Heavy baryon chiral perturbation theory with light deltas

Abstract

We demonstrate how heavy mass methods, previously applied to chiral perturbation theory calculations involving the interactions of nucleons and pions, can be generalized to include interactions with the ∆(1232) in a systematic formalism which we call the "small scale expansion".

Decuplet baryon masses in partially quenched chiral perturbation theory

“…In part, these operators absorb some effects of the unphysical, off-shell degrees of freedom [44]. The operators relevant to the self energy of the decuplet baryons are…”

ρ→ππ decay in nuclear medium

“…Whereas the couplings of mesons to nucleons listed above are well established and the corresponding parameters are well known (except for the long-lasting controversy with κ ρ ), the relativistic couplings involving the ∆ resonance are a topic of an on-going research and discussion [57,58,59,60]. Several structures are possible for these vertices, and ambiguities related to the choice of the so-called off-shell parameters have not been resolved.…”

“…In addition to the mentioned ambiguities in the choice of the form of the ∆ couplings [57,58,59,60], there are uncertainties in the values of the coupling constants. For some constants one typically uses the quark model predictions, or the large-N c arguments which relate the ∆ couplings to the nucleon couplings [63,64,65].…”

Photo- and electro-production of mesons on nucleons and nuclei

“…We deal here only about the S-wave part of the baryon meson interaction and take for the Rarita-Schwinger fields T µ the representation T u µ from ref. [23,24] with u µ the Rarita-Schwinger spinor. Let us recall the identification of the SU(3) component of T to the physical states [25,26]:…”