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\nImpurity scatteri ng [1\,2] and/or higher order loop processes in the clean system [3] c ause a redistribution of the critical scattering at the hot lines all over the Fermi surface\, leading to a weakly momentum dependent critic al self-energy. We derive a self-consistent equation for the qp effect ive mass which allows for two physical solutions: the usual weak coupl ing spin density wave solution and a strong coupling solution featurin g a power law divergence of the effective mass as a function of energy scale. The resulting spin excitation spectrum obeys E/T scaling with dynamical exponent z=4 and correlation length exponent nu=1/3\, in exc ellent agreement with data for YbRh2Si2 [1\,2]. Results of our theory applied to three-dimensional metals featuring quasi-two-dimensional sp in fluctuations will be presented with the aim of explaining the obser ved properties of the AFM quantum critical point of CeCu(6-x)Aux \, in particular the E/T scaling exhibited by inelastic neutron scattering data. In that case we find z=8/3 and nu=3/7[3]. Finally\, the microsco pic underpinning of our theory will be addressed\, including the issue s of qp renormalization\, vertex corrections\, interaction of bosonic fluctuations in the renormalization group sense\, and higher loop corr ections [3].

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\n[1] P. Woelfle\, and E. Abrahams\, Phys. R ev. B 84\, 041101 (2011)\; Ann. Phys. (Berlin) 523\, 591 (2011)\; Phys . Rev. B 80\, 235112 (2009).

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\n[2] E.Abrahams and P. Woel fle\, PNAS \, 3228 (2012).

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\n[3] E. Abrahams\, J. Schmali an\, and P. Woelfle\, to be published.

\n URL:https://www.physics.wisc.edu/events/?id=3023 END:VEVENT END:VCALENDAR