Measurement of the double differential Drell-Yan and associated jet cross sections at low and high invariant masses in proton-proton collisions at 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 of proton-proton collision data recorded with the CMS detector at the LHC at 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 GeV in the range 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

The rising behavior at small 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 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 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

Figure 2	Description
	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
	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
	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
	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

Monte Carlo Comparisons

Figure 7

Description

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
	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
	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