Precise Predictions for Hadronic Higgs Decays

Abstract

The prospect of future electron-positron colliders operating as "Higgs factories" in a clean experimental environment presents one of the most promising avenues for Higgs precision measurements. In order to capitalise on this, we need to have good theoretical control over these observables. In this talk, I will report on recent calculations in Hadronic Higgs decays, focusing in particular on the variations between the dominant $H\to b \bar{b}$ channel via a Yukawa interaction, and the sub-dominant $H\to gg$ channel. Using the newly-developed "generalised antenna formalism", we have been able to calculate jet-rates and classical QCD event-shape observables up to NNLO accuracy, providing us with the means to quantify the differences between the two decay modes. For a subset of observables, we also match these NNLO results to NNLL resummation to obtain valid predictions even in the back-to-back limit.

Figures (6)

• Figure 1: Normalised three-jet decay rate at LO (green), NLO (blue) and NNLO (red) for Higgs decay to bottom quarks (left), Higgs to gluons (centre), and the weighted sum of the different decay modes (right). The corresponding inclusive decay rate is used as normalisation (see text).
• Figure 2: Thrust distributions for the $H\to b\bar{b}$ channel (top row), the $H\to gg$ channel (middle row) and the sum of all decay modes at NNLO (bottom row). In Frames 1 and 2, the LO (green), NLO (blue), and NNLO (red) are shown. In Frame 3, the individual contributions of the $H\to b\bar{b}$ (orange), $H\to gg$ (purple), and the $H\to c\bar{c}$ (light blue) channels are displayed alongside the sum (teal).
• Figure 3: Comparison of resummed results for thrust at LL (green), NLL (blue), and NNLL (red) in $H\to q\bar{q}$ decays (left) and $H\to gg$ decays (right).
• Figure 4: Comparison between the expansion of the resummation formula (solid lines) and the fixed-order results (dashed lines) up to $\mathcal{O}(\alpha_s)$ (LO, green), $\mathcal{O}(\alpha_s^2)$ (NLO, blue) and $\mathcal{O}(\alpha_s^3)$ (NNLO, red). The difference between the fixed-order and the expansion of the resummation formula is shown in the lower frames.
• Figure 5: Thrust distribution results for fixed-order predictions matched to resummation in the logR scheme, for the $H\to q\bar{q}$ channel (left column) and the $H\to gg$ channel (right column), on a linear scale (top row) and on a log scale (bottom row). The curves represent the LO calculation matched to NLL resummation (green), NLO matched to NNLL (blue) and NNLO matched to NNLL (red). Vertical error bars indicate statistical Monte Carlo errors, while error bands show the combined scale variation