Exploring correlations between HEFT Higgs couplings $$\kappa _V$$ κ V and $$\kappa _{2V}$$ κ 2 V via HH production at $$e^+e^-$$ e + e - colliders

Abstract

Abstract In this work we explore the phenomenological implications at future $$e^+e^-$$ e + e - colliders of assuming anomalous couplings of the Higgs boson to gauge bosons HVV and HHVV $$(V=W,Z)$$ ( V = W , Z ) given by the $$\kappa $$ κ -modifiers with respect to the Standard Model couplings, $$\kappa _V$$ κ V and $$\kappa _{2V},$$ κ 2 V , respectively. For this study we use the Higgs Effective Field Theory (HEFT) where these two $$\kappa $$ κ parameters are identified with the two most relevant effective couplings at leading order, concretely $$a=\kappa _V$$ a = κ V and $$b=\kappa _{2V}.$$ b = κ 2 V . Our focus is put on these two couplings and their potential correlations which we believe carry interesting information on the underlying ultraviolet theory. The particular studied process is $$e^+e^- \rightarrow HH \nu \bar{\nu },$$ e + e - → H H ν ν ¯ , where the vector boson scattering subprocess $$WW \rightarrow HH$$ W W → H H plays a central role, specially at the largest planned energy colliders. Our detailed study of this process as a function of the energy and the angular variables indicates that the produced Higgs bosons in the BSM scenarios will have in general a high transversality as compared to the SM case if $$\kappa _V^2 \ne \kappa _{2V}.$$ κ V 2 ≠ κ 2 V . In order to enhance the sensitivity to these HEFT parameters $$\kappa _V$$ κ V and $$\kappa _{2V}$$ κ 2 V and their potential correlations we propose here some selected differential cross sections for the $$e^+e^- \rightarrow HH \nu \bar{\nu }$$ e + e - → H H ν ν ¯ process, where different kinematic properties of the BSM case with respect to the SM are manifested. Finally, we will focus on the dominant Higgs decays to $$b {\bar{b}}$$ b b ¯ pairs leading to final events with 4 b-jets and missing transverse energy from the undetected neutrinos and will provide the expected accessibility to the $$(\kappa _V,\kappa _{2V})$$ ( κ V , κ 2 V ) effective couplings and their potential correlations. In our study we will consider the three projected energies for $$e^+e^-$$ e + e - colliders of 500 GeV, 1000 GeV and 3000 GeV.