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-- BenoitRoland - 26-Mar-2012

Study of the underlying event at forward rapidity in proton-proton collisions at the LHC

Contents:

Abstract

We study the underlying event activity in pp collisions at forward rapidity ( $5.2 &lt; \vert\eta\vert &lt; 6.6$ ) by measuring the ratio of the energy density, $dE/d\eta$ , between events with a charged particle jet produced at central rapidity ( $\vert\eta\vert &lt; 2$ ) 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 ( $\sqrt{\rm{s}} = 0.9, 2.76 \;\rm{and}\; 7 \;\rm{TeV}$ ). 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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.

Figure

Caption

Ratio of the energy deposited in the pseudorapidity range $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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.

Ratio of the energy deposited in the pseudorapidity range $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ in minimum-bias events as a function of $\sqrt{s}$ , normalized to the energy density at $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ in minimum-bias events as a function of $\sqrt{s}$ , normalized to the energy density at $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ in events with a charged particle jet in the range $\vert\eta^{\rm{jet}}\vert &lt; 2$ as a function of $\sqrt{s}$ , normalized to the energy density at $\sqrt{s} =$ 2.76 TeV. The $p_{\rm{T}}$ 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.

Energy density in the pseudorapidity range $5.2 &lt; \vert\eta\vert &lt; 6.6$ in events with a charged particle jet in the range $\vert\eta^{\rm{jet}}\vert &lt; 2$ as a function of $\sqrt{s}$ , normalized to the energy density at $\sqrt{s} =$ 2.76 TeV. The $p_{\rm{T}}$ threshold used for charged particle jets is 10 GeV $/c$

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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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.

Figure

Caption

Ratio of the energy deposited in the pseudorapidity range $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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.

Ratio of the energy deposited in the pseudorapidity range $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ in minimum-bias events as a function of $\sqrt{s}$ , normalized to the energy density at $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ in minimum-bias events as a function of $\sqrt{s}$ , normalized to the energy density at $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ in events with a charged particle jet in the range $\vert\eta^{\rm{jet}}\vert &lt; 2$ as a function of $\sqrt{s}$ , normalized to the energy density at $\sqrt{s} =$ 2.76 TeV. The $p_{\rm{T}}$ 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.

RelativeLeadingjetEflow_vs_cmenergy_cosmicray_public.png

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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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.

Figure

Caption

	Ratio of the energy deposited in the pseudorapidity range $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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.

Ratio of the energy deposited in the pseudorapidity range $5.2 &lt; \vert\eta\vert &lt; 6.6$ for events with a charged particle jet with $\vert\eta^{\rm{jet}}\vert &lt; 2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum $p_{\rm{T}}$ for $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ in minimum-bias events as a function of $\sqrt{s}$ , normalized to the energy density at $\sqrt{s} =$ 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 $5.2 &lt; \vert\eta\vert &lt; 6.6$ in events with a charged particle jet in the range $\vert\eta^{\rm{jet}}\vert &lt; 2$ as a function of $\sqrt{s}$ , normalized to the energy density at $\sqrt{s} =$ 2.76 TeV. The $p_{\rm{T}}$ 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 $\xi$ selection (extra public material) (click on plot to get .pdf)

Figure	Caption
	$\log_{10}(\xi_{\rm{Y}})$ vs. $\log_{10}(\xi_{\rm{X}})$ for all generated events (orange) and for generated events selected at the detector level (blue) for $\sqrt{s} =$ 7 TeV. Single diffractive dissociation events have a $\xi_{\rm{X}}$ or $\xi_{\rm{Y}}$ value equal to ( $\approx 10^{-7.7}$ at $\sqrt{s} =$ 7 TeV), while double diffractive dissociation and non-diffractive events have $\xi_{\rm{X}}$ and $\xi_{\rm{Y}}$ 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.

Figure

Caption

$\log_{10}(\xi_{\rm{Y}})$ vs. $\log_{10}(\xi_{\rm{X}})$ for all generated events (orange) and for generated events selected at the detector level (blue) for $\sqrt{s} =$ 7 TeV. Single diffractive dissociation events have a $\xi_{\rm{X}}$ or $\xi_{\rm{Y}}$ value equal to

( $\approx 10^{-7.7}$ at $\sqrt{s} =$ 7 TeV), while double diffractive dissociation and non-diffractive events have $\xi_{\rm{X}}$ and $\xi_{\rm{Y}}$ 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.

