Higgs couplings and Naturalness in the littlest Higgs model with T-parity at the LHC and TLEP

TL;DR

This paper analyzes how current and future collider data constrain the parameters of the littlest Higgs model with T-parity, focusing on Higgs couplings, naturalness, and the masses of new particles.

Contribution

It provides updated bounds on the model's scale and top partner mass using recent data and forecasts future collider sensitivities to these parameters.

Findings

Current data exclude the scale f up to 600 GeV at 2σ.

Future TLEP measurements could push this limit above 3 TeV.

The top partner mass m_{T_{+}} is constrained up to 880 GeV at 2σ.

Abstract

Motivated by the recent LHC Higgs data and null results in searches for any new physics, we investigate the Higgs couplings and naturalness in the littlest Higgs model with T-parity. By performing the global fit of the latest Higgs data, electroweak precise observables and $R_{b}$ measurements, we find that the scale $f$ can be excluded up to 600 GeV at $2\sigma$ confidence level. The expected Higgs coupling measurements at the future collider TLEP will improve this lower limit to above 3 TeV. Besides, the top parnter mass $m_{T_{+}}$ can be excluded up to 880 GeV at $2\sigma$ confidence level. The future HL-LHC can constrain this mass in the region $m_{T_{+}} < 2.2$ TeV corresponding to the fine-tuning being lager than 1%.