First measurement of the underlying event activity at the LHC with √ s = 0 . 9 TeV The CMS
نویسندگان
چکیده
A measurement of the underlying activity in scattering processes with p T scale in the GeV region is performed in proton–proton collisions at √ s = 0.9 TeV, using data collected by the CMS experiment at the LHC. Charged particle production is studied with reference to the direction of a leading object, either a charged particle or a set of charged particles forming a jet. Predictions of several QCD-inspired models as implemented in PYTHIA are compared, after full detector simulation, to the data. The models generally predict too little production of charged particles with pseudorapidity |η| < 2, p T > 0.5 GeV/c, and azimuthal direction transverse to that of the leading object.
منابع مشابه
مطالعه تولید منحصر بفرد جفت پایونهای مثبت و منفی در برخوردهای پروتون-پروتون با مرکز جرم 7 ترا الکترون ولت
The exclusive production of charged pions, are reported in the proton-proton collisions, where the π+π- pair is emitted at the central rapidity, y, and the scattered protons stay intact (p) without detection. This measurement is performed with the CMS detector at the LHC, using a data sample corresponding to an integrated luminosity of 450 μb-1 collected at a center-of-mass energy of 7 TeV. Th...
متن کاملMeasurement of the top quark mass using proton-proton data at sqrt(s) = 7 and 8 TeV
A new set of measurements of the top quark mass are presented, based on the proton-proton data recorded by the CMS experiment at the LHC at √ s = 8 TeV corresponding to a luminosity of 19.7 fb−1. The top quark mass is measured using the lepton+jets, all-jets and dilepton decay channels, giving values of 172.35 ± 0.16 (stat) ± 0.48 (syst) GeV, 172.32 ± 0.25 (stat) ± 0.59 (syst) GeV, and 172.82 ±...
متن کاملMeasurement of the ratio of the inclusive 3-jet cross section to the inclusive 2-jet cross section in pp collisions at sqrt(s) = 7 TeV and first determination of the strong coupling constant in the TeV range
A measurement is presented of the ratio of the inclusive 3-jet cross section to the inclusive 2-jet cross section as a function of the average transverse momentum, 〈pT1,2〉, of the two leading jets in the event. The data sample was collected during 2011 at a proton-proton centre-of-mass energy of 7 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 5.0 fb−1. The s...
متن کاملCMS results on soft diffraction
Diffractive interactions are characterized by the presence of at least one non-exponentially suppressed large rapidity gap (lrg) in the final state, defined as a region in pseudorapidity devoid of particles. The origin of lrgs is attributed to a color-singlet exchange with vacuum quantum numbers, referred to as Pomeron (IP ) exchange. Soft diffractive interactions (with no hard scale) cannot be...
متن کاملSoft Qcd with the Atlas Detector at the Lhc
Abstract. Soft QCD measurements using proton-proton collisions at √ s = 900 GeV and 7 TeV recorded with the ATLAS detector at the LHC are presented. Charged particle distributions were measured using tracks reconstructed in the ATLAS inner detector. Activity in the underlying event was studied using independent measurements from tracking detectors and calorimeters. Two-particle angular correlat...
متن کامل