Measurement of inelastic, single- and double-diffraction cross sections in proton–proton collisions at the LHC with ALICE (original) (raw)

2013, The European Physical Journal C

Measurements of cross sections of inelastic and diffractive processes in proton-proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass M X < 200 GeV/c 2) σ SD /σ INEL = 0.21 ± 0.03, 0.20 +0.07 −0.08 , and 0.20 +0.04 −0.07 , respectively at centre-of-mass energies √ s = 0.9, 2.76, and 7 TeV; for double diffraction (for a pseudorapidity gap η > 3) σ DD /σ INEL = 0.11 ± 0.03, 0.12 ± 0.05, and 0.12 +0.05 −0.04 , respectively at √ s = 0.9, 2.76, and 7 TeV. To measure the inelastic cross section, beam properties were determined with van der Meer scans, and, using a simulation of diffraction adjusted to data, the following values were obtained: σ INEL = 62.8 +2.4 −4.0 (model) ± 1.2(lumi) mb at √ s = 2.76 TeV and 73.2 +2.0 −4.6 (model) ± 2.6(lumi) mb at √ s = 7 TeV. The single-and double-diffractive cross sections were calculated combining relative rates of diffraction with inelastic cross sections. The results are compared to previous measurements at proton-antiproton and protonproton colliders at lower energies, to measurements by other experiments at the LHC, and to theoretical models.