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Sep 18, 2013
09/13
by
N. Barnea; E. Friedman
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The strength of the low energy K^- nucleus real potential has recently received renewed attention in view of experimental evidence for the possible existence of strongly bound K^- states. Previous fits to kaonic atom data led to either 'shallow' or to 'deep' potentials, where only the former are in agreement with chiral approaches but only the latter can produce strongly bound states. Here we explore the uncertainties of the K^- nucleus optical potentials, obtained from fits to kaonic atom...
Source: http://arxiv.org/abs/nucl-th/0611020v2
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62
Sep 20, 2013
09/13
by
E. Z. Liverts; N. Barnea
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This work is concerned with multi-dimensional integrals, which are making their appearance in few-body atomic and nuclear physics. It is shown that the relevant two- and three-dimensional integrals can be reduced to one-dimensional form. This implies that the internal one- and two-dimensional integrals can be evaluated in explicit analytic form in term of the familiar generalized hypergeometric functions. Some of the integrals are presented here for the first time.
Source: http://arxiv.org/abs/1002.3442v2
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49
Sep 19, 2013
09/13
by
J. Vijande; N. Barnea; A. Valcarce
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We present a generalization of the hyperspherical harmonic formalism to study systems made of quarks and antiquarks of the same flavor. This generalization is based on the symmetrization of the $N-$body wave function with respect to the symmetric group using the Barnea and Novoselsky algorithm. Our analysis shows that four-quark systems with non-exotic $2^{++}$ quantum numbers may be bound independently of the quark mass. $0^{+-}$ and $1^{+-}$ states become attractive only for larger quarks...
Source: http://arxiv.org/abs/hep-ph/0610124v1
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34
Sep 23, 2013
09/13
by
J. Vijande; A. Valcarce; N. Barnea
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We present an exact calculation of $S$ and $P$ wave $QQ\bar n\bar n$ states using different standard nonrelativistic quark--quark potentials. We explore in detail the charm and bottom sectors looking for bound states that could be measured within existing facilities. Against the proliferation of four--quark states sometimes predicted in the literature, we found a small number of candidates to be stable. We analyze their properties in a trial to distinguish between compact and molecular states....
Source: http://arxiv.org/abs/0903.2949v1
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110
Sep 17, 2013
09/13
by
A. Valcarce; J. Vijande; N. Barnea
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The physics of charm has become one of the best laboratories exposing the limitations of the naive constituent quark model and also giving hints into a more mature description of hadron spectroscopy. Recent discoveries are a challenge that have revolutionized our understanding of the hadron spectra. In this talk we address the study of many-quark components in charmonium spectra. To make the physics clear we also discuss exotic many-quark systems.
Source: http://arxiv.org/abs/0711.3114v1
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31
Jul 20, 2013
07/13
by
N. Barnea; J. Vijande; A. Valcarce
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We present a generalization of the hyperspherical harmonic formalism to study systems made of quarks and antiquarks of the same flavor. This generalization is based on the symmetrization of the $N-$body wave function with respect to the symmetric group using the Barnea and Novoselsky algorithm. The formalism is applied to study four-quark systems by means of a constituent quark model successful in the description of the two- and three-quark systems. The results are compared to those obtained by...
Source: http://arxiv.org/abs/hep-ph/0604010v1
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Sep 19, 2013
09/13
by
J. Vijande; N. Barnea; A. Valcarce
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We present an exact method based on a hyperspherical harmonic expansion to study systems made of quarks and antiquarks of the same flavor. Our formalism reproduces and improves the results obtained with variational approaches. This analysis shows that identical-flavor four-quark systems with non-exotic $2^{++}$ quantum numbers may be bound independently of the quark mass. $0^{+-}$ and $1^{+-}$ states become attractive only for larger quarks masses.
Source: http://arxiv.org/abs/hep-ph/0610287v1
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9.0
Jun 27, 2018
06/18
by
N. Barnea; E. Friedman; A. Gal
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We report on precise hyperspherical-basis calculations of $\eta NN$ and $\eta NNN$ quasibound states, using energy dependent $\eta N$ interaction potentials derived from coupled-channel models of the $S_{11}$ $N^{\ast}(1535)$ nucleon resonance. The $\eta N$ attraction generated in these models is too weak to generate a two-body bound state. No $\eta NN$ bound-state solution was found in our calculations in models where Re $a_{\eta N}\lesssim 1$ fm, with $a_{\eta N}$ the $\eta N$ scattering...
