Angular distributions in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>t</mml:mi><mml:mover accent="true"><mml:mi>t</mml:mi><mml:mo stretchy="false">¯</mml:mo></mml:mover><mml:mi>H</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mi>H</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:mi>b</mml:mi><mml:mover accent="true"><mml:mi>b</mml:mi><mml:mo stretchy="false">¯</mml:mo></mml:mover><mml:mo stretchy="false">)</mml:mo></mml:math>reconstructed events at the LHC

Santos, S. P. Amor Dos; Araque, J. P.; Cantrill, R.; Castro, N. F.; Fiolhais, M. C. N.; Frederix, Rikkert; Martins, R. S.; Santos, Rui; Silva, J.; Onofre, A.; Peixoto, Hugo; Reigoto, A.

doi:10.1103/physrevd.92.034021

Cited by 19 publications

(20 citation statements)

References 72 publications

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“…Moreover, background discrimination in this channel can be enhanced using these angular variables. Although results are consistent with what was observed in an analysis of the dileptonic tth channel [17,18], the signal sensitivity of the semileptonic analysis reported here is larger than the dileptonic one. As in the dileptonic analysis [18], all the mixed states of CP-even and CP-odd couplings gave results between the ones obtained with cos α ¼ 0 and cos α ¼ 1; only these two extreme cases are considered in the present analysis.…”

Section: Introductionsupporting

confidence: 80%

“…The results obtained in the semileptonic channel are almost a factor 2 better than the ones presented for the dileptonic channel in Ref. [17]. Combining both channels should allow one to decrease the luminosity needed to probe the structure of Higgs boson couplings to the top quarks.…”

Section: Resultsmentioning

confidence: 56%

“…Given the good performance of the kinematic reconstruction in semileptonic decays of tth, we study the following angular distributions and corresponding asymmetries defined in Ref. [17]: cosðθ¯t FB , as defined in Ref. [15].…”

Section: Angular Observablesmentioning

confidence: 99%

“…For the reconstruction of the angular distributions, we use the spin helicity formalism and, generically, define θ X Y as the angle between the momentum direction of the Y particle (or system), measured in the rest frame of X, with respect to the direction of X, in the rest frame of its parent particle [17]. As particles follow successive decays starting from the tth center-of-mass system (X ¼ tth) until all intermediate particles have decayed, X defined above includes three-, two-, and single-particle systems.…”

Section: Angular Observablesmentioning

confidence: 99%

“…We consider several CP-sensitive angular distributions introduced in the literature [15][16][17]. These are evaluated for the first time in semileptonic final states of tth decays in this paper.…”

Section: Introductionmentioning

confidence: 99%

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CP tests of Higgs couplings in tt¯h semileptonic events at the LHC

2018

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The CP nature of the Higgs coupling to top quarks is addressed in this paper, in single charged lepton final states of tth events produced in proton-proton collisions at the LHC. Pure scalar (h ¼ H) and pseudoscalar (h ¼ A) Higgs boson signal events, generated with MADGRAPH5_AMC@NLO, are fully reconstructed using a kinematic fit. Angular distributions of the decay products, as well as CP-sensitive asymmetries, are exploited to separate and gain sensitivity to possible pseudoscalar components of the Higgs boson and reduce the contribution from the dominant irreducible background ttbb. Significant differences are found between the pure CP-even and -odd signal hypotheses as well as with respect to the Standard Model background, in particular the ttbb contribution. Such differences survive the event reconstruction, allowing one to define optimal observables to extract the Higgs couplings parameters from a global fit. A dedicated analysis is applied to efficiently identify signal events and reject as much as possible the expected Standard Model background. The results obtained are compared with a similar analysis in the dilepton channel. We show that the single lepton channel is more promising overall and can be used in combination to study the CP nature of the Higgs coupling to top quarks.

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Section: Introductionsupporting

confidence: 80%

Section: Resultsmentioning

confidence: 56%

Section: Angular Observablesmentioning

confidence: 99%

Section: Angular Observablesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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CP tests of Higgs couplings in tt¯h semileptonic events at the LHC

2018

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Light Higgs searches in $$ t\overline{t}\phi $$ production at the LHC

Azevedo

Capucha

Gouveia

et al. 2021

J. High Energ. Phys.

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In this paper we propose a new reconstruction method to explore the low mass region in the associated production of top-quark pairs ($$ t\overline{t} $$ t t ¯ ) with a generic scalar boson (ϕ) at the LHC. The new method of mass reconstruction shows an improved resolution of at least a factor of two in the low mass region when compared to previous methods, without the loss of sensitivity of previous analyses. It turns out that it also leads to an improvement of the mass reconstruction of the 125 GeV Higgs for the same production process. We use an effective Lagrangian to describe a scalar with a generic Yukawa coupling to the top quarks. A full phenomenological analysis was performed, using Standard Model background and signal events generated with MadGraph5_aMC@NLO and reconstructed using a kinematic fit. The use of CP-sensitive variables allows then to maximize the distinction between CP-even and CP-odd components of the Yukawa couplings. Confidence Levels (CLs) for the exclusion of ϕ bosons with mixed CP (both CP-even and CP-odd components) were determined as a function of the top Yukawa couplings to the ϕ boson. The mass range analysed starts slightly above the ϒΥ mass up to 40 GeV, although the analysis can be used for an arbitrary mass. If no new light scalar is found, exclusion limits at 95% CL for the absolute value of the CP-even and CP-odd Yukawa are derived. Finally, we analyse how these limits constrain the parameter space of the complex two-Higgs doublet model (C2HDM).

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Probing the top-Higgs Yukawa CP structure in dileptonic $$ t\overline{t}h $$ with M2-assisted reconstruction

Gonçalves

Kim

Kong

2018

J. High Energ. Phys.

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Constraining the Higgs boson properties is a cornerstone of the LHC program. We study the potential to directly probe the Higgs-top CP-structure via the tth channel at the LHC with the Higgs boson decaying to a bottom pair and top-quarks in the dileptonic mode. We show that a combination of laboratory and tt rest frame observables display large CP-sensitivity, exploring the spin correlations in the top decays. To efficiently reconstruct our final state, we present a method based on simple mass minimization and prove its robustness to shower, hadronization and detector effects. In addition, the mass reconstruction works as an extra relevant handle for background suppression. Based on our results, we demonstrate that the Higgs-top CP-phase (α) can be probed up to cos α < 0.7 at the high luminosity LHC.

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Angular distributions intt¯H(H→bb¯)reconstructed events at the LHC

Cited by 19 publications

References 72 publications

CP tests of Higgs couplings in tt¯h semileptonic events at the LHC

CP tests of Higgs couplings in tt¯h semileptonic events at the LHC

Light Higgs searches in $$ t\overline{t}\phi $$ production at the LHC

Probing the top-Higgs Yukawa CP structure in dileptonic $$ t\overline{t}h $$ with M2-assisted reconstruction

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