Abstract
We investigate the prospect of the LHC for discovering new physics effects via new strategies in the same-sign top pair and same-sign top pair associated with a $W$ boson signatures. Significant enhancement in production of same-sign top quarks (plus a $W$ boson) is a joint property of several models beyond the standard model. We concentrate on the leptonic (electron and muon) decay of the top quarks and study the exclusion reach of the LHC data for a simplified model approach where top quark flavor changing could occur through a $Z'$ or a neutral scalar $\phi$ exchange. Less background contributions and clean signature are the advantages of the leptonic decay mode of the top quarks in the same-sign production processes. A combination is performed on both same-sign top pair and same-sign top pair plus a $W$ boson production modes which enables us to reach a large fraction of the model parameter space. Assuming the couplings of new physics of the order of $10^{-2}$, the mass of a flavor changing $Z'$ or a neutral scalar above 1 TeV could be excluded. We propose a momentum dependent charge asymmetry and angular observables in the same-sign top process which provide the possibility of separation of new physics signal from the SM backgrounds as well as discrimination of the flavor changing $tuX$ from $tcX$, where $X = Z',\phi$.
Highlights
Despite the marvelous successes of the standard model (SM) at the electroweak scale, we strongly believe there exists new physics (NP) beyond the SM
We investigate the prospect of the LHC for discovering new physics effects via new strategies in the same-sign top pair and same-sign top pair associated with a W boson signatures
We propose a momentum dependent charge asymmetry and angular observables in the same-sign top process which provide the possibility of separation of new physics signal from the SM backgrounds as well as discrimination of the flavor changing tuX from tcX, where X 1⁄4 Z0, φ
Summary
Despite the marvelous successes of the standard model (SM) at the electroweak scale, we strongly believe there exists new physics (NP) beyond the SM. Another class of beyond the SM theories leading to possible top quark FCNCs through a neutral scalar φ or a vector Z0 is related to the hidden sector In these models, the dark matter candidate from the hidden sector can couple to the SM fields in a flavor changing way through a vector or a scalar mediator [36,37]. We study the same-sign top pair production at the LHC sensitivity on the basis of a simplified model approach describing the top quark flavor changing through a scalar or a vector boson.
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