The relevance of polarized bZ production at LHC

TL;DR

This paper analyzes the Z polarization asymmetry in bZ production at the LHC, showing it is stable against theoretical uncertainties and could independently verify the SM discrepancy observed in LEP1 measurements.

Contribution

It demonstrates that the Z polarization asymmetry A_Z is theoretically stable and can serve as an independent test of the SM discrepancy in Z -> bbbar asymmetry.

Findings

A_Z remains unaffected by QCD and electroweak corrections.

A_Z could confirm the LEP1 Z -> bbbar asymmetry discrepancy.

Potential to observe a 10% deviation if SM discrepancy is real.

Abstract

We consider the Z polarization asymmetry A_Z=(sigma(Z_R)-sigma(Z_L))/(sigma(Z_R)+sigma(Z_L)) in the process of associated bZ production at the LHC. We show that in the Standard Model (SM) this quantity is essentially given by its Born approximation, remaining almost unaffected by QCD scales and parton distribution functions variations as well as by electroweak corrections. The theoretical quantity that appears in A_Z is the same that provides the LEP1 Z -> b bbar forward-backward asymmetry, the only measured observable still in some contradiction with the SM prediction. In this sense, A_Z would provide the possibility of an independent verification of the possible SM discrepancy, which could reach, if consistency with LEP1 measurements is imposed, values of the relative ten percent size.