Symmetries and similarities for spin orientation parameters in at SM thresholds

Abstract

We consider the spin orientation of the final Z bosons for the processes in the Standard Model. We demonstrate that at the threshold energies of these processes the analytical expressions for the Z boson polarization vectors and alignment tensors coincide (e + e − → ZH, Zγ) or are very similar (e + e − → ZZ). In addition, we present interesting symmetry properties for the spin orientation parameters.

Survey of top quark polarization at a polarized lineare+e−collider

“…[26]. Similar simplifications for polarization observables occur for the threshold production of gauge boson pairs [27]. …”

“…Since for h þ ¼ 0 the gain factor K G is equal to 1 and since P eff ¼ h À , the rate depends linearly on h À as displayed in Eqs. (27) and (28). The rate is largest for h À ¼ À1 and then linearly drops to its lowest value at h À ¼ þ1.…”

New physics in e + e − → Zγ at the ILC with polarized beams: explorations beyond conventional anomalous triple gauge boson couplings

“…The individual values of these triple gauge boson couplings (TGCs) as described before are zero at tree level in the SM, with non-zero values arising at higher orders or in composite models. These anomalous couplings have been extensively studied in the literature in the context of different colliders 1 [11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Moreover there has been a lot of work in the literature [8,10,13,17,23] where effective Lagrangians or effective momentum-space vertices and the associated form factors in neutral gauge boson production have been discussed.…”