Amand Faessler

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Received XXX The nuclear matrix elements M 0ν of the neutrinoless double beta decay (0νββ) of most nuclei with known 2νββ-decay rates are systematically evaluated using the Quasiparticle Random Phase Approximation (QRPA) and Renormalized QRPA (RQRPA). The experimental 2νββ-decay rate is used to adjust the most relevant parameter, the strength of the(More)
During the last decade, the problem of the description of hadrons in dense and hot nuclear matter received great attention. The purpose of the current investigations is to determine experimentally mass shifts and the broadening of hadronic resonances at finite density and temperature. The dilepton spectra from heavy-ion collisions are a suitable tool for(More)
We study the strong and electromagnetic decay properties of scalar mesons above 1 GeV within a chiral approach. The scalar-isoscalar states are treated as mixed states of quarkonia and glueball configurations. A fit to the experimental decay rates listed by the Particle Data group is performed to extract phenomenological constraints on the nature of the(More)
We examine the pion exchange mode of neutrinoless double beta decay (0νββ) induced by the R-parity violating quark-lepton operators of the su-persymmetric (SUSY) extensions of the standard model of the electroweak interactions. The corresponding nuclear matrix elements are evaluated within the renormalized quasiparticle random phase approximation with(More)
We calculate the electromagnetic moments and radii of the ∆(1232) in the nonrel-ativistic quark model, including two-body exchange currents. We show that two-body exchange currents lead to nonvanishing ∆ and N → ∆ transition quadrupole moments even if the wave functions have no D-state admixture. The usual explanation based on the single-quark transition(More)
We show that, within the quasiparticle random phase approximation (QRPA) and the renormalized QRPA (RQRPA) based on the Bonn-CD nucleon-nucleon interaction, the competition between the pairing and the neutron-proton particle-particle and particle-hole interactions causes contributions to the neutrinoless double-beta decay matrix element to nearly vanish at(More)
Estimates of nuclear matrix elements for neutrinoless double beta decay (0ν2β) based on the quasiparticle random phase approximations (QRPA) are affected by theoretical uncertainties, which can be substantially reduced by fixing the unknown strength parameter g pp of the residual particle-particle interaction through one experimental constraint — most(More)
We discuss the dressing of constituent quarks with a pseudoscalar meson cloud within the effective chiral quark model. SU (3) f symmetry breaking effects are included explicitly. Our results are compared with those of the traditional meson cloud approach in which pions are coupled to the nucleon. The pionic dressing of the constituent quarks explains the(More)
A new scheme for testing nuclear matter equations of state (EoSs) at high densities using constraints from neutron star (NS) phenomenology and a flow data analysis of heavy-ion collisions is suggested. An acceptable EoS shall not allow the direct Urca process to occur in NSs with masses below 1.5M , and also shall not contradict flow and kaon production(More)
We present a hybrid equation of state (EoS) for dense matter that satisfies phe-nomenological constraints from modern compact star (CS) observations which indicate high maximum masses (M ∼ 2M ⊙) and large radii (R > 12 km). The corresponding isospin symmetric EoS is consistent with flow data analyses of heavy-ion collisions and a deconfinement transition at(More)