Description: In-medium chiral perturbation theory beyond the mean-field approximation

This title appears in the Scientific Report : 2002

In-medium chiral perturbation theory beyond the mean-field approximation

An explicit expression for the generating functional of two-flavor low-energy QCD with external sources in the presence of nonvanishing nucleon densities was derived recently (J. A. Oller, Phys. Rev. C 65 (2002) 025204). Within this approach we derive power counting rules for the calculation of in-m...

Personal Name(s):	Meissner, U.G.
	Oller, J. A. / Wirzba, A.
Contributing Institute:	Institut 3 (Theoretische Kernphysik); IKP-TH
Published in:	Annals of physics, 297 (2002) S. 27 - 66
Imprint:	Amsterdam [u.a.] Elsevier 2002
Physical Description:	27 - 66
DOI:	10.1006/aphy.2002.6244
Document Type:	Journal Article
Research Program:	Physik der Hadronen
Series Title:	Annals of Physics 297
Subject (ZB):	nuclear matter perturbation theory: chiral effective Lagrangian nucleon nucleon: interaction pi nucleon: interaction pi pi: interaction quark: condensation n-point function pi: mass pi: condensation pi: coupling wave function: renormalization symmetry: SU(2) x SU(2) numerical calculations: interpretation of experiments chiral perturbation theory finite density pion properties in the medium
Link:	OpenAccess OpenAccess
	Publikationsportal JuSER

Please use the identifier: http://dx.doi.org/10.1006/aphy.2002.6244 in citations.
Please use the identifier: http://hdl.handle.net/2128/10730 in citations.

An explicit expression for the generating functional of two-flavor low-energy QCD with external sources in the presence of nonvanishing nucleon densities was derived recently (J. A. Oller, Phys. Rev. C 65 (2002) 025204). 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 (nonstandard counting) for vanishing residual nucleon energies. We also establish the different scales for the range of applicability of this perturbative expansion, which are root6pif(pi) similar or equal to 0.7 GeV for standard and 6pi(2)f(pi)(2)/2m(N) similar or equal to 0.27 GeV for nonstandard 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 amass shift for negatively charged pions in heavy nuclei, DeltaM(pi)- =(18 +/- 5) MeV, 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) --> gammagamma decay amplitude up to the same order, The study of pipi scattering requires the use of the nonstandard counting and the calculation is done at leading order. Even at that order we establish new contributions not considered so far. We also point toward further possible improvements of this scheme and touch upon its relation to more conventional many-body approaches. (C) 2002 Elsevier Science (USA).