Measurement of the Underlying Event Activity in the Drell-Yan process in proton-proton collisions at √s = 7 TeV

A measurement of the underlying event activity using Drell-Yan events is performed in proton-proton collisions at a centre-of-mass energy √s = 7 TeV using data, corresponding to an integrated luminosity of 2.2 fb-1 collected in CMS experiment during 2011. The Drell-Yan process with muonic final state, q q- → μ+ μ-, provides an excellent way to study the underlying event activity by separating the hard interaction from the soft component. The UE activity is observed to be independent of the di-muon invariant mass in a region above 40 GeV/c2, implying a saturation of the multiple parton interactions at these energy scales. The boost of the dimuon system considered has been constrained in this measurement to reduce the contribution of radiation balancing the boost. A slow growth of the activity is observed with increasing transverse momentum of the di-muon system which can be attributed to the increase in radiation. The data are corrected to the particle level and compared with the predictions of various Monte-Carlo generators and hadronization models.

Approved Plots

  • Table 1:
    Summary of the systematic uncertainties (%) from different sources. The first three rows show the systematic uncertainties for the particle density in the towards, transverse and away regions, whereas the last three rows report the systematic uncertainties for the energy density in three regions. The numbers out of parentheses refer to the densities as a function of Mμμ and those in parentheses correspond to the study as a function of pTμμ.

Table 1

link to .pdf:

  • Figure 1:
    The UE activity as function of invariant mass (Mμμ) for events with requirement of pTμμ < 5 GeV/c for the charged particles having Δφ < 120o: (left) particle density; (centre) energy density; (right) ratio of the energy and particle density together with the predictions of PYTHIA-6 Z2, Powheg Z2, PYTHIA-8 4C and Herwig++ LHC-UE7-2 (with and without MPI). Plots in bottom row show the ratio of MC prediction and the measurement for the corresponding observables. The inner band shows the statistical uncertainity of data whereas the outer band represents the total uncertainty (statistical and systematic uncertainties added in quadrature).

Figure1

link to .pdf:

  • Figure 2:
    The UE activity in the towards (upper row), transverse (central row) and away (bottom row) regions as function of pTμμ for events with requirement of 81 < Mμμ < 101 GeV/c2: (left) particle density; (centre) energy density; (right) the ratio of the energy density and the particle density together with the predictions of MadGraph Z2, Powheg Z2, PYTHIA-8 4C and Herwig++ LHC-UE7-2 (with and without MPI).

Figure21 Figure22 Figure23

link to .pdf:

  • Figure 3:
    Ratios, as a function of the pTμμ, of MC predictions to the measurements in the towards (upper row), transverse (bottom row) and away (bottom row) regions for events with the requirement of 81 < Mμμ < 101 GeV/c2: (left) particle density; (centre) energy density; (right) the ratio of the energy density and particle density. The inner band shows the statistical uncertainity of data whereas the outer band represents the total uncertainty (statistical and systematic uncertainties added in quadrature).

Figure31 Figure32 Figure33

link to .pdf:

  • Figure 4:
    The charge multiplicity (upper row) and pT spectrum (bottom row) of the selected tracks: (left) comparison of the normalized distribution in the away, transverse and towards region for events with requirement of 81 < Mμμ < 101 GeV/c2; (centre) comparisons of the normalized distribution in transverse region for events with the requirement of 81 < Mμμ < 101 GeV/c2 and pTμμ < 5 GeV/c; and (right) comparison of the normalized distribution with the prediction of various simulations in transverse region for events with the requirement of 81 < Mμμ < 101 GeV/c2and bottom panel shows the ratio of monte-carlo prediction and the measurements.

Figure41 Figure42

link to .pdf:

  • Figure 5:
    Comparison of the UE activity measured in hadronic and Drell-Yan events as a function of pTleading jet and pTμμ respectively; (left) particle density, (centre) energy density and (right) ratio of energy and particle density in transverse region.

