Electroweak corrections and anomalous triple gauge-boson couplings in WW and WZ production at the LHC

TL;DR

Problem: accurately probing anomalous triple gauge-boson couplings in WW and WZ production at the LHC requires precise theoretical predictions. Approach: combine a complete four-fermion calculation with electroweak ${\cal O}(\alpha)$ corrections in the double-pole approximation and include leading high-energy logs and real-photon emissions; also parameterize anomalous TGCs with a form-factor-preserved unitarity. Findings: electroweak corrections can mimic or mask anomalous TGC signals, often exceeding the size of the new-physics effects; neglecting them can lead to misinterpretation. Significance: highlights the necessity of including EW corrections in LHC analyses of di-boson production and provides a Monte Carlo tool for such studies.

Abstract

We have analysed the production of WW and WZ vector-boson pairs at the LHC. These processes give rise to four-fermion final states, and are particularly sensitive to possible non-standard trilinear gauge-boson couplings. We have studied the interplay between the influence of these anomalous couplings and the effect of the complete logarithmic electroweak O(α) corrections. Radiative corrections to the Standard Model processes in double-pole approximation and non-standard terms due to trilinear couplings are implemented into a Monte Carlo program for p p -> 4f (+γ) with final states involving four or two charged leptons. We numerically investigate purely leptonic final states and find that electroweak corrections can fake new-physics signals, modifying the observables by the same amount and shape, in kinematical regions of statistical significance.

Figures (4)

• Figure 1: Structure of the process ${\rm p}$ p${\rm p}$ p$\to V_1 V_2+X \to 4f+X$ in ${{\rm DPA}}$
• Figure 2: Distributions for ${\rm W}$ W${\rm Z}$ Z$$ production. (a) Maximal transverse momentum of the charged leptons. (b) Energy of the reconstructed ${\rm Z}$ Z$$-boson. (c) Difference in rapidity between the reconstructed ${\rm Z}$ Z$$-boson and the charged lepton coming from the ${\rm W}$ W$$-boson decay. (d) Rapidity of the reconstructed ${\rm Z}$ Z$$-boson. The contributions of the eight final states $l\nu_ll^\prime\bar{l^\prime}$ where $l,l^\prime =e,\mu$ are summed up, and standard cuts as well as $P_{{\rm T}}({\rm Z}$ Z$)> 250\,{\rm GeV}$ are applied. Legends as explained in the text.
• Figure 3: Distributions for ${\rm W}$ W${\rm Z}$ Z$$ production. (a) Maximal transverse momentum of the charged leptons. (b) Energy of the reconstructed ${\rm Z}$ Z$$-boson. (c) Difference in rapidity between the reconstructed ${\rm Z}$ Z$$-boson and the charged lepton coming from the ${\rm W}$ W$$-boson decay. (d) Rapidity of the reconstructed ${\rm Z}$ Z$$-boson. The contributions of the eight final states $l\nu_ll^\prime\bar{l^\prime}$ where $l,l^\prime =e,\mu$ are summed up, and standard cuts as well as $P_{{\rm T}}(l)> 70\,{\rm GeV}$ are applied. Legends as explained in the text.
• Figure 4: Distributions for ${\rm W}$ W${\rm W}$ W$$ production. (a) Maximal transverse momentum of the charged leptons. (b) Energy of the ${\rm W}$ W$$-boson. (c) Rapidity difference of the two charged leptons. (d) Rapidity of the ${\rm W}$ W$^-$ boson. The contributions of the four final states $l\bar{\nu}_l\nu_{l^\prime}\bar{l^\prime}$ where $l,l^\prime =e,\mu$ are summed up, and standard cuts as well as $M_{{\rm inv}}(l \bar{l^\prime})> 500 \,{\rm GeV}$ and $|\Delta y_{l\bar{l^\prime}}|< 3$ are applied. Legends as explained in the text.