The baryon axial current in large NcN_c chiral perturbation theory

Feb 26, 2014
109 pages
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Abstract: (arXiv)
In this thesis we calculate the baryon axial current within the combined framework of the 1/Nc1/N_c expansion and chiral perturbation theory, where NcN_c is the number of colors. This calculation shall consider Feynman diagrams to order of one-loop, octet and decuplet intermediaries states. We obtain corrections due to one-loop and perturbative SU(3) symmetry breaking. The first corrections come from Feynman diagrams, then talk about a broken chiral symmetry in the implicit limit mq0m_q \rightarrow 0, where mqm_q is the quark mass and the second corrections are obtained by ignoring isospin breaking and in that case the SU(3) symmetry breaking a first-order perturbation is included, leading an explicit break symmetry. The matrix elements of the spatial components of the axial operator between the states of the spin flavor symmetry, give the typical values of the axial vector coupling. For the baryon octet, links axial vector are gAg_A, just as they are defined in experiments of baryon semileptonic decays, where gA1.27g_A \approx 1.27 for neutron beta decay. In strong decays of the baryon axial vector couplings are gg, which are extracted from the widths of the strong decays of baryon decuplet to octet of baryons and pions. The calculation of this work allows us to make various settings by minimum squares, i.e., adjusting our analytical expressions with data pilot can make the comparison between theory and experiment. We found the comparison of our theoretical results with the experiment are in total agreement.
Note:
  • Ph.D. Thesis, IF-UASLP, December 2012, 109 pages, fully in Spanish
  • thesis
  • quantum chromodynamics: effective Lagrangian
  • effective Lagrangian: chiral
  • perturbation theory: chiral
  • perturbation theory: correction
  • correction: higher-order
  • perturbation theory: higher-order
  • higher-order: 1
  • expansion 1/N: color
  • baryon: octet