Higgs couplings to fermions and origin of mass

4 problems

• Does the Higgs field give the electron its mass?

  Open

  The electron couples to the Higgs so weakly (strength about 3 in a million) that the coupling has never been detected. Measuring it would show whether the Higgs field is the source of the mass of the particle that sets the size of atoms.

• Do the muon and charm quark couple to the Higgs with SM strength?

  Open

  The Higgs has been seen decaying to the heavy third-generation fermions, but its decays to the muon and to the charm quark (second-generation particles) are rare and only hinted at. Confirming them would show that the Higgs gives mass the same way across generations.

• Does the top-Higgs coupling contain a CP-violating component?

  Open

  The SM predicts that the interaction between the Higgs and the top quark respects CP, the combined mirror and particle-antiparticle symmetry. A CP-violating part would be a new source of the matter-antimatter difference.

• Is the Higgs total decay width equal to the SM 4.1 MeV?

  Open

  The width of the Higgs measures how fast it decays and counts every decay, including decays to unknown particles. The SM predicts 4.1 MeV, far too narrow to resolve directly at the LHC.