Z+Jets Inclusive Cross Section Analysis
IFAE-Barcelona
IFAE-Barcelona


Authors

Monica D'Onofrio (donofrio@fnal.gov)

Mario Martínez (mmp@fnal.gov)

Oriol Saltó (salto@fnal.gov)

CDF, FNAL,
P.0. Box 500, M.S. 318
Batavia, Illinois 60510
USA


Measurement of the Inclusive Jet Cross Sections in Z/γ*(→e+e-)+jets Production
(2.7 fb-1 analysis)
Results with 1.7 fb-1 published in Phys. Rev. Lett. 100, 102001 (2008)

We present results on inclusive Z/γ*(→e+e-)+jets production in p-pbar collisions at √s = 1.96 TeV using data collected with the upgraded Collider Detector at Fermilab in Run II corresponding to an integrated luminosity of 2.7 fb-1. Jets are reconstructed using the Midpoint algorithm with R=0.7. Measurements are performed as a function of jet transverse momentum and jet rapidity for jets with pTjet>30 GeV/c and |yjet|<2.1. The measurements are corrected to the hadron level and compared to NLO pQCD predictions, the latter including additional parton-to-hadron non-pQCD contributions.

  • Figures published in the PRL paper based on 1.7 fb-1
    • Fig. 1: Inclusive jet cross section in Z/γ*(→e+e-)+≥1 jet and Z/γ*(→e+e-)+≥2 jets production as a function of pTjet.
      • Figure with "(a)", "(b)" and "(c)" labels gif & eps
      • Figure without the labels gif & eps
    • Fig. 2: Total inclusive cross section as a function of inclusive jet multiplicity (≥Njets).
      • Figure with "(a)" and "(b)" labels gif & eps
      • Figure without the labels gif & eps


  • Public Note based on 1.7 fb-1 results [here] The details of the analysis explained in the public note are also valid for the 2.7 fb-1 results.

  • Blessed Results 2.7 fb-1
    The measurements are performed in the kinematic range defined as:
    • Two electrons with ET > 25 GeV
    • At least one central electron: |ηe| < 1.0
    • Second electron central or forward : |ηe| < 1.0 or 1.2 < |ηe| < 2.8
    • Z mass window: 66 < Mee < 116 GeV/c2
    • ΔR(e,jet) > 0.7
    Jets are searched for using the MidPoint algorithm with R=0.7.
    Measurements are defined for hadron level jets with pTjet > 30 GeV/c and |yjet| < 2.1.

    • Mee mass distribution gif & eps
      Measured Mee invariant mass distribution in the region 46 < Mee < 136 GeV/c2 for data compared to the SM prediction in events with at least one jet. The plot includes 20 GeV/c2 sidebands around the defined signal region. The measurement only includes statistical uncertainties.


    • Inclusive jet cross section in Z/γ*+≥1 jet and Z/γ*+≥2 jets production as a function of pTjet
      Measured inclusive cross section for Z/γ*+jets production as a function of pTjet compared to NLO pQCD predictions as determined using MCFM. The pQCD prediction includes an additional Chad factor that accounts for non-pQCD contributions. Systematic uncertainties on data and theoretical predictions are included.

      • Inclusive jet cross section in Z/γ*+≥1 jet and Z/γ*+≥2 jets production in the same plot gif & eps
      • Inclusive jet cross section in Z/γ*+≥1 jet showing also the Chad factors gif & eps (Relative contributions to the total systematic uncertainty gif & eps)
      • Inclusive jet cross section in Z/γ*+≥2 jets showing also the Chad factors gif & eps (Relative contributions to the total systematic uncertainty gif & eps)



    • Nth leading jet cross section in Z/γ*+≥N jets production as a function of pTjet
      Measured Nth leading jet cross section in Z/γ*+≥N jets production as a function of pTjet compared to NLO pQCD predictions as determined using MCFM. The pQCD prediction includes an additional Chad factor that accounts for non-pQCD contributions. Systematic uncertainties on data and theoretical predictions are included.

      • 1st leading jet in Z/γ*+≥1 jet and 2nd leading jet in Z/γ*+≥2 jets cross sections in the same plot gif & eps
      • 1st leading jet cross section in Z/γ*+≥1 jet production showing also the Chad factors gif & eps (Relative contributions to the total systematic uncertainty gif & eps)
      • 2nd leading jet cross section in Z/γ*+≥2 jets production showing also the Chad factors gif & eps (Relative contributions to the total systematic uncertainty gif & eps)



    • Inclusive jet cross section in Z/γ*+≥1 jet and Z/γ*+≥2 jets production as a function of |yjet|
      Measured inclusive cross section for Z/γ*+jets production as a function of |yjet| compared to NLO pQCD predictions as determined using MCFM. The pQCD prediction includes an additional Chad factor that accounts for non-pQCD contributions. Systematic uncertainties on data and theoretical predictions are included.

      • Inclusive jet cross section in Z/γ*+≥1 jet and Z/γ*+≥2 jets production in the same plot gif & eps
      • Inclusive jet cross section in Z/γ*+≥1 jet showing also the Chad factors gif & eps (Relative contributions to the total systematic uncertainty gif & eps)
      • Inclusive jet cross section in Z/γ*+≥2 jets showing also the Chad factors gif & eps (Relative contributions to the total systematic uncertainty gif & eps)



    • Total Inclusive Cross Section vs Inclusive Jet Multiplicity gif & eps
      Measured cross section as a function of inclusive jet multiplicity compared to NLO pQCD predictions as determined using MCFM. In the ratio plot, data and NLO theory are referred to LO predictions. Systematic uncertainties on data and theoretical predictions are included.


    • σN/σN-1 cross section ratio gif & eps
      Ratio of the total inclusive jet cross section for Z/γ*+≥N jets (σN) over the total inclusive jet cross section for Z/γ*+≥(N-1) jets (σN-1). The plot includes the NLO pQCD predictions (as determined using MCFM) for σ2/σ1. The pQCD prediction includes an additional Chad factor that accounts for non-pQCD contributions. Systematic uncertainties on data and theoretical predictions are included.


    • Jet Shapes
      Measured differential and integrated jet shapes compared to different Monte Carlo predictions with different Underlying Event (UE) settings. The data are compared to PYTHIA Tune A, PYTHIA Tune DW and PYTHIA without UE Monte Carlo predictions. The measurements only include statistical uncertainties.



    • Energy Flow gif & eps
      Measured energy flow in the transverse plane for Z/γ*+jets events. Event-by-event, φ=0 is defined along the direction of the Z/γ* boson. The measurement is performed considering calorimeter towers with |y|<0.7 and compared to PYTHIA Tune A and PYTHIA Tune DW Monte Carlo predictions. The measurements only include statistical uncertainties.


    • Z/γ*(→e+e-)+4 jets events
      We find two Z/γ*(→e+e-)+4 jets events in the 1.7 fb-1 of data used. The details on one of the events are given below.
      • Lego plot of the calorimeter towers gif & eps
      • Transverse view of the tracker and the calorimeter towers gif & eps


            Created by Mario Martínez (mmp@fnal.gov)
             Last modified by Oriol Saltó (salto@fnal.gov) on July 24th, 2008