When the Higgs meets the top: Search fort→ch0at the LHC

Abstract

The newly discovered "Higgs" boson h 0 , being lighter than the top quark t, opens up new probes for flavor and mass generation. In the general two Higgs doublet model, new ct, cc and tt Yukawa couplings could modify h 0 properties. If t → ch 0 occurs at the percent level, the observed ZZ * and γγ signal events may have accompanying cbW activity coming from tt feeddown. We suggest that t → ch 0 can be searched for via h 0 → ZZ * , γγ, W W * and bb, perhaps even τ + τ − modes in tt events. Existing data might be able to reveal some clues for t → ch 0 signature, or push the branching ratio B(t → ch 0 ) down to below the percent level.

Search for top quark decays t → qH with H → γγ using the ATLAS detector

“…Examples of such extensions are the quark-singlet model (QS) [18][19][20], two-Higgs-doublet models (2HDM) of type I, with explicit flavour conservation, and of type II, such as the minimal supersymmetric standard model (MSSM) [21][22][23][24][25][26][27]. In 2HDM without explicit flavour conservation (type III) [28][29][30][31][32][33][34][35][36], the tc(u)H couplings are present at tree level. For a review of the different models see ref.…”

Enhancing thj production from top-Higgs FCNC couplings

“…mechanism [15][16][17][18]. But they can be greatly enhanced by the extended flavor structures in many new physics models, for example the minimal supersymmetric model (MSSM) with/without R-parity [19][20][21][22][23][24][25][26][27][28][29][30][31][32], two-Higgsdoublet model (2HDM) type-III [33][34][35][36][37][38][39][40][41][42][43][44][45], and the other miscellaneous models [46][47][48][49][50][51][52][53][54][55][56][57][58][59][60]. So the study of top-Higgs FCNC interactions is a common interest of the theory and experiment communities [61][62][6...…”

Higgs bosons from top quark decays

“…NLO QCD contributions increase this by 10% [8]. However, new physics beyond the SM (BSM), such as an extended Higgs sector [6,[9][10][11][12] or Supersymmetry (SUSY) [13][14][15], can significantly enhance this decay, making it a very sensitive channel to new physics.…”

“…As dimension-six tW bh verticies originate from terms of the form tW b(v + h) [25,29], the size of anomalous 4-point tW bh couplings are restricted to be small by the stringent limits on anomalous tW b couplings [28,30,[37][38][39][40]. Anomalous htc/u couplings are constrained to be small [12,[41][42][43].…”