Production of two $c \bar c$ pairs in double-parton scattering

TL;DR

The paper investigates production of two charm-anticharm pairs in proton-proton collisions via double-parton scattering at high energies. It adopts a simple factorized DPS formalism with a fixed sigma_eff and LO gluon-gluon fusion inputs to estimate inclusive and differential cross sections. Key finding: at LHC energies DPS contributions can be as large as or dominate over SPS, raising unitarity considerations, and affect charm production phenomenology. The work identifies DPS-specific observables, especially c and cbar rapidity correlations, invariant masses, and pair transverse momentum, as potential experimental signatures, and discusses forward detector strategies and future refinements (NLO, hadronization).

Abstract

We discuss production of two pairs of $c \bar c$ within a simple formalism of double-parton scattering (DPS). Surprisingly very large cross sections, comparable to single-parton scattering (SPS) contribution, are predicted for LHC energies. Both total inclusive cross section as a function of energy and differential distributions for $\sqrt{s}$ are shown. We discuss a perspective how to identify the double scattering contribution.

Figures (6)

• Figure 1: Mechanism of $c \bar{c} c \bar{c}$ production via double-parton scattering.
• Figure 2: Total LO cross section for single-parton and double-parton scattering as a function of center-of-mass energy (left panel) and uncertainties due to the choice of (factorization, renormalization) scales (right panel). We show in addition a parametrization of the total cross section in the left panel. Cross section for DPS should be multiplied in addition by a factor 2 in the case when all $c$ ($\bar{c}$) are counted.
• Figure 3: Distribution in rapidity (left panel) and transverse momentum (right panel) of $c$ or $\bar{c}$ quarks at $\sqrt{s}$ = 7 TeV. Cross section for DPS should be multiplied in addition by a factor 2 in the case when all $c$ ($\bar{c}$) are counted.
• Figure 4: Uncertainties related to renormalization and factorization scales choice for distributions in rapidity (left panel) and transverse momentum (right panel) of $c$ or $\bar{c}$ quarks at $\sqrt{s}$ = 7 TeV. Cross section for DPS should be multiplied in addition by a factor 2 in the case when all $c$ ($\bar{c}$) are counted.
• Figure 5: Distribution in rapidity difference (left panel) and in invariant mass of the $c\bar{c}$ pair (right panel) at $\sqrt{s}$ = 7 TeV.