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


Authors

Stefano Camarda (camarda@fnal.gov)

Sebastian Grinstein (gris@fnal.gov)

Mario Martínez (mmp@fnal.gov)

Lorenzo Ortolan (loreorto@ifae.es)

Veronica Sorin (vsorin@fnal.gov)

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


Measurement of Cross Sections in Z/γ*(→l+l-)+jets Production
(8.2 fb-1 analysis)

We present results on Z/γ*(→l+l-)+jets production (with l an electron or muon) 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 8.2 fb-1. Jets are reconstructed using the Midpoint algorithm with R=0.7. Measurements are performed 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.



  • Blessed Results 8.2 fb-1
    The measurements are performed in the kinematic range defined as:
    • Two central muons or electrons , |η&mu| < 1.0 , with PT > 25 GeV
    • Z mass window: 66 < M&mu&mu < 116 GeV/c2
    • ΔR(&mu,jet) > 0.7
    Measurements are performed independently for the electron and the muon channel. The cross sections are combined using a modified BLUE algorithm that take into account asymmetric errors. For information on each particular channel , please refer to the public web page for muons and for electrons .
    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.

    • Jet cross section in Z/γ*+≥1,2,3 jets production as a function of the 1st, 2nd or 3rd leading pTjet
      Measured cross section for Z/γ*+jets production as a function of the 1st, 2nd or 3rd leading pTjet compared to NLO pQCD predictions as determined using MCFM and/or BLACKHAT+SHERPA. The pQCD prediction includes an additional Chad factor that accounts for non-pQCD contributions. Systematic uncertainties on data and theoretical predictions are included.

      • Jet cross section in Z/γ*+≥1 jet eps
      • Jet cross section in Z/γ*+≥2 jets eps
      • Jet cross section in Z/γ*+≥3 jets eps



    • Inclusive jet cross section in Z/γ*+≥1,2,3 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 and/or BLACKHAT+SHERPA. 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 eps
      • Inclusive jet cross section in Z/γ*+≥2 jets eps
      • Inclusive jet cross section in Z/γ*+≥3 jets eps



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


    • Inclusive jet cross section in Z/γ*+≥1,2,3 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 and/or BLACKHAT+SHERPA. 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 eps
      • Inclusive jet cross section in Z/γ*+≥2 jets eps
      • Inclusive jet cross section in Z/γ*+≥3 jets eps



    • Cross section in Z/γ*+≥1,2,3 jets production as a function of HTjet (sum of the transverse momentum of the jets passing kinematic requirements)
      Measured cross section for Z/γ*+jets production as a function of HTjet compared to NLO pQCD predictions as determined using MCFM and/or BLACKHAT+SHERPA. The pQCD prediction includes an additional Chad factor that accounts for non-pQCD contributions. Systematic uncertainties on data and theoretical predictions are included.

      • Cross section in Z/γ*+≥1 jet eps
      • Cross section in Z/γ*+≥2 jets eps
      • Cross section in Z/γ*+≥3 jets eps



    • Cross section in Z/γ*+≥2 jets production as a function of Mjj, ΔRjj , Δφjj , MZjj and PTjj
      Measured cross section for Z/γ*+2 jets production as a function of various variables compared to NLO pQCD predictions as determined using MCFM and/or BLACKHAT+SHERPA. The pQCD prediction includes an additional Chad factor that accounts for non-pQCD contributions. Systematic uncertainties on data and theoretical predictions are included.

      • Cross section as function of Mjj eps
      • Cross section as function of ΔRjj eps
      • Cross section as function of Δφjj eps
      • Cross section as function of MZjj eps
      • Cross section as function of PTjj eps



    • Mee mass distribution
      Measured Mee invariant mass distribution for data compared to the SM prediction (only statistical uncertainties included) :
      • in events with at least one jet eps .


    • M&mu&mu mass distribution
      Measured M&mu&mu invariant mass distribution for data compared to the SM prediction (only statistical uncertainties included) :
      • in events with at least one jet eps .






            Last modified by Stefano Camarda (camarda@fnal.gov) on July 02, 2010