Boson Exchange Potential Research Articles

Interaction and identification of meson–baryon molecule

The challenges with the molecular model of the multiquark systems are the identification of the hadronic molecules and the interaction between two color neutral hadrons. We study the di-hadronic molecular systems with proposed interaction potential as s-wave one boson exchange potential along with Screen Yukawa-like potential, and arrived with the proposal that within hadronic molecule the two color neutral hadrons experience the dipole-like interaction. The present study is the continuation of our previous study \cite{arxiv-Rathaud-penta}. With the proposed interaction potential, the mass spectra of $\Sigma_{s}K^{*}$, $\Sigma_{c}K^{*}$, $\Sigma_{b}K^{*}$, $\Sigma_{s}D^{*}$, $\Sigma_{c}D^{*}$, $\Sigma_{b}D^{*}$, $\Sigma_{s}B^{*}$, $\Sigma_{c}B^{*}$, $\Sigma_{b}B^{*}$, $\Xi_{s}K^{*}$, $\Xi_{c}K^{*}$, $\Xi_{b}K^{*}$, $\Xi_{s}D^{*}$, $\Xi_{c}D^{*}$, $\Xi_{b}D^{*}$, $\Xi_{s}B^{*}$, $\Xi_{c}B^{*}$, $\Xi_{b}B^{*}$ meson-baryon molecules are predicted. The Weinberg compositeness theorem which provides clue for the compositeness of the state is used for determination of the scattering length and effective range. The present study predict $P_{c}(4450)$ pentaquark sate as $\Sigma_{c}D^{*}$ molecule with $I(J^{P})=\frac{1}{2}(\frac{3}{2}^{-})$. The formalism also predicts some very interesting open as well as hidden flavour near threshold molecular pentaquark states.

Microscopic Calculation of the Optical Model Potential from One Boson Exchange Poten­tials

A new method for calculating the optical model potential from One Boson Exchange Potentials (OBEPs) is developed. The G-matrix is calculated by solving the Bethe-Goldstone equation in momentum space. Using vector brackets these G-matrix elements can be transformed from the center of mass representation into the laboratory system. This allows the evaluation of the (r-matrix interaction between nucleons in bound states and those in a plane-wave state. The lowest order contribution to the real part of the potential comes from the Hartree-Fock term, while the lowest order contribution to the imaginary part comes from the two-particle-one-hole (2p1h) diagram. Calculations for 16O and 40Ca have been carried out. Local approximations are obtained by describing the results for the central part in terms of a Woods-Saxon potential and those for the spin-orbit part in terms of the corresponding derivatives. The dependence of these potentials on energy and angular momentum is discussed. The parameters for these local approximations are in good agreement with empirical fits.

Interaction and Identification of the Di-Hadronic Molecules

In this article, we study the interesting problem of identification and interaction of the hadronic molecules. The One Boson Exchange potential along with Yukawa screen like potential in their relative s-wave state is used for the calculation of the mass spectra. Along with interaction potential, we propose the two color neutral hadrons pursue the dipole-like interaction for formation of the hadronic molecule. For the identification, we use the Weinberg’s compositeness theorem to distinguish hadronic molecules from other hadronic states. With the present interaction potential, we have calculated the mass spectra of di-mesonic states, namely, $$K\overline{K}$$ , $$\rho \overline{\rho }$$ , $$K^{*}\overline{K^{*}}$$ , $$D\overline{D^{*}}$$ ( $$\overline{D}D^{*}$$ ), $$D^{*}\overline{D^{*}}$$ , $$B\overline{B^{*}}$$ , $$B^{*}\overline{B^{*}}$$ , $$D^{*\pm }\overline{D_{1}^{0}}$$ , $$ D^{0}\overline{K^{\pm }}$$ , $$D^{*0}\overline{K^{\pm }}$$ , with their possible quantum number.

Detailed description of exclusive muon capture rates using realistic two-body forces

Starting from state-by-state calculations of exclusive rates of the ordinary muon capture (OMC), we evaluated total muon-capture rates for a set of light- and medium-weight nuclear isotopes. We employed a version of the proton-neutron quasi-particle random phase approximation (pn-QRPA, for short) which uses as realistic nuclear forces the Bonn C-D one boson exchange potential. Special attention was paid on the percentage contribution to the total muon-capture rate of specific low-spin multipolarities resulting by summing over the corresponding multipole transitions. The nuclear method used offers the possibility of estimating separately the individual contributions to the total and partial rates of the polar-vector and axial-vector components of the weak interaction Hamiltonian for each accessible final state of the daughter nucleus. One of our main goals is to provide a reliable description of the charge changing transitions matrix elements entering the description of other similar semileptonic nuclear processes like the charged-current neutrino-nucleus reactions, the electron capture on nuclei, the single \b{eta}-decay mode, etc., which play important role in currently interesting laboratory and astrophysical applications like the neutrino-detection through lepton- nucleus interaction probes, and neutrino-nucleosynthesis. Such results can be also be useful in various ongoing muon-capture experiments at PSI, Fermilab, JPARC and RCNP.

