Nonperturbative corrections and showering in NLO-matched event generators

Abstract

We study contributions from nonperturbative effects and parton showering in NLO event generators, and present applications to jet final states. We find pT-dependent and rapidity-dependent corrections which can affect the shape of observed jet distributions at the LHC. We illustrate numerically the kinematic shifts in longitudinal momentum distributions from the implementation of energy-momentum conservation in collinear shower algorithms.

Figures (3)

• Figure 1: The NP correction factors to jet transverse momentum distributions obtained using Pythia and Powheg respectively, for $|y|<0.5$ and $2 < |y|< 2.5$. Left: $R=0.5$; Right: $R=0.7$.
• Figure 2: The parton shower correction factor to jet transverse momentum distributions, obtained from Eq. (\ref{['npK3']}) using Powheg for $|y|<0.5$ and $2 < |y|< 2.5$. Left: $R=0.5$; Right: $R=0.7$.
• Figure 3: Distributions in the parton longitudinal momentum fraction $x$ before (POWHEG) and after parton showering (POWHEG+PS), for inclusive jet production at different rapidities for jets with $p_T> 18$ GeV obtained by the anti-kt jet algorithm with $R=0.5$. Shown is the effect of intrinsic $k_t$, initial (IPS) and initial+final state (IFPS) parton shower.