Higgs boson decay anomalies indicative of deviations from the predictions of the Standard Model of particle physics

The viability of the fourth-family model under the current Large Hadron Collider (LHC) experimental constraints on the invisible mode of the fourth-family neutrino was studied, with an illustration that suppressed Yukawa couplings for fourth-family quarks and leptons can simultaneously satisfy the bounds of invisible Higgs decay while producing the observed diphoton decay rate. The traditional diphoton invariant mass search methodology for LHC data was adopted in the reconstruction of the Standard Model (SM) signal as a baseline for studying the potential beyond the Standard Model (BSM) physics suppression. The reconstructed signal was assessed, illustrating the BSM suppression associated with the hypothetical scenario of the fourth-family neutrino and the associated cosmological constraints on the adopted model. To reconcile the existence of heavy fourth-family neutrinos with experimental constraints that limit the possible contributions from the fourth-family at the LHC, our analysis incorporated suppressed Yukawa couplings and decoupling effects within the theoretical framework of the nonbaryonic Dark Matter (DM) of the universe, considering that heavy fermions may contribute less than naively expected if their masses are close to or beyond the current collider limits.