Doesn't need spelling out for the CERN Courier

mbar = millibar, BaBar = keep as it is!, Kbar = a bar above the ‘K’, bbbar = a bar above the 2nd ‘b’

An experiment conducted at the High Energy Accelerator Research Organization (KEK) in Japan from 1999 to 2010.

Brookhaven National Laboratory

Spell out in first use then use acronym for the CERN Courier