects. This quantity is introduced in the non-relativistic case, and its generalization in a Poincar\'e covariant framework, in plane wave impulse approximation for the moment being, is outlined. Studying the light-front spin-dependent spectral function for a J=1/2 system, such as the nucleon, it is found that, within the light-front dynamics with a fixed number of constituents and in the valence approximation, only three of the six leading twist T-even transverse-momentum distributions are independent.
    Few-Body Systems 11/2014;
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    ABSTRACT: Double parton distribution functions (dPDF), accessible in high energy proton-proton and proton nucleus collisions, encode information on how partons inside a proton are correlated among each other and could represent a tool to explore the 3D proton structure. In recent papers, double parton correlations have been studied in the valence quark region, by means of constituent quark models. This framework allows to understand clearly the dynamical origin of the correlations and to establish which, among the features of the results, are model independent. Recent relevant results, obtained in a relativistic light-front scheme, able to overcome some drawbacks of previous calculations, such as the poor support, will be presented. Peculiar transverse momentum correlations, generated by the correct treatment of the boosts, are obtained. The role of spin correlations will be also shown. In this covariant approach, the symmetries of the dPDFs are unambiguously reproduced. The study of the QCD evolution of the model results has been performed in the valence sector, showing that, in some cases, the effect of evolution does not cancel that of correlations.
    Few-Body Systems 11/2014;
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    ABSTRACT: Isoscalar monopole excitation to cluster states in light nuclei is in general strong as to be comparable with the single particle strength and shares about 20 % of the sum rule value. The isoscalar monopole strength function in 16O is discussed up to ${E_x \lesssim 40 \, {\rm MeV}.}$ We found that (1) two different types of monopole excitations exist in 16O; one is the monopole excitation to cluster states which is dominant in the lower energy part, and the other is the monopole excitation of the mean-field type such as one-particle one-hole (1p1h) which is attributed mainly to the higher energy part, and (2) this character of the monopole excitations originates from the fact that the ground state of 16O with the dominant doubly closed shell structure has a duality of the mean-field-type as well as alpha-clustering character.
    Few-Body Systems 08/2014; 54(7-10).
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    ABSTRACT: We show that three-quark axial currents as required by broken SU(6) spin-flavor symmetry reduce the quark spin contribution to proton spin from $\Sigma_p = 1$ (one-quark axial current value) to $\Sigma_p = 0.41(12)$ consistent with the empirical value $\Sigma_{p, exp} = 0.33(08)$. In the case of the $\Delta^+(1232)$ baryon, we find that three-quark axial currents increase the one-quark axial current value $\Sigma_{\Delta^+} = 3$ to $\Sigma_{\Delta^+} = 3.87(22)$. We also calculate the quark orbital angular momenta $L_u$ and $L_d$ in the proton and $\Delta^+$ and interpret our results in terms of the prolate and oblate geometric shapes of these baryons consistent with their intrinsic quadrupole moments.
    Few-Body Systems 08/2014; 55(8-10).
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    ABSTRACT: At the Mainz Microtron MAMI exploratory experiments on the spectroscopy of mesonic weak decays (MWD) of electroproduced Λ-hypernuclei were performed. A unique setup was realized to use the broad momentum-band kaon spectrometer Kaos at zero degree angle with respect to the high-intensity electron beam direction to tag strangeness producing processes. A sample of order 10^3 MWD from a beryllium target was collected by the coincidence technique with the high-resolution multi-spectrometer facility of the A1 Collaboration. It is conjectured that this sample contains monochromatic two-body decays from stopped hyperfragment decays as well as a wide momentum distribution of quasi-free produced Λ- and Σ-hyperon decays and three-body decays from hyperfragments. Stopped hyperfragments will be identified as monochromatic peaks in the π − momentum spectrum from which their masses can be extracted with a precision of 50 keV/c^2.
    Few-Body Systems 08/2014; 55(8-10):887-892.
