Separating Electroweak and Strong interactions in Drell-Yan processes at LHC: leptons angular distributions and reference frames

Abstract

Among the physics goals of LHC experiments, precision tests of the Standard Model in the Strong and Electroweak sectors play an important role. Because of nature of the proton-proton processes, observables based on the measurement of the direction and energy of leptons provide the most precise signatures. In the present paper, we concentrate on the angular distribution of Drell-Yan process leptons, in the lepton-pair rest-frame. The vector nature of the intermediate state imposes that distributions are to a good precision described by spherical polynomials of at most second order. We show that with the proper choice of the coordinate frames, only one coefficient in this polynomial decomposition remains sizable, even in the presence of one or two high $p_T$ jets. The necessary stochastic choice of the frames relies on probabilities independent from any coupling constants. This remains true when one or two partons accompany the lepton pairs. In this way electroweak effects can be better separated from strong interaction ones for the benefit of the interpretation of the measurements. Our study exploits properties of single gluon emission matrix elements which are clearly visible if a conveniently chosen form of their representation is used. We rely also on distributions obtained from matrix element based Monte Carlo generated samples of events with two leptons and up to two additional partons in test samples. Incoming colliding protons' partons are distributed accordingly to PDFs and are strictly collinear to the corresponding beams.

22 pages 9 figures

References in corpus (14)

• Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC
• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• Vector boson production at hadron colliders: a fully exclusive QCD calculation at NNLO
• Electroweak gauge boson production at hadron colliders through O(alpha_s^2)
• FEWZ 2.0: A code for hadronic Z production at next-to-next-to-leading order
• Precision electroweak calculation of the production of a high transverse-momentum lepton pair at hadron colliders
• The W boson production cross section at the LHC through O(alpha_s^2)
• Mixed QCD-electroweak O(α_sα) corrections to Drell-Yan processes in the resonance region: pole approximation and non-factorizable corrections
• NNLOPS accurate Drell-Yan production
• Measurements of differential and double-differential Drell-Yan cross sections in proton-proton collisions at 8 TeV
• First Measurement of the Angular Coefficients of Drell-Yan $e^{+}{e}^{-}$ pairs in the Z Mass Region from $p\bar{p}$ Collisions at $\sqrt{s}$ = 1.96 TeV
• Model-independent constraints on the shape parameters of dilepton angular distributions
• Drell-Yan lepton angular distributions in perturbative QCD
• Gauge invariant sub-structures of tree-level double-emission exact QCD spin amplitudes

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• Prospects of non-resonant di-Higgs searches and Higgs boson self-coupling measurement at the HE-LHC using machine learning techniques
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• Electron-positron, parton-parton and photon-photon production of $\tau$-lepton pairs: anomalous magnetic and electric dipole moments spin effects
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