Search Results - (Author, Cooperation:M. G. Huber)

2018-03-13

American Physical Society (APS)

0031-9007

1079-7114

Physics

Atomic, Molecular, and Optical Physics

2018-10-11

Institute of Physics (IOP)

1367-2630

Physics

2018-10-31

American Physical Society (APS)

0031-9007

1079-7114

Physics

Atomic, Molecular, and Optical Physics

2015-09-25

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

1434-601X

Springer Online Journal Archives 1860-2000

Physics

Abstract A classification of the eigenstates of the harmonic quadrupole oscillator is given within the framework of the Lie-AlgebraB 2 ofR(5). There still exists the problem of complete classification, since the multiplicityd v (l 2) for seniority numbersv≧6 may be greater than one. For these multiplicitiesd v (l 2) easily managable recursion formulae are derived and therefore their explicit calculation for arbitraryv andl 2 is easily possible.

Electronic Resource

1434-601X

Springer Online Journal Archives 1860-2000

Physics

Abstract The recently observed distribution of the transition strength of the isoscalar Giant Quadrupole Resonances can be explained by the admixture of (2p 2h)-excitations to the conventional (1p 1h)-configurations. The calculations agree nicely with (α, α′) and (e, e′) experiments. Due to the same mechanisme the Giant Monopole Strength is expected to be spread between 20 MeV and 40 MeV which makes it probably very difficult to detect such resonances experimentally.

Electronic Resource

1434-6052

Springer Online Journal Archives 1860-2000

Physics

Abstract Charmonium $$c\bar c$$ and bottomonium $$b\bar b$$ are investigated in the framework of a constituent quark model. A scalar confining and a one-gluon exchange (OGE) potential are used in a nonrelativistic reduction to order (p/m)2. Therefore the model includes spin dependent as well as spin independent terms. Their influence on the meson mass spectra and decay widths is analysed. We find that the experimental spectra can be reproduced by using a full model as well as by using a reduced version neglecting the spin independent terms. For both versions we calculate leptonic and radiative decay widths including relativistic corrections for the current operators. We find that for leptonic decays inclusion of all terms of the OGE potential gives better results than the non-relativistic formulas. For radiative transitions relativistic corrections are important.

Electronic Resource

1434-601X

12.40.Qq ; 13.30.Eg ; 14.20.−c

Springer Online Journal Archives 1860-2000

Physics

Abstract Within the framework of the non-relativistic quark model (NRQM) we discuss the influence of the coupling between baryonic excitations and meson fields. This leads to the interpretation of the baryon resonances as bound (q)3-configurations embedded in the corresponding meson-baryon continua. This concept is formulated analytically and applied to the description of the low-lying (N=0)- and (N=1)-multiplets with strangeness (S=0) and (S=−1). It turns out that the effects of this coupling are comparable in size to the effects induced by the hyperfine interaction. In particular, a remarkable cancellation of the spin-orbit forces of theqq-interaction and the meson-baryon interaction is observed. The implications of the strong baryon-meson coupling on the baryon-baryon interaction and on the formulation of the Hamiltonian for a multibaryon system are briefly discussed.

Electronic Resource

1434-601X

12.40.Qq ; 14.20.-c

Springer Online Journal Archives 1860-2000

Physics

Abstract It is shown that within the framework of a non-relativistic quark model with string-like confinement and an instanton induced residual quark-quark interaction it is possible to account simultaneously for the baryon and the meson spectra, including theπ- η- η′ splitting for pseudoscalar mesons, up to energies of roughly 2 GeV.

Electronic Resource

1434-601X

21.10.−k ; 24.90.+d ; 25.10.+s ; 25.70.−z

Springer Online Journal Archives 1860-2000

Physics

Abstract The production of pions in nuclear collisions is analyzed in terms of a microscopic reaction model, where the free energy of the entrance channel is transferred to the final channel through the coupling of the relative motion to the internal excitation of N*-resonances. Such a model allows quite naturally for a consistent analysis of the exclusive and the inclusive production of pions. It turns out that the pionic fusion cross section is determined predominantly by the spectroscopic parentage between the initial target projectile combination and the final nucleus, whereas the inclusive part is dominated by the energy dependence of the phase space factor, i.e. by the number of the degrees of freedom which are relevant in a given kinematical situation. This model is applied to the analysis of available experimental data from threshold to the Δ(1232)-region. A consistent analysis of both the inclusive and the exclusive part of the pion spectrum is presented.

Electronic Resource

1434-601X

13.30.Eg ; 12.40.Aa ; 14.20.Gk

Springer Online Journal Archives 1860-2000

Physics

Abstract Within the framework of the constituent quark model we discuss the effects of different types of meson-baryon-baryon vertex operators on the form factors and the coupling strengths of the lowest-lying positive and negative parity non-strange baryons. We compare the quark pair creation model (3P0-model) with the SU(6)-model in which mesons are treated as elementary fields that directly couple to the quarks. The latter model is employed both in the so-called static limit and in a modification motivated by Galilei invariance. It is demonstrated that the inclusion of non-static effects simulates some features of the3P0 vertex. Especially the reaction πN→ππN is found to be very sensitive to the different assumptions on the dynamics of theq¯q pair creation process. More indirect hints for the internal structure of the mesons might be obtained from the predicted asymmetry for the two form factors ofN→Δ+π andΔ→N+π, which occurs in the3P0-model, only.

Electronic Resource

1434-601X

Springer Online Journal Archives 1860-2000

Physics

Abstract The isovector Giant Quadrupole Resonances (GQR) of12C and16O have been investigated in a (1p1h) and (2p2h) modelspace using bound state wavefunctions. The results indicate a strong splitting of the (1p1h) E2 strength in both nuclei due to the coupling to the (2p2h) configurations. Such an effect has not been found in the case of the Giant Dipole resonance. This qualitatively different behaviour can be understood from the unperturbed particle hole energies of the 1 and E2 Giant Resonances, respectively.

Electronic Resource