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    ABSTRACT: We describe results for the pion distribution amplitude (PDA) at the non-perturbative scale $\mu=~$2GeV by projecting the Poincar\'e-covariant Bethe-Salpeter wave-function onto the light-front and use it to investigate the ultraviolet behavior of the electromagnetic form factor, $F_\pi(Q^2)$, on the entire domain of spacelike $Q^2$. The significant dilation of this PDA compared to the known asymptotic PDA is a signature of dynamical chiral symmetry breaking (DCSB) on the light front. We investigate the transition region of $Q^2$ where non-perturbative behavior of constituent-like quarks gives way to the partonic-like behavior of quantum chromodynamics (QCD). The non-perturbative approach is based on the Dyson-Schwinger equation (DSE) framework for continuum investigations in QCD. The leading-order, leading-twist perturbative QCD result for $Q^2 F_\pi(Q^2)$ underestimates the new DSE computation by just 15\% on $Q^2\gtrsim 8\,$GeV$^2$, in stark contrast with the result obtained using the asymptotic PDA.
    Few-Body Systems 07/2014; 55(5-7).
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    ABSTRACT: An introductory to generalized parton distributions is given which emphasizes their spectral property and its uses as well as the equivalence of various GPD representations. Furthermore, the status of the theory and phenomenology of hard exclusive processes is shortly reviewed.
    Few-Body Systems 05/2014; 55(5-7).
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    ABSTRACT: 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 $E_N^i$ being the energy of the ground ($i=0$) and first-excited ($i=1$) state of the system, for $N\le16$. We discuss the extension of the Efimov radial law, derived by Efimov for $N=3$, to general $N$.
    Few-Body Systems 04/2014; 55(8-10).
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    ABSTRACT: In this paper we study the chiral phase transition of QCD at ?nite temperature and density by using the rank-2 con?ning separable gluon propagator model in the framework of Dyson-Schwinger Equations. The critical end point is located at (T_CEP, {\mu}_CEP) = (69 MeV, 270.3 MeV). It is also found that the first order phase transition might not end at one point, but experiences a two-phase coexisting meta-stable state. A comparison with the results in the previous literature is given.
    Few-Body Systems 04/2014; 55(1).
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    ABSTRACT: We produce a Lorentz boosted two-body potential for particles of different mass that is phase equivalent to a given realistic non-relativistic two-body potential. The relativistic potential is related to the nonrelativistic potential using the Coester-Pieper-Serduke scheme, which ensures that the same scattering wave functions are obtained from the relativistic and non-relativistic potentials. This implies that the phase shifts are identical functions of the relative momentum. To construct the potential we use an iterative scheme that generalizes one that has been applied successfully to two-body systems with equal masses.
    Few-Body Systems 03/2014; 55(11).
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    ABSTRACT: In this work, we present an investigation on the spatial entanglement entropies in the helium atom by using highly correlated Hylleraas functions to represent the S-wave states. Singlet-spin 1sns 1Se states (with n = 1 to 6) and triplet-spin 1sns 3Se states (with n = 2 to 6) are investigated. As a measure on the spatial entanglement, von Neumann entropy and linear entropy are calculated. Furthermore, we apply the Schmidt-Slater decomposition method on the two-electron wave functions, and obtain eigenvalues of the one-particle reduced density matrix, from which the linear entropy and von Neumann entropy can be determined.
    Few-Body Systems 03/2014;
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    ABSTRACT: We present the approximate analytical solutions of Duffin-Kemmer-Petiau equation with a vector Hellmann potential for spin-zero particles. The energy eigenvalues and the corresponding eigenfunctions are obtained in closed form and some numerical results are included.
    Few-Body Systems 02/2014; 55(3).
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    ABSTRACT: In the past decade, there has been substantial progress in the derivation of nuclear forces from chiral effective field theory. Accurate two-nucleon forces have been constructed at next-to-next-to-next-to-leading order (N3LO) and applied (together with three-nucleon forces at NNLO) to nuclear few- and many-body systems—with a good deal of success. This may suggest that the 80-year old nuclear force problem has finally been cracked. Not so! Some pretty basic issues are still unresolved. In this talk, I focus on the two most pressing ones, namely, the proper renormalization of the two-nucleon potential and subleading many-body forces.
    Few-Body Systems 02/2014; 54(1-4).