Colour–colour diagram containing the locus of LBGs according to Pentericci et al. (2010). Filled and open dots represent LAEs and non-LAEs, respectively. Orange and blue dots represent galaxies at z > 2.75 and z < 2.75, respectively. Red dots are PACS-detected galaxies and shaded zone is the area where LBGs are located. For clarity, the galaxies with a U − V colour greater than 5.5 are assigned U − V = 5.5.