Detecting and Studying Higgs Bosons at a Photon-Photon Collider

TL;DR

This work provides a comprehensive assessment of Higgs detection and property measurement at a photon-photon collider tied to a future linear collider. By using realistic CAIN-based γγ luminosity spectra and detector-level simulations, it demonstrates that a SM-like light Higgs can have its γγ width measured to ≈2–3% accuracy, and that heavy MSSM Higgs bosons H^0/A^0 (and a light A^0 in a general 2HDM) could be discovered in substantial portions of the LHC wedge region, often complementing LHC and e+e− LC capabilities. It also outlines strategies to determine the CP nature of Higgs states via photon polarization and discusses the practical running scenarios that optimize discovery potential. The study emphasizes the synergy between γγ Higgs physics and broader collider programs, highlighting detector design and polarization requirements as critical for achieving the projected sensitivities. Overall, γγ collisions offer a powerful, complementary path to completing the Higgs sector map below ≈500 GeV and probing extended Higgs sectors with high precision.

Abstract

We examine the potential for detecting and studying Higgs bosons at a photon-photon collider facility associated with a future linear collider. Our study incorporates realistic $\gam\gam$ luminosity spectra based on the most probable available laser technology. Results include detector simulations. We study the cases of: a) a SM-like Higgs boson; b) the heavy MSSM Higgs bosons; c) a Higgs boson with no $WW/ZZ$ couplings from a general two Higgs doublet model.

Figures (25)

• Figure 1: The normalized differential luminosity ${1\over {\cal L}_{\gamma\gamma}}{d{\cal L}_{\gamma\gamma}\over dy}$ and the corresponding $\langle \lambda\lambda' \rangle$ for $\lambda_e=\lambda'_e=.4$ (80% polarization) and three different choices of the initial laser photon polarizations $P$ and $P'$. The distributions shown are for $\rho^2\ll 1$Ginzburg:1983vmGinzburg:1984yr. Results for $x=5.69$, $x=4.334$ and $x=1.86$ are compared.
• Figure 2: We plot the CAIN cainref predictions for the $\gamma\gamma$ luminosity, $L=d{\cal L}/dE_{\gamma\gamma}$, in units of $~{\rm fb}^{-1}/3.33 ~{\rm GeV}$ (3.33 GeV being the bin size) for circularly polarized [case (II)] photons assuming a $10^7$ sec year, $\sqrt s=160~{\rm GeV}$, 80% electron beam polarization, and a 1.054/3 micron laser wave length. Beamstrahlung and other effects are included. The dashed (dotted) curve gives the component of the total luminosity that derives from the $J_z=0$ ($J_z=2$) two-photon configuration. Also plotted is the corresponding value of $\langle \lambda\lambda' \rangle$ [given by $\langle \lambda\lambda' \rangle=(L_{J_z=0}-L_{J_z=2})/(L_{J_z=0}+L_{J_z=2})$].
• Figure 3: Higgs signal and heavy quark backgrounds in units of events per 2 GeV for a Higgs mass of 120 GeV and assuming a running year of $10^7$ sec. We have employed the cuts as given in the text.
• Figure 4: $5\sigma$ discovery contours for MSSM Higgs boson detection in various channels are shown in the $[m_{A^0},\tan\beta]$ parameter plane, assuming maximal mixing and an integrated luminosity of $L=300~{\rm fb}^{-1}$ for the ATLAS detector. This figure is preliminary atlasmaxmix.
• Figure 5: We plot the integrated $H^0$ and $A^0$ Higgs cross sections $I_\sigma$, as defined in Eq. (\ref{['ngamgam']}), as a function of Higgs mass, for a variety of $\tan\beta$ values. We employ the maximal-mixing scenario with $m_{\rm SUSY}=1~{\rm TeV}$. Supersymmetric particle loops are neglected.