Production of $e^{+} e^{-}$ in proton-lead collision: photon-photon fusion

TL;DR

This paper investigates photon-photon fusion processes producing electron-positron pairs in proton-lead collisions at LHC energies, using a $k_{T}$-factorisation approach to analyze various differential distributions and structure function parametrizations.

Contribution

It provides a detailed theoretical analysis of photon-initiated dielectron production in proton-lead collisions, incorporating elastic and dissociative processes with modern structure functions.

Findings

Differential distributions in invariant mass, rapidity, and transverse momentum are presented.

Two-dimensional distributions in $ ext{log}_{10} x_{Bj}$ and $ ext{log}_{10} Q^{2}$ are analyzed.

Differences between structure function parametrizations are quantified.

Abstract

We analyze the photon-initiated processes for production of $ e ^ + e ^- $ pairs in proton-nucleus collisions at LHC energy, taking into account both elastic processes and proton dissociations in the low-mass region (LMR) and intermediate-mass region (IMR) as defined by the ALICE collaboration. The calculations are performed within the $k_{\rm T}$-factorisation approach, including transverse momenta of intermediate photons. We discuss several differential distributions in invariant mass of both the leptons $M_{ll}$, pair rapidity $Y_{ll}$ and transverse momenta of the lepton pair $p_{t,ll}$. In addition, we present the two-dimensional distributions in $\log_{10} x_{Bj}$ and $\log_{10} Q^{2}$ and ($\log_{10} W,\log_{10} Q^{2}$) the arguments of the deep-inelastic structure functions. All presented results were obtained with modern parametrizations of proton structure functions. Limiting to small invariant masses of dielectrons one tests structure functions in the nonperturbative region of small $Q^2$ and/or small $W$. We quantify difference for different parametrizations from the literature.