

Seminar "Complex analysis in several variables" (Vitushkin Seminar)
December 5, 2012 16:45, Moscow, MSU, auditorium 1304






Integervalued characteristics of solutions of a noncommutative sigmamodel
A. V. Domrina^{} 
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Abstract:
We consider solutions of a noncommutative sigmamodel (quantum analogues of harmonic twospheres in a unitary group) that can be represented as finitedimensional perturbations of the identity operator in a Hilbert space. Such solutions have three integervalued characteristics: the normalized energy $e$, the canonical rank $r$, and the minimal uniton number $u$. We prove that always $e\geq r\geq u$ and $2e\geq u(u+1)$ (till
now, it was known only that $e\geq r$ and $e\geq u$) and discuss the issue of sufficiency of these inequalities for the existence of a solution with such characteristics.