Heavy quark symmetry in multihadron systems

We discuss the properties of hadronic systems containing one heavy quark in the heavy quark limit. The heavy quark symmetry guarantees the mass degeneracy of the states with total spin and parity $(j-1/2)^{P}$ and $(j+1/2)^{P}$ with $j \geq 1/2$, because the heavy-quark spin is decoupled from the total spin $j$ of the light components called brown muck. We apply this idea to heavy multi-hadron systems, and formulate the general framework to analyze their properties. We demonstrate explicitly the spin degeneracy and the decomposition of the wave functions in exotic heavy hadron systems generated by the one boson exchange potential. The masses of the brown muck can be extracted from theoretical and experimental hadron spectra, leading to the color non-singlet spectroscopy.

Coupled S-States OF Relativistic Two-Particle Systems WITH Energy-Dependent Single Boson Exchange Potentials

Numerical solutions of the equations of quantum field theory describing bound s-states of systems of two particles for single boson exchange potentials depending on the energy of the system have been found. On the basis of these solutions, the transition frequencies of the system from the first excited state to the ground state and the decay widths of the bound state of two particles into two photons have been calculated. The obtained energy spectra and decay widths are compared with the experimentally measured values for positronium.

Solution of the Relativistic Bound State Problem for Hadrons

A second order extension of a generalised QED Lagrangian (including boson-boson coupling) has been used to describe qhadrons. Assuming massless elementary fermions (quantons) this results in a finite theory without open parameters, which may be regarded as a fundamental description of the strong interaction. Two potentials are deduced, a boson-exchange potential and one, which can be identified with the known confinement potential in hadrons. This formalism has been applied the mesonic systems !(782), Φ(1020), J= (3097) and Y(9460) with a good description of their masses. The most important results are: 1. The confinement of hadrons is not due to colour, but is a general property of relativistic bound states. 2. Massive quarks in the Standard Model (QCD) are understood as effective fermions with a mass given by the binding energy in the boson-exchange potential.

Hadronic molecules for charmed and bottom baryons near thresholds

We study hadronic molecules formed by a heavy meson and a nucleon, $DN$ and ${D}^{*}N$ ($\overline{B}N$ and ${\overline{B}}^{*}N$) systems. Respecting the heavy quark symmetry and chiral symmetry, we consider the $DN\mathrm{\text{\ensuremath{-}}}{D}^{*}N$ ($\overline{B}N\mathrm{\text{\ensuremath{-}}}{\overline{B}}^{*}N$) mixing induced by the one boson exchange potential including the tensor force. We find many bound and resonant states with ${J}^{P}=1/{2}^{\ifmmode\pm\else\textpm\fi{}}$, $3/{2}^{\ifmmode\pm\else\textpm\fi{}}$, $5/{2}^{\ifmmode\pm\else\textpm\fi{}}$, and $7/{2}^{\ensuremath{-}}$ in isospin singlet channels, while we find only a few resonant states with ${J}^{P}=1/{2}^{\ensuremath{-}}$ in isospin triplet channels. The analysis of $DN$ and ${D}^{*}N$ ($\overline{B}N$ and ${\overline{B}}^{*}N$) molecules will be useful to study mass spectra of excited charmed (bottom) baryons with large angular momenta, when their masses are close to the $DN$ and ${D}^{*}N$ ($\overline{B}N$ and ${\overline{B}}^{*}N$) thresholds.

DECAYS OF FOURTH GENERATION BOUND STATES

We consider the decay modes of the heavy [Formula: see text] bound states originating from Higgs boson exchange between quark–antiquark pair. In case of a small coupling between the fourth and lower generation the main decay mode is [Formula: see text] annihilation. We show that for a vector state the dominant decay modes are Higgs-gamma and Higgs-Z decays, while for a pseudoscalar state the strong two-gluon decay mode dominates. The bound states are very narrow. The ratio of the total width to the binding energy is less than 1% if we are not extremely close to the critical quark mass where the binding energy is very small. The discussed decay modes exist for any fermion–antifermion bound states including heavy leptons and heavy neutrinos if their masses are high enough to form a bound state due to attractive Higgs boson exchange potential.

Relativistic bound state approach to fundamental forces including gravitation

To describe the structure of particle bound states of nature, a relativistic bound state formalism is presented, which requires a Lagrangian including scalar coupling of two boson fields. The underlying mechanisms are quite complex and require an interplay of overlapping boson fields and fermion-antifermion production. This gives rise to two potentials, a boson-exchange potential and one identified with the long sought confinement potential in hadrons. With minimal requirements, two elementary massless fermions (quantons) - with and without charge - and one gauge boson, hadrons and leptons but also atoms and gravitational systems are described by bound states with electric and magnetic coupling between the charges and spins of quantons. No need is found for colour, Higgs-coupling and supersymmetry.

