Summary
A unifying treatment ofSU 2 andSU 1.1 6j-coefficients with discrete unitary representation is realized through a generalizing functionΦ 6j . From the invariance properties ofΦ 6j , as a by-product, the symmetry group of theSU 1.1 6j-coefficient with discrete unitary representations is obtained. The asymptotic connection ofΦ 6j with the generalized 3j-coefficients is pointed out.
Riassunto
Introducendo una funzione generalizzatriceΦ 6j si effettua una trattazione unificata dei coefficienti 6j diSU 2 e diSU 1.1 con parametri corrispondenti a rappresentazioni unitarie discrete. Dalle proprietà di invarianza diΦ 6j si ottiene come conseguenza il gruppo di simmetria dei coefficienti 6j diSU 1.1 relativi a rappresentazioni unitarie discrete. Si studia la connessione asintotica diΦ 6j con i coefficienti 3j generalizzati.
Реэюме
С помошью обобшенной функции Φ6j реалиэуется унифицированное рассмотрениеSU 2 иSU 1,1 6j-козффициентов в случае дискретного унитарного представления. Иэ инвариантных свойств Φ6j получается группа симметрии дляSU 1,1 6j-козффициентов в случае дискретного унитарного представления. Отмечается свяэь Φ6j с обобшенными 3j-козффициентами.
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References
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We do not have a simple recipe to do this, however we remark that the same technique used byG. Racah (Phys. Rev.,62, 438 (1942), Appendix B) to perform closely the summations when expressing the 6j as a sum of products of four 3j’s should apply also to theSU 1,1 case when only d.u.r. are involved.
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In ref. (4), {ie94-1} is kept integer, so that the factor {ie94-2} is omitted.
G −1 can be expressed in terms of a7 F 6 in 16 different ways which correspond to the different choices of the setσ in eq. (2.6). To perform the limit {ie97-1} → ∞, the most convenient choices are the ones with |σ|=3, because in this case7 F 6 {ie97-2}3 F 2 and the result can be directly compared with the definition ofF n . If |σ|=1 one getsF n expressed in terms of a series6 F 5 of argument −1 and if |σ|=5 the limit cannot be performed as it leads outside the convergency domain of the series. These statements agree with Sect.5 of ref. (10).
This property was pointed out in ref. (4).
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D’Adda, A., Ponzano, G. & D’Auria, R. Generalized 6j-coefficients and their symmetries. Nuov Cim A 23, 69–102 (1974). https://doi.org/10.1007/BF02748294
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DOI: https://doi.org/10.1007/BF02748294