Topics: High Energy Physics - Phenomenology, Nuclear Experiment, Nuclear Theory
Source: http://arxiv.org/abs/1505.02588
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39
Sep 21, 2013
09/13
by
G. Orlandini; N. Barnea; W. Leidemann
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A different formulation of the effective interaction hyperspherical harmonics (EIHH) method, suitable for non-local potentials, is presented. The EIHH method for local interactions is first shortly reviewed to point out the problems of an extension to non-local potentials. A viable solution is proposed and, as an application, results on the ground-state properties of 4- and 6-nucleon systems are presented. One finds a substantial acceleration in the convergence rate of the hyperspherical...
Source: http://arxiv.org/abs/1008.4492v1
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88
Jul 20, 2013
07/13
by
N. Barnea; A. Gal; E. Z. Liverts
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Binding energies and widths of three-body KbarNN, and of four-body KbarNNN and KbarKbarNN nuclear quasibound states are calculated in the hyperspherical basis, using realistic NN potentials and subthreshold energy dependent chiral KbarN interactions. Results of previous K^-pp calculations are reproduced and an upper bound is placed on the binding energy of a K^-d quasibound state. A self consistent handling of energy dependence is found to restrain binding, keeping the calculated four-body...
Source: http://arxiv.org/abs/1203.5234v3
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42
Sep 19, 2013
09/13
by
J. Vijande; E. Weissman; N. Barnea; A. Valcarce
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The four--quark system $c\bar c n\bar n$ is studied in the framework of the constituent quark model. Using different types of quark-quark potentials, we solve the four--body Schr\"odinger equation by means of the hyperspherical harmonic formalism. Exploring the low laying $J^{PC}$ states for different isospin configurations no four-quark bound states have been found. Of particular interest is the possible four-quark structure of the X(3872). We rule out the possibility that this particle...
Source: http://arxiv.org/abs/0708.3285v1
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53
Sep 21, 2013
09/13
by
S. Bacca; N. Barnea; W. Leidemann; G. Orlandini
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The longitudinal response function of 4He is calculated with the Argonne V18 potential. The comparison with experiment suggests the need of a three-body force. When adding the Urbana IX three-body potential in the calculation of the lower longitudinal multipoles, the total strength is suppressed in the quasi-elastic peak, towards the trend of the experimental data.
Source: http://arxiv.org/abs/0712.1493v1
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53
Sep 23, 2013
09/13
by
J. Vijande; E. Weissman; A. Valcarce; N. Barnea
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eye 53
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We present an exact method to study four-quark systems based on the hyperspherical harmonics formalism. We apply it to several physical systems of interest containing two heavy and two light quarks using different quark-quark potentials. Our conclusions mark the boundaries for the possible existence of compact, non-molecular, four-quark bound states. While $QQ\bar n \bar n$ states may be stable in nature, the stability of $Q\bar Qn \bar n$ states would imply the existence of quark correlations...
Source: http://arxiv.org/abs/0710.2516v1
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42
Sep 22, 2013
09/13
by
S. Bacca; N. Barnea; W. Leidemann; G. Orlandini
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We present an ab-initio study of the isoscalar monopole excitations of 4He using different realistic nuclear interactions, including modern effective field theory potentials. In particular we concentrate on the transition form factor $F_{\cal M}$ to the narrow $0^+$ resonance close to threshold. F_M exhibits a strong potential model dependence, and can serve as a kind of prism to distinguish among different nuclear force models. Comparing to the measurements obtained from inelastic electron...
Source: http://arxiv.org/abs/1210.7255v2
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12
Jun 28, 2018
06/18
by
G. Orlandini; S. Bacca; N. Barnea; W. Leidemann
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In this contribution we review and clarify the arguments which might allow the interpretation of the isoscalar monopole resonance of $^4$He as a collective breathing mode.
