Abstract
A novel invariant decomposition of diagonalizable \(n \times n\) matrices into n commuting matrices is presented. This decomposition is subsequently used to split the fundamental representation of \(\mathfrak {su}({3})\) Lie algebra elements into at most three commuting elements of \(\mathfrak {u}({3})\). As a result, the exponential of an \(\mathfrak {su}({3})\) Lie algebra element can be split into three commuting generalized Euler’s formulas, or conversely, a Lie group element can be factorized into at most three generalized Euler’s formulas. After the factorization has been performed, the logarithm follows immediately.
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The same logic is also valid for the complex logarithm of a complex number \(U = e^{i \theta }\), if the complex logarithm is defined as \({{\,\textrm{Ln}\,}}U = \widehat{\langle U\rangle }_2 \arccos (\langle U\rangle _0)\), where \(\langle U\rangle _0 = \tfrac{1}{2} (U + U^*)\) and \(\langle U\rangle _2 = \tfrac{1}{2} (U - U^*)\). This construction allows us to maintain the distinction between \(\pm U\), without requiring us to first distinguish the appropriate quadrant of the complex plane before computing \(\arctan \), such as is typically done in complex analysis.
References
Ablowitz, M. J., Fokas, A. S.: Complex Variables: Introduction and Applications. 2nd ed. Cambridge Texts in Applied Mathematics. Cambridge University Press, (2003). https://doi.org/10.1017/CBO9780511791246.
Curtright, T.L., Zachos, C.K.: Elementary results for the fundamental representation of SU(3). Rept. Math. Phys. 76, 401–404 (2015). https://doi.org/10.1016/S0034-4877(15)30040-9
DeGrand, T., DeTar, C.: Lattice Methods for Quantum Chromodynamics (2006). https://doi.org/10.1142/6065
Doran, C., et al.: Lie groups as spin groups. J. Math. Phys. 34(8), 3642–3669 (1993). https://doi.org/10.1063/1.530050
Gell-Mann, M.: “The Eightfold Way: A Theory of strong interaction symmetry”. In: (Mar. 1961). https://doi.org/10.2172/4008239.
Giusti, L., et al.: Problems on lattice gauge fixing. Int. J. Mod. Phys. A 16, 3487–3534 (2001). https://doi.org/10.1142/S0217751X01004281
Hestenes, D., Sobczyk, G.: Clifford algebra to geometric calculus : a unified language for mathematics and physics. Dordrecht; Boston; Hing- ham, MA, U.S.A.: D. Reidel ; Distributed in the U.S.A. and Canada by Kluwer Academic Publishers (1984)
Mandula, J.E., Ogilvie, M.: The gluon is massive: a lattice calculation of the gluon propagator in the Landau Gauge. Phys. Lett. B 185, 127–132 (1987). https://doi.org/10.1016/0370-2693(87)91541-3
Peskin, M. E., Schroeder, D. V.: An Introduction To Quantum Field Theory. Frontiers in Physics. Avalon Publishing, (1995). isbn: 9780813345437
Roelfs, M., De Keninck, S.: “Graded Symmetry Groups: Plane and Simple”. In: (under review at AACA). arXiv: 2107.03771
Van Kortryk, T.S.: Matrix exponentials, SU(N) group elements, and real polynomial roots. J. Math. Phys. 57(2), 021701 (2016). https://doi.org/10.1063/1.4938418
Acknowledgements
The author would like to thank Prof. David Dudal, Prof. Anthony Lasenby, and Steven De Keninck for valuable discussions about this research. Additional gratitude goes to the insights provided by geometric algebra, and [4, 7] in particular, which were the driving force behind this research. The research of M. R. was supported by KU Leuven IF project C14/16/067.
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Communicated by Uwe Kaehler.
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Roelfs, M. Geometric Invariant Decomposition of \(\text {SU}(\textbf{3})\). Adv. Appl. Clifford Algebras 33, 5 (2023). https://doi.org/10.1007/s00006-022-01252-w
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DOI: https://doi.org/10.1007/s00006-022-01252-w