Figure5

link to .pdf:

-- SunilBansal - 12-Dec-2011

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf Fig1_bottom_centre.pdf r1 manage 17.1 K 2011-12-13 - 05:00 SunilBansal ratio of energy density for MC and Data in towards + transverse region (Δφ < 120 degrees)
PDFpdf Fig1_bottom_left.pdf r1 manage 17.6 K 2011-12-13 - 05:01 SunilBansal ratio of particle density for MC and Data in towards + transverse region (Δφ < 120 degrees)
PDFpdf Fig1_bottom_right.pdf r1 manage 16.9 K 2011-12-13 - 05:03 SunilBansal ratio of energy/particle density for MC and Data in towards + transverse region (Δφ < 120 degrees)
PDFpdf Fig1_top_centre.pdf r1 manage 18.4 K 2011-12-13 - 05:04 SunilBansal energy density for MC and Data in towards + transverse region (Δφ < 120 degrees)
PDFpdf Fig1_top_left.pdf r1 manage 18.2 K 2011-12-13 - 05:06 SunilBansal particle density for MC and Data in towards + transverse region (Δφ < 120 degrees)
PDFpdf Fig1_top_right.pdf r1 manage 18.4 K 2011-12-13 - 05:09 SunilBansal energy/particle density for MC and Data in towards + transverse region (Δφ < 120 degrees)
PDFpdf Fig2_bottom_centre.pdf r1 manage 16.4 K 2011-12-13 - 05:05 SunilBansal energy density for MC and Data in away region (Δφ > 120 degrees)
PDFpdf Fig2_bottom_left.pdf r1 manage 16.9 K 2011-12-13 - 05:08 SunilBansal particle density for MC and Data in away region (Δφ > 120 degrees)
PDFpdf Fig2_bottom_right.pdf r1 manage 16.6 K 2011-12-13 - 05:11 SunilBansal energy/particle density for MC and Data in away region (Δφ > 120 degrees)
PDFpdf Fig2_centre_centre.pdf r1 manage 17.4 K 2011-12-13 - 05:05 SunilBansal energy density for MC and Data in transverse region (60 < Δφ < 120 degrees)
PDFpdf Fig2_centre_left.pdf r1 manage 17.5 K 2011-12-13 - 05:07 SunilBansal particle density for MC and Data in transverse region (60 < Δφ < 120 degrees)
PDFpdf Fig2_centre_right.pdf r1 manage 17.8 K 2011-12-13 - 05:10 SunilBansal energy/particle density for MC and Data in transverse region (60 < Δφ < 120 degrees)
PDFpdf Fig2_top_centre.pdf r1 manage 17.8 K 2011-12-13 - 05:06 SunilBansal energy density for MC and Data in towards region (Δφ < 60 degrees)
PDFpdf Fig2_top_left.pdf r1 manage 18.1 K 2011-12-13 - 05:08 SunilBansal particle density for MC and Data in towards region (Δφ < 60 degrees)
PDFpdf Fig2_top_right.pdf r1 manage 18.0 K 2011-12-13 - 05:10 SunilBansal energy/particle density for MC and Data in towards region (Δφ < 60 degrees)
PDFpdf Fig3_bottom_centre.pdf r1 manage 19.1 K 2011-12-13 - 05:01 SunilBansal ratio of energy density for MC and Data in away region (Δφ > 120 degrees)
PDFpdf Fig3_bottom_left.pdf r1 manage 20.1 K 2011-12-13 - 05:02 SunilBansal ratio of particle density for MC and Data in away region (Δφ > 120 degrees)
PDFpdf Fig3_bottom_right.pdf r1 manage 19.2 K 2011-12-13 - 05:04 SunilBansal ratio of energy/particle density for MC and Data in away region (Δφ > 120 degrees)
PDFpdf Fig3_centre_centre.pdf r1 manage 18.5 K 2011-12-13 - 05:00 SunilBansal ratio of energy density for MC and Data in transverse region (60 < Δφ < 120 degrees)
PDFpdf Fig3_centre_left.pdf r1 manage 19.4 K 2011-12-13 - 05:02 SunilBansal ratio of particle density for MC and Data in transverse region (60 < Δφ < 120 degrees)
PDFpdf Fig3_centre_right.pdf r1 manage 18.2 K 2011-12-13 - 05:03 SunilBansal ratio of energy/particle density for MC and Data in transverse region (60 < Δφ < 120 degrees)
PDFpdf Fig3_top_centre.pdf r1 manage 17.3 K 2011-12-13 - 05:01 SunilBansal ratio of energy density for MC and Data in towards region (Δφ < 60 degrees)
