Exact Classical Effective Potential

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dc.creatorSamson, J H
dc.date1999-05-26
dc.date.accessioned2026-07-07T06:16:35Z
dc.date.available2026-07-07T06:16:35Z
dc.descriptionA quantum spin system can be modelled by an equivalent classical system, with an effective Hamiltonian obtained by integrating all non-zero frequency modes out of the path integral. The effective Hamiltonian H_eff(S_i) derived from the coherent-state integral is highly singular: the quasiprobability density exp(-beta H_eff), a Wigner function, imposes quantisation through derivatives of delta functions. This quasiprobability is the distribution of the time-averaged lower symbol of the spin in the coherent-state integral. We relate the quantum Monte Carlo minus-sign problem to the non-positivity of this quasiprobability, both analytically and by Monte Carlo integration.
dc.description4 pages
dc.identifierhttps://arxiv.org/abs/quant-ph/9905089
dc.identifierhttp://arxiv.org/abs/quant-ph/9905089
dc.identifierProceedings of Sixth International Conference on Path Integrals from peV to TeV, Firenze, eds R Casalbuoni et al (World Scientific 1999), 550-553
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/94105
dc.subjectQuantum Physics
dc.subjectStatistical Mechanics
dc.titleExact Classical Effective Potential
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