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BenoitRoland - 26-Mar-2012
Study of the underlying event at forward rapidity in proton-proton collisions at the LHC
Abstract
We study the underlying event activity in pp collisions at forward rapidity (

) by measuring the ratio of the energy density,

, between events with a charged particle jet produced at central rapidity (

) and inclusive events. The energy density ratio is measured as a function of the charged particle jet transverse momentum at three different proton-proton centre-of-mass energies (

). In addition, the relative increase of the energy density in inclusive events and in events with a central charged particle jet as a function of centre-of-mass energy is studied. The results are compared to MC generators for pp collisions and discussed in terms of the underlying event activity.
Comparisons to PYTHIA and HERWIG predictions (PAS) (click on plot to get .pdf)
Figure |
Caption |
|
Ratio of the energy deposited in the pseudorapidity range for events with a charged particle jet with with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum for 0.9 TeV. Corrected results are compared to the PYTHIA and HERWIG++ MC models. Error bars indicate the statistical error on the data points, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
|
Ratio of the energy deposited in the pseudorapidity range for events with a charged particle jet with with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum for 2.76 TeV. Corrected results are compared to the PYTHIA and HERWIG++ MC models. Error bars indicate the statistical error on the data points, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
|
Ratio of the energy deposited in the pseudorapidity range for events with a charged particle jet with with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum for 7 TeV. Corrected results are compared to the PYTHIA and HERWIG++ MC models. Error bars indicate the statistical error on the data points, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
|
Energy density in the pseudorapidity range in minimum-bias events as a function of , normalized to the energy density at 2.76 TeV. Corrected results are compared to the PYTHIA and HERWIG++ MC models. Statistical errors are smaller than the markers size, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
|
Energy density in the pseudorapidity range in events with a charged particle jet in the range as a function of , normalized to the energy density at 2.76 TeV. The threshold used for charged particle jets is 10 GeV at all centre-of-mass energies. Corrected results are compared to the PYTHIA and HERWIG++ MC models. Statistical errors are smaller than the markers size, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
Comparisons to cosmic ray model predictions (PAS) (click on plot to get .pdf)
Figure |
Caption |
|
Ratio of the energy deposited in the pseudorapidity range for events with a charged particle jet with with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum for 0.9 TeV. Corrected results are compared to MC models used in cosmic ray physics. Error bars indicate the statistical error on the data points, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
|
Ratio of the energy deposited in the pseudorapidity range for events with a charged particle jet with with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum for 2.76 TeV. Corrected results are compared to MC models used in cosmic ray physics. Error bars indicate the statistical error on the data points, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
|
Ratio of the energy deposited in the pseudorapidity range for events with a charged particle jet with with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum for 7 TeV. Corrected results are compared to MC models used in cosmic ray physics. Error bars indicate the statistical error on the data points, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
|
Energy density in the pseudorapidity range in minimum-bias events as a function of , normalized to the energy density at 2.76 TeV. Corrected results are compared to MC models used in cosmic ray physics. Statistical errors are smaller than the markers size, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
|
Energy density in the pseudorapidity range in events with a charged particle jet in the range as a function of , normalized to the energy density at 2.76 TeV. The threshold used for charged particle jets is 10 GeV at all centre-of-mass energies. Corrected results are compared to MC models used in cosmic ray physics. Statistical errors are smaller than the markers size, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
Comparisons to PYTHIA and HERWIG predictions (extra public material) (click on plot to get .pdf)
Figure |
Caption |
|
Ratio of the energy deposited in the pseudorapidity range for events with a charged particle jet with with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum for 0.9 TeV. Corrected results are compared to the PYTHIA and HERWIG++ MC models. Error bars indicate the statistical error on the data points, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
|
Ratio of the energy deposited in the pseudorapidity range for events with a charged particle jet with with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum for 2.76 TeV. Corrected results are compared to the PYTHIA and HERWIG++ MC models. Error bars indicate the statistical error on the data points, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
|
Ratio of the energy deposited in the pseudorapidity range for events with a charged particle jet with with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum for 7 TeV. Corrected results are compared to the PYTHIA and HERWIG++ MC models. Error bars indicate the statistical error on the data points, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
|
Energy density in the pseudorapidity range in minimum-bias events as a function of , normalized to the energy density at 2.76 TeV. Corrected results are compared to the PYTHIA and HERWIG++ MC models. Statistical errors are smaller than the markers size, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
|
Energy density in the pseudorapidity range in events with a charged particle jet in the range as a function of , normalized to the energy density at 2.76 TeV. The threshold used for charged particle jets is 10 GeV at all centre-of-mass energies. Corrected results are compared to the PYTHIA and HERWIG++ MC models. Statistical errors are smaller than the markers size, while the grey band around data points represents the statistical and systematic uncertainties added in quadrature. |
Detector level cuts versus particle level
selection (extra public material) (click on plot to get .pdf)
Figure |
Caption |
|
vs. for all generated events (orange) and for generated events selected at the detector level (blue) for 7 TeV. Single diffractive dissociation events have a or value equal to ( at 7 TeV), while double diffractive dissociation and non-diffractive events have and values ranging from 0 to 1. The green lines indicate the particle level cuts. At the particle level, all events to the top and to the right of the green lines are selected. |