Conserving and gapless approximations for the composite bosons in terms of the constituent fermions

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dc.creatorStrinati, G. C.
dc.creatorPieri, P.
dc.date2004-06-17
dc.date.accessioned2026-07-07T02:58:40Z
dc.date.available2026-07-07T02:58:40Z
dc.descriptionA long-standing problem with the many-body approximations for interacting condensed bosons has been the dichotomy between the ``conserving'' and ``gapless'' approximations, which either obey the conservations laws or satisfy the Hugenholtz-Pines condition for a gapless excitation spectrum, in the order. It is here shown that such a dichotomy does not exist for a system of composite bosons, which form as bound-fermion pairs in the strong-coupling limit of the fermionic attraction. By starting from the constituent fermions, for which conserving approximations can be constructed for any value of the mutual attraction according to the Baym-Kadanoff prescriptions, it is shown that these approximations also result in a gapless excitation spectrum for the boson-like propagators in the broken-symmetry phase. This holds provided the corresponding equations for the fermionic single- and two-particle Green's functions are solved self-consistently.
dc.description4 pages, 1 figure
dc.identifierhttps://arxiv.org/abs/cond-mat/0406393
dc.identifierhttp://arxiv.org/abs/cond-mat/0406393
dc.identifierEurophys. Lett. 71, 359 (2005)
dc.identifierdoi:10.1209/epl/i2005-10097-y
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/24196
dc.subjectSuperconductivity
dc.subjectStatistical Mechanics
dc.titleConserving and gapless approximations for the composite bosons in terms of the constituent fermions
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