Second resonance of the Higgs field: more signals from the LHC experiments

Abstract

Theoretical arguments and lattice simulations suggest that, beside the known resonance of mass $m_h=$ 125 GeV, the Higgs field might exhibit a second resonance with a larger mass $(M_H{)}^{\mathrm{theor}}=690\pm 10(\mathrm{stat})\pm 20(\mathrm{sys})\mathrm{GeV}$ which, however, would couple to longitudinal W's with the same typical strength as the low-mass state at 125 GeV and thus represent a relatively narrow resonance mainly produced at LHC by gluon-gluon fusion. By looking for some evidence in the LHC data, we argue that the existence of a new resonance in the predicted mass region finds support in two analyses by ATLAS (searching for heavy resonances decaying into final states with 4 charged leptons or $\gamma \gamma$ pairs) and in more recent CMS results (searching for heavy resonances decaying into a pair of $h(125)$ bosons or looking for $\gamma \gamma$ pairs produced in $pp$ double-diffractive scattering). Since the correlation of these measurements is very small and since, having some definite theoretical prediction, local deviations from the pure background are not downgraded by the look-elsewhere effect, we emphasize the instability of the present situation that could probably be resolved by just adding two crucial, missing samples of RUN2 data.

Comments: 17 pages, 4 figures, 3 tables. More refined of the ATLAS 4-lepton events and more careful discussion of the systematic uncertainties