Double Higgs Production and Quadratic Divergence Cancellation in Little Higgs Models with T Parity

TL;DR

This paper investigates Higgs pair production at the LHC in Little Higgs models, linking the production process to the mechanism that cancels Higgs quadratic divergences. Using the Littlest Higgs model with and without T-parity, the authors compute gg→HH amplitudes including triangle and box diagrams with both the SM top and the heavy top partner, derive the couplings, and evaluate cross sections with LoopTools. They show that T-parity allows a low symmetry-breaking scale f (~500 GeV), leading to sizable deviations from the SM in Higgs pair production, especially for light Higgs. The results indicate that LHC observations of Higgs pair production could distinguish Little Higgs scenarios from the SM in favorable regions and provide a test of the divergence-cancellation structure.

Abstract

We analyze double Higgs boson production at the Large Hadron Collider in the context of Little Higgs models. In double Higgs production, the diagrams involved are directly related to those that cause the cancellation of the quadratic divergence of the Higgs self-energy, providing a robust prediction for this class of models. We find that in extensions of this model with the inclusion of a so-called T-parity, there is a significant enhancement in the cross sections as compared to the Standard Model.

Figures (6)

• Figure 1: One-loop corrections to the Higgs mass, to order $v/f$: (a) standard top quark loop, (b) mixture of standard and extra top quark loop, (c) extra top quark loop with a 4-particle vertex, and (d) tadpoles with standard and with extra top quark loops. There are other diagrams but they are suppressed by factors of order $(v/f)^2$ or higher.
• Figure 2: Triangle contributions to Higgs boson pair production at LHC in a Little Higgs model.
• Figure 3: Box contributions to Higgs boson pair production at LHC in a Little Higgs model.
• Figure 4: Cross section for double Higgs production at the LHC for $M_T = 4$ TeV and $f =500$ GeV (dashed line), $1000$ GeV (short dashed line) and $2000$ GeV (dotted line). In solid line is shown the SM result.
• Figure 5: Cross section for double Higgs production at the LHC for $M_H = 200$ GeV and $f = 1000$ GeV, as a function of the heavy top quark mass $M_T$.