Revised production cross-section of γ-rays in p-p collisions with LHC data for the study of TeV γ-ray astronomy

► We present the production cross-section of gamma-rays based on p-p collisions. ► We use the most recent LHC (Large Hadron Collider) data, revising the previous one. ► We succeed in reproducing the production cross section in the very wide energy ranges, 1 GeV to LHC energy around 3 PeV. ► The present formula is valid and useful for future TeV gamma-ray astronomy.