Existence of ground states for approximately inner two--parameter $C_0$--groups on $C^*$--algebras

Document Type : Research Paper

Authors

Department of Mathematics, Mashhad Branch, Islamic Azad University, Mashhad, Iran.

Abstract

In this paper, we generalize the definitions of approximately inner $C_0$-groups and their ground states to the two- parameter case and study necessary and sufficient conditions for a state to be ground state. Also we prove that any approximately inner two- parameter $C_0$--group must have at least one ground state. Finally some applications are given.

Keywords

Main Subjects


R. Abazari, A. Niknam and M. Hassani, Approximately Inner Two--parameter C0--group of Tensor Product of C*--algebras, Aust. J. Basic & Appl. Sci. 5 (2011), no. 9, 2120--2126.
E. M. Alfsen and F. W. Shultz, State spaces of operator algebras: Basic theory, orientations, and C*-products, Bull. Amer. Math. Soc. 41 (2004), no. 4, 535--539.
V. Castern, Generators of strongly continuous semigroups, Pitman Advanced Publishing, Research Note, 1985.
N. Dunford and I. E. Segal, Semi-groups of operators and the Weierstrass theorem, Bull. Amer. Math. Soc. 52 (1946) 911--914.
K. Engel and R. Nagel, One-Parameter Semigroups for Linear Evolution Equations, Graduate Texts in Mathematics, 194, Springer-Verlag, New York, 2000.
B. Helffer, Spectral theory and its applications. Cambridge Studies in Advanced Mathematics, 139. Cambridge University Press, Cambridge, 2013.
E. Hille and R. S. Phillips, Functional analysis and semi-groups, Third printing of the revised edition of 1957. American Mathematical Society Colloquium Publications, 31, Amer. Math. Soc., Providence, 1974.
O. A. Ivanova, Certain theorems on an n-parametric semigroup of bounded linear operators and their application in the theory of functions (Russian), Toer. Funkcii Funkcional. Anal. i Prilozeu, Vyp 2 (1966) 34-41.
M. Janfada, On two-parameter regularized semigroups and the Cauchy problem, Abstr. Appl. Anal. (2009), Article ID 415847, 15 pages.
M. Janfada and A. Niknam, Two- parameter Dynamical system and application, J. Sci. Islam. Repub. Iran 15 (2004), no. 2, 163--169, 192.
M. Khanehgir, M. Janfada and A. Niknam, Inhomogeneous two-parameter abstract Cauchy problem, Bull. Iranian Math. Soc. (2005), no. 2, 71--81, 88.
M. Khanehgir, M. Janfada and A. Niknam, Two-parameter integrated semigroups and two-parameter abstract Cauchy problems, J. Inst. Math. Comput. Sci. Math. Ser. 18 (2005), no. 1, 1--12.
A. G. Miamee and H. Salehi, Harmonizability, V -boundedness and stationary dilation of stochastic processes, Indiana Univ. Math. J. 27 (1978), no. 1, 37--50.
M. A. Naimark, Normed Rings, Noordhoff N. V., Groningen, 1964.
A. Niknam, Infinitesimal generators of C*-Algebras, Potential Anal. 6 (1997), no. 1, 1--9.
A. Pazy, Semigroups of Linear Operators and Applications to Partial Differential Equations, Springer-Verlag, New York, 1983.
R. T. Powers, S. Sakai, Existence of ground states and KMS states for approximately inner dynamics, Comm. Math. Phys. 39 (1975) 273--288.
S. Sakai, C*-algebra and W*-algebra, Springer-Verlag, New York-Heidelberg, 1971.
S. Sakai, Operator Algebras in Dynamical Systems, Cambridge University Press, Cambridge, 1991.
L. Schwartz, Theorie des distrbutions, Paris: Hermann. Part I (1957), part II (1959).