Mesons and Baryons: Parity Partners

Abstract

We calculate masses of light and heavy mesons as well as baryons of negative parity containing $u,d,s,c$ and $b$ quarks. It is an extension of our previous work where we had studied the positive parity baryons. We adopt a quark-diquark picture of baryons where the diquarks are non-pointlike with a finite spatial extension. The mathematical foundation for this analysis is implemented through a symmetry-preserving Schwinger-Dyson equations treatment of a vector-vector contact interaction, which preserves key features of quantum chromodynamics, such as confinement, chiral symmetry breaking, axial vector Ward-Takahashi identity and low-energy Goldberger-Treiman relations. This treatment simultaneously describes mesons and provides attractive correlations for diquarks in the $\overline{3}$ representation. Employing this model, we compute the spectrum and masses of all spin-1/2 and spin-3/2 baryons of negative parity, supplementing our earlier evaluation of positive parity baryons, containing 1, 2 or 3 heavy quarks. In the process, we calculate masses of a multitude of mesons and corresponding diquarks. Wherever possible, we make comparisons of our results with known experimental observations as well as theoretical predictions of several models and approaches including lattice quantum chromodynamics, finding satisfactory agreement. We also make predictions for heavier states not yet observed in the experiment.

10 pages, 4 figures

References in corpus (12)

• Hadron Properties and Dyson-Schwinger Equations
• Dressed-quark anomalous magnetic moments
• Abelian anomaly and neutral pion production
• pi- and rho-mesons, and their diquark partners, from a contact interaction
• Pion form factor from a contact interaction
• Masses of ground and excited-state hadrons
• Spectrum of light- and heavy-baryons
• Masses of Light and Heavy Mesons and Baryons: A Unified Picture
• Masses of positive- and negative-parity hadron ground-states, including those with heavy quarks
• Hadron Physics and the Dyson--Schwinger Equations of QCD
• Parity partners in the baryon resonance spectrum
• Extension of the Nambu--Jona-Lasinio model at high densities and temperatures by using an implicit regularization scheme