In-medium chiral perturbation theory beyond the mean-field approximation
| Autor: | Andreas Wirzba, José Antonio Oller, Ulf-G. Meißner |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2001 |
| Předmět: |
Quark
interaction [nucleon nucleon] Particle physics Chiral perturbation theory n-point function Nuclear Theory condensation [pi] SU(2) x SU(2) [symmetry] FOS: Physical sciences General Physics and Astronomy chiral [perturbation theory] finite density mass [pi] Nuclear Theory (nucl-th) Renormalization High Energy Physics - Phenomenology (hep-ph) Pion interaction [pi nucleon] renormalization [wave function] coupling [pi] pion properties in the medium interpretation of experiments [numerical calculations] ddc:530 Nuclear Experiment (nucl-ex) Nuclear Experiment interaction [pi pi] chiral perturbation theory Quantum chromodynamics Physics effective Lagrangian Order (ring theory) condensation [quark] Pseudoscalar High Energy Physics - Phenomenology nuclear matter High Energy Physics::Experiment Nucleon |
| Zdroj: | Annals of physics 297, 27-66 (2002). doi:10.1006/aphy.2002.6244 |
| DOI: | 10.1006/aphy.2002.6244 |
| Popis: | An explicit expression of the generating functional of two-flavor low-energy QCD with external sources in the presence of non-vanishing nucleon densities has been derived recently [1]. Within this approach we derive power counting rules for the calculation of in-medium pion properties. We develop the so-called standard rules for residual nucleon energies of the order of the pion mass and a modified scheme (non-standard counting) for vanishing residual nucleon energies. We also establish the different scales for the range of applicability of this perturbative expansion, which are \sqrt{6}\pi f_\pi\simeq 0.7 GeV for the standard and 6\pi^2 f_\pi^2/2m_N\simeq 0.27 GeV for non-standard counting, respectively. We have performed a systematic analysis of n-point in-medium Green functions up to and including next-to-leading order when the standard rules apply. These include the in-medium contributions to quark condensates, pion propagators, pion masses and couplings of the axial-vector, vector and pseudoscalar currents to pions. In particular, we find a mass shift for negatively charged pions in heavy nuclei that agrees with recent determinations from deeply bound pionic Pb-207. We have also established the absence of in-medium renormalization in the \pi^0 \to \gamma\gamma decay amplitude up to the same order. The study of \pi\pi scattering requires the use of the non-standard counting and the calculation is done at leading order. Even at that order we establish new contributions not considered so far. We also point towards further possible improvements of this scheme and touch upon its relation to more conventional many-body approaches. Comment: 40 pages, 12 figures, version to appear in Ann. Phys |
| Databáze: | OpenAIRE |
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