Renormalization versus strong form factors for one-boson-exchange potentials

We analyze the One Boson Exchange Potential from the point of view of Renormalization theory. We show that the nucleon-meson Lagrangean while predicting the NN force does not predict the NN scattering matrix nor the deuteron properties unambiguously due to the appearance of short distance singularities. While the problem has traditionally been circumvented by introducing vertex functions via phenomenological strong form factors, we propose to impose physical renormalization conditions on the scattering amplitude at low energies. Working in the large Nc approximation with pi,sigma,rho and omega mesons, we show that, once these conditions are applied, results for low energy phases of proton-neutron scattering as well as deuteron properties become largely insensitive to the form factors and to the vector mesons and yield a reasonable agreement with the data, for realistic values of the coupling constants.

Bound states of the heavy flavor vector mesons andY(4008)andZ1+(4050)

The $D^{*}\bar{D}^{*}$ and $B^{*}\bar{B}^{*}$ systems are studied dynamically in the one boson exchange model, where $\pi$, $\eta$, $\sigma$, $\rho$ and $\omega$ exchanges are taken into account. Ten allowed states with low spin parity are considered. We suggest that the $1^{--}$, $2^{++}$, $0^{++}$ and $0^{-+}$ $B^{*}\bar{B}^{*}$ molecules should exist, and the $D^{*}\bar{D}^{*}$ bound states with the same quantum numbers very likely exist as well. However, the CP exotic ($1^{-+}$, $2^{+-}$) $B^{*}\bar{B}^{*}$ and $D^{*}\bar{D}^{*}$ states may not be bound by the one boson exchange potential. We find that the I=0 configuration is more deeply bound than the I=1 configuration, hence $Z^{+}_1(4050)$ may not be a $D^{*}\bar{D}^{*}$ molecule. Although Y(4008) is close to the $D^{*}\bar{D}^{*}$ threshold, the interpretation of Y(4008) as a $D^{*}\bar{D}^{*}$ molecule is not favored by its huge width. $1^{--}$ $D^{*}\bar{D}^{*}$ and $B^{*}\bar{B}^{*}$ states can be produced copiously in $e^{+}e^{-}$ annihilation, detailed scanning of the $e^{+}e^{-}$ annihilation data near the $D^{*}\bar{D}^{*}$ and $B^{*}\bar{B}^{*}$ threshold is an important check to our predictions.

Two-body effects in coherent η-meson photoproduction on the deuteron in the region of theS11(1535)resonance

Coherent $\eta$-meson photoproduction on the deuteron has been studied, where the emphasis is on the relative importance of two-body contributions from hadronic rescattering and electromagnetic meson exchange currents besides the impulse approximation. For the elementary photoproduction amplitude a coupled resonance model developed by Bennhold and Tanabe has been used which fits reasonably well the experimental data. The rescattering effects are treated within a coupled channel approach considering the intermediate excitation of the $P_{11}(1440)$, $D_{13}(1520)$, and $S_{11}(1535)$ nucleon resonances. The hadronic interaction between nucleon and resonances is modeled by one boson exchange potentials, which we have considered both in the static approximation as well as fully retarded. The sum of all considered two-body effects results in an enhancement of the total cross section between 10 in the maximum and 25 percent closer to threshold around 680 MeV if the hadronic interaction is treated retarded. This enhancement shows up in the differential cross sections mainly at backward angles. It increases steadily from only a few percent at $0^\circ$ to more than a factor two at $180^\circ$ for a photon energy of 680 MeV. Two-body effects become also significant in certain polarization observables. Finally, no discrepancy has been found for the ratio of the isoscalar amplitude to the proton amplitude between coherent and incoherent $\eta$-photoproduction on the deuteron due to a nonvanishing complex and energy dependent phase relation.

Relationship of Field-Theory Based Single-Boson-Exchange Potentials to Static Ones

It is shown that field-theory based single boson exchange potentials cannot be identified to those of the Yukawa or Coulomb type that are currently inserted in the Schr\"odinger equation. The potential which is obtained rather corresponds to this current single boson exchange potential corrected for the probability that the system under consideration is in a two-body component, therefore missing contributions due to the interaction of these two bodies while bosons are exchanged. The role of these contributions, which involve at least two boson exchanges, is examined. The conditions that allow one to recover the usual single boson exchange potential are given. It is shown that the present results have some relation: i) to the failure of the Bethe-Salpeter equation in reproducing the Dirac or Klein-Gordon equations in the limit where one of the constituent has a large mass, ii) to the absence of corrections of relative order alpha log(1/alpha) to a full calculation of the binding energy in the case of neutral massless bosons or iii) to large corrections of wave-functions calculated perturbatively in some light-front approaches.

