Unravelling the anomalous gauge boson couplings in ZW± production at the LHC and the role of spin-1 polarizations

Abstract

We study the anomalous couplings in ZW ± production in 3l + E T channel at the LHC for √ s = 13 TeV. We use cross section, azimuthal asymmetry, forward-backward asymmetry and polarization asymmetries of Z and reconstructed W to estimate simultaneous limits on the anomalous triple gauge boson couplings (aTGC) for both effective vertex formalism as well as effective operator approach using Markov-Chain-Monte-Carlo (MCMC) method for luminosities 35.9 fb −1 , 100 fb −1 , 300 fb −1 and 1000 fb −1 . The trilepton invariant mass (m 3l ) and the transverse momentum of Z (p T (Z)) are found to be sensitive to the aTGC for the cross section as well as for the asymmetries. We observed that the asymmetries significantly improve the measurement of anomalous couplings if a deviation from the Standard Model (SM) is observed.

On two-body and three-body spin correlations in leptonic $t\bar{t}Z$ production and anomalous couplings at the LHC

“…cross terms, and four for C A 2 -C V 2 cross terms) to obtain the semi analytical expressions for the cross section and all asymmetries. For the cross section, following expression is used to fit the data [48]:…”

“…The polarizations of top quarks, Z boson, and spin correlations of t, t and Z can be useful observables to study the t tZ interaction. There has been a lot of interest in recent days in the polarizations of top quarks , Z/W boson [36][37][38][39][40][41][42][43][44][45][46][47][48][49], including the t t spin correlation [23,[50][51][52][53][54][55][56][57][58][59][60][61][62][63][64] for the study of new physics beyond the SM. Measurement on the top polarizations and t t spin correlations are performed earlier at the Tevatron [65][66][67][68][69][70][71] and recently at the Large Hadron Collider (LHC) by ATLAS and CMS experiments [72][73][74][75][76][77][78][79][80][81]…”

Breaking down the entire spectrum of spin correlations of a pair of particles involving fermions and gauge bosons

“…Usually, these effects lead to lower sensitivity to anomalous couplings, but in some cases, the sensitivity can go up, e.g., see Ref. [75] for W polarizations.…”

“…The top quark polarizations and spin correlations have also been measured at the Tevatron [46][47][48][49][50][51][52] as well as at the large hadron collider ( LHC) [53][54][55][56][57][58][59][60][61][62][63]. Lately, polarization for Z and W bosons also got some attention in probing new physics [3,[64][65][66][67][68][69][70][71][72][73][74][75]. The polarizations of Z and W have also been measured recently at the LHC in ZW production process [76].…”

Automated predictions from polarized matrix elements

“…Likewise, the direct simulation of polarized parton scattering in hadron collisions using public Monte Carlo (MC) tools is found almost exclusively at leading order (LO) and again restricted to certain scattering topologies [52]. Though the availability of such public tools has led to a number of complimentary investigations on the production of polarized EW bosons at the LHC [52][53][54][55][56][57][58].…”