Single top quark production as a probe of anomalous tqγ and tqZ couplings at the FCC-ee

Khanpour, Hamzeh; Khatibi, Sara; Yanehsari, M. Khatiri; Najafabadi, M. Mohammadi

doi:10.1016/j.physletb.2017.10.047

Cited by 36 publications

(27 citation statements)

References 76 publications

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“…Their branching fractions are estimated to be of O(10 −17 ) and O(10 −14 ) respectively in the standard model [7], that is why observation of those processes will be a clear evidence of possible new physics beyond the standard model. Indeed, a lot of efforts have already been made to analyze the tqZ interactions, where q = u/c, based on the effective Lagrangian in order to probe top-quark FCNC [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. In most of the studies, however, only some couplings included in the effective Lagrangian have been treated as free parameters at once fixing the others.…”

Section: Introductionmentioning

confidence: 99%

Studying flavor-changing neutral tqZ couplings: Current constraints and future prospects

2019

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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 couplings coming from SU(3) × SU(2) × U(1) invariant dimension-6 effective operators. The four coupling constants in each interaction are treated as complex numbers independent of each other, and constraints on them are derived by using the present experimental limits of the branching fractions for t → uZ and t → cZ processes. Future improvements of those constraints are also discussed as well as possibilities of measurements of these couplings at the High-Luminosity Large Hadron Collider.

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Section: Introductionmentioning

confidence: 99%

Studying flavor-changing neutral tqZ couplings: Current constraints and future prospects

2019

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“…One nice place to look for such FCNC processes is the rare decays of top quark in the context of some new physics model. There have been many studies to consider the rare decays of the top quark in the SM [31][32][33][34][35][36][37][38][39][40][41][42][43] as well as in various BSM scenarios, e.g., in supersymmetry [44][45][46][47][48][49][50][51], two Higgs doublet model (2HDM) [52][53][54][55][56], warped extra dimension [57], UED [58], etc. A model independent effective field theory based study of FCNC top decays can be found in [59,60].…”

Section: Introductionmentioning

confidence: 99%

Rare top decays in minimal and nonminimal universal extra dimension models

Dey

Jha

2016

Phys. Rev. D

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The flavour changing decays of the top quark are severely suppressed in the Standard Model by virtue of the Glashow-Iliopoulos-Maiani mechanism. Many beyond Standard Model extensions predict the decay rates at a level that is observable in the LHC. We perform a complete one-loop calculation of the flavour changing top quark decays t → cγ and t → ch in the universal extra dimensional model. Apart from considering the decay rates in the minimal version of the model, we also calculate the rates in the non-minimal scenario where the presence of boundary localised terms interestingly modify the set-up. We find that the decay rates in the minimal variant of the model do not change much from their Standard Model values. In the non-minimal version of this model, these decay rates can be higher for specific choices of the boundary localised parameters for a certain range of inverse compactification radius. But these model parameters lead to Kaluza-Klein particle masses that are in tension with various searches at the LHC.

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“…GeV has been given by Ref. [57], but only for the 3 twofermion coefficients. We show them in the same plot.…”

Section: Fcc-ee Projection At the Center-of-mass Energy Of 240mentioning

confidence: 99%

“…[68], and later searched at the LEP2 by the L3 and DELPHI collaborations [43,45], but the threebody decay through four-fermion FCN interactions have never been searched at Tevatron or LHC. For prospects on future e + e − colliders, four-fermion couplings have also been neglected in the studies of single top at TESLA and at FCC-ee [56,57], though the recent CLIC yellow report has included them [58]. However, four-fermion operators are indispensable for a complete characterization of the top-quark flavor properties.…”

Section: Introductionmentioning

confidence: 99%

Probing the top quark flavor-changing couplings at CEPC *

Shi

Zhang

2019

Chinese Phys. C

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We propose to study the flavor properties of the top quark at the future Circular Electron Positron Collider (CEPC) in China. We systematically consider the full set of 56 real parameters that characterize the flavorchanging neutral interactions of the top quark, which can be tested at the CEPC by the single top production channel. Compared with current bounds from the LEP2 data and the projected limits at the high-luminosity LHC, we find that the CEPC could improve the limits on four-fermion flavor-changing coefficients by one to two orders of magnitude, and in the meantime providing similar sensitivities on two-fermion flavor-changing coefficients. Overall, the CEPC could explore a large fraction of currently allowed parameter space that will not be covered by the upgrade of the LHC. We show that the c-jet tagging capacity at the CEPC could further improve its sensitivity to top-charm flavor-changing couplings. If a signal is observed, the kinematic distribution as well as the c-jet tagging could be exploited to pinpoint the sizes of various flavor-changing couplings, providing valuable information on the flavor properties of the top quark.

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Single top quark production as a probe of anomalous tqγ and tqZ couplings at the FCC-ee

Cited by 36 publications

References 76 publications

Studying flavor-changing neutral tqZ couplings: Current constraints and future prospects

Studying flavor-changing neutral tqZ couplings: Current constraints and future prospects

Rare top decays in minimal and nonminimal universal extra dimension models

Probing the top quark flavor-changing couplings at CEPC *

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