Applicability of transverse mass scaling in hadronic collisions at energies available at the CERN Large Hadron Collider

摘要

We present a study on the applicability of transverse mass scaling for identified particle spectra in proton-proton collisions at s~(1/2) = 7 TeV based on data taken by the ALICE experiment at the LHC. The measured yields are parametrized and compared to estimates obtained from a generalized transverse mass scaling approach applied to different reference particle spectra. It is found that generalized transverse mass scaling is not able to describe the measured spectra over the full range in transverse momentum. At low p_T, deviations of 20% or more are obtained, in particular, if pions are used as reference particles. A better scaling performance is obtained when kaons are used as reference particles. At high p_T all tested spectra with the possible exception of the charged kaons exhibit a scaling behavior. Investigating the feed-down contributions from resonance decays to the charged pion yields reveals, that using them as reference a general scaling may not be achievable. Our findings imply that for precision measurements of direct photon and di-electron spectra at low transverse momentum one should measure the relevant hadronic background, instead of relying on mT scaling for its estimate.