Measurement of the double differential Drell-Yan and associated jet cross sections at low and high invariant masses in proton-proton collisions at $\sqrt s = 7 $ TeV

Abstract

Measurements of the differential Drell-Yan and associated jet cross section as a function of the Drell-Yan mass are presented in the di-muon channel. The data set is based on an integrated luminosity of 4.9 $fb^{-1} $ of proton-proton collision data recorded with the CMS detector at the LHC at $\sqrt s = 7 $ TeV. Cross sections as a function of the Drell-Yan transverse momentum are measured differentially in the Drell-Yan mass range of 30 to 1500 GeV. The cross section for Drell-Yan production in association with one or two jets with $p_{T}^{jet} > 30 $ GeV in the range $|\eta^{jet} |< 4.5$ is measured. In addition, the jet multiplicity in Drell-Yan production as a function of the rapidity separation of the leading jet and the Drell-Yan is presented. All measurements are compared to predictions of Monte Carlo even generators predictions based on multiparton matrix elements plus parton showers.

Motivation

Figure 1 Description
MotivationPlot.gif The rising behavior at small $p_{T}$ is described by soft gluon resummation, and is treated in the simulation by initial state parton showers. A similar behavior is observed for the DY+1 jet distributions, however, the maximum is shifted to larger values, and in the case of DY+1 jet the maximum is around 30 GeV, which is the $p_{T}$ threshold for the jets. With the DY+1 jet selection the range of soft gluon resummation is enlarged, from around 5 GeV in the inclusive case to around 30 GeV in the jet case, thus allowing to observe perturbative large $p_{T}$ jet-resummation. In the simulation without initial state parton shower a sharp drop of the cross section below 30 GeV is observed

Inclusive Drell-Yan double differential Cross Section $d^2 \sigma / dm dp_{T} $

Figure 2 Description
dimuonPtM30_45H_normToZ_log_B_unf.gif dimuonPtM45_60H_normToZ_log_B_unf.gif dimuonPtM60_120H_normToZ_log_B_unf.gif
dimuonPtM120_200H_normToZ_log_B_unf.gif dimuonPtM200_1500H_normToZ_log_B_unf.gif
Drell-Yan di-muon transverse momentum distribution normalized to the Z resonance region (60-120 GeV) in five different invariant mass regions covering the range from 30 - 1500 GeV. The vertical error bars on data indicate the statistical uncertainties and the error band represents the correlated systematic uncertainties. Data are compared to MADGRAPH + PYTHIA6.

Figure 3 Description
dimuonPt_1j_M30_45H_normToZ_log_B_unf.gif
dimuonPt_1j_M45_60H_normToZ_log_B_unf.gif
dimuonPt_1j_M60_120H_normToZ_log_B_unf.gif
dimuonPt_1j_M120_200H_normToZ_log_B_unf.gif
dimuonPt_1j_M200_1500H_normToZ_log_B_unf.gif

DY + 1 jet di-muon transverse momentum distribution normalized to the Z resonance region (60-120 GeV) in five different invariant mass regions covering the range from 30 - 1500 GeV. The vertical error bars on data indicate the statistical uncertainties and the error band represents the correlated systematic uncertainties. Data are compared to MADGRAPH + PYTHIA6.
Figure 4 Description
dimuonPt_2j_M30_45H_normToZ_log_B_unf.gif
dimuonPt_2j_M45_60H_normToZ_log_B_unf.gif
dimuonPt_2j_M60_120H_normToZ_log_B_unf.gif
dimuonPt_2j_M120_200H_normToZ_log_B_unf.gif
dimuonPt_2j_M200_1500H_normToZ_log_B_unf.gif

DY + 2 jets di-muon transverse momentum distribution normalized to the Z resonance region (60-120 GeV) in five different invariant mass regions covering the range from 30 - 1500 GeV. The vertical error bars on data indicate the statistical uncertainties and the error band represents the correlated systematic uncertainties. Data are compared to MADGRAPH + PYTHIA6.

Drell-Yan Cross Section measurement as a function of the rapidity difference between the Drell-Yan pair and the leading jet

Figure 5 Description
leadingJetdyfwd_1j_M30_60H_normToZ_lin_B_unf.gif
leadingJetdyfwd_1j_M60_120H_normToZ_lin_B_unf.gif
leadingJetdyfwd_1j_M120_1500H_normToZ_lin_B_unf.gif
leadingJetdyfwd_2j_M30_60H_normToZ_lin_B_unf.gif
leadingJetdyfwd_2j_M60_120H_normToZ_lin_B_unf.gif
leadingJetdyfwd_2j_M120_1500H_normToZ_lin_B_unf.gif
Drell-Yan di-muon rapidity difference between the Drell-Yan and the leading jet (normalized to the Z resonance region) for DY + 1 jet (upper row) and DY + 2 jets (lower row) production. Data are compared to MADGRAPH + PYTHIA6.

Jet multiplicity in Drell-Yan + jet events

Figure 6 Description

nJetsIndyDYj12D_1j_M60_120H_lin_B.gif

Average number of jets in forward Drell-Yan production as a function of the rapidity separation between the Drell-Yan and the leading jet. The measured cross section is compared to the MADGRAPH MC predictions.

Monte Carlo Comparisons

Figure 7 Description
dimuonPtM60_120H_normToZ_log_B_unf_rivet.gif
dimuonPt_1j_M60_120H_normToZ_log_B_unf_rivet.gif
dimuonPt_2j_M60_120H_normToZ_log_B_unf_rivet.gif
dimuonPtM60_120H_normToZ_lin_B_unf_rivet.gif
dimuonPt_1j_M60_120H_normToZ_lin_B_unf_rivet.gif
dimuonPt_2j_M60_120H_normToZ_lin_B_unf_rivet.gif
Inclusive DY, DY + 1 and DY + 2 jets di-muon transverse momentum distribution normalized to the Z resonance region (60-120 GeV) in Z invariant mass regions. In logarithmic scale in the top and linear scale in the bottom. The vertical error bars on data indicate the statistical uncertainties and the error band represents the correlated systematic uncertainties. Data are compared to differnt Monte Carlo predictions.

Figure 8 Description
leadingJetdyfwd_1j_M60_120H_normToZ_lin_B_unf_rivet.gif
leadingJetdyfwd_2j_M60_120H_normToZ_lin_B_unf_rivet.gif

Drell-Yan di-muon rapidity difference between the Drell-Yan and the leading jet (normalized to the Z resonance region) for DY + 1 jet (left) and DY + 2 jets (right) for the Z invarinat mass bin. Data are compared to different MC predictions.

Figure 9 Description

nJetsIndyDYj12D_1j_M60_120H_lin_B_rivet.gif

Average number of jets in forward Drell-Yan production as a function of the rapidity separation between the Drell-Yan and the leading jet. The measured cross section is compared to the different MC predictions.

-- SamanthaDooling - 11 Mar 2014

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Topic revision: r11 - 2014-04-30 - SamanthaDooling
 
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