Search for optimal conditions for exploring double-parton scattering in four-jet production: $k_t$-factorization approach

TL;DR

The study addresses how to maximize and identify double-parton scattering (DPS) contributions in four-jet production by employing $k_T$-factorization, which naturally includes higher-order effects through parton transverse momentum distributions. It analyzes SPS and DPS using a pocket-formula framework with an effective cross section $σ_{eff}$ and proposes observables such as $ΔY$, $Δφ_{jj}$, $ΔS$, and $Δφ_{3j}^{min}$ to distinguish the two mechanisms, validated against CMS data for soft jet cuts. The results indicate DPS is enhanced in certain phase-space regions (large rapidity gaps, small azimuthal separations) but remains smaller than in some LO collinear estimates, and underscore the potential to extract or test a kinematics-dependent $σ_{eff}$. The work provides practical guidance for CMS/ATLAS analyses to search for DPS signatures and map the partonic correlations inside protons.

Abstract

In the present paper we discuss how to maximize the double-parton scattering (DPS) contribution in four-jet production by selecting kinematical cuts. Here both single-parton and double-parton scattering effects are calculated in the $k_T$-factorization approach, following our recent developments of relevant methods and tools. Several differential distributions are shown and discussed in the context of future searches for DPS effects, such as rapidity of jets, rapidity distance, and azimuthal correlations between jets. The dependences of the relative DPS amount is studied as function of those observables. The regions with an enhanced DPS contribution are identified. Future experimental explorations could extract more precise values of $σ_{eff}$ and its potential dependence on kinematical variables.

Figures (12)

• Figure 1: Rapidity distribution of the leading, 2nd, 3rd and 4th jets. The SPS contribution is shown by the dotted line while the DPS contribution by the dashed line.
• Figure 2: Distribution in the $\Delta S$ variable. The SPS contribution is shown by the dotted line while the DPS contribution by the dashed line.
• Figure 3: Rapidity distribution of leading and subleading jets for $\sqrt{s}$ = 7 TeV (left column) and $\sqrt{s}$ = 13 TeV (right column) for the symmetric cuts. The SPS contribution is shown by the dotted line while the DPS contribution by the dashed line. The relative contribution of DPS is shown in the extra lower panels.
• Figure 4: Distribution in rapidity distance between the most remote jets for the symmetric cut with $p_T >$ 20 GeV for $\sqrt{s}$ = 7 TeV (left) and $\sqrt{s}$ = 13 TeV (right). The SPS contribution is shown by the dotted line while the DPS contribution by the dashed line. The relative contribution of DPS is shown in the extra lower panels.
• Figure 5: Distribution in relative azimuthal angle between the most remote jets for the symmetric cut with $p_T >$ 20 GeV for $\sqrt{s}$ = 7 TeV (left) and $\sqrt{s}$ = 13 TeV (right). The SPS contribution is shown by the dotted line while the DPS contribution by the dashed line. The relative contribution of DPS is shown in the extra lower panels.