Electroweak anomalies: muon g-2, W mass, 95 GeV

4 problems

• Why do e+e- to pi+ pi- cross-section measurements disagree?

  Open

  Measurements of how often electron-positron collisions make two pions disagree between experiments, and with supercomputer calculations. This number feeds the muon magnet prediction.

• Does the SM match the final muon g-2 measurement?

  Partially resolved

  The muon behaves like a tiny magnet whose strength was measured to about one part in ten million. The SM prediction now agrees, but only after replacing one method of computing the strong-force part with another.

• Is there a new scalar boson near 95 GeV?

  Open

  Searches for extra Higgs-like particles at the LHC, and earlier at the LEP collider, show small excesses of events near 95 GeV, below the known 125 GeV Higgs. Each excess is weak by itself, and it is unknown whether they come from one real particle.

• What explains the CDF W mass measurement disagreement?

  Partially resolved

  In 2022 the CDF experiment reported a W boson mass well above the SM prediction. Later measurements at the LHC agree with the SM, leaving the CDF result unexplained.