Topic: Nuclear Theory
Source: http://arxiv.org/abs/1510.02248
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131
Sep 17, 2013
09/13
by
J. Vijande; E. Weissman; A. Valcarce; N. Barnea
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eye 131
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To obtain an exact solution of a four-body system containing two quarks and two antiquarks interacting through two-body terms is a cumbersome task that has been tackled with more or less success during the last decades. We present an exact method for the study of four-quark systems based on the hyperspherical harmonics formalism that allows us to solve it without resorting to further approximations, like for instance the existence of diquark components. We apply it to systems containing two...
Source: http://arxiv.org/abs/0711.3118v1
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36
Sep 20, 2013
09/13
by
G Orlandini; W Leidemann; V D Efros; N Barnea
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eye 36
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Integral transform approaches are numerous in many fields of physics, but in most cases limited to the use of the Laplace kernel. However, it is well known that the inversion of the Laplace transform is very problematic, so that the function related to the physical observable is in most cases unaccessible. The great advantage of kernels of bell-shaped form has been demonstrated in few-body nuclear systems. In fact the use of the Lorentz kernel has allowed to overcome the stumbling block of the...
Source: http://arxiv.org/abs/1002.2926v1
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61
Sep 19, 2013
09/13
by
V. D. Efros; W. Leidemann; G. Orlandini; N. Barnea
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eye 61
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The LIT method has allowed ab initio calculations of electroweak cross sections in light nuclear systems. This review presents a description of the method from both a general and a more technical point of view, as well as a summary of the results obtained by its application. The remarkable features of the LIT approach, which make it particularly efficient in dealing with a general reaction involving continuum states, are underlined. Emphasis is given on the results obtained for electroweak...
Source: http://arxiv.org/abs/0708.2803v2
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3.0
Jun 28, 2018
06/18
by
N. Nevo Dinur; C. Ji; S. Bacca; N. Barnea
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Measuring the 2S-2P Lamb shift in a hydrogen-like muonic atom allows one to extract its nuclear charge radius with a high precision that is limited by the uncertainty in the nuclear structure corrections. The charge radius of the proton thus extracted was found to be 7-sigma away from the CODATA value, in what has become the yet unsolved "proton radius puzzle". Further experiments currently aim at the isotopes of hydrogen and helium: the precise extraction of their radii may provide a...
Topic: Nuclear Theory
Source: http://arxiv.org/abs/1512.05773
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37
Sep 22, 2013
09/13
by
N. Barnea; V. D. Efros; W. Leidemann; G. Orlandini
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eye 37
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The Lorentz integral transform method is briefly reviewed. The issue of the inversion of the transform, and in particular its ill-posedness, is addressed. It is pointed out that the mathematical term ill-posed is misleading and merely due to a historical misconception. In this connection standard regularization procedures for the solution of the integral transform problem are presented. In particular a recent one is considered in detail and critical comments on it are provided. In addition a...
Source: http://arxiv.org/abs/0906.5421v2
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47
Sep 21, 2013
09/13
by
J. Vijande; A. Valcarce; J. -M. Richard; N. Barnea
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eye 47
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The physics of charm has become one of the best laboratories exposing the limitations of the naive constituent quark model and also giving hints into a more mature description of meson spectroscopy, beyond the simple quark--antiquark configurations. In this talk we review some recent studies of multiquark components in the charm sector and discuss in particular exotic and non-exotic four-quark systems, both with pairwise and many-body forces.
Source: http://arxiv.org/abs/0902.1657v1
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53
Sep 20, 2013
09/13
by
S. Bacca; H. Arenhoevel; N. Barnea; W. Leidemann; G. Orlandini
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eye 53
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Inclusive electron scattering off 4He is calculated exactly with a complete treatment of the final state interaction within a simple semirealistic potential model. We discuss results for both the longitudinal and the transverse response functions, at various momentum transfers. A consistent meson exchange current is implemented. Good agreement with available experimental data is found for the longitudinal response function, while some strength is still missing in the transverse response...
