arXiv subjects

E. ~Klempt

Publications and source records attributed to E. ~Klempt.

2 recordsLinked to original sources

arXiv2010

Is chiral symmetry broken and or restored in high-mass light baryons?

Based on a thorough comparison of the nucleon and $Δ$ excitation spectrum with models we show that parity doublets observed in the mass spectra do not entail the consequence that highly excited $N$ or $Δ$ resonances are insensitive to chiral symmetry breaking. Instead, the mechanism of mass generation in excited states is suggested to be the same as for the baryon ground states: the mass is assigned to fluctuating gluon fields and their strong attraction. In excited baryons, the field energy has to be integrated over a larger volume, and the total mass increases. Thus, also the additional mass of resonances, the excitation energy, is generated by spontaneous breaking of chiral symmetry.

hep-ph↗

arXiv2010

Measurement of the reaction $γp \rightarrow K^ + Σ^{\pm}π^{\mp}$ at photon energies up to 2.6 GeV

The reactions $γp \rightarrow K^{+}Σ^{\pm}π^{\mp}$ were studied with the SAPHIR detector using a tagged photon beam at the electron stretcher facility ELSA in Bonn. The decays $Σ^{-} \rightarrow nπ^{-}$ and $Σ^{+} \rightarrow nπ^{+}, pπ^0$ were fully reconstructed. Reaction cross sections were measured as a function of the photon energy from threshold up to $2.6\,$GeV with considerably improved statistics compared to a previous bubble chamber measurement. The cross sections rise monotonously with increasing photon energy. The two-particle mass distributions of $Σ^{\pm}π^{\mp}$ and $K^+π^-$ show substantial production of resonant states.

nucl-ex↗