Results 1 - 10 of 27
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[en] The formalism developed recently to study vector meson-vector meson interaction, and applied to the case of ρρ, is extended to study the interaction of the nonet of vector mesons among themselves. The interaction leads to poles of the scattering matrix corresponding to bound states or resonances. We show that 11 states (either bound or resonant) get dynamically generated in nine strangeness-isospin-spin channels. Five of them can be identified with those reported in the PDG, i.e., the f0(1370), f0(1710), f2(1270), f2'(1525), and K2*(1430). The masses of the latter three tensor states have been used to fine-tune the free parameters of the unitary approach, i.e., the subtraction constants in evaluating the vector meson-vector meson loop functions in the dimensional regularization scheme. The branching ratios of these five dynamically generated states are found to be consistent with data. The existence of the other six states should be taken as predictions to be tested by future experiments.
[en] Using the local hidden gauge formalism for the vector meson-vector meson interaction within a unitary approach we find that 11 states get dynamically generated. Five of them are associated to the f0(1370), f0(1710), f2(1270), f2'(1525), and K2*(1430) resonances, by comparing the mass, width, and decay pattern of these states with those of their experimental counterparts. At the same time we predict six other states with the quantum numbers of h1, a0, b1, a2, K0*, and K1 which could be tested by future experiments.
[en] We calculate the SU(3)-breaking corrections to the hyperon vector coupling f1(0) up to O(p4) in covariant baryon chiral perturbation theory with dynamical octet and decuplet contributions. We find that the decuplet contributions are of similar or even larger size than the octet ones. Combining both, we predict positive SU(3)-breaking corrections to all the four independent f1(0)'s (assuming isospin symmetry), which are consistent, within uncertainties, with the latest results from large Nc fits, chiral quark models, and quenched lattice QCD calculations.
[en] We present a calculation of the leading SU(3)-breaking O(p3) corrections to the electromagnetic moments and charge radius of the lowest-lying decuplet resonances in covariant chiral perturbation theory. In particular, the magnetic dipole moment of the members of the decuplet is predicted fixing the only low-energy constant (LEC) present up to this order with the well-measured magnetic dipole moment of the Ω-. We predict μΔ++=6.04(13) and μΔ+=2.84(2), which agree well with the current experimental information. For the electric quadrupole moment and the charge radius, we use state-of-the-art lattice QCD results to determine the corresponding LECs, whereas for the magnetic octupole moment there is no unknown LEC up to the order considered here, and we obtain a pure prediction. We compare our results with those reported in large Nc, lattice QCD, heavy-baryon chiral perturbation theory, and other models.
[en] We investigate the neutrino induced coherent pion production reaction at low and intermediate energies. The model includes pion, nucleon, and Δ(1232) as the relevant hadronic degrees of freedom. Nuclear medium effects on the production mechanisms and pion distortion are taken into account. We find that the dominance of the Δ excitation holds due to large cancellations among the background contributions. We consider two sets of vector and axial-vector N-Δ transition form factors, evidencing the strong sensitivity of the results to the axial coupling C5A(0). The differences between neutrino and antineutrino cross sections, emerging from interference terms, are also discussed
[en] We report a theoretical study of the axial nucleon-to-delta (1232) (N→Δ) transition form factors up to one-loop order in relativistic baryon chiral perturbation theory. We adopt a formalism in which the Δ couplings obey the spin-3/2 gauge symmetry and, therefore, decouple the unphysical spin-1/2 fields. We compare the results with phenomenological form factors obtained from neutrino bubble-chamber data and in quark models.
[en] We report upon 11 composite meson states, dynamically generated from the vector meson–vector meson interaction using the local hidden gauge formalism within a unitary approach. Six of these states are associated to the f0(1370), f0(1710), f2(1270), f'2(1525), a2(1320) and K*2(1430) resonances. At the same time we predict five other states with the quantum numbers of h1, a0, b1, K*0, and K1 which could be tested by future experiments.
[en] In this paper, we report a systematic study of the heaviest nuclei within the relativistic mean field (RMF) model. By comparing our results with those of the Hartree-Fock-Bogoliubov method (HFB) and the finite range droplet model (FRDM), the stability and the shape of the heaviest nuclei are discussed. The theoretical predictions as well as the existing experimental data indicate that the experimentally synthesized superheavy nuclei are in between the fission stability line, the line connecting the nucleus with maximum binding energy per nucleon in each isotopic chain, and the β-stability line, the line connecting the nucleus with maximum binding energy per nucleon in each isobaric chain. It is shown that both the fission stability line and the β-stability line tend to be more proton rich in the superheavy region. Meanwhile, all the three theoretical models predict most synthesized superheavy nuclei to be deformed