Probing Higgs Bosons with Large Bottom Yukawa Coupling at Hadron Colliders

TL;DR

The paper develops a model-independent framework to probe Higgs bosons with large bottom Yukawa couplings via the φ b bbar -> b bbar b bbar channel at the Tevatron and the LHC. It estimates signals and major backgrounds, applies asymmetric kinematic cuts, and derives a minimum enhancement factor K_min relating observable signal to the SM case. Applying this to dynamical models with strongly coupled electroweak sectors and to MSSM in the large tanβ regime, it shows that current and future hadron colliders can either discover or strongly constrain such scenarios, with Tevatron Run II testing many regions and the LHC extending reach up to ~1 TeV for certain states. The results highlight the bb-associated Higgs channel as a valuable complement to LEP and other Higgs searches, while noting uncertainties from missing NLO corrections and the need for efficient b-tagging and triggering.

Abstract

The small mass of the bottom quark, relative to its weak isospin partner, the top quark, makes the bottom an effective probe of new physics in Higgs and top sectors. We study the Higgs boson production associated with bottom quarks, ppbar/pp to phi+b+bbar to 4b, at the Fermilab Tevatron and the CERN LHC. We find that strong and model-independent constraints on the size of the phi-b-bbar coupling can be obtained for a wide range of Higgs boson masses. Their implications for the composite Higgs models with strong dynamics associated with the third family quarks (such as the top-condensate/topcolor models with naturally large bottom Yukawa couplings), and for the supersymmetric models with large tan(beta), are analyzed. We conclude that the Tevatron and the LHC can put stringent bounds on these models, if the phi+b+bbar signal is not found.

Figures (16)

• Figure 1: Representative leading order Feynman diagrams for $\phi b \bar{b}$ production at a hadron collider. The decay $\phi \rightarrow b \bar{b}$ is not shown.
• Figure 2: Representative Feynman diagrams for leading order $Z b \bar{b}$ production at a hadron collider. The decay $Z \rightarrow b \bar{b}$ is not shown.
• Figure 3: Representative leading order Feynman diagrams for QCD $b \bar{b} b \bar{b}$ production at a hadron collider.
• Figure 4: Representative leading order Feynman diagrams for QCD $b \bar{b} j j$ production at a hadron collider.
• Figure 5: Figure (a) shows the distribution of the QCD $b \bar{b} b \bar{b}$ background (solid curve) and $K = 40$$\phi b \bar{b}$ signal (dashed curve) cross sections in $p^{(1)}_T$ at the Tevatron Run II after the acceptance cuts. [$K=y_b/(y_b)_{\rm SM}$, cf. Eq. (1).] Figure (b) presents the distribution of $p^{(2)}_T$ at the Tevatron Run II after applying the cut to $p^{(1)}_T$, illustrating the utility of asymmetric cuts on $p^{(1)}_T$ and $p^{(2)}_T$ in extracting the $\phi b \bar{b}$ signal from the QCD background.