Probing the CP properties of top Yukawa coupling at an e+e− collider

Hagiwara, Kaoru; Yokoya, Hiroshi; Zheng, Y.

doi:10.1007/jhep02(2018)180

Cited by 16 publications

(19 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By using the identities (2.33) and (2.35) among the sub-amplitudes, we find the relation 37) between Mσ and M σ , whenσ = −σ. It is worth noting that if we ignore the absorptive phase of the amplitudes, such as the top quark width in the propagator, the above identity gives…”

Section: Jhep09(2020)101mentioning

confidence: 97%

“…Hadronically decaying t andt events can have sensitivity to the asymmetries, because their decay density matrix polarimeter introduced in ref. [37] retains strong sensitivity to the t andt polarizations, and also because the CP asymmetry of the polarizations, P 2 (thj) ≈ −P 2 (thj) in figure 15 tells that the observable asymmetries in the decay distributions are the same between t andt events even if we cannot distinguish between them. Although the direct test of CP violation cannot be made in the hadronic decay modes, the sensitivity to the sign and the magnitude of the CP violating phase ξ can be improved by assuming the SM radiative contribution to the asymmetries [43].…”

Section: Jhep09(2020)101mentioning

confidence: 99%

“…In this appendix we give t andt decay angular distributions for both semi-leptonic and hadronic decay modes. The decay density matrix for semi-leptonic decay modes is very simple because it depends only on the charged lepton polar and azimuthal angles [28,37,39] dρ(t → b + ν) = B(t → b ν)…”

Section: B Polarized T Andt Decay Distributionsmentioning

confidence: 99%

See 2 more Smart Citations

Probing the top Yukawa coupling at the LHC via associated production of single top and Higgs

Barger

Hagiwara

Zheng

2020

J. High Energ. Phys.

Self Cite

View full text Add to dashboard Cite

We study Higgs boson production associated with single top or anti-top via t-channel weak boson exchange at the LHC. The process is an ideal probe of the top quark Yukawa coupling, because we can measure the relative phase of htt and hWW couplings, thanks to the significant interference between the two amplitudes. By choosing the emitted W momentum along the polar axis in the th ($$ \overline{t}h $$ t ¯ h ) rest frame, we obtain the helicity amplitudes for all the contributing subprocesses analytically, with possible CP phase of the Yukawa coupling. We study the azimuthal asymmetry between the W emission and the Wb ($$ \overline{b} $$ b ¯ ) → t($$ \overline{t} $$ t ¯ ) h scattering planes, as well as several t and $$ \overline{t} $$ t ¯ polarization asymmetries as a signal of CP violating phase in the htt coupling. Both the azimuthal asymmetry and the polarization perpendicular to the scattering plane are found to have the opposite sign between the top and anti-top events. We identify the origin of the sign of asymmetries, and propose the possibility of direct CP violation test in pp collisions by comparing the top and anti-top polarization at the LHC.

show abstract

Section: Jhep09(2020)101mentioning

confidence: 97%

Section: Jhep09(2020)101mentioning

confidence: 99%

See 1 more Smart Citation

Probing the top Yukawa coupling at the LHC via associated production of single top and Higgs

Barger

Hagiwara

Zheng

2020

J. High Energ. Phys.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Angular distribution of decay products, in particular the visible lepton from its semileptonic decay is found to carry polarization information of the parent top quark [10]. Extraction of polarization information of top quark by exploiting the various kinematic distributions of charged lepton is discussed in great detail in the literature [10][11][12][13][14][15][16][17]. Moreover, top polarization also has been studied well using the matrix element method [6,[18][19][20] In this study we attempt to develop a strategy to measure the top quark polarization in its hadronic decay, in particular when it is boosted.…”

Section: Introductionmentioning

confidence: 99%

Boosted top quark polarization

et al. 2019

View full text Add to dashboard Cite

In top quark production, the polarization of top quarks, decided by the chiral structure of couplings, is likely to be modified in the presence of any new physics contribution to the production. Hence it is a good discriminator for those new physics models wherein the couplings have a chiral structure different than that in the Standard Model (SM). In this note we construct probes of the polarization of a top quark decaying hadronically, using easily accessible kinematic variables such as the energy fraction or angular correlations of the decay products. Tagging the boosted top quark using jet sub structure technique, we study robustness of these observables for a benchmark process, W → tb. We demonstrate that the energy fraction of b-jet in the laboratory frame and a new angular variable, constructed by us in the top rest frame, are both very powerful tools to discriminate between the left and right polarized top quarks. Based on the polarization sensitive angular variables, we construct asymmetries which reflect the polarization. We study the efficacy of these variables for two new physics processes where which give rise to boosted top quarks: (i) decay of the top squark in the context of supersymmetry searches, and (ii) decays of the Kaluza-Klein(KK) graviton and KK gluon, in Randall Sundrum(RS) model. Remarkably, it is found that the asymmetry can vary over a wide range about +20% to -20%. The dependence of asymmetry on top quark couplings of the new particles present in these models beyond the SM (BSM) is also investigated in detail. 1

show abstract

“…However, these possible CP-violating interactions are one-loop suppressed, arising only via operators of dimension-6 or higher [20,21]. On the other hand, CP-odd Higgs fermion interactions could manifest already at the tree level, being naturally more sensitive to new physics [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. Of special interest is the Higgs coupling to top quarks, as y SM t ∼ 1.…”

Section: Introductionmentioning

confidence: 99%

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.

View full text Add to dashboard Cite

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.

show abstract

Probing the CP properties of top Yukawa coupling at an e+e− collider

Cited by 16 publications

References 27 publications

Probing the top Yukawa coupling at the LHC via associated production of single top and Higgs

Probing the top Yukawa coupling at the LHC via associated production of single top and Higgs

Boosted top quark polarization

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

Contact Info

Product

Resources

About