Micaela Oertel

Strange quark matter with dynamically generated quark masses

Abstract Bulk properties of strange quark matter (SQM) are investigated within the SU(3) Nambu–Jona-Lasinio model. In the chiral limit the model behaves very similarly to the MIT bag model which is often used to describe SQM. However, when we introduce realistic current quark masses, the strange quark becomes strongly disfavored, because of its large dynamical mass. We conclude that SQM is not absolutely stable.

Meson properties in the 1/Nc-corrected NJL model

Abstract Properties of mesons are investigated within the Nambu–Jona-Lasinio model. We include meson-loop corrections, which are generated via a systematic 1/ N c -expansion in next-to-leading order. We show that our scheme is consistent with chiral symmetry, in particular with the Goldstone theorem and the Gell-Mann–Oakes–Renner relation. The numerical part focuses on the pion and the ρ -meson sector. For the latter the 1/ N c -corrections are crucial in order to include the dominant ρ → ππ -decay channel, while the leading-order approximation only contains unphysical q q -decay channels. We show that a satisfactory description of the pion electromagnetic form factor can be obtained. Similarities and differences to hadronic models are discussed.

Meson loop effects in the NJL model at zero and nonzero temperature

AbstractWe compare two different possibilities of including meson-loop corrections in the Nambu-Jona-Lasinio model: a strict 1/Nc expansion in the next-to-leading order and a nonperturbative scheme corresponding to a one-meson-loop approximation to the effective action. Both schemes are consistent with chiral symmetry, in particular, with the Goldstone theorem and the Gell-Mann-Oakes-Renner relation. The numerical part at zero temperature focuses on the pion and the ρ-meson sector. For the latter, meson-loop corrections are crucial in order to include the dominant ρ → ππ-decay channel, while the standard Hartree + RPA approximation only contains unphysical n

Quark droplets in the NJL mean field

m_pi ,f_pi ,leftlangle {bar psi psi } rightrangle

Diquark Condensation in Electrically and Color Neutral Quark Matter

n-decay channels. We find that n

Meson loop effects in the Nambu-Jona-Lasinio model

qbar q