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who
pdf	Ratio_vs_pt_corrected_2760GeV_cosmicray_public.pdf	r1	manage	16.5 K	2012-03-26 - 19:48	BenoitRoland
png	Ratio_vs_pt_corrected_2760GeV_cosmicray_public.png	r1	manage	16.5 K	2012-03-26 - 19:49	BenoitRoland
pdf	Ratio_vs_pt_corrected_2760GeV_extra_public.pdf	r1	manage	16.6 K	2012-03-26 - 20:11	BenoitRoland
png	Ratio_vs_pt_corrected_2760GeV_extra_public.png	r1	manage	17.1 K	2012-03-26 - 20:12	BenoitRoland
pdf	Ratio_vs_pt_corrected_2760GeV_public.pdf	r1	manage	16.5 K	2012-03-26 - 18:29	BenoitRoland
png	Ratio_vs_pt_corrected_2760GeV_public.png	r1	manage	16.9 K	2012-03-26 - 18:30	BenoitRoland
pdf	Ratio_vs_pt_corrected_7TeV_cosmicray_public.pdf	r1	manage	16.5 K	2012-03-26 - 19:48	BenoitRoland
png	Ratio_vs_pt_corrected_7TeV_cosmicray_public.png	r1	manage	17.4 K	2012-03-26 - 19:49	BenoitRoland
pdf	Ratio_vs_pt_corrected_7TeV_extra_public.pdf	r1	manage	16.6 K	2012-03-26 - 20:11	BenoitRoland
png	Ratio_vs_pt_corrected_7TeV_extra_public.png	r1	manage	17.7 K	2012-03-26 - 20:13	BenoitRoland
pdf	Ratio_vs_pt_corrected_7TeV_public.pdf	r1	manage	16.4 K	2012-03-26 - 18:30	BenoitRoland
png	Ratio_vs_pt_corrected_7TeV_public.png	r1	manage	17.8 K	2012-03-26 - 18:31	BenoitRoland
pdf	Ratio_vs_pt_corrected_900GeV_cosmicray_public.pdf	r1	manage	16.5 K	2012-03-26 - 19:48	BenoitRoland
png	Ratio_vs_pt_corrected_900GeV_cosmicray_public.png	r1	manage	16.7 K	2012-03-26 - 19:49	BenoitRoland
pdf	Ratio_vs_pt_corrected_900GeV_extra_public.pdf	r1	manage	16.7 K	2012-03-26 - 20:11	BenoitRoland
png	Ratio_vs_pt_corrected_900GeV_extra_public.png	r1	manage	17.5 K	2012-03-26 - 20:12	BenoitRoland
pdf	Ratio_vs_pt_corrected_900GeV_public.pdf	r1	manage	16.5 K	2012-03-26 - 18:29	BenoitRoland
png	Ratio_vs_pt_corrected_900GeV_public.png	r1	manage	17.2 K	2012-03-26 - 18:30	BenoitRoland
pdf	RelativeEflow_vs_cmenergy_cosmicray_public.pdf	r1	manage	14.0 K	2012-03-26 - 19:48	BenoitRoland
png	RelativeEflow_vs_cmenergy_cosmicray_public.png	r1	manage	13.5 K	2012-03-26 - 19:49	BenoitRoland
pdf	RelativeEflow_vs_cmenergy_extra_public.pdf	r1	manage	14.1 K	2012-03-26 - 20:12	BenoitRoland
png	RelativeEflow_vs_cmenergy_extra_public.png	r1	manage	14.4 K	2012-03-26 - 20:13	BenoitRoland
pdf	RelativeEflow_vs_cmenergy_public.pdf	r1	manage	14.0 K	2012-03-26 - 18:30	BenoitRoland
png	RelativeEflow_vs_cmenergy_public.png	r1	manage	14.1 K	2012-03-26 - 18:31	BenoitRoland
pdf	RelativeLeadingjetEflow_vs_cmenergy_cosmicray_public.pdf	r1	manage	14.1 K	2012-03-26 - 19:49	BenoitRoland
png	RelativeLeadingjetEflow_vs_cmenergy_cosmicray_public.png	r1	manage	14.8 K	2012-03-26 - 19:50	BenoitRoland
pdf	RelativeLeadingjetEflow_vs_cmenergy_extra_public.pdf	r1	manage	14.2 K	2012-03-26 - 20:12	BenoitRoland
png	RelativeLeadingjetEflow_vs_cmenergy_extra_public.png	r1	manage	15.7 K	2012-03-26 - 20:13	BenoitRoland
pdf	RelativeLeadingjetEflow_vs_cmenergy_public.pdf	r1	manage	14.1 K	2012-03-26 - 18:30	BenoitRoland
png	RelativeLeadingjetEflow_vs_cmenergy_public.png	r1	manage	15.6 K	2012-03-26 - 18:31	BenoitRoland
pdf	cutlines_7TeV.pdf	r1	manage	698.0 K	2012-03-26 - 20:46	BenoitRoland
png	cutlines_7TeV.png	r1	manage	54.3 K	2012-03-26 - 20:49	BenoitRoland

Topic revision: r1 - 2012-03-26 - BenoitRoland

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Study of the underlying event at forward rapidity in proton-proton collisions at the LHC

Abstract

Comparisons to PYTHIA and HERWIG predictions (PAS) (click on plot to get .pdf)

Comparisons to cosmic ray model predictions (PAS) (click on plot to get .pdf)

Comparisons to PYTHIA and HERWIG predictions (extra public material) (click on plot to get .pdf)

Detector level cuts versus particle level selection (extra public material) (click on plot to get .pdf)

Detector level cuts versus particle level $\xi$ selection (extra public material) (click on plot to get .pdf)