Source: http://arxiv.org/abs/nucl-th/0612009v1
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47
Jul 20, 2013
07/13
by
S. Bacca; H. Arenhoevel; N. Barnea; W. Leidemann; G. Orlandini
texts
eye 47
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The Li7 total photoabsorption cross section is calculated microscopically. As nucleon-nucleon interaction the semi-realistic central AV4' potential with S- and P-wave forces is taken. The interaction of the final 7-nucleon system is fully taken into account via the Lorentz Integral Transform (LIT) method. For the calculation of the LIT we use expansions in hyperspherical harmonics (HH) in conjunction with the HH effective interaction (EIHH) approach. The convergence of the LIT expansion is...
Source: http://arxiv.org/abs/nucl-th/0406080v1
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46
Sep 22, 2013
09/13
by
E. O'Connor; D. Gazit; C. J. Horowitz; A. Schwenk; N. Barnea
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We extend the virial equation of state to include 3H and 3He nuclei, and predict significant mass-three fractions near the neutrinosphere in supernovae. While alpha particles are often more abundant, we demonstrate that energy transfer cross-sections for muon and tau neutrinos at low densities are dominated by breakup of the loosely-bound 3H and 3He nuclei. The virial coefficients involving A=3 nuclei are calculated directly from the corresponding nucleon-3H and nucleon-3He scattering phase...
Source: http://arxiv.org/abs/nucl-th/0702044v2
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3.0
Jun 30, 2018
06/18
by
S. Bacca; N. Barnea; G. Hagen; M. Miorelli; G. Orlandini; T. Papenbrock
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eye 3
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We combine the coupled-cluster method and the Lorentz integral transform for the computation of inelastic reactions into the continuum. We show that the bound-state-like equation characterizing the Lorentz integral transform method can be reformulated based on extensions of the coupled-cluster equation-of-motion method, and we discuss strategies for viable numerical solutions. Starting from a chiral nucleon-nucleon interaction at next-to-next-to-next-to-leading order, we compute the giant...
Topics: Nuclear Experiment, Nuclear Theory
Source: http://arxiv.org/abs/1410.2258
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6.0
Jun 30, 2018
06/18
by
F. Ferrari Ruffino; N. Barnea; S. Deflorian; W. Leidemann; D. Lonardoni; G. Orlandini; F. Pederiva
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eye 6
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The Non-Symmetrized Hyperspherical Harmonics method (NSHH) is introduced in the hypernuclear sector and benchmarked with three different ab-initio methods, namely the Auxiliary Field Diffusion Monte Carlo method, the Faddeev-Yakubovsky approach and the Gaussian Expansion Method. Binding energies and hyperon separation energies of three- to five-body hypernuclei are calculated by employing the two-body $\Lambda$N component of the phenomenological Bodmer-Usmani potential, and a hyperon-nucleon...
Topic: Nuclear Theory
Source: http://arxiv.org/abs/1701.06399
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7.0
Jun 29, 2018
06/18
by
M. Miorelli; S. Bacca; N. Barnea; G. Hagen; G. R. Jansen; G. Orlandini; T. Papenbrock
texts
eye 7
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The electric dipole polarizability quantifies the low-energy behaviour of the dipole strength and is related to critical observables such as the radii of the proton and neutron distributions. Its computation is challenging because most of the dipole strength lies in the scattering continuum. In this paper we combine integral transforms with the coupled-cluster method and compute the dipole polarizability using bound-state techniques. Employing different interactions from chiral effective field...
Topic: Nuclear Theory
Source: http://arxiv.org/abs/1604.05381
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59
Sep 21, 2013
09/13
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H. Kamada; A. Nogga; W. Gloeckle; E. Hiyama; M. Kamimura; K. Varga; Y. Suzuki; M. Viviani; A. Kievsky; S. Rosati; J. Carlson; Steven C. Pieper; R. B. Wiringa; P. Navratil; B. R. Barrett; N. Barnea; W. Leidemann; G. Orlandini
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In the past, several efficient methods have been developed to solve the Schroedinger equation for four-nucleon bound states accurately. These are the Faddeev-Yakubovsky, the coupled-rearrangement-channel Gaussian-basis variational, the stochastic variational, the hyperspherical variational, the Green's function Monte Carlo, the no-core shell model and the effective interaction hyperspherical harmonic methods. In this article we compare the energy eigenvalue results and some wave function...
Source: http://arxiv.org/abs/nucl-th/0104057v3
