Anomalous Higgs Yukawa Couplings

Understand

In the standard model, the Higgs boson $h$ couples to the quarks and charged leptons according to the well-known formula $(m_\psi/v) h \bar{\psi}\psi$, where $\psi$ = quark (q) or lepton (l) and $v$ = 246 GeV is its vacuum expectation value.

• Suppose $m_\psi$ is of radiative origin instead, then the effective $h \bar{\psi}\psi$ Yukawa coupling will not be exactly $m_\psi/v$.
• We show for the first time quantitatively how this may shift the observed branching fraction of $h \to \bar{b}b$ and $h \to \tau^+ \tau^-$ upward or downward.
• Thus the precision measurements of Higgs decay to fermions at the Large Hadron Collider, due to resume operation in 2015, could be the key to possible new physics.