253 research outputs found
Different polarization definitions in same-sign scattering at the LHC
We study the polarization of positively charged 's in the scattering of
massive electroweak bosons at hadron colliders. We rely on the separation of
weak boson polarizations in the gauge-invariant, doubly-resonant part of the
amplitude in Monte Carlo simulations. Polarizations depend on the reference
frame in which they are defined. We discuss the change in polarization
fractions and in kinematic distributions arising from defining polarization
vectors in two different reference frames which have been employed in recent
experimental analyses.Comment: added reference to CMS measurement, typos corrected, matches PLB
published versio
Factorisation and Subtraction beyond NLO
We provide a general method to construct local infrared subtraction
counterterms for unresolved radiative contributions to differential cross
sections, to any order in perturbation theory. We start from the factorised
structure of virtual corrections to scattering amplitudes, where soft and
collinear divergences are organised in gauge-invariant matrix elements of
fields and Wilson lines, and we define radiative eikonal form factors and jet
functions which are fully differential in the radiation phase space, and can be
shown to cancel virtual poles upon integration by using completeness relations
and general theorems on the cancellation of infrared singularities. Our method
reproduces known results at NLO and NNLO, and yields substantial
simplifications in the organisation of the subtraction procedure, which will
help in the construction of efficient subtraction algorithms at higher orders.Comment: 34 pages, 3 figure
Local Analytic Sector Subtraction at NNLO
We present a new method for the local subtraction of infrared divergences at
next-to-next-to-leading order (NNLO) in QCD, for generic infrared-safe
observables. Our method attempts to conjugate the minimal local counterterm
structure arising from a sector partition of the radiation phase space with the
simplifications following from analytic integration of the counterterms. In
this first implementation, the method applies to final-state massless
particles. We show how our method compactly organises infrared subtraction at
NLO, we deduce in detail the general structure of the subtraction terms at
NNLO, and we provide a proof of principle with a complete application to a
simple process at NNLO.Comment: Matching journal version, minor correction
Local analytic sector subtraction for final state radiation at NNLO
We present recent developments of the local analytic sector subtraction of
infrared singularities for final state real radiation at NNLO in QCD.Comment: 10 page
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