SOFT QCD RESULTS FROM ATLAS AND CMS CLAUDIA-ELISABETH WULZ, for the ATLAS and CMS Collaborations

The ATLAS and CMS Collaborations have measured properties of minimum bias events and have determined characteristics of the underlying event in proton-proton collisions at three LHC centre-of-mass energies. Comparisons to common phenomenological models and partially to other experiments have been made. The production of the strange particles K0S,Λ and Ξ is discussed. Particle correlation studies, in particular Bose-Einstein as well as long- and short-range angular correlations in proton-proton and lead ion events are explained. 1 Properties of minimum bias events Ideally minimum bias events are those recorded with a totally inclusive trigger. The exact def-inition depends on the experiment. Usually minimum bias only refers to non-single-diffractive (NSD) events. In ATLAS 1 and CMS 2 similar minimum bias trigger detectors are used. AT-LAS has two stations of Minimum Bias Trigger Scintillators (MBTS) located upstream and downstream at z = ±3.56 m from the nominal collision vertex in the pseudorapidity intervals 2.09 < |η | < 2.82 and 2.82 < |η | < 3.84. CMS has Beam Scintillator Counters (BSC) at z = ±10.86 m within 3.23 < |η | < 4.65. Both experiments also use signals from a beam pick-up based timing system (BPTX) at z = ±175 m with a time resolution of 200 ps in their minimum bias trigger. Transverse momentum spectra of charged particles have been measured in a large range of pT. Fig. 1 shows results from the CMS experiment and comparisons to CDF data 3. Calorimeter-based transverse energy triggers have been used in the high-pT-region instead of the normal min-imum bias trigger. The data are fully corrected. The inclusive invariant cross-section expressed as a function of the scaling variable xT = 2pT / s is given by Eq. 1