Search results for "few-body systems"
showing 10 items of 48 documents
Relativistic corrections and unitary equivalence in elastic electron deuteron scattering.
1993
The role of unitary equivalence of relativistic corrections in elastic electron deutron scattering is studied, starting from a class of approximately, unitarily equivalent Hamiltonians and using consistent charge density operators. The connection of various formal approaches for deriving the relativistic corrections to wave functions and operators are discussed in detail. For reasons of simplicity, we have chosen a pure one-pion-exchange model and calculated the charge and quadrupole form factors of the deuteron. The numerical results show that the unitary equivalence holds at small momentum transfers, but breaks down rather soon with increasing momentum transfers (\ensuremath{\lesssim}5 ${…
Two-body effects in coherent η-meson photoproduction on the deuteron in the region of theS11(1535)resonance
2001
Coherent \ensuremath{\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 that fits reasonably well with 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 b…
Neutral baryonic systems with strangeness
2020
We review the status as regards the existence of three- and four-body bound states made of neutrons and $\Lambda$ hyperons. For interesting cases, the coupling to neutral baryonic systems made of charged particles of different strangeness has been addressed. There are strong arguments showing that the $\Lambda nn$ system has no bound states. $\Lambda\Lambda nn$ strong stable states are not favored by our current knowledge of the strangeness $-1$ and $-2$ baryon-baryon interactions. However, a possible $\Xi^- t$ quasibound state decaying to $\Lambda\Lambda nn$ might exist in nature. Similarly, there is a broad agreement about the nonexistence of $\Lambda\Lambda n$ bound states. However, the …
THE POSSIBLE DI-OMEGA DIBARYON IN QUARK CLUSTER MODEL
2014
The mixing of scalar mesons is introduced into the baryon-baryon system in the chiral SU(3) quark model to further dynamically investigate the Di-omega state by using the same parameters as those in reasonably describing the experimental hyperon-nucleon and nucleon-nucleon scattering data. Two different mixings of scalar mesons, the ideal mixing and 19° mixing, are discussed, and compared with no mixing. The results show that it is still deeply bound state if 19° mixing is adopted, the same as those of no mixing. However, for ideal mixing, the binding energy is reduced quite a lot, yet it is still a bound state.
Maximal isospin few-body systems of nucleons and $\Xi$ hyperons
2016
By using local central Yukawa-type interactions that reproduce the low-energy parameters of the latest updates of the Nijmegen ESC08c potentials we show that the $N\Xi$, $NN\Xi$, $N\Xi\Xi$ and $NN\Xi\Xi$ systems with maximal isospin are bound. Since in these states the strong decay $N\Xi\to\Lambda\Lambda$ is forbidden by isospin conservation, these strange few-body systems will be stable under the strong interaction. These results may suggest that other states with different number of $N$'s and $\Xi$'s in the maximal isospin channel could also be bound.
Measurement of the ExclusiveH3e(e,e′p)Reaction Below the Quasielastic Peak
2004
New, high-precision measurements of the 3He(e,ep) reaction using the A1 Collaboration spectrometers at the Mainz microtron MAMI are presented. These were performed in antiparallel kinematics at energy transfers below the quasielastic peak, and at a central momentum transfer of 685 MeV/c. Cross sections and distorted momentum distributions were extracted and compared to theoretical predictions and existing data. The longitudinal and transverse behavior of the cross section was also studied. Sizable differences in the cross-section behavior from theoretical predictions based on the plane wave impulse approximation were observed in both the two- and three-body breakup channels. Full Faddeev-ty…
Recent Developments in one and two Pion Production in Elementary Reactions and Few-Body Systems
1995
In this talk we cover several issues concerning pion production. The first one is the pp → ppπ 0 reaction where an alternative explanation based on the off shell extrapolation of the πN amplitude is offered. A recent model for the γN → ππN reaction is presented and a new kind of exchange current is constructed from it which allows one to address problems like double ∆ photoproduction from the deuteron. Finally the (γ, ππ) reaction in nuclei is studied and shown to be highly sensitive to the renormalization of the pions in nuclei.
Two, three, many body systems involving mesons
2011
In this talk we show recent developments on few body systems involving mesons. We report on an approach to Faddeev equations using chiral unitary dynamics, where an explicit cancellation of the two body off shell amplitude with three body forces stemming from the same chiral Lagrangians takes place. This removal of the unphysical off shell part of the amplitudes is most welcome and renders the approach unambiguous, showing that only on shell two body amplitudes need to be used. Within this approach, systems of two mesons and one baryon are studied, reproducing properties of the low lying $1/2^+$ states. On the other hand we also report on multirho and $K^*$ multirho states which can be asso…
Coulomb effects in deuteron breakup by proton impact
1994
We present the first results of a calculation of kinematically complete differential cross sections for the proton-induced deuteron breakup reaction, obtained by using a three-body formalism based on momentum space integral equations which correctly takes into account the Coulomb repulsion between the two protons. Comparison with experimental data is made.
Binding of charmonium with two- and three-body nuclei
2006
The energies of the (eta_c d) and (eta_c 3He) bound states are calculated on the basis of exact three- and four-body AGS equations. For the eta_c N interaction a Yukawa-type potential has been adopted. The calculations are done for a certain range of its strength parameter. The results obtained are quite different from calculations based on the folding model.