Measurement and effective field theory interpretation of the photon-fusion production cross section of a pair of W bosons in proton-proton collisions at $\sqrt{s}$ = 13 TeV

TL;DR

This paper reports the first observation of photon-fusion W boson pair production at the LHC, measuring cross sections consistent with the Standard Model and constraining anomalous gauge couplings using effective field theory.

Contribution

It provides the first measurement of photon-fusion W boson pair production cross sections at 13 TeV and interprets results within an effective field theory framework.

Findings

Measured total cross section: 643^{+82}_{-78} fb

Fiducial cross section: 3.96^{+0.53}_{-0.51} fb

Results agree with Standard Model predictions

Abstract

This analysis presents an observation of the photon-fusion production of W boson pairs using the CMS detector at the LHC. The total cross section of the W$^+$W$^-$ production in photon fusion is measured using proton-proton collision data with an integrated luminosity of 138 fb$^{-1}$ collected with the CMS detector in 2016$-$2018 at a center-of-mass energy of $\sqrt{s}$ = 13 TeV. Events are selected in the final state with one isolated electron and one isolated muon, and no additional tracks associated with the electron-muon production vertex. The total and fiducial production cross sections are 643$^{+82}_{-78}$ fb and 3.96$^{+0.53}_{-0.51}$ fb, respectively, in agreement with the standard model predictions of 631 $\pm$ 126 fb and 3.87 $\pm$ 0.77 fb. This agreement enables stringent constraints to be imposed on anomalous quartic gauge couplings within a dimension-8 effective field theory framework.