A phenomenological profile of the Higgs boson

Abstract

A discussion is given of the production, decay and observability of the scalar Higgs boson H expected in gauge theories of the weak and electromagnetic interactions such as the Weinberg-Salam model. After reviewing previous experimental limits on the mass of the Higgs boson, we give a speculative cosmological argument for a small mass. If its mass is similar to that of the pion, the Higgs boson may be visible in the reactions π −p → Hn or γp → Hp near threshold. If its mass is ≲300 MeV, the Higgs boson may be present in the decays of kaons with a branching ratio O(10 −7), or in the decays of one of the new particles: 3.7 → 3.1 + H with a branching ratio O(10 −4). If its mass is ⩽4 GeV, the Higgs boson may be visible in the reaction pp → H + X, H → μ + μ −. If the Higgs boson has a mass ⩽2 m μ , the decays H → e +e − and H → γγ dominate, and the lifetime is O(6 × 10 −4 to 2 × 10 −12) seconds. As thresholds for heavier particles (pions, strange particles, new particles) are crossed, decays into them become dominant, and the lifetime decreases rapidly to O(10 −20) sec for a Higgs boson of mass 10 GeV. Decay branching ratios in principle enable the quark masses to be determined.