Summary
We discuss the four-dimensional nonlinear sigma-model with an internalO(n) invariance coupled to the metric tensor field satisfying Einstein equations. We derive a bound on the coupling constant between the sigma-field and the metric tensor using the theory of harmonic maps. A special attention is paid to Einstein spaces and some new explicit solutions of the model are constructed.
Riassunto
Si discute il modello sigma non lineare quadridimensionale con un'invarianza internaO(n) accoppiato al campo tensoriale metrico che soddisfa le equazioni di Einstein. Si deriva un limite sulla costante di accoppiamento tra il campo σ e il tensore metrico, usando la teoria delle mappe armoniche. Si rivolge una speciale attenzione agli spazi di Einstein e si costruiscono alcune nuove soluzioni esplicite del modello.
Резюме
Мы обсуждаем четырехмерную нелинейную сигма-модель с внутреннейO(n) инвариантностью, связанной с метрическим тензорным полем, которое удовлетворяет уравнениям Эйнштейна. Мы выводим границу для постоянной связи между сигма-полем и метрическим тензором, используя теорию гармонических отображений. Особое внимание уделяется пространствам Эйнштейна и конструируются некоторые новые решения предложенной модели.
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Ghika, G., Vişinescu, M. Four-dimensional sigma-model coupled to the metric tensor field. Nuov Cim B 59, 59–74 (1980). https://doi.org/10.1007/BF02739046
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DOI: https://doi.org/10.1007/BF02739046