Measurement of the underlying event activity using charged particle jets in proton-proton collisions at √s = 2.76 TeV
Abstract
A measurement of the underlying event (UE) activity in proton-proton collisions
is performed using events with a leading charged particle jet produced at central pseudo rapidity (

)
and of transverse momentum in the range of 1 to 100 GeV.
The analysis uses 0.3

of integrated luminosity at the centre-of-mass energy of 2.76 TeV at the LHC by the CMS experiment.
The UE activity is measured as a function of

in terms of the average multiplicity and
scalar-

sum of charged particles with

and

GeV in the azimuthal region
transverse to the leading jet direction.
By dividing the transverse region into the minimum and maximum activity sides with respect to the leading jet,
further information on the dynamics of the UE is obtained.
The measurements are compared to previous results at 0.9 and 7 TeV and to predictions of several QCD-inspired models
providing constraints for the tuning parameters involved.
Results at
= 2.76 TeV
Transverse densities
TransMIN densities
TransMAX densities
TransDIF densities
Comparison with
= 0.9 TeV and 7 TeV data
Additional plots
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XavierJanssen - 2014-10-30