Constraints on the Universal Varying Yukawa Couplings: from SM-like to Fermiophobic

Varying the Standard Model (SM) fermion Yukawa couplings universally by a generic positive scale factor ($F_{Yu}$), we study the phenomenological fit to the current available experimental results for the Higgs boson search at hadron colliders. We point out that the Higgs production cross section and its decay branching ratio to $γγ$ can be varied oppositely by $F_{Yu}$ to make their product almost invariant. Thus, our scenario and the SM Higgs are indistinguishable in the inclusive $H\to γγ$ channel. The current measurements on direct Yukawa coupling strength in the $H\to b\bar{b}/ττ$ channel are not precise enough to fix the scale factor $F_{Yu}$. The most promising is the vector-boson-fusion channel in which the CMS has already observed possible suppression effect on the Yukawa couplings. Further more, the global $χ^2$ fit of the experimental data can get the optimal value by introducing a suppression factor $F_{Yu}\sim1/2$ on the SM Yukawa couplings.

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