Higgs data does not rule out a sequential fourth generation with an extended scalar sector

Understand

Contrary to the common perception, we show that the current Higgs data does not eliminate the possibility of a sequential fourth generation that get their masses through the same Higgs mechanism as the first three generations.

• The inability to fix the sign of the bottom-quark Yukawa coupling from the available data plays a crucial role in accommodating a chiral fourth generation which is consistent with the bounds on the Higgs signal strengths.
• We show that effects of such a fourth generation can remain completely hidden not only in the production of the Higgs boson through gluon fusion but also to its subsequent decay to $\gamma\gamma$ and $ Z\gamma$.
• This, however, is feasible only if the scalar sector of the Standard Model is extended.