FEWZ 2.0: A code for hadronic Z production at next-to-next-to-leading order

We introduce an improved version of the simulation code FEWZ (Fully Exclusive W and Z Production) for hadron collider production of lepton pairs through the Drell-Yan process at next-to-next-to-leading-order (NNLO) in the strong coupling constant. The program is fully differential in the phase space of leptons and additional hadronic radiation. The new version offers users significantly more options for customization. FEWZ now bins multiple, user-selectable histograms during a single run, and produces parton distribution function (PDF) errors automatically. It also features a signifcantly improved integration routine, and can take advantage of multiple processor cores locally or on the Condor distributed computing system. We illustrate the new features of FEWZ by presenting numerous phenomenological results for LHC physics. We compare NNLO QCD with initial ATLAS and CMS results, and discuss in detail the effects of detector acceptance on the measurement of angular quantities associated with Z-boson production. We address the issue of technical precision in the presence of severe phase-space cuts.Comment: 29 pages, 13 figure

LHC and dark matter signals of Z' bosons

We customize the simulation code FEWZ (Fully Exclusive W, Z Production) to study Z' production at the LHC for both \sqrt{s}=8 TeV and 14 TeV. Using the results of our simulation for several standard benchmark Z' models, we derive a semi-empirical expression for the differential cross section, that permits the determination of Z' couplings in a model-independent manner. We evaluate cross sections and other observables for large classes of models, including the common E_6, left-right and B-L models, as a function of model parameters. We also consider a hidden sector Z' that couples to standard model fermions via kinetic and mass mixing and serves as a mediator of isospin-violating interactions with dark matter. We combine the results of LHC Z' searches and dark matter direct detection experiments with global electroweak data to obtain mass-dependent constraints on the model parameters.Comment: 30 pages, 19 figures, 2 tables. Published versio

Measurement of the Drell-Yan cross section in pp collisions at √s = 7 TeV

The Drell-Yan differential cross section is measured in pp collisions at √s=7 TeV, from a data sample collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 36 pb^(−1). The cross section measurement, normalized to the measured cross section in the Z region, is reported for both the dimuon and dielectron channels in the dilepton invariant mass range 15–600 GeV. The normalized cross section values are quoted both in the full phase space and within the detector acceptance. The effect of final state radiation is also identified. The results are found to agree with theoretical predictions

Z→ττZ \to \tau\tau and W→τντW \to \tau\nu_\tau Cross-Sections at the LHC

Measurements of the $Z \to \tau\tau$ and $W \to \tau\nu_\tau$ cross-sections at the LHC with data taken at $\sqrt{s} = 7$ TeV are reported for the ATLAS, CMS, and LHCb experiments. All results are found to agree with the Standard Model.Comment: 4 pages, 1 figur

Precision Drell-Yan Measurements at the LHC and Implications for the Diphoton Excess

Precision measurements of the Drell-Yan (DY) cross section at the LHC constrain new physics scenarios that involve new states with electroweak (EW) charges. We analyze these constraints and apply them to models that can address the LHC diphoton excess at 750 GeV. We confront these findings with LEP EW precision tests and show that DY provides stronger constraints than the LEP data. While 8 TeV data can already probe some parts of the interesting region of parameter space, LHC14 results are expected to cover a substantial part of the relevant terrain. We derive the bounds from the existing data, estimate LHC14 reach and compare them to the bounds one gets from LEP and future FCC-ee precision measurements.Comment: 21 pages, 7 figures; v2: minor change

NLO+NLL limits on W′W' and Z′Z' gauge boson masses

QCD resummation predictions for the production of new charged ($W'$) and neutral ($Z'$) heavy gauge bosons decaying leptonically are presented. These results are obtained with our resummation code at next-to-leading order and next-to-leading logarithmic (NLO+NLL) accuracy. Our predictions are compared to PYTHIA at leading order (LO) supplemented with parton showers (PS) and FEWZ at NLO and next-to-next-to-leading order (NNLO) for the $p_T$-differential and total cross sections in the Sequential Standard Model (SSM) and general SU(2)$\times$SU(2)$\times$U(1) models. We show that the importance of resummation for total cross sections increases with the gauge boson mass. Finally, the latest ATLAS and CMS results are reinterpreted to derive new limits at NLO+NLL on $W'$ and $Z'$ boson masses in general extensions of the Standard Model.Comment: Proceeding of the XXIII International Workshop on Deep Inelastic Scattering and Related Subjects, April 27 - May 1, 2015, Southern Methodist University, Dallas, Texa

Evaluation of the Theoretical Uncertainties in the W to Lepton and Neutrino Cross Sections at the LHC

We study the sources of systematic errors in the measurement of the W to lepton and neutrino cross-sections at the LHC. We consider the systematic errors in both the total cross-section and acceptance for anticipated experimental cuts. We include the best available analysis of QCD effects at NNLO in assessing the effect of higher order corrections and PDF and scale uncertainties on the theoretical acceptance. In addition, we evaluate the error due to missing NLO electroweak corrections and propose which MC generators and computational schemes should be implemented to best simulate the events.Comment: 33 pages, 109 eps figures, uses JHEP3.cls, rotating.sty Version 2 corrects an error in Table 1, adds some references, and updates an author addres

Recent constraints on the parton distributions in the proton and the measurement of αS\alpha_S from ATLAS and CMS

Recent results on cross sections sensitive to the parton distribution functions (PDFs) within the proton from the ATLAS and CMS Collaborations are presented. The potential impact on the inclusion of these data in fits to the PDFs is discussed. Recent results from fits including the data from jet, or vector boson production from the ATLAS and CMS experiments are discussed.Comment: On behalf of the ATLAS and CMS collaborations. Proceedings for Rencontres de Moriond EW 2014. 8 pages, 7 figure