Search

Using SU(3) lattice QCD, we investigate role of spatial gluons for hadron masses in the Coulomb gauge, considering the relation between QCD and the quark model. From the Coulomb-gauge configurations at the quenched level on a 163 × 32 lattice at β = 6.0, we consider the A⃗ = 0 projection, where all the spatial gluon fields are set to zero. In this projection, the inter-quark potential is unchanged. We investigate light hadron masses and find that nucleon and delta baryon masses are almost degenerate. This result suggests that the N-Δ mass difference arises from the color-magnetic interactions, which is consistent with the quark model picture. Next, as a generalization of this projection, we expand spatial gluon fields in terms of Faddeev-Popov eigenmodes and leave only some partial components. We find that the N – Δ and 0++ – 2++ glueball mass splittings are almost reproduced only with 1 % low-lying components. This suggests that low-lying color-magnetic interaction leads to the hadron mass splitting. [ABSTRACT FROM AUTHOR]

In a recent JLab 3H(e,e′K+) experiment a structure near the ΣNN threshold was observed, which was interpreted to be a T = 1 resonance. Using separable NN and ΛN−ΣN potentials in the Faddeev equations, we demonstrate that it is possible that both T = 0 and T = 1 resonances may have been excited. Moreover, their pole positions, in our model calculation, are sufficiently close to one another that it is unlikely that these resonances in the ΣNN spectrum can be resolved. [ABSTRACT FROM AUTHOR]

Elastic electron-3He scattering is studied in the relativistic impulse approximation. The amplitudes for the three-nucleon system – 3He – are obtained by solving the relativistic generalization of the Faddeev equation. The charge and magnetic form factor are calculated and compared with the experimental data for the momentum transfer squared up to 100 fm-2. The influence of the various nucleon form factors is investigated. [ABSTRACT FROM AUTHOR]

We investigate the structure of quantum corrections in N = 1 supersymmetric theories using the higher covariant derivative method for regularization. In particular, we discuss the non-renormalization theorem for the triple gauge-ghost vertices and its connection with the exact NSVZ β-function. Namely, using the finiteness of the triple gauge-ghost vertices we rewrite the NSVZ equation in a form of a relation between the β-function and the anomalous dimensions of the quantum gauge superfield, of the Faddeev-Popov ghosts, and of the matter superfields. We argue that it is this form that follows from the perturbative calculations, and give a simple prescription how to construct the NSVZ scheme in the non-Abelian case. These statements are confirmed by an explicit calculation of the three-loop contributions to the β-function containing Yukawa couplings. Moreover, we calculate the two-loop anomalous dimension of the ghost superfields and demonstrate that for doing this calculation it is very important that the quantum gauge superfield is renormalized non-linearly. [ABSTRACT FROM AUTHOR]

We start from the observation that, in the confining phase of QCD, the instantaneous color-Coulomb potential in Coulomb gauge is confining. This suggests that, in the confining phase, the dynamics, as expressed in the set of Schwinger-Dyson equations, may be dominated by the purely instantaneous terms. We develop a calculational scheme that expresses the instantaneous dynamics in the local formulation of QCD that includes a cut-off at the Gribov horizon. [ABSTRACT FROM AUTHOR]

An experiment to investigate the 1H(d,pp)n breakup reaction using a deuteron beam of 340, 380 and 400 MeV and the WASA detector has been performed at the Cooler Synchrotron COSY-Jülich. The studied energy region, below but close to a pion production threshold, may provide information on various aspects of nuclear interactions, in particular on relativistic effects and their interplay with the three nucleon force (3NF). The almost 4π geometry of the WASA detector gives an unique possibility to study the different aspects of nucleon-nucleon dynamics in the three nucleon system. The main steps of the analysis, including energy calibration, PID and studied of effciency, and their impact on final accuracy of the result, will be discussed. [ABSTRACT FROM AUTHOR]

We summarize recent progress in describing the confinement-deconfinement transition from a novel perturbative approach. [ABSTRACT FROM AUTHOR]

