Precision Measurement with Diboson at the LHC

Abstract

Precision measurements at the LHC can provide probes of new physics, and they are complementary to direct searches. The high energy distribution of di-boson processes ($WW,WZ,Vh$) is a promising place, with the possibility of significant improvement in sensitivity as the data accumulates. We focus on the semi-leptonic final states, and make projections of the reach for future runs of the LHC with integrated luminosities of 300 fb$^{-1}$ and 3 ab$^{-1}$. We emphasize the importance of tagging the polarization of the vector bosons, in particular for the $WW$ and $WZ$ channels. We employ a combination of kinematical distributions of both the $W$ and $Z$, and their decay products to select the longitudinally polarized $W$ and $Z$. We have also included our projections for the reach using the associated production of vector boson and the Higgs. We demonstrate that di-boson measurement in the semi-leptonic channel can surpass the sensitivity of the precision measurement at LEP, and they can be significantly more sensitive than the HL-LHC $h \to Z \gamma$ measurements. Compared with fully leptonic decaying $WZ$ channel, the reach from semi-leptonic channel can be better with effective suppression of the reducible background and systematic error. We have also considered the reaches on the new physics mass scale in different new physics scenarios, including the Strongly Interacting-Light Higgs (SILH), the Strongly Coupled Multi-pole Interaction (Remedios), and the class of models with partially composite fermions. We find that in the SILH and non-compact Remedios scenario with large coupling $g_* > 7$, measurements in the di-boson channel is more sensitive than the Drell-Yan di-lepton channel at the HL-LHC.