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A. Blotz

Publications and source records attributed to A. Blotz.

10 recordsLinked to original sources
arXiv1996

A Top Quark Soliton and its Anomalous Chromomagnetic Moment

We show that under the assumption of dynamical symmetry breaking of electro weak interactions by a top quark condensate, motivated by the Top Mode Standard Model, the top quark in this effective theory can be considered then as chiral color soliton (qualiton). This is realized in an effective four-fermion interaction with chiral $SU(3)_c$ as well as $SU(2)_L\otimes U_Y(1)$ symmetry. In the pure top sector the qualiton consists of a top valence quark and a Dirac sea of top and anti-top quark coupled to a color octet of Goldstone pions. The mass spectra, isoscalar quadratic radii and the anomalous chromomagnetic moment due to a non-trivial color form factor are calculated with zero and finite current top masses and effects at the Hadron Colliders are discussed. The anomalous chromomagnetic moment turns out to have a value consistent with the top production rates of the D0- and CDF-measurements.

hep-ph↗
arXiv1996

Baryons as non-topological chiral solitons

The present review gives a survey of recent developments and applications of the Nambu--Jona-Lasinio model with $N_f=2$ and $N_f=3$ quark flavors for the structure of baryons. The model is an effective chiral quark theory which incorporates the SU(N$_f$)$_L\otimes$SU(N$_f$)$_R\otimes$U(1)$_V$ approximate symmetry of Quantum chromodynamics. The approach describes the spontaneous chiral symmetry breaking and dynamical quark mass generation. Mesons appear as quark-antiquark excitations and baryons arise as non-topological solitons with three valence quarks and a polarized Dirac sea. For the evaluation of the baryon properties the present review concentrates on the non-linear Nambu--Jona-Lasinio model with quark and Goldstone degrees of freedom which is identical to the Chiral quark soliton model obtained from the instanton liquid model of the QCD vacuum. In this non-linear model, a wide variety of observables of baryons of the octet and decuplet is considered. These include, in particular, electromagnetic, axial, pseudoscalar and pion nucleon form factors and the related static properties like magnetic moments, radii and coupling constants of the nucleon as well as the mass splittings and electromagnetic form factors of hyperons. Predictions are given for the strange form factors, the scalar form factor and the tensor charge of the nucleon.

hep-ph↗
arXiv1995

Magnetic Moments of the SU(3) Octet Baryons in the semibosonized SU(3) Nambu-Jona-Lasinio Model

We investigate the magnetic moments of the SU(3) octet baryons in the framework of the $SU(3)$ semibosonized Nambu--Jona--Lasinio model. The rotational $1/N_c$ corrections and strange quark mass in linear order are taken into account. We derive general relations between magnetic moments of the SU(3) octet baryons, based on the symmetry of our model. These relations indicate that higher order corrections such as $O(m_s/N_c)$ and $O(m^{2}_{s})$ are relatively small. The magnetic moments of the octet baryons predicted by our model are quantitatively in a good agreement with experimental results within about 15$\%$.

hep-ph↗
arXiv1995

The Constituent Quark Limit and the Skyrmion Limit of the Chiral Quark Soliton Model

We calculate $g_A^3$ and $g_A^0$ in the Chiral Quark-Soliton Model (or equivalently in semibosonized Nambu--Jona-Lasinio model) in the limit of small and large soliton size. In small soliton limit we recover the results of the Constituent Quark Model. The agreement between the two models is achieved due to the recently calculated $1/\Nc$ contributions to $g_A^3$ and to $g_A^0$. In the case of $g_A^3$ these terms arise from the {\it time-ordering} of the collective operators. For large solitons simple scaling arguments show that the $1/\Nc$ contributions vanish with the inverse power of the soliton size.

hep-ph↗
arXiv1994

Hyperon in Chiral Effective Quark Models

Baryonic correlation functions are calculated within an effective chiral quark model motivated by the instanton liquid model of QCD. Using a flavour SU(3) symmetry for the local four-quark interaction and taking rotational zero modes for the quantization into account low-energy hadronic observables are in surprising agreement with experimental data. (Talk presented at the Conference on Hypernuclear and Strange Particle Physics (HYP94), Vancouver, B.C., Canada, 4.-8- Juli 1994)

hep-ph↗
arXiv1994

Axial Properties of the Nucleon with $1/N_c$-Corrections in the solitonic SU(3)-NJL-Model

Within the semibosonized SU(3)-NJL model the mass splittings of baryons and the axial vector coupling constants of the nucleon are evaluated. The mass splittings of the hyperons are reproduced with great accuracy if second order corrections in $m_s$ are taken into account. New corrections to the axial vector currents coming from the subleading terms in the $1/N_c$ expansion are shown to be non-vanishing and substantially improving the phenomenological predictions for axial quantities. Finally the numerical values for the $g_{\rm A}$'s are $g_A^{(0)}=0.37$, $g_A^{(3)}=1.38$ and $g_A^{(8)}=0.31$ reproducing reasonably well the recent data from lepton scattering.

hep-ph↗
arXiv1994

Baryons in Effective Chiral Quark Models with Polarized Dirac Sea

We give a comprehensive review of concepts and numerical calculations for SU(2) and SU(3) baryonic systems which are considered as many body systems composed of three quarks coupled to a polarized Dirac sea by a Nambu--Jona-Lasinio like interaction. The general formalism as well as the construction and numerical solution of non-topological mean field solitons are exhibited. Systems with good spin/flavour/isospin/momentum quantum numbers are obtained by using the SU(2)/SU(3)-cranking and the pushing approach. The article contains also recent results for various extensions of the model, e.g. vector and axialvector couplings or the inclusion of scale invariance. Furthermore the relationship of this approach to topological models (Skyrme type) as well as to (valence-)quark-meson models (Gell-Mann--Levi chiral sigma model) is explained. (to be publ. in Rep.Prog.Phys.)

hep-ph↗
arXiv1993

Rotational Corrections to Axial Currents in Semibosonized SU(3) Nambu--Jona-Lasinio Model

We examine $O(1/\Ne)$ rotational corrections to axial couplings \gt~ and \go~ in the framework of the semibosonized SU(3) Nambu--Jona-Lasinio model. A novelty is due to the observation that the rotational (cranking) velocity and the rotation matrix itself do not commute within semiclassical quantization scheme. If time ordering in the quark loop is maintained new contributions, which have no analogue in the Skyrme model, appear. They substantially improve numerical results for the axial couplings which without the present corrections are badly underestimated.

hep-ph↗
arXiv1993

Hyperons as Solitons in Chiral Quark Model

The paper describes the quantization of the SU(3) smibosonized Nambu-Jona-Lasinio model and results for mass splittings, including isospin splittings, and axial couplings. The agreement with the data is surprisingly good.

hep-ph↗