Vadim Lensky, Vladimir Pascalutsa
Published 2008-03-28, updated 2008-12-16Version 2
We compute the Compton scattering off the nucleons in the framework of manifestly covariant baryon chiral perturbation theory (B$\chi$PT). The results for observables differ substantially from the corresponding calculations in heavy-baryon chiral perturbation theory (HB$\chi$PT), most appreciably in the forward kinematics. We verify that the covariant $p^3$ result fulfills the forward-Compton-scattering sum rules. We also explore the effect of the $\Delta$(1232) resonance at order $p^4/\varDelta$, with $\varDelta\approx 300$ MeV, the resonance excitation energy. We find that the substantial effect of the $\Delta$-excitation on the nucleon polarizabilities can naturally be accommodated in the manifestly covariant calculation.
Comments: 6 pages, 4 figures, REVTeX; Major revision, the effect of Delta is computed entirely to order p^4 over the Delta-nulceon mass difference
Journal: Pisma Zh.Eksp.Teor.Fiz.89:127-132,2009; JETP Lett.89:108-113,2009
Masses and magnetic moments of ground-state baryons in covariant baryon chiral perturbation theory
Quark mass dependence of the ground-state octet baryons in next-to-next-to-next-to-leading order covariant baryon chiral perturbation theory
Decuplet baryon masses in covariant baryon chiral perturbation theory
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