Analysis ofNNamplitudes up to 2.5 GeV: An optical model and geometric interpretation

We analyse the SM97 partial wave amplitudes for nucleon--nucleon (NN) scattering to 2.5 GeV, in which resonance and meson production effects are evident for energies above pion production threshold. Our analyses are based upon boson exchange or quantum inversion potentials with which the sub-threshold data are fit perfectly. Above 300 MeV they are extrapolations, to which complex short ranged Gaussian potentials are added in the spirit of the optical models of nuclear physics and of diffraction models of high energy physics. The data to 2.5 GeV are all well fit. The energy dependences of these Gaussians are very smooth save for precise effects caused by the known $\Delta$ and N$^\star$ resonances. With this approach, we confirm that the geometrical implications of the profile function found from diffraction scattering are pertinent in the regime 300 MeV to 2.5 GeV and that the overwhelming part of meson production comes from the QCD sector of the nucleons when they have a separation of their centres of 1 to 1.2 fm. This analysis shows that the elastic NN scattering data above 300 MeV can be understood with a local potential operator as well as has the data below 300 MeV.

Consistent description ofNNandπNinteractions using the solitary boson exchange potential

A unified description of $\mathrm{NN}$ and $\ensuremath{\pi}N$ elastic scattering is presented in the framework of the one solitary boson exchange potential (OSBEP). This model already successfully applied to analyze $\mathrm{NN}$ scattering is now extended to describe $\ensuremath{\pi}N$ scattering while also improving its accuracy in the $\mathrm{NN}$ domain. We demonstrate the importance of regularization of $\ensuremath{\pi}N$ scattering amplitudes involving $\ensuremath{\Delta}$ isobars and derivative meson-nucleon couplings, as this model always yields finite amplitudes without recourse to phenomenological form factors. We find an empirical scaling relation of the meson self-interaction coupling constants consistent with that previously found in the study of $\mathrm{NN}$ scattering. Finally, we demonstrate that the OSBEP model does not contradict the soft-pion theorems of $\ensuremath{\pi}N$ scattering.

Nucleon-nucleon scattering observables from solitary boson exchange potential

The one solitary boson exchange potential (OSBEP) is used to evaluate observables of $\mathrm{NN}$ elastic scattering below pion threshold. In this approach, we use a nonlinear model of self-interacting mesons as a substitution for the commonly used phenomenological form factors. $\mathrm{NN}$ data support an empirical scaling law between the pion and other meson fields, which suggests a link to QCD and significantly reduces the number of parameters in the boson exchange potential. The analysis of $\mathrm{np}$ and $\mathrm{pp}$ observables distinguishes the model by its fit and few adjustable parameters. An outlook to apply OSBEP in $\ensuremath{\pi}N$ systems is given.

Nonlinear approach toNNinteractions using self-interacting meson fields

Motivated by the success of models based on chiral symmetry in $\mathrm{NN}$ interactions, we investigate self-interacting scalar, pseudoscalar, and vector meson fields and their impact for $\mathrm{NN}$ forces. We parametrize the corresponding nonlinear field equations and get analytic wavelike solutions. A probability amplitude for the propagation of particle states is calculated and applied in the framework of a boson-exchange $\mathrm{NN}$ potential. Using a proper normalization of the meson fields makes all self-scattering amplitudes finite. The same normalization is able to substitute for the phenomenological form factors used in conventional boson-exchange potentials and thus yields a phenomenological understanding of this part of the $\mathrm{NN}$ interaction. We find an empirical scaling law which relates the meson self-interaction couplings to the pion mass and self-interaction coupling constant. Our model yields $\mathrm{np}$ phase shifts comparable to the Bonn B potential results and deuteron properties, in excellent agreement with experimental data.

A Classical Chiral Invariant Theory Method of N-N Interaction

Within the framework of meson exchange theory, the N-N interaction is derived by a classical field method from a chiral σ-ω model. The nuclear potential derived is similar to the ordinary one boson exchange potential.

Effect of the nucleon-delta interaction on properties of the three-nucleon ground state.

Wave-function components containing a single \ensuremath{\Delta} isobar are included in the calculation of the three-nucleon bound state. In extension to previous work, a nucleon-\ensuremath{\Delta} potential based on meson exchange is incorporated in the interaction models. The interaction models are constructed phase equivalent with the purely nucleonic Paris and Bonn one boson exchange potential in q space (OBEPQ) potentials. The nucleon-\ensuremath{\Delta} potential yields an additional contribution of the order of 0.1--0.2 MeV to the effective three-nucleon force. Its effect on the electromagnetic properties of the three-nucleon bound state is also considered and found to be small.