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Minijet transverse energy production in the next-to-leading order in hadron and nuclear collisions

A. V. Leonidov, D. M. Ostrovsky

TL;DR

This work assesses the accuracy of minijet-driven transverse energy predictions by performing a next-to-leading order (NLO) QCD calculation for pp collisions and propagating the results to nuclear collisions via a Glauber model. Using the Kunzst-Soper Monte Carlo framework with a central-rapidity minijet definition, it finds substantial NLO enhancements in pp cross sections, with K-factors around 1.9 for RHIC and 2.1 for LHC. In nuclear collisions, NLO corrections broaden the E⊥ spectrum without drastically changing its shape, implying higher event-by-event energy and potentially more favorable conditions for collective behavior. The study underscores the need for higher-order resummation and nonlinear effects to refine predictions for initial conditions in heavy-ion dynamics.

Abstract

The transverse energy flow generated by minijets in hadron and nuclear collisions into a given rapidity window in the central region is calculated in the next-to-leading (NLO) order in QCD at RHIC and LHC energies. The NLO transverse energy production in pp collisions cross sections are larger than the LO ones by the factors of K_{RHIC} ~ 1.9 and K_{LHC} ~ 2.1 at RHIC and LHC energies correspondingly. These results were then used to calculate transverse energy spectrum in nuclear collisions in a Glauber geometrical model. We show that accounting for NLO corrections in the elementary pp collisions leads to a substantial broadening of the E_{perp} distribution for the nuclear ones, while its form remains practically unchanged.

Minijet transverse energy production in the next-to-leading order in hadron and nuclear collisions

TL;DR

This work assesses the accuracy of minijet-driven transverse energy predictions by performing a next-to-leading order (NLO) QCD calculation for pp collisions and propagating the results to nuclear collisions via a Glauber model. Using the Kunzst-Soper Monte Carlo framework with a central-rapidity minijet definition, it finds substantial NLO enhancements in pp cross sections, with K-factors around 1.9 for RHIC and 2.1 for LHC. In nuclear collisions, NLO corrections broaden the E⊥ spectrum without drastically changing its shape, implying higher event-by-event energy and potentially more favorable conditions for collective behavior. The study underscores the need for higher-order resummation and nonlinear effects to refine predictions for initial conditions in heavy-ion dynamics.

Abstract

The transverse energy flow generated by minijets in hadron and nuclear collisions into a given rapidity window in the central region is calculated in the next-to-leading (NLO) order in QCD at RHIC and LHC energies. The NLO transverse energy production in pp collisions cross sections are larger than the LO ones by the factors of K_{RHIC} ~ 1.9 and K_{LHC} ~ 2.1 at RHIC and LHC energies correspondingly. These results were then used to calculate transverse energy spectrum in nuclear collisions in a Glauber geometrical model. We show that accounting for NLO corrections in the elementary pp collisions leads to a substantial broadening of the E_{perp} distribution for the nuclear ones, while its form remains practically unchanged.

Paper Structure

This paper contains 4 sections, 7 equations, 4 figures.

Table of Contents

  1. Introduction
  2. NLO minijet transverse energy production in hadron collisions
  3. NLO transverse energy production in nuclear collisions
  4. Discussion

Figures (4)

  • Figure 1: NLO (solid line) and LO (dashed line) transverse energy spectrum in a unit central rapidity window for pp collisions at RHIC energy $\sqrt{s}=200$ GeV
  • Figure 2: NLO (solid line) and LO (dashed line) transverse energy spectrum in a unit central rapidity window for pp collisions at LHC energy $\sqrt{s}=5500$ GeV
  • Figure 3: NLO (solid line) and LO (dashed line) transverse energy spectrum in a unit central rapidity window for PbPb collisions at RHIC energy $\sqrt{s}=200$ GeV
  • Figure 4: NLO (solid line) and LO (dashed line) transverse energy spectrum in a unit central rapidity window for PbPb collisions at LHC energy $\sqrt{s}=5500$ GeV