相关论文: Studying flavor-changing neutral tqZ couplings: Cu…
We study possible non-standard $tuZ$ and $tcZ$ couplings, which induce flavor-changing neutral-current decays of the top quark, in the effective-Lagrangian framework. The corresponding interaction Lagrangian comes from several $SU(3) \times…
Possible non-standard tqZ couplings, where q=c or u, originated from general flavor-changing-neutral-current interactions are studied model-independently using the effective Lagrangian consisting of several SU(3)xSU(2)xU(1) invariant…
Possible non-standard couplings which could contribute to the t -> b W process are studied based on the effective-Lagrangian approach. The corresponding effective Lagrangian consists of four kinds of dimension-6 effective operators, each of…
Within the model-independent framework of $SU(3)\times SU(2)\times U(1)$ gauge-invariant dimension-six operators, we study flavor-changing $Wtq$ couplings ($q=d,s$) and related four-quark contact interactions involving the top. We obtain…
The measurements of the top quark flavor changing neutral current interactions are one of the most important goals of the top quark physics program in the present and the future collider experiments. These measurements provide direct…
We present a search for flavor changing neutral currents in decays of top quarks. The analysis is based on a search for ttbar -> l'null + jets (l, l' = e, mu) final states using 4.1 fb^-1 of integrated luminosity of ppbar collisions at…
We study low energy experimental constraints on an anomalous top-quark coupling associated with the flavor-changing neutral current vertex $Z \bar t c$. In view of these constraints, we discuss the experimental observability of the induced…
A search for flavor-changing neutral-current couplings between a top quark, an up or charm quark and a $Z$ boson is presented, using proton-proton collision data at $\sqrt{s} = 13$ TeV collected by the ATLAS detector at the Large Hadron…
The possibility of an anomalous coupling between the top and charm quarks and the gluon field is explored in a model-independent way using an effective Lagrangian that is gauge-invariant under a non-linear realization of SU(3)$_{C} \times$…
General non-standard $tbW$ couplings are studied as model independently as possible based on the effective Lagrangian consisting of the dimension-6 operators, which is an extension of the standard-model Lagrangian. The $tbW$-interaction…
The top quark flavor changing neutral current processes are extremely suppressed within the Standard Model. Nevertheless, they could be enhanced in a new physics model beyond the Standard Model. Investigating the top quark's flavor changing…
For a model with a fourth family of quarks, new sources of flavor changing neutral currents are identified by confronting the unitary 4x4 quark mixing matrix with the experimental measured values of the familiar 3x3 quark mixing matrix. By…
We survey the flavor-changing neutral couplings (FCNC) of the top quark predicted by some extensions of the Standard Model: THDM, SUSY, L-R symmetric, TC2, 331, and models with extra quarks. Since the expected sensitivity of the LHC and ILC…
The possibility of exploring the flavor changing neutral current $tcZ/tc\gamma$ couplings in the production vertex for the reaction $\epem\to t\bar c + \bar tc$ is examined. Using a model independent parameterization for the effective…
Top flavour-changing neutral interactions with a light quark q=u,c and a gauge or Higgs boson are very suppressed within the Standard Model (SM), but can reach observable levels in many of its extensions. We review the possible size of the…
A search for the flavour-changing neutral-current decay $t\to qZ$ is presented. Data collected by the ATLAS detector during 2012 from proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of $\sqrt{s}=8$ TeV,…
We examine flavour-changing neutral-current decays of the top quark, $t\to q \gamma$, $t \to qZ$, $t \to q H$, and $ t\to q g$ (with $q=u, c$), in the Alternative Left-Right Model, a left right-symmetric model featuring exotic quarks and…
Focusing attention on top-quark pair production and its decay processes at the LHC, non-standard top-quark couplings are studied based on the effective Lagrangian constructed with SU(3)X SU(2)X U(1) invariant dimension-6 operators. The…
We present a search for flavor changing neutral currents (FCNC) in decays of top quarks. The analysis is based on a search for $t\bar{t}\rightarrow\ell'\nu\ell\bar{\ell}$+jets ($\ell, \ell' = e,\mu$) final states using 4.1 {\rm fb}$^{-1}$…
We recently studied possible non-standard tbW couplings based on the effective-Lagrangian which consists of four kinds of SU(3) x SU(2) x U(1) invariant dimension-6 effective operators and gave an experimentally allowed region for each…