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For the t --> W b decay mode, an intensity-ratio equivalence for two distinct Lorentz-invariant couplings is shown to be a consequence of symmetries of tWb-transformations. Three explicit tWb-transformations connect the four standard…

High Energy Physics - Phenomenology · Physics 2007-05-23 Charles A. Nelson

For the observed t --> W b decay, an intensity-ratio equivalence-theorem for two Lorentz-invariant couplings is shown to be related to symmetries of tWb-transformations. Three explicit tWb-transformations, A_{+}=M A_{SM}, ... relate the…

High Energy Physics - Phenomenology · Physics 2007-05-23 Charles A. Nelson

This talk concerns some theoretical patterns of the helicity amplitudes for t --> W b decay. The patterns involve both the standard model's four decay helicity amplitudes, A_{SM}, and also the amplitudes A_{+} in the case of an additional…

High Energy Physics - Phenomenology · Physics 2007-05-23 Charles A. Nelson

The standard model(SM) predicts only a $g_{V-A}$ coupling in $t \to W^+ b$ decay. However, if additional Lorentz structures exist, they can manifest themselves in high energy processes such as this via non-SM values of the helicity…

High Energy Physics - Phenomenology · Physics 2011-09-13 Charles A. Nelson , Andrew M. Cohen

Due to the absence of hadronization effects and the large top mass, top quark decay will be uniquely sensitive to fundamental electroweak physics at the Tevatron, at the LHC, and at a future linear collider. A complete measurement of the…

High Energy Physics - Phenomenology · Physics 2009-01-07 Charles A. Nelson

In the standard model, for the t --> W b decay mode, the relative phase is 0-degrees between the dominant A(0,-1/2) and A(-1, -1/2) helicity amplitudes. However, in the case of an additional large t_R --> b_L chiral weak-transition moment,…

High Energy Physics - Phenomenology · Physics 2008-10-09 Charles A. Nelson

To quantitatively assay future measurements of competing observables in t --> W b decay, we consider the g_{V-A} coupling values of the helicity decay parameters versus those for "(V-A)+ Single Additional Lorentz Structures". There are 2…

High Energy Physics - Phenomenology · Physics 2007-05-23 Charles A. Nelson

The most general Lorentz-invariant decay-density-matrix for $t\to W^{+}b\to (l^{+}\nu)b$, or for $t\to W^{+}b\to (j_{\bar d}j_u)b$, is expressed in terms of eight helicity parameters. The parameters are physically defined in terms of…

High Energy Physics - Phenomenology · Physics 2009-10-30 Charles A. Nelson , Brian T. Kress , Marco Lopes , Thomas P. McCauley

The modularity property of the helicity formalism is used to provide amplitude expressions and stage-two spin-correlation functions which can easily be used in direct experimental searches for electro-weak symmetries and dynamics in the…

High Energy Physics - Phenomenology · Physics 2009-10-30 Charles A. Nelson , Brian T. Kress , Marco Lopes , Thomas P. McCauley

Tests of the Lorentz structure of t --> W b decay will be carried out at the Tevatron, and later at the LHC and at a NLC. To quantitatively assay future measurements of competing observables, we consider the (V-A) coupling values of the…

High Energy Physics - Phenomenology · Physics 2012-08-27 Charles A. Nelson , L. J. Adler,

To enable an evaluation of future measurements of the helicity parameters for " t --> W b " decay in regard to " T_FS violation", this paper considers the effects of an additional pure-imaginary coupling, (i g/2 Lambda) or (i g), associated…

High Energy Physics - Phenomenology · Physics 2012-08-27 Charles A. Nelson , L. J. Adler,

The asymmetries ${\cal A}_k \equiv [\Gamma(\twddec) -\Gamma(\tbwddec)] /[\Gamma(\twddec) + \Gamma(\tbwddec)]$ in the partial widths of the top quark decays are discussed within the Standard Model (SM), the Two-Higgs-Doublet Model (2HDM) and…

High Energy Physics - Phenomenology · Physics 2009-09-01 B. Grzadkowski , W. -Y. Keung

We investigate several quantities, defined in the decays of top quark pairs, which can be used to explore non-standard Wtb interactions. Two new angular asymmetries are introduced in the leptonic decay of top (anti)quarks. Both are very…

High Energy Physics - Phenomenology · Physics 2008-11-26 J. A. Aguilar-Saavedra , J. Carvalho , N. Castro , A. Onofre , F. Veloso

A supersymmetric model with four generations is proposed, in which the top quark is approximately degenerate in mass with the $W^{\pm}$ gauge boson, $m_t\simeq m_W$, leading to values of $R_b$ in better agreement with the present…

High Energy Physics - Phenomenology · Physics 2008-11-26 M. Carena , H. E. Haber , C. E. M. Wagner

Measurements of several top-quark properties, obtained from the CMS data collected in 2011 and 2012 at centre-of-mass energies of 7 and 8 TeV are presented. The results include measurements of the top pair charge asymmetry, the W helicity…

High Energy Physics - Experiment · Physics 2019-08-14 Efe Yazgan

The latest results on top quark physics, namely single top quark production cross sections, $W$-boson helicity and asymmetry measurements are used to probe the Lorentz structure of the $Wtb$ vertex. The increase of sensitivity to new…

Quantum tomography in high-energy physics processes has usually been restricted to the spin degrees of freedom. We address the case of top quark decays $t \to W b$, in which the orbital angular momentum ($L$) and the spins of $W$ and $b$…

High Energy Physics - Phenomenology · Physics 2024-07-12 J. A. Aguilar-Saavedra

We introduce a new asymmetry in the decay t -> W b -> l nu b, which is shown to be directly proportional to the polarisation of the top quark along a chosen axis, times a sum of W helicity fractions. The latter have already been precisely…

High Energy Physics - Phenomenology · Physics 2015-06-11 J. A. Aguilar-Saavedra , R. V. Herrero-Hahn

We describe a realistic, renormalizable, supersymmetric ``quindecuplet'' model in which the top quark, left handed bottom quark, and up-type Higgs boson are composite, with a compositeness scale $\sim 1-3$ TeV. The top-Higgs Yukawa coupling…

High Energy Physics - Phenomenology · Physics 2009-10-28 Ann E. Nelson , Matthew J. Strassler

We calculate the independent helicity amplitudes in the decays $B \to K^* \ell^+ \ell^-$ and $B \to \rho \ell \nu_\ell$ in the so-called Large-Energy-Effective-Theory (LEET). Taking into account the dominant $O(\alpha_s)$ and SU(3)…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. Salim Safir
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