Freiburg 2008 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 11: QCD (Theorie)

T 11.6: Vortrag

Montag, 3. März 2008, 18:00–18:15, KGI-HS 1132

W⁺–boson helicity fractions in the decay t → b + W⁺ +g for hard and noncollinear gluons — Stefan Groote^1,3, Wen-sheng Huo², •Kadeer Alimujiang¹, and Juergen Koerner¹ — ¹Institut für Physik, 55099 Mainz, Germany — ²Department of Physics, Xinjiang University, 830046 Urumqi, P.R. China — ³Tartu Ülikooli Teoreetilise Füüsika Instituut, Tähe 4, EE-51010 Tartu, Estonia

We calculate the helicity fractions of W⁺–bosons from the one gluon decay t → b + W⁺ + g. In order to stay away from the IR and mass singular regions of phase space we cut on the invariant mass of the gluon plus bottom quark system: (p_b + p_g)² ≥ m_t² z_c. We present analytical results for the three helicity rates Γ_L, Γ₊ and Γ₋ (longitudinal, transverse-plus and transverse-minus) in their dependence on the cut parameter z_c.