Width Effects on Near Threshold Decays of the Top Quark t cWW,cZZ and of Neutral Higgs Bos.pdfVIP

MADPH-05-1425,CUMQ/HEP-134,WM-05-108 Width Effects on Near Threshold Decays of the Top Quark t → cWW, cZZ and of Neutral Higgs Bosons Shaouly Bar-Shalom,1, ∗ Gad Eilam,1, 2, † Mariana Frank,3, ‡ and Ismail Turan3, 4, § 1Department of Physics, Technion-Israel Institute of Technology, 32000 Haifa, Israel 2Department of Physics, University of Wisconsin, Madison, WI 53706, USA 5 3Department of Physics, Concordia University, 0 0 7141 Sherbrooke St. West, Montreal, Quebec, CANADA H4B 1R6 2 4Particle Theory Group, Department of Physics, p e College of William and Mary, Williamsburg, VA 23187-8795, USA S 0 (Dated: February 2, 2008) 2 Abstract 2 v 7 The nonzero widths of heavy particles become significant when they appear in the final state 6 1 of any decay occurring just around its kinematical threshold. To take into account such effects, a 6 0 procedure, called the convolution method, was proposed by Altarelli, Conti and Lubicz. We expand 5 0 their study which included only threshold effects for t → bW Z in the standard model. We discuss / h 0 0 p finite width effects in the three body decays t → cW W, cZZ and A (h ) → tbW in the type III - p version of a two Higgs doublet model. In particular, we find a substantial enhancement in the decay e h −3 0 : t → cZZ , which brings its branching ratio to BR(t → cZZ ) ∼ 10 , and in the decay A → tbW , v i which, unlike the h0 ca