The possibility of a quantum phase transition in a d-dimensional model with quenched disorder is analyzed via a renormalization group treatment without using the dimensionality epsilon(tau) of the imaginary time direction tau as an additional small expansion parameter. We work at the fixed physical value epsilon(tau) = 1 from the beginning, assuming the infinite correlation length in the timelike direction at temperature T = 0 as generated by an appropriate limit of a time-dependent random potential with long-range correlation in time. A stable fixed point is found to occur for realistic dimensionalities which, in the time-totally-correlated limit, is assumed to govern an exotic second order quantum phase transition in the original physical model. Also in the present approach a double expansion procedure is used but, more physically, we involve the extension of the random correlation in the tau direction rather than the artificial and doubtful expansion in small epsilon(tau).

Exotic quantum phase transitions in systems with quenched disorder

DE CESARE, Luigi;MERCALDO, Maria Teresa
2002

Abstract

The possibility of a quantum phase transition in a d-dimensional model with quenched disorder is analyzed via a renormalization group treatment without using the dimensionality epsilon(tau) of the imaginary time direction tau as an additional small expansion parameter. We work at the fixed physical value epsilon(tau) = 1 from the beginning, assuming the infinite correlation length in the timelike direction at temperature T = 0 as generated by an appropriate limit of a time-dependent random potential with long-range correlation in time. A stable fixed point is found to occur for realistic dimensionalities which, in the time-totally-correlated limit, is assumed to govern an exotic second order quantum phase transition in the original physical model. Also in the present approach a double expansion procedure is used but, more physically, we involve the extension of the random correlation in the tau direction rather than the artificial and doubtful expansion in small epsilon(tau).
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11386/1065186
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