Using the BRST invariant version of the higher covariant derivative regularization, we demonstrate that in N = 1 supersymmetric gauge theories the three-point vertices with two ghost legs and a single leg of the quantum gauge superfield are finite in all orders. This theorem is proved by the help of the Slavnov-Taylor identities and the supergraph technique. Its correctness is verified by explicit one-loop calculation. Using finiteness of the considered vertices we express the NSVZ relation in terms of the anomalous dimensions of the gauge superfield, of the Faddeev-Popov ghosts, and of the matter superfields. [ABSTRACT FROM AUTHOR]

A three-charge-particle system (p, μ-, p+) with an additional matter-antimatter, i.e. p-p+, nuclear interaction is the subject of this work. Specifically, we carry out a few-body computation of the following protonium formation reaction: p + (p+μ-)1s → (pp+)1s + μ-, where p+ is a proton, p is an antiproton, μ- is a muon, and a bound state of p+ and its counterpart p is a protonium atom: Pn = (pp+). The low-energy cross sections and rates of the Pn formation reaction are computed in the framework of a Faddeev-like equation formalism. The strong p-p+ interaction is approximately included in this calculation. [ABSTRACT FROM AUTHOR]

Recent progress in few-body problem physics based on the three-body Faddeev equations is reviewed for three-related fields. The first field involves the description of light nuclear reactions in terms of multi-channel three-body Faddeev equations. The second field is the investigation of the two- and three-body threshold behaviors for the NNp system using the three-body Faddeev equations, where the pD and the NNπ or N- (Nπ) scattering lengths are calculated, and also we show that the NNπ potential has a long range term of 1/r² form. The third is a new Coulomb treatment in terms of a generalized screening range to describe on-shell Coulomb amplitudes which is useful in the threebody Faddeev equations. This procedure reproduces both of the Coulomb phase shift and the wave function from the electron-electron to the heavy-ion-heavy-ion systems. [ABSTRACT FROM AUTHOR]

The current status of the reaction theory of nuclear collisions involving weakly-bound exotic nuclei is presented. The problem is addressed within the Continuum Discretized Coupled Channel (CDCC) framework, recalling its foundations and applications, as well as its connection with the Faddeev formalism. Recent developments and improvements of the method, such as core and target excitations and the extension to three-body projectiles, are presented. The use of the CDCC wave function in the calculation of inclusive breakup reactions is also introduced. [ABSTRACT FROM AUTHOR]

Results on three-nucleon (3N) elastic scattering and breakup below the pion production threshold are discussed. The large discrepancies found between a theory based on numerical solutions of 3N Faddeev equations with standard nucleon-nucleon (NN) potentials only and data point to the need for three-nucleon forces (3NF's). This notion is supported by the fact that another possible reason for the discrepancies in elastic nucleon-deuteron (Nd) scattering, relativistic effects, turned out to be small. Results for a new generation of chiral NN forces (up to N4LO) together with theoretical truncation errors are shown. They support conclusions obtained with standard NN potentials [ABSTRACT FROM AUTHOR]

The three-body kaonic K̅pp and K̅K̅p clusters are studied using the method of hyperspherical harmonics (HH) in momentum representation and differential Faddeev equations (DFE). We use different NN and K̅N interactions. Results obtained by the methods of HH and DFE are in reasonable agreement. The binding energy and the width show very strong dependence on the K̅N potential. We have two different classes of results: the results based on phenomenological strong K̅N potential, and the results obtained with much weaker chiral SU(3)-based K̅N potential. [ABSTRACT FROM AUTHOR]

We solved the Faddeev equations in the Λnn system (Jπ = ½+, T = 1). There is no bound state but found a resonance state. Complex Energy Method helps to find the location of the resonance energy in the complex Riemann sheet. We obtained a resonance energy E = 0.25 - 0.40i MeV using the realistic NN and YN Nijmegen potential. As a preliminary result the recent Nijmegen YN potential (NSC97f) gives 0.60± 0.05 - (0.25 ± 0.05)i MeV. We discuss importance of an irreducible three-body force to make it bound. [ABSTRACT FROM AUTHOR]

