Abstract
Longitudinal polarisation of the weak bosons is a direct consequence of Electroweak symmetry breaking mechanism providing an insight into its nature, and is instrumental in searches for physics beyond the Standard Model. We perform a polarisation study of the diboson production in the pp → {mathrm{e}}^{+}{v}_{mathrm{e}}{mu}^{-}{overline{v}}_{mu } process at NNLO QCD in the fiducial setup inspired by experimental measurements at ATLAS. This is the first polarisation study at NNLO. We employ the double-pole approximation framework for the polarised calculation, and investigate NNLO effects arising in differential distributions.
Highlights
Combined NLO EW and (N)NLO QCD [31, 32] computations are available for a variety of setups and observables
Resummation and parton shower effects have been studied in the context of weak boson pair production [33,34,35,36,37]
NNLO corrections are important for the differential distributions in diboson production, where NLO scale uncertainty exceeds the intrinsic uncertainty related to the theoretical definition of boson polarisation
Summary
In this paper we study the resonant production and subsequent decay of (un)polarised W +W −-boson pairs at the LHC in the different flavour di-leptonic decay channel, i.e. We consider two commonly used approximations both resulting in on-shell amplitudes for polarised W-bosons: the so-called pole approximation or, in this case, double-pole approximation (DPA), and the narrow-width approximation (NWA). Both methods neglect single-resonant contributions present in the general process pp → e+νeμ−νμ and introduce uncertainties which are formally of O(ΓW/MW). In order to guarantee gauge invariance, one defines an on-shell projection to map the off-shell kinematics of the decay products point-by-point to the on-shell kinematics This allows the same factorization as in eq (2.3) by neglecting single-resonant diagrams. Consider the diboson mass frame by a direct boost from Lab frame In this frame individual boson momenta are equal and back-to-back, but generally not on-shell. It has been observed that the frame choices tend to be rather complementary to each other in their discrimination power to isolate polarisations [6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
