Köln 2004 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 32: Theory V

HK 32.2: Group Report

Wednesday, March 10, 2004, 14:30–15:00, D

Chiral dynamics of baryons as bound states of constituent quarks — •Valery Lyubovitskij, Thomas Gutsche, Amand Faessler, Kem Pumsa-ard, and Ping Wang — Institut für Theoretische Physik, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany

We developed a manifestly Lorentz invariant chiral quark model for the study of baryons as bound states of constituent quarks in an extention of our previous approach [1,2]. The approach is based on a non-linear chirally symmetric Lagrangian, which involves effective degrees of freedom - constituent quarks and the chiral (meson) fields. In the first step, this Lagrangian can be used to perform a dressing of the constituent quarks by a cloud of light pseudoscalar mesons and other heavy states using the calculational technique developed by Becher and Leutwyler [3]. We calculate the dressed transition operators with a proper chiral expansion which are relevant for the interaction of quarks with external fields in the presence of a virtual meson cloud. Next, these operators are used in the calculation of baryon matrix elements using an effective Lagrangian describing the coupling of a baryon field to the interpolating three-quark current [2].

[1] V. E. Lyubovitskij, Th. Gutsche and A. Faessler, Phys. Rev. C 64 (2001) 065203; V. E. Lyubovitskij et al., Phys. Rev. C 65 (2002) 02520; C 66 (2002) 055204; C 68 (2003) 015205; Phys. Lett. B 520 (2001) 204

[2] A. Faessler et al., Phys. Lett. B 518 (2001) 55

[3] T. Becher and H. Leutwyler, Eur. Phys. J. C 9 (1999) 643