Abstract
In this paper we study the transverse energy spectrum for the Drell-Yan process. The transverse energy is measured within the central region defined by a (pseudo-) rapidity cutoff. Soft-collinear effective theory (SCET) is used to factorize the cross section and resum large logarithms of the rapidity cutoff and ratios of widely separated scales that appear in the fixed order result. We develop a framework which can smoothly interpolate between various regions of the spectrum and eventually match onto the fixed order result. This way a reliable calculation is obtained for the contribution of the initial state radiation to the measurement. By comparing our result for Drell-Yan against Pythia we obtain a simple model that describes the contribution from multiparton interactions (MPI). A model with little or no dependence on the primary process gives results in agreement with the simulation. Based on this observation we propose MPI insensitive measurements. These observables are insensitive to the MPI contributions as implemented in Pythia and we compare against the purely perturbative result obtained with the standard collinear factorization.
Highlights
In experimental and Monte Carlo studies a class of observables known as multiparton interactions (MPI) sensitive observables are used to probe the underling event activity in hadronic colliders
We study the dependence of the model on the hard scale of the process using Pythia simulations and we find that below the TeV scale the MPI distribution is independent of the hard scale
In this work we review the analysis of ref. [15] and we illustrate how within the framework of soft-collinear effective theory [16,17,18,19] (SCET) we can study the effects of rapidity cutoff on resummed transverse energy distributions measured in hadronic collisions
Summary
We illustrate how within the framework of SCET we can reliably describe the transverse energy distribution for the process qq → γ∗ + X for phenomenologically interesting values of the transverse energy and the rapidity cutoff. [15] that when a rapidity cutoff is imposed the transverse energy distribution is insensitive to the cutoff parameter only in the region ET Qr In this region the transverse energy spectrum can be described with the factorization theorem for the global case and for this reason we begin in section 2.1 presenting a factorization theorem for the global definition of ET.
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