Insight into particle production mechanisms via angular correlations of identified particles in pp collisions at √s = 7 TeV

Two-particle angular correlations were mea- sured in pp collisions at √s = 7 TeV for pions, kaons, pro- tons, and lambdas, for all particle/anti-particle combinations in the pair. Data for mesons exhibit an expected peak domi- nated by effects associated with mini-jets and are well repro- duced by general purpose Monte Carlo generators. However, for baryon–baryon and anti-baryon–anti-baryon pairs, where both particles have the same baryon number, a near-side anti- correlation structure is observed instead of a peak. This effect is interpreted in the context of baryon production mecha- nisms in the fragmentation process. It currently presents a challenge to Monte Carlo models and its origin remains an open question.