Nucleon-deuteron (Nd) scattering, for which a rigorous formulation in terms of Faddeev equations exists and exact solutions of these equations for any dynamical input can be obtained, offers a good opportunity to study the dynamical aspects of 3NFs, such as momentum and spin dependences. Since the first indication of 3NF effects in Nd elastic scattering around 100 MeV/nucleon, precise measurements of proton-deuteron / neutron-deuteron scattering have been extensively performed at 60-300 MeV/nucleon. Direct comparison between the data and the Faddeev calculations based on realistic nucleon-nucleon forces plus 2π-exchange three nucleon forces draws the following conclusions. (1) The 3NF is definitely needed in Nd elastic scattering. (2) The spin dependent parts of the 3NFs may be deficient. (3) The shorter-range components of the 3NFs are probably required for the cross section as well as the spin observables at backward angles with increasing an incident energy. [ABSTRACT FROM AUTHOR]

The three-body approach based on the configuration space Faddeev equations for systems of non-identical particles is proposed to describe light hypernuclei (A=6,7, S=-1) with α particle clustering. We focus on the model (α+∧)+n+n for 7∧He hypernucleus for which the first experimental data have been recently reported. New evaluation for hyperon binding energy in 7∧He is done by using a relation between energies of the spin doublet (1-,2-) of 6∧He and the 7∧He ground state. Energies of low-lying levels of 6∧He hypernucleus are calculated within the cluster α + ∧ + n model. [ABSTRACT FROM AUTHOR]

We address the question of whether there might exist a resonance in the nn∧ system, using a rank one separable potential formulation of the Hamiltonian. We explore the eigenvalues of the kernel of the Faddeev equation in the complex energy plane using contour rotation to allow us to analytically continue the kernel onto the second energy sheet. We follow the largest eigenvalue as the n∧ potentials are scaled and the nn∧ continuum is turned into a resonance and then into a bound state of the system. [ABSTRACT FROM AUTHOR]

The behaviour of an Efimov excited state is studied within a three-body Faddeev formalism for a general neutron-neutron-core system, where neutron-core is bound and neutron-neutron is unbound, by considering zero-ranged as well as finite-ranged twobody interactions. For the finite-ranged interactions we have considered a one-term separable Yamaguchi potential. The main objective is to study range corrections in a scaling approach, with focus in the exotic carbon halo nucleus 20C [ABSTRACT FROM AUTHOR]

The electromagnetic monopole (E0) transition of the 12C nucleus, the 0+ ground state to three α-particles (3α) continuum states, is calculated by applying the Faddeev three-body formalism in coordinate space accommodating the long range Coulomb potential between α particles. Results show that there are two 0+ states, 12C(0+3 ) and 12C(0+4 ) states at excitation energies around 10 MeV, which is consistent with results of recent semi-microscopic calculations and analysis of α-12C inelastic scattering. [ABSTRACT FROM AUTHOR]

We present an R-matrix-based model for three-body final states that has aspects of the Faddeev approach to three-particle scattering. The model is applied to describing the nucleon spectra for breakup reactions in the A = 6 systems. Calculations using a charge-symmetric parametrization agree fairly well with the experimental data, although they indicate larger contributions from the 5He or 5Li ground state are necessary. [ABSTRACT FROM AUTHOR]

Amongst the bound states produced by the strong interaction, radially excited meson and nucleon states offer an important phenomenological window into the longrange behavior of the coupling constant in Quantum Chromodynamics. We here report on some technical details related to the computation of the bound state's eigenvalue spectrum in the framework of Bethe-Salpeter and Faddeev equations. [ABSTRACT FROM AUTHOR]

Four-nucleon reactions above the breakup threshold are described by solving Faddeev-Yakubovsky equations for the realistic nuclear Hamiltonians. Complex-scaling method is applied in order to simplify the boundary conditions. [ABSTRACT FROM AUTHOR]

Recently developed chiral two-nucleon (2N) potentials are applied to various processes in three-nucleon (3N) systems within the approach based on Faddeev equations. The predictions for the cross sections in elastic nucleon-deuteron (Nd) scattering and for radiative proton-deuteron (pd) capture are similar to results based on the AV18 potential. The very good convergence with respect to the chiral expansion and a weak dependence on a regularization parameter are observed. This gives hope that the Hamiltonian combining these 2N potentials with consistent 3N forces will become an important tool to study nuclear structure and processes. [ABSTRACT FROM AUTHOR]

