Matrix elements of class I irreducible representations of the group SO(n)

1972 ◽  
Vol 11 (3) ◽  
pp. 516-518 ◽  
Author(s):  
M. S. Kil'dyushov
1968 ◽  
Vol 9 (6) ◽  
pp. 959-964
Author(s):  
C. Fronsdal ◽  
Harun Ar‐Rashid
Keyword(s):  
Class I ◽  

In contrast to what would be expected from a straightforward application of the Wigner-Eckart theorem, a simple factorization can often be made of matrix elements of operators that represent parts of the Coulomb interaction between f electrons in atoms. This property, which was discovered by Racah, is explained by using as basic states those in which the electrons are divided into two classes according to their spin orientation. The two collections of electrons are coupled through the irreducible representations of the group G 2 to which they belong, and this permits many of Racah’s proportionality constants to be related to isoscalar factors. The analogous factorizations that Feneuille found for the configurations (s + d) N are also discussed.


The orbital and charge-spin fractional parentage coefficients for the nuclear d 3 and d 4 con­figurations are derived using group theory. The orbital coefficients are given in a form appropriate to the new subclassification of the states according to irreducible representations of R 5 discussed in part I (Jahn 1950). Using these coefficients the complete energy matrices for the d 3 and d 4 configurations are derived, for a general charge-symmetric central two-body interaction, from the known energy matrix for the d 2 configuration.


Symmetry ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1120
Author(s):  
Carlo Heissenberg ◽  
Franco Strocchi

The matrix elements of operators transforming as irreducible representations of an unbroken symmetry group G are governed by the well-known Wigner–Eckart relations. In the case of infinite-dimensional systems, with G spontaneously broken, we prove that the corrections to such relations are provided by symmetry breaking Ward identities, and simply reduce to a tadpole term involving Goldstone bosons. The analysis extends to the case in which an explicit symmetry breaking term is present in the Hamiltonian, with the tadpole term now involving pseudo Goldstone bosons. An explicit example is discussed, illustrating the two cases.


2014 ◽  
Vol 55 (1) ◽  
pp. 011703 ◽  
Author(s):  
Mark D. Gould ◽  
Phillip S. Isaac ◽  
Jason L. Werry

The formulae of Redmond are used to construct expressions for the fractional parentage coefficients relating the configurations l 3 and l 2 . The explicit occurrence of godparent states is avoided for the quartet states of f 3 and also for a sequence of doublet states. The latter are defined by the set of quantum numbers f 3 WUSLJJ 2 , where W and U are irreducible representations of the groups R 7 and G 2 . Matrix elements of the type ( f 3 WUSL || U k || f 3 W'U'SL' ), where U k is the sum of the three irreducible tensor operators u k corresponding to the three f electrons, are tabulated for k = 2, 4 and 6 and for all values of W, U, S and L .


Author(s):  
M. D. Gould

AbstractPolynomial identities satisfied by the generators of the Lie groups O(n) and U(n) are rederived. Using these identities the reduced matrix elements of the Lie groups U(n) and O(n) are evaluated as rational functions of the IR labels occurring in the canonical chainsThis method does not require an explicit realization of the Lie algebras and their representations using bosons. Finally, trace formulae encountered previously by several authors for finite dimensional irreducible representations are shown to hold on arbitrary representations admitting an infinitesimal character.


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