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Possible non-standard tuZ and tcZ interactions, which induce flavor-changing neutral-current decays of the top quark, are studied in the effective-Lagrangian framework. The corresponding Lagrangian consists of four kinds of non-standard…

High Energy Physics - Phenomenology · Physics 2019-11-11 Zenro Hioki , Kazumasa Ohkuma , Akira Uejima

We explore the capability of a 500 or 1000 GeV $e^+e^-$ linear collider to measure anomalous quartic gauge boson couplings. In the framework of a non-linear effective Lagrangian with a custodial $SU)2)$ symmetry, there are only two…

High Energy Physics - Phenomenology · Physics 2007-05-23 S. Dawson , A. Likhoded , G. Valencia , O. Yushchenko

We propose a rather general description of residual New Physics (NP) effects on the top quark couplings. These effects are described in terms of 20 gauge invariant $dim=6$ operators involving gauge and Higgs bosons as well as quarks of the…

High Energy Physics - Phenomenology · Physics 2009-10-28 G. J. Gounaris , M. Kuroda , F. M. Renard

We discuss new physics in top-quark interactions, using an effective field theory approach. We consider top-quark decay, single top production, and top-quark pair production. We identify 15 dimension-six operators that contribute to these…

High Energy Physics - Phenomenology · Physics 2011-02-18 Cen Zhang , Scott Willenbrock

We present the calculations of the complete next-to-leading order (NLO) inclusive total cross sections for the associated production processes $pp\to \tilde{t}_i\tilde{\chi}_k^-+X$ in the Minimal Supersymmetric Standard Model at the CERN…

High Energy Physics - Phenomenology · Physics 2011-09-13 Li Gang Jin , Chong Sheng Li , Jian Jun Liu

We compute the total cross-section and invariant mass distribution for heavy-quark pair production in $e^+e^-$ annihilation at the next-to-next-to-next-to-leading order in QCD. The obtained results are expressed as piecewise functions…

High Energy Physics - Phenomenology · Physics 2024-03-12 Xiang Chen , Xin Guan , Chuan-Qi He , Xiao Liu , Yan-Qing Ma

We analyze new physics contributions to $e^+e^-\to W^+W^-$ at the TeV energy scale, employing an effective field theory framework. A complete basis of next-to-leading order operators in the standard model effective Lagrangian is used, both…

High Energy Physics - Phenomenology · Physics 2015-06-15 G. Buchalla , O. Cata , R. Rahn , M. Schlaffer

Effective Lagrangians with dimension-six operators are widely used to analyse Higgs and other electroweak data. We show how to build a basis of operators such that each operator corresponds to a coupling which is well measured or will be in…

High Energy Physics - Phenomenology · Physics 2015-06-22 Eduard Masso

In this paper we present updated constraints on the top-quark sector of the Standard Model Effective Field Theory using data available from Tevatron, LEP and the LHC. Bounds are obtained for the Wilson coefficients from a global fit…

High Energy Physics - Phenomenology · Physics 2025-11-10 Fernando Cornet-Gomez , Víctor Miralles , Marcos Miralles López , María Moreno Llácer , Marcel Vos

A sequential fourth generation of quarks and leptons is allowed by precision electroweak constraints if the mass splitting between the heavy quarks is between 50 and 80 GeV. Although heavy quarks can be easily detected at the LHC, it is…

High Energy Physics - Phenomenology · Physics 2008-11-26 Erin De Pree , Marc Sher , Ismail Turan

We use dijet measurements from the Large Hadron Collider to constrain ten third-generation four-quark operators in the Standard Model effective field theory. At tree level, only the five operators involving four bottom quarks are directly…

High Energy Physics - Phenomenology · Physics 2026-03-31 Maximilian Freiheit , Ulrich Haisch

Standard Model predictions for the reactions with six fermions in the final state relevant for top quark pair production and decay at linear colliders are discussed. An issue of the double resonance signal versus non doubly resonant…

High Energy Physics - Phenomenology · Physics 2009-11-07 Adam Biernacik , Karol Kolodziej

The total cross section for top quark pair production close to threshold in e+e- annihilation is investigated. Details are given about the calculation at next-to-next-to-leading logarithmic order. The summation of logarithms leads to a…

High Energy Physics - Phenomenology · Physics 2008-11-26 A. H. Hoang , A. V. Manohar , I. W. Stewart , T. Teubner

The contribution of dimension-seven operators to anomalous FCNC-interactions of the t-quarks with a photon and a gluon is considered. The phenomenological Lagrangian and Feynman rules are derived. There are evaluated the expressions for the…

High Energy Physics - Phenomenology · Physics 2018-03-02 V. V. Denisov , S. R. Slabospitskii

Using non-relativistic effective theories, new next-to-next-to-leading order (NNLO) QCD corrections to the total $t\bar t$ production cross section at the Linear Collider have been calculated recently. In this article the NNLO calculations…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. H. Hoang , M. Beneke , K. Melnikov , T. Nagano , A. Ota , A. A. Penin , A. A. Pivovarov , A. Signer , V. A. Smirnov , Y. Sumino , T. Teubner , O. Yakovlev , A. Yelkhovsky

A study on effective anomalous interactions up to dimension 5 of the top quark with the electroweak gauge bosons is made in the non-linear Chiral Lagrangian approach. Bounds on the anomalous dimension four terms are obtained from their…

High Energy Physics - Phenomenology · Physics 2014-11-17 F. Larios , Ehab Malkawi , C. -P. Yuan

We present the results of the computation of the next-to-leading order QCD corrections to the production cross section of a Higgs boson in association with a top-antitop pair at the LHC, including the three relevant dimension-six operators…

High Energy Physics - Phenomenology · Physics 2016-11-23 Fabio Maltoni , Eleni Vryonidou , Cen Zhang

Measurement of the top-Yukawa coupling is important to understand the fermion mass generation mechanism and dynamics of electroweak symmetry breaking. We discuss the top quark anomalous couplings which can be described by higher dimensional…

High Energy Physics - Phenomenology · Physics 2009-02-16 Shinya Kanemura , Koichi Matsuda , Daisuke Nomura , Koji Tsumura

Effective Lagrangians can be used to parametrize the effects of physics beyond the standard model. Assuming the complete theory is a gauge theory, we determine which effective operators may be generated at tree level, and which are only…

High Energy Physics - Phenomenology · Physics 2009-10-28 C. Arzt , M. B. Einhorn , J. Wudka

We present a complete next-to-leading order study of top-squark pair production at the LHC, including QCD and EW corrections. The calculation is performed within the Minimal Supersymmetric Standard Model and numerical results are presented…

High Energy Physics - Phenomenology · Physics 2015-06-19 Jan Germer , Wolfgang Hollik , Jonas M. Lindert , Edoardo Mirabella