Six-jet production from triple parton scatterings in proton-proton collisions at the LHC

TL;DR

This paper investigates six-jet production in proton-proton collisions at the LHC as a way to observe triple parton scatterings, calculating cross sections and analyzing the potential for experimental detection.

Contribution

It provides the first detailed calculation of triple parton scattering contributions to six-jet production at the LHC using NLO QCD methods.

Findings

TPS contributes about 20% to 6-jet yields at pT > 20 GeV.

TPS can be observed with about 50 pb^{-1} of data at the LHC.

Triple parton scattering is a significant component in multi-jet events.

Abstract

The production of six energetic jets in proton-proton (pp) collisions at the LHC is studied as a means to directly observe for the first time the simultaneous scattering of three partons. The single-parton-scattering (SPS) cross sections for the production 2-, 3-, 4-, and 6-jets in pp collisions at center-of-mass energies of $\sqrt{s} = 14$ TeV, are calculated up to next-to-leading-order (NLO) accuracy in perturbative quantum chromodynamics with the MadGraph5_aMC@NLO and ALPGEN codes complemented with Pythia-8 for parton showering, hadronization, and decays. Jets are reconstructed using the anti-$k_T$ algorithm with distance parameter $R=0.4$. Assuming factorization of multiple hard-scattering probabilities in terms of SPS cross sections, the contributions to six-jet production from double- (DPS) and triple- (TPS) parton scatterings are derived. We find that the TPS contributions represent a ${\approx}20\%$ (${\approx}1\%$) fraction of the total 6-jets yields for minimum jet transverse momenta of $p_{T,min} = 20$ ($40$) GeV. A detailed multivariate analysis with realistic simulations of fully reconstructed jet samples for the TPS signal and DPS and SPS backgrounds indicates that TPS can be observed in events with six jets with $p_{T,min}=40$ GeV each, by collecting an integrated luminosity of $\mathcal{O}(50$ pb$^{-1}$) in a dedicated low-pileup run at the LHC.