Eur. Phys. J. C (2018) 78: 671
https://doi.org/10.1140/epjc/s10052-018-6136-y

Regular Article - Theoretical Physics

Precise predictions for same-sign W-boson scattering at the LHC

¹ INFN, Sezione di Torino, Via P. Giuria 1, 10125, Turin, Italy
² Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Emil-Hilb-Weg 22, 97074, Würzburg, Germany
³ Department Physik, Universität Siegen, Walter-Flex-Str.3, 57068, Siegen, Germany
⁴ Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Str. 3, 79104, Freiburg, Germany
⁵ Technische Universität München, James-Franck-Str. 1, 85748, Garching, Germany
⁶ University and INFN, Milano-Bicocca, piazza della Scienza, 3, 20126, Milan, Italy
⁷ Dipartimento di Fisica and INFN, Sezione di Pavia, Universitá di Pavia, Via A. Bassi 6, 27100, Pavia, Italy
⁸ IBM Italia s.p.a. Circonvallazione Idroscalo, 20090, Segrate, MI, Italy
⁹ Institute for Theoretical Physics, University of Tübingen, Auf der Morgenstelle 14, 72076, Tübingen, Germany
¹⁰ Physik-Institut, Universität Zürich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
¹¹ Dipartimento di Fisica, Università di Torino, Via P. Giuria 1, 10125, Turin, Italy
¹² Particle Physics, Faculty of Physics, University of Vienna, Vienna, Austria
¹³ Institute for Theoretical Physics, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
¹⁴ DESY Theory Group, Notkestr. 85, 22607, Hamburg, Germany
¹⁵ Laboratoire de Physique Théorique et Hautes Énergies (LPTHE), UMR 7589, Sorbonne Université et CNRS, 4 place Jussieu, 75252, Paris Cedex 05, France
¹⁶ Theoretical Physics Department, CERN, 1211, Geneva 23, Switzerland
¹⁷ Nikhef, Science Park 105, 1098 XG, Amsterdam, The Netherlands

^* e-mail: mpellen@physik.uni-wuerzburg.de

Received: 4 April 2018
Accepted: 5 August 2018
Published online: 22 August 2018

Abstract

Vector-boson scattering processes are of great importance for the current run-II and future runs of the Large Hadron Collider. The presence of triple and quartic gauge couplings in the process gives access to the gauge sector of the Standard Model (SM) and possible new-physics contributions there. To test any new-physics hypothesis, sound knowledge of the SM contributions is necessary, with a precision which at least matches the experimental uncertainties of existing and forthcoming measurements. In this article we present a detailed study of the vector-boson scattering process with two positively-charged leptons and missing transverse momentum in the final state. In particular, we first carry out a systematic comparison of the various approximations that are usually performed for this kind of process against the complete calculation, at LO and NLO QCD accuracy. Such a study is performed both in the usual fiducial region used by experimental collaborations and in a more inclusive phase space, where the differences among the various approximations lead to more sizeable effects. Afterwards, we turn to predictions matched to parton showers, at LO and NLO: we show that on the one hand, the inclusion of NLO QCD corrections leads to more stable predictions, but on the other hand the details of the matching and of the parton-shower programs cause differences which are considerably larger than those observed at fixed order, even in the experimental fiducial region. We conclude with recommendations for experimental studies of vector-boson scattering processes.