Improved bounds on W−W′ mixing with ATLAS resonant WZ production data at the LHC at

Abstract

New charged vector bosons W decaying into gauge boson pairs W Z are predicted in many scenarios of new physics, including models with an extended gauge sector (EGM). Due to the large variety of models (other unification groups, models with Supersymmetry, Little Higgs Models, Extra Dimensions) the more general EGM approach is here considered. For what concerns Wproduction, these models are parametrised by two parameters, the W mass M W and the W -W mixing parameter ξ. The diboson W Z production allows to place stringent constraints on this mixing angle and the W mass, which we determine and present for the first time by using data from pp collisions at √ s = 13 TeV recorded by the ATLAS detector at the CERN LHC, with integrated luminosity of 36.1 fb −1 . By comparing the experimental limits to the theoretical predictions for the total cross section of W resonant production and its subsequent decay into W Z pairs, we show that the derived constraints on the mixing angle are rather severe, between 10 −4 and 10 −3 , i.e., greatly improved with respect to those derived from the global analysis of electroweak data which yield ξ < ∼ 10 −2 . We combine the limits derived from W Z production data with those obtained from the W → eν process in order to significantly extend the exclusion region in the M W -ξ parameter plane and obtain the most stringent exclusion limits to date. We present the combined allowed parameter space for the EGM W boson after incorporating indirect constraints from low energy electroweak data, direct search constraints from Tevatron and from the LHC Run I with 7 and 8 TeV as well as at Run II with 13 TeV data. * Inna.Serenkova@cern.ch † Per.Osland@uib.no ‡ pankov@ictp.it

Dirac neutrinos in an SU(2) left-right symmetric model

“…21has an upper limit sin ξ < 10 −4 . Recent analysis comparing the experimental limits to the theoretical calculations for the total W 2 resonant production and the decay W 2 → WZ implies that mixing angle ξ is between 10 −4 and 10 −3 , excluding ξ ≃ 6 × 10 −6 [37].…”

The charged-current non-standard neutrino interactions at the LHC and HL-LHC

“…( 2) can be used to describe the CC NSI. The mixing angle between the new gauge boson W and the SM W boson was found to be very small [23,29], we neglect this mixing effect in this paper.…”

“…In the following sections, we take Γ W /M W = 0.1 as same as Refs [17,19]. In this case, 3 The constraints on the CC NSI parameters at the LHC A simple and efficient way to search for the gauge boson W at the LHC is through its single s-channel resonance and subsequent leptonic decay [23]. Since the main components of protons are u and d quarks, the contribution of the u d process is much larger than that of the cs process.…”

“…In this article, based on the Monte-Carlo (MC) simulation, we will discuss the constraints on the CC NSI parameters via the process pp → + ν with the emphasis on the contributions of the interference between the CC NSI and the SM. The limits on W production was set in LHC experiments mainly by Br(pp → W X)×Br(W → ν ), the interference effect was not generally considered [17,23], which, as will be shown, turns out to be very important. Except for that, the sensitives of the process pp → + ν to the new charged gauge boson W at the future runs of the LHC are also discussed.…”

High-precision limits on $W$-$W'$ and $Z$-$Z'$ mixing from diboson production using the full LHC Run 2 ATLAS data set

“…Previous analyses of the Z-Z and W -W mixing [36][37][38] were carried out using the diboson production data set corresponding to the time-integrated luminosity of ∼ 36 fb −1 collected in 2015 and 2016 with the ATLAS and CMS collaborations at √ s = 13 TeV where electroweak Z and W gauge bosons decay into the semileptonic channel [39] or into the dijet final state [40]. The results of the present analysis benefit from the increased size of the data sample corresponding to an integrated luminosity of 139 fb −1 recorded by the ATLAS detector in Run 2 [35] which is almost four times larger than what was available for the previous study in the semileptonic final state 6 .…”