Abstract:The derivation of non-Markovian quantum kinetic equations is reconsidered in the framework of density operators. Conventional-derivations use for the decoupling of the BBGKY-hierarchy the assumption of vanishing thretpartide correlations ~1 2 3 e 0. This yields non-Markovian kinetic equations with infinite memory depth. We discuss a different closure. relation to the hierarchy, which overcomes this difficulty without sasumptions on weakening of initial correlations and in fact corresponds to the indurion of se… Show more
“…of Eq. (15) we have to replace (for details see [50]) (33) and similarly for the terms with 1 W 2. This gives rise to Pauli-blocking and exchange contributions in the retarded self-energy 7 + and to an additional contribution (due to the second term on the r.h.s.…”
Section: (Anti)-symmetrization For Fermionsâbosonsmentioning
confidence: 98%
“…are included to achieve a consistent treatment of the collision integral and self-energy [38,48]. The simpler case of self-energy in the second Born approximation has been developed in [27,26,49] and is studied in detail in [50]. Damping effects have also been derived for the electron phonon problem in [22].…”
Section: B Generalized Binary Collision Approximation; Selfenergymentioning
“…of Eq. (15) we have to replace (for details see [50]) (33) and similarly for the terms with 1 W 2. This gives rise to Pauli-blocking and exchange contributions in the retarded self-energy 7 + and to an additional contribution (due to the second term on the r.h.s.…”
Section: (Anti)-symmetrization For Fermionsâbosonsmentioning
confidence: 98%
“…are included to achieve a consistent treatment of the collision integral and self-energy [38,48]. The simpler case of self-energy in the second Born approximation has been developed in [27,26,49] and is studied in detail in [50]. Damping effects have also been derived for the electron phonon problem in [22].…”
Section: B Generalized Binary Collision Approximation; Selfenergymentioning
“…The last equality in Eq. ( 28) follows with the help of the expressions (2), (7), and (22). Now taking into account the renormalizing factors standing with the second terms in Eqs.…”
Section: Approximations For the Spectral Functionmentioning
On the basis of the Kadanoff-Baym (KB) version of the time-dependent Green's function method, a new Ansatz for the approximation of a spectral function is offered. The Ansatz possesses all the advantages of quasiparticle and extended quasiparticle approximations and satisfies the KB equation for a spectral function in the case of slightly nonequilibrium system when disturbances in space and time are taken into consideration in the gradient approximation. This feature opens opportunities for the microscopic derivation of the Landau kinetic equation for the quasiparticle distribution function of the normal Fermi liquid and provides the widening of these equation's temperature range of validity.
“…Since the first numerical applications of the KBequations by Danielewicz [2] several contributions to this evolving new field have been published with applications to nuclear matter [5,3,6,7], to one-and two-band semiconductors [8,9],to phonon-production in e-e collisions in plasmas [10] as well as to electron plasmas in general [11,12]. Details of the computational methods is published in Computer Physics Communications [13].…”
The Kadanoff-Baym (KB) equations are solved numerically for infinite nuclear matter. In particular we calculate correlation energies and correlation times. Approximating the Green's functions in the KB collision kernel by the free Green's functions the Levinson equation is obtained. This approximation is valid for weak interactions and/or low densities. It relates to the extended quasi-classical approximation for the spectral function. Comparing the Levinson, Born and KB calculations allows for an estimate of higher order spectral corrections to the correlations. A decrease in binding energy is reported due to spectral correlations and off-shell parts in the reduced density matrix.
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