PDFpdf Fig3_top_left.pdf r1 manage 19.4 K 2011-12-13 - 05:02 SunilBansal ratio of particle density for MC and Data in towards region (Δφ < 60 degrees)
PDFpdf Fig3_top_right.pdf r1 manage 18.8 K 2011-12-13 - 05:03 SunilBansal ratio of energy/particle density for MC and Data in towards region (Δφ < 60 degrees)
PDFpdf Fig4_bottom_centre.pdf r1 manage 19.5 K 2011-12-13 - 04:59 SunilBansal comparison of transverse momentum of tracks in transverse region for events having invariant mass in [81-101] GeV/c2 and for events with dimuon transverse momentum < 5 GeV/c
PDFpdf Fig4_bottom_left.pdf r1 manage 22.6 K 2011-12-13 - 04:59 SunilBansal comparison of transverse momentum of tracks in towards, transverse and away region for events having invariant mass in [81-101] GeV/c2
PDFpdf Fig4_bottom_right.pdf r1 manage 23.2 K 2011-12-13 - 04:59 SunilBansal comparison of transverse momentum of tracks in transverse region for MC and data for events having invariant mass in [81-101] GeV/c2
PDFpdf Fig4_top_centre.pdf r1 manage 18.8 K 2011-12-13 - 05:07 SunilBansal comparison of track multiplicity in transverse region for events having invariant mass in [81-101] GeV/c2 and for events with dimuon transverse momentum < 5 GeV/c
PDFpdf Fig4_top_left.pdf r1 manage 23.2 K 2011-12-13 - 05:08 SunilBansal comparison of track multiplicity in towards, transverse and away region for events having invariant mass in [81-101] GeV/c2
PDFpdf Fig4_top_right.pdf r1 manage 21.3 K 2011-12-13 - 05:06 SunilBansal comparison of track multiplicity in transverse region for MC and data for events having invariant mass in [81-101] GeV/c2
PDFpdf Fig5_centre.pdf r1 manage 18.5 K 2011-12-13 - 05:04 SunilBansal comparison of energy density in transverse region in leading jet and DY events
PDFpdf Fig5_left.pdf r1 manage 18.9 K 2011-12-13 - 05:07 SunilBansal comparison of particle density in transverse region in leading jet and DY events
PDFpdf Fig5_right.pdf r1 manage 19.6 K 2011-12-13 - 05:10 SunilBansal comparison of energy/particle density in transverse region in leading jet and DY events
PNGpng Figure1.png r2 r1 manage 114.7 K 2011-12-12 - 14:01 SunilBansal  
PNGpng Figure21.png r1 manage 76.7 K 2011-12-12 - 14:05 SunilBansal  
PNGpng Figure22.png r1 manage 83.5 K 2011-12-12 - 14:05 SunilBansal  
PNGpng Figure23.png r1 manage 86.0 K 2011-12-12 - 14:05 SunilBansal  
PNGpng Figure31.png r1 manage 71.0 K 2011-12-12 - 14:26 SunilBansal  
PNGpng Figure32.png r1 manage 76.2 K 2011-12-12 - 14:27 SunilBansal  
PNGpng Figure33.png r1 manage 72.6 K 2011-12-12 - 14:27 SunilBansal  
PNGpng Figure41.png r1 manage 81.7 K 2011-12-12 - 14:27 SunilBansal  
PNGpng Figure42.png r1 manage 89.1 K 2011-12-12 - 14:27 SunilBansal  
PNGpng Figure5.png r1 manage 51.9 K 2011-12-12 - 14:28 SunilBansal  
PDFpdf Table.pdf r1 manage 26.8 K 2011-12-13 - 05:11 SunilBansal Summary of systematic uncertainty
PNGpng Table.png r1 manage 36.1 K 2011-12-12 - 15:33 SunilBansal  
Edit | Attach | Watch | Print version | History: r6 < r5 < r4 < r3 < r2 | Backlinks | Raw View | WYSIWYG | More topic actions
Topic revision: r6 - 2011-12-16 - KajariMazumdar
 
    • Cern Search Icon Cern Search
    • TWiki Search Icon TWiki Search
    • Google Search Icon Google Search

    CMSPublic All webs login

This site is powered by the TWiki collaboration platform Powered by PerlCopyright & 2008-2019 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki? Send feedback