HEPAP
High-Energy Physics Advisory Panel (in the US)
High-Energy Physics Advisory Panel (in the US)
Technology Transfer Network of institutions active in particle, astroparticle and nuclear physics
High-field magnets
High-Intensity and Energy ISOLDE
Upper-case "H", lower-case "b".
Avoid the tautology "Higgs-boson particle". A boson is a particle; there is no need to repeat yourself.
Named after the English physicist Peter Higgs, the Higgs boson is a subatomic particle whose existence is predicted by the theory that unified the weak and electromagnetic interactions.
High-radiation materials test facility
High-Luminosity Large Hadron Collider, High-Luminosity LHC (also: HiLumi)
Capital letters, note the hyphen.
The High-Luminosity LHC project (HL-LHC) will take the accelerator to new energy frontiers.
High-Momentum Particle Identification Detector