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The renormalization factor, dubbed “quasiparticle charge” Ze, of the coupling between the supercurrent and quasiparticles was analyzed in the context of high temperature cuprates in a recent paper by Ioffe and Millis [cond-mat/0112509 (unpublished)]. They observed that Ze in cuprates deviates from the BCS value (Ze=1), which was interpreted as the proximity effect near a Mott insulator. Here we show that the deviation from Ze=1 can occur, in general, even in the absence of quasiparticle interactions, when the superconducting order coexists with another order parameter with the same internal symmetry. As an example, we compute the coefficient of the linear temperature dependence of the superfluid density when the d-wave superconducting state coexists with the orbital antiferromagnetic state (d-density wave), and find that Ze varies from 1/2‾√ to 1.

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© 2002 The American Physical Society