The configuration-space Faddeev equations are derived for p-d scattering taking into account the difference in interaction between the participant particles. Appropriate modifications have been made in the well-known configuration-space equations for n-d scattering. To show the effect of these modifications, the s-wave calculations are performed for bound state and scattering problems. We model the charge symmetry breaking effect for 3H and 3He with a modified Malfliet-Tjon MT I-III potential. Results obtained for elastic n-d and p-d scattering at Elab=14.1 MeV are compared with our prediction (Ref. [1]) and those of the Los-Alamos/Iowa group (Ref. [2]) . [ABSTRACT FROM AUTHOR]

We study the many-body interaction between a D* and multi-ρ using the Fixed Center Approximation of the Faddeev equations. We use an extrapolation to SU(4) of the hidden gauge formalism. We select the f2(1270) and D* 2(2460) states which come from ρρ and ρD* interaction, respectively. Then let a third particle, ρ, D*, or a resonance collide with them. We find several new charmed resonances, D*3, D*4, D*5 and D*6 , which are not yet listed in the PDG. [ABSTRACT FROM AUTHOR]

Results on three-nucleon (3N) elastic scattering below the pion production threshold are discussed with an emphasis on the need for a three-nucleon force (3NF). The large discrepancies found between a theory based on numerical solutions of 3N Faddeev equations with (semi)phenomenological NN potentials only and data point to the need for 3NF's. This notion is supported by the fact that another possible reason for the discrepancies in elastic nucleon-deuteron (Nd) scattering, relativistic effects, turned out to be small. Results for new generation of chiral NN forces (up to N4LO) together with theoretical truncation errors are shown. [ABSTRACT FROM AUTHOR]

The kaonic clusters ...NN and ...NNN are studied within the method of hyperspherical functions in the momentum representation. Binding energies and widths of three- and four-body nuclear quasibound states are calculated by employing realistic NN potentials and the energy dependent chiral ...N interaction, as well as a phenomenological ...N potential. The comparison of the results of calculations obtained in the framework of the variational method, Faddeev, Faddeev-Yakubovsky equations, and method of hyperspherical functions in configuration space are discussed. [ABSTRACT FROM AUTHOR]

We study the ρB*B̅N* system solving the Faddeev equations in the fixed center approximation. The B*B̅N* system will be considered forming a cluster, and using the two-body ρB* unitarized scattering amplitudes in the local Hidden Gauge approach we find a new I(JPC) = 1(3−−) state. The mass of the new state corresponds to a two particle invariant mass of the ρB* system close to the resonant energy of the B*2(5747), indicating that the role of this J = 2 resonance is important in the dynamical generation of the new state. [ABSTRACT FROM AUTHOR]

6He has a cluster structure with a tight 4He (α) core surrounded by two loosely bound neutrons (n) making it a halo nucleus. The leading-order (LO) Halo Effective Field Theory (EFT) [1, 2] calculations using momentum-space Faddeev equations pertinent to a bound 6He were carried out in [3]. In this work, we investigate 6He up to next-to-leading order (NLO) within Halo EFT. [ABSTRACT FROM AUTHOR]

The two-body threshold behavior at NN1 and πD are investigated by using the multi-channel Lippmann-Schwinger equations with an energy dependent two-body quasi potential, which are analytically continued from the three-body Faddeev equations at the three-body break up threshold. Our calculated NN1 and πD scattering lengths show better agreement with the experimental data for NN and πD systems than those from the original NNπ three-body Faddeev equations. [ABSTRACT FROM AUTHOR]

Treating (d, p) reactions in a Faddeev-AGS framework requires the interactions in the sub-systems as input. We derived separable representations for the neutronand proton-nucleus interactions from phenomenological global optical potentials. In order to take into account excitations of the nucleus, excitations need to be included explicitly, leading to a coupled-channel separable representation of the optical potential. [ABSTRACT FROM AUTHOR]

Formalism of the configuration-space Faddeev equations is applied to analyze the bound state problem of ΛNN system. The simulated NSC97f potential for ΛN interaction and semi-realistic NN potentials are used for calculations. We predict a broad Λnn resonance near threshold. A spin dependent three-body ΛNN potential has been proposed to explain experimental evidence for 3 Λn bound state. The potential is defined by a Gaussian function of a hyper-radius. It was found that such potential with appropriate spin dependence does not support a bound state of 3 Λn. A short range form of the potential generates non-physical solutions of the Faddeev equations. [ABSTRACT FROM AUTHOR]