Flavor changing<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>Z</mml:mi><mml:mo>′</mml:mo></mml:msup></mml:math>couplings at the LHC

Gupta, Sudhir Kumar; Valencia, G.

doi:10.1103/physrevd.82.035017

Cited by 18 publications

(16 citation statements)

References 27 publications

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“…Measurements of neutral K, D, and B meson mixing restrict couplings among the first two generations and the b quark to be quite small [41][42][43]. However, flavor-changing processes involving the top quark are relatively unconstrained by experiment, so that couplings such asūtZ may be substantial.…”

Section: Figmentioning

confidence: 99%

LightZ′bosons at the Tevatron

et al. 2011

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New gauge bosons with Standard Model-like couplings to leptons are constrained by collider searches to be heavier than approximately ∼1 TeV. A Z boson with suppressed couplings to leptons, however, could be much lighter and possess substantial couplings to Standard Model quarks. In this article, we consider a new leptophobic Z gauge boson as a simple and well motivated extension of the Standard Model, and discuss several of its possible signatures at the Tevatron. We find that three of the recent anomalies reported from the Tevatron-in particular the top-quark forward-backward asymmetry and excesses in the 3b and W + 2 jets final states-could be explained by a new Z with a mass of approximately 150 GeV, relatively large couplings to quarks, and suppressed couplings to electrons and muons. Moreover, we find that such a particle could also mediate the interactions of dark matter, leading to potentially interesting implications for direct detection experiments.

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Section: Figmentioning

confidence: 99%

LightZ′bosons at the Tevatron

et al. 2011

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“…The flavor changing Z has been also expected in theories with dynamical symmetry breaking approach. The top quark flavor changing have already been studied in many papers in the context of non-universality, where the strength of the couplings are different among different generations [21][22][23][24][25][26][27][28][29][30][31][32][33]. There are also beyond the SM theories where the flavor changing could proceed through color sextet vector and scalar bosons [34,35].…”

Section: Introductionmentioning

confidence: 99%

Same-sign top pair plus W production in flavor changing vector and scalar models

et al. 2018

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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 φ 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 , φ.

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“…The models generating the observed Tevatron A t FB at tree level mainly fall into two categories: (i) s-channel exchange of vector mediators, the couplings of which to the top and the light quarks are axial and of opposite sign [11][12][13][14][15][16][17][18][19], 1 or (ii) t-channel exchange of flavor violating mediators such as new W 0 =Z 0 gauge bosons [21][22][23][24][25][26][27] or colored particles [28][29][30]. For various models of types (i) and (ii), comparative studies can be found in the literature [31][32][33][34][35][36][37][38][39].…”

Section: Introductionmentioning

confidence: 99%

Searching for top flavor violating resonances

2011

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We study new top flavor violating resonances that are singly produced in association with a top at the LHC. Such top flavor violating states could be responsible for the Tevatron top forward-backward asymmetry. Since top flavor violating states can directly decay to a top (or antitop) and jet, and are produced in conjunction with another (oppositely charged) top, the direct signature of such states is a tj (or " tj) resonance in t " tj events. In general, these states can be very light and have Oð1Þ couplings to the top sector so that they are copiously produced. We present a search strategy and estimate the discovery potential at the early LHC by implementing the strategy on simulated data. For example, with 1 fb À1 at 7 TeV, we estimate that a W 0 coupling to d R " t R can be constrained at the 3 level for g R ¼ 1 and m W 0 ¼ 200 GeV, weakening to g R ¼ 1:75 for m W 0 ¼ 600 GeV. With the search we advocate here, a bound at a similar level could be obtained for top flavor violating Z 0 s, as well as triplet and sextet diquarks.

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Flavor changingZ′couplings at the LHC

Cited by 18 publications

References 27 publications

LightZ′bosons at the Tevatron

LightZ′bosons at the Tevatron

Same-sign top pair plus W production in flavor changing vector and scalar models

Searching for top flavor violating resonances

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