Full analysis of general non-standard tbW couplings

Hioki, Zenrō; Ohkuma, Kazumasa

doi:10.1016/j.physletb.2015.11.029

Cited by 17 publications

(22 citation statements)

References 52 publications

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“…3. The new bounds onc γ and c W t lie well below the prospected sensitivities of the LHC [18,21,27] and envisioned [20,21] collider experiments.…”

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confidence: 77%

“…Despite the vast literature on top-gluon [5][6][7][8][9][10][11][12][13][14][15][16], top-photon [17][18][19][20][21], top-W [22][23][24][25][26][27][28], top Yukawa [29][30][31][32][33][34][35][36] couplings, and global analyses [37][38][39][40][41][42], the impact of electric dipole moments (EDMs) has received comparatively little attention [17,29,37,43,44]. The central new element of our work is the systematic inclusion of EDM constraints.…”

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confidence: 99%

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Is there room forCPviolation in the top-Higgs sector?

et al. 2016

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We discuss direct and indirect probes of chirality-flipping couplings of the top quark to Higgs and gauge bosons, considering both CP-conserving and CP-violating observables, in the framework of the Standard Model effective field theory. In our analysis we include current and prospective constraints from collider physics, precision electroweak tests, flavor physics, and electric dipole moments (EDMs). We find that low-energy indirect probes are very competitive, even after accounting for long-distance uncertainties. In particular, EDMs put constraints on the electroweak CP-violating dipole moments of the top that are two to three orders of magnitude stronger than existing limits. The new indirect constraint on the top EDM is given by |dt| < 5 · 10−20 e cm at 90% C.L. Introduction:The top quark might offer a first gateway to physics beyond the Standard Model (BSM), due to its large coupling to the Higgs and hence to the electroweak symmetry breaking sector. In several scenarios, ranging from partial compositeness [1] to supersymmetric models with light stops [2], enhanced deviations from the SM are expected in the top sector which can be relevant for electroweak baryogenesis [2,3]. Experiments at the Large Hadron Collider (LHC) offer a great opportunity to directly probe non-standard top quark couplings. On the other hand, these same couplings also affect via quantum corrections processes that do not involve a top quark. Such "indirect probes" give very valuable complementary information and in several cases constrain non-standard top couplings more strongly than direct searches.In this letter we discuss direct and indirect probes of chirality-flipping top-Higgs couplings, including both CP-conserving (CPC) and CP-violating (CPV) interactions, the latter being of great interest in light of Sakharov's conditions for baryogenesis [4]. Despite the vast literature on top-gluon [5][6][7][8][9][10][11][12][13][14][15][16] [37][38][39][40][41][42], the impact of electric dipole moments (EDMs) has received comparatively little attention [17,29,37,43,44]. The central new element of our work is the systematic inclusion of EDM constraints. Even after properly taking into account the hadronic and nuclear uncertainties [44], EDMs dominate the bounds on all the CPV top couplings. Our major finding is that bounds on the top EDM (weak EDM) are improved by three (two) orders of magnitude over the previous literature. As part of our analysis, we also update indirect constraints from Higgs production and decay.We work in the linear SM Effective Field Theory (SM-EFT) framework [45][46][47][48][49]. We assume that a gap exists between the scale of new physics Λ and the electroweak scale v = 246 GeV and keep only the leading terms in (v/Λ) 2 , corresponding to dimension-six operators. We assume that at the high-scale Λ the largest non-standard effects appear in the top sector, and hence set to zero all

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“…3. The new bounds onc γ and c W t lie well below the prospected sensitivities of the LHC [18,21,27] and envisioned [20,21] collider experiments.…”

mentioning

confidence: 77%

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confidence: 99%

Is there room forCPviolation in the top-Higgs sector?

et al. 2016

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“…[12,30,31,33,35,44,[46][47][48]). Forc γ ,c W t ,c W b , we find that EDMs provide stronger bounds than previously realized.…”

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confidence: 99%

Constraining the top-Higgs sector of the standard model effective field theory

et al. 2016

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Working in the framework of the Standard Model Effective Field Theory, we study chirality-flipping couplings of the top quark to Higgs and gauge bosons. We discuss in detail the renormalization group evolution to lower energies and investigate direct and indirect contributions to high-and low-energy CP-conserving and CP-violating observables. Our analysis includes constraints from collider observables, precision electroweak tests, flavor physics, and electric dipole moments. We find that indirect probes are competitive or dominant for both CP-even and CP-odd observables, even after accounting for uncertainties associated with hadronic and nuclear matrix elements, illustrating the importance of including operator mixing in constraining the Standard Model Effective Field Theory. We also study scenarios where multiple anomalous top couplings are generated at the high scale, showing that while the bounds on individual couplings relax, strong correlations among couplings survive. Finally, we find that enforcing minimal flavor violation does not significantly affect the bounds on the top couplings.

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“…Thus, model-independent analyses would be an important key to building new-physics models beyond the standard model as a bottom-up approach. In this proceedings, we report the constraints on the most general non-standard tbW couplings in the effective Lagrangian based on our two recent studies [1,2].…”

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confidence: 99%

“…Table 2: Allowed maximum and minimum values of non-standard-top-decay couplings in the case that all the couplings are dealt with as free parameters except for Re(δ f L 1 ) being set to be zero. The preceding works are listed in [1,2], and here we add Refs. [5,6,7] to the lists.…”

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confidence: 99%

Constraints on generalized nonstandard $tbW$ couplings

Ohkuma¹,

Hioki²,

Uejima³

2017

Proceedings of 38th International Conference on High Energy Physics — PoS(ICHEP2016)

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General non-standard tbW couplings are studied as model independently as possible based on the effective Lagrangian consisting of the dimension-6 operators, which is an extension of the standard-model Lagrangian. The tbW -interaction Lagrangian in this framework includes four kinds of couplings, which could be complex. Constraints on those non-standard tbW couplings are obtained by comparing the experimental data related to the t → bW process with the corresponding theoretical formulas derived from the effective Lagrangian. The constraints on some sets of the non-standard couplings are shown not to be so strong because those couplings balance out each other as we treat all the non-standard couplings as complex numbers at the same time.

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Full analysis of general non-standard tbW couplings

Cited by 17 publications

References 52 publications

Is there room forCPviolation in the top-Higgs sector?

Is there room forCPviolation in the top-Higgs sector?

Constraining the top-Higgs sector of the standard model effective field theory

Constraints on generalized nonstandard $tbW$ couplings

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