Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Multiple Parton Interactions in Z+4j, W\pm W\pm +0/2j and W+ W- +2j production at the LHC

Ezio Maina

TL;DR

This study evaluates the impact and observability of Multiple Parton Interactions at the LHC across Z+4j, W±W±+0/2j, and W+W−+2j final states with leptonic decays. Using DPI and TPI formalisms, generated event samples, and fixed-order perturbation theory with jet/lepton cuts, the work estimates MPI cross sections, key kinematic discriminants, and signal significances. It finds DPI-dominated Z+4j signals with sizable S/B under angular cuts, promising prospects for exploring triple parton interactions, and demonstrates that MPI in W±W±+0/2j can yield observable same-sign diboson signals, while MPI is negligible as a background to H→WW in VBF after applying standard Higgs-search cuts. The findings highlight MPI as a tool to study multi-parton correlations and as a controllable background in certain Higgs and electroweak channels.

Abstract

The expected rate for Multiple Parton Interactions (MPI) at the LHC is large. This requires an estimate of their impact on all measurement foreseen at the LHC. Conversely it provides new means of studying MPI at the LHC. In this paper we examine the role of MPI at the LHC, with the design energy of 14 TeV, in - Z production in association with four jets, - W\pm W\pm in association with zero or two jets. -W+ W- in association with two jets. In all cases the vector bosons are assumed to decay leptonically. The MPI contribution to Z+4j is dominated by events with two jets with balancing transverse momentum. It is possible to achieve a good signal to background ratio, close to 20%, for MPI compared to Single Interaction processes by selecting events with two jets with large separation in the transverse plane. The corresponding statistical significance for a luminosity of 1 inverse fb is about 6.9 for the mu+mu- channel alone. The final state channel in which only two same-sign high transverse momentum charged leptons are required and additional hard jets are vetoed is dominated by MPI, with an expected yield of 2500 events with the full LHC luminosity.

Multiple Parton Interactions in Z+4j, W\pm W\pm +0/2j and W+ W- +2j production at the LHC

TL;DR

This study evaluates the impact and observability of Multiple Parton Interactions at the LHC across Z+4j, W±W±+0/2j, and W+W−+2j final states with leptonic decays. Using DPI and TPI formalisms, generated event samples, and fixed-order perturbation theory with jet/lepton cuts, the work estimates MPI cross sections, key kinematic discriminants, and signal significances. It finds DPI-dominated Z+4j signals with sizable S/B under angular cuts, promising prospects for exploring triple parton interactions, and demonstrates that MPI in W±W±+0/2j can yield observable same-sign diboson signals, while MPI is negligible as a background to H→WW in VBF after applying standard Higgs-search cuts. The findings highlight MPI as a tool to study multi-parton correlations and as a controllable background in certain Higgs and electroweak channels.

Abstract

The expected rate for Multiple Parton Interactions (MPI) at the LHC is large. This requires an estimate of their impact on all measurement foreseen at the LHC. Conversely it provides new means of studying MPI at the LHC. In this paper we examine the role of MPI at the LHC, with the design energy of 14 TeV, in - Z production in association with four jets, - W\pm W\pm in association with zero or two jets. -W+ W- in association with two jets. In all cases the vector bosons are assumed to decay leptonically. The MPI contribution to Z+4j is dominated by events with two jets with balancing transverse momentum. It is possible to achieve a good signal to background ratio, close to 20%, for MPI compared to Single Interaction processes by selecting events with two jets with large separation in the transverse plane. The corresponding statistical significance for a luminosity of 1 inverse fb is about 6.9 for the mu+mu- channel alone. The final state channel in which only two same-sign high transverse momentum charged leptons are required and additional hard jets are vetoed is dominated by MPI, with an expected yield of 2500 events with the full LHC luminosity.

Paper Structure

This paper contains 7 sections, 21 equations, 7 figures, 6 tables.

Table of Contents

  1. Introduction
  2. Calculation
  3. Studying MPI in $Z+4j$ processes
  4. Studying MPI in $W^{\pm} W{^\pm} +0/2j$ processes
  5. MPI in $W^{+} W^{-}+2j$ processes: a background to Higgs production via vector fusion in the $H\rightarrow WW \rightarrow \ell\ell\nu\nu$ channel?
  6. Conclusions
  7. A loose argument for the relative size of the effective cross sections in Double and Triple Parton Interactions

Figures (7)

  • Figure 1:
  • Figure 2: Distribution of the total invariant mass of the events for the different contributions and for their sum. Cuts as in Eq.(\ref{['eq:cuts']}), Eq.(\ref{['eq:cuts_iso']}) and Eq.(\ref{['cuts:DeltaEta']}). The curves in the lower plot are normalized to unit area.
  • Figure 3: Largest $\Delta\phi$ separation between jet pairs for the different contributions and for their sum. Cuts as in Eq.(\ref{['eq:cuts']}), Eq.(\ref{['eq:cuts_iso']}) and Eq.(\ref{['cuts:DeltaEta']}). The curves in the lower plot are normalized to unit area.
  • Figure 4: $\Delta\phi$ separation between the two most energetic jets (on the left) and between the two least energetic among the four jets (on the right) for the different contributions and for their sum. Cuts as in Eq.(\ref{['eq:cuts']}), Eq.(\ref{['eq:cuts_iso']}) and Eq.(\ref{['cuts:DeltaEta']}). The curves in the lower plot are normalized to unit area.
  • Figure 5: $\Delta\phi$ separation between the two jets which do not belong to the pair with the largest $\Delta\phi$ in the event. Cuts as in Eq.(\ref{['eq:cuts']}), Eq.(\ref{['eq:cuts_iso']}), Eq.(\ref{['cuts:DeltaEta']}) and Eq.(\ref{['cuts:DeltaPhi']}).
  • ...and 2 more figures