Measurement of the cross-section for Z → e+e- production in pp collisions at $\sqrt{s}=7$ TeV

Abstract

A measurement of the cross-section for pp → Z → e + e − is presented using data at √ s = 7 TeV corresponding to an integrated luminosity of 0.94 fb −1 . The process is measured within the kinematic acceptance p T > 20 GeV/c and 2 < η < 4.5 for the daughter electrons and dielectron invariant mass in the range 60-120 GeV/c 2 . The cross-section is determined to be σ(pp → Z → e + e − ) = 76.0 ± 0.8 ± 2.0 ± 2.6 pb where the first uncertainty is statistical, the second is systematic and the third is the uncertainty in the luminosity. The measurement is performed as a function of Z rapidity and as a function of an angular variable which is closely related to the Z transverse momentum. The results are compared with previous LHCb measurements and with theoretical predictions from QCD.

Vector boson production at hadron colliders: transverse-momentum resummation and leptonic decay

“…9 An analogous measurement of the φ * distribution at the LHC was reported by the LHCb Collaboration [128] with an integrated luminosity of 0.94 fb −1 . In the small-φ * region, the bin sizes of the LHCb measurement are rather large (with respect to those of the ATLAS measurement [127]), with only two (four) bins in the region φ * < 0.1 (φ * < 0.2).…”

Measurement of forward Z → e+e− production at s = 8 $$ \sqrt{s}=8 $$ TeV

“…Thus, as in ref. [4], the distribution of the angular variable φ * , which is correlated with p T but less affected by bremsstrahlung, is studied. The φ * variable [5] is defined in terms of the directions of the particle momenta…”

“…2 In this paper, we present a measurement of the cross-section for pp → Z → e + e − using the data recorded by LHCb in 2012 at √ s = 8 TeV, corresponding to an integrated luminosity of 2.0 fb −1 . The approach is essentially the same as that used in a previous study of the same channel at √ s = 7 TeV [4]. The current measurement, as well as being at a higher centre-of-mass energy, benefits from a significantly higher and more precisely determined integrated luminosity, and from stable trigger conditions.…”

“…The efficiency is determined using simulated events, with data used to assess the systematic uncertainty as described in section 4. In contrast to the earlier analysis [4], the particle-level electron momentum used here is the momentum before…”

Improving quark flavor separation with forward W and Z production at LHCb

“…NNPDF3.1 includes the complete LHCb √ s = 7 and 8 TeV measurements of inclusive W and Z production in the forward region in the muon channel [7,8], which supersede all previous measurements in the same final state. These new measurements complement earlier LHCb data already included in NNPDF3.0 [9,10]. In this contribution, we explore the impact of the LHCb data on the NNPDF3.1 analysis and show how sizable constraints are derived at large-x for all the light quark PDFs and for the charm PDF.…”