The Precision of Higgs Boson Measurements and Their Implications

TL;DR

The paper surveys how future colliders can illuminate the Higgs sector, emphasizing precision measurements at a Linear Collider to test SM predictions and reveal extended Higgs sectors such as the MSSM and NMSSM. It analyzes mass, width, quantum numbers, and couplings of a SM-like Higgs, detailing how different facilities (LHC, Tevatron, LC, γC, μC) can measure these properties and what that implies about new physics. It highlights CP violation, heavy Higgs states, and exotic sectors like singlets and radions, showing complementary discovery reach across collider types and parameter spaces. The work argues that while the LHC can establish a Higgs-like state and its basic properties, a high-precision, dedicated lepton collider is essential to fully resolve the Higgs sector and constrain or reveal physics beyond the Standard Model.

Abstract

The prospects for a precise exploration of the properties of a single or many observed Higgs bosons at future accelerators are summarized, with particular emphasis on the abilities of a Linear Collider (LC). Some implications of these measurements for discerning new physics beyond the Standard Model (SM) are also discussed.

Figures (6)

• Figure 1: (left) Required integrated luminosity to achieve different levels of statistical significance for SM Higgs boson searches at the Tevatron; (right) Statistical significance of SM Higgs boson searches for different amounts of integrated luminosity at the LHC.
• Figure 2: (left) Higgsstrahlung and $WW$-fusion cross sections for SM Higgs boson production at a LC for various $\sqrt{s}$; (right) Recoil mass spectrum for $e^+e^-\to Zh$ with $Z\to\mu^+\mu^-$ signal and continuum background at a $\sqrt{s}=350$ GeV LC with 500 fb$^{-1}$ of data and $m_h=120$ GeV.
• Figure 3: Relative accuracy expected at the LHC with 200 fb$^{-1}$ of data for (a) various ratios of Higgs boson partial widths and (b) the indirect determination of partial and total widths $\tilde{\Gamma}$ and $\tilde{\Gamma}_i=\Gamma_i(1-\epsilon)$. Simulations have been performed at the parton level for WBF processes. Width ratio extractions only assume $W,Z$ universality, which can be tested at the 15 to 30% level (solid line). Indirect width measurements assume $b,\tau$ universality in addition and require a small branching ratio $\epsilon$ for unobserved modes like $H\to c\bar{c}$ and decays beyond the SM.
• Figure 4: Contours of $\delta {\rm BR}(b) = 3$ and 6% (solid), $\delta {\rm BR}(W) = 8$ and 16% (long-dashed) and $\delta {\rm BR}(g) = 8$ and 16% (short-dashed) in the three benchmark scenarios.
• Figure 5: LHC coverage of the $m_A-\tan\beta$ plane for a conservative Susy model, but neglecting potentially large corrections at large $\tan\beta$.