Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

HECTOR 1.00 - A program for the calculation of QED, QCD and electroweak corrections to ep and lN deep inelastic neutral and charged current scattering

A. Arbuzov, D. Bardin, J. Bluemlein, L. Kalinovskaya, T. Riemann

TL;DR

HECTOR 1.00 presents a Fortran package for computing radiative QED, QCD, and electroweak corrections to neutral- and charged-current deep inelastic scattering cross sections in ep and lN collisions. It combines methodologies from HELIOS (LLA/QED) and TERAD (O(α) EW/QED with soft-photon exponentiation), enabling semi-analytical calculations across multiple variable sets and including low-Q^2 modifications. The framework supports LO and NLO QCD through MSbar and DIS factorization schemes, various structure-function parameterizations, and flexible input options, with extensive user configurability and example benchmarks. The work provides a practical tool for precision DIS analyses at HERA and LEP×LHC (and muon targets), enabling percent-level radiative corrections for diverse experimental setups and observables, along with detailed guidance for interfacing PDFs and structure functions.

Abstract

A description of the Fortran program HECTOR for a variety of semi-analytical calculations of radiative QED, QCD, and electroweak corrections to the double-differential cross sections of NC and CC deep inelastic charged lepton proton (or lepton deuteron) scattering is presented. HECTOR originates from the substantially improved and extended earlier programs HELIOS and TERAD91. It is mainly intended for applications at HERA or LEPxLHC, but may be used also for muon scattering in fixed target experiments. The QED corrections may be calculated in different sets of variables: leptonic, hadronic, mixed, Jaquet-Blondel, double angle etc. Besides the leading logarithmic approximation up to order O(alpha^2), exact order O(alpha) corrections and inclusive soft photon exponentiation are taken into account. The photoproduction region is also covered.

HECTOR 1.00 - A program for the calculation of QED, QCD and electroweak corrections to ep and lN deep inelastic neutral and charged current scattering

TL;DR

HECTOR 1.00 presents a Fortran package for computing radiative QED, QCD, and electroweak corrections to neutral- and charged-current deep inelastic scattering cross sections in ep and lN collisions. It combines methodologies from HELIOS (LLA/QED) and TERAD (O(α) EW/QED with soft-photon exponentiation), enabling semi-analytical calculations across multiple variable sets and including low-Q^2 modifications. The framework supports LO and NLO QCD through MSbar and DIS factorization schemes, various structure-function parameterizations, and flexible input options, with extensive user configurability and example benchmarks. The work provides a practical tool for precision DIS analyses at HERA and LEP×LHC (and muon targets), enabling percent-level radiative corrections for diverse experimental setups and observables, along with detailed guidance for interfacing PDFs and structure functions.

Abstract

A description of the Fortran program HECTOR for a variety of semi-analytical calculations of radiative QED, QCD, and electroweak corrections to the double-differential cross sections of NC and CC deep inelastic charged lepton proton (or lepton deuteron) scattering is presented. HECTOR originates from the substantially improved and extended earlier programs HELIOS and TERAD91. It is mainly intended for applications at HERA or LEPxLHC, but may be used also for muon scattering in fixed target experiments. The QED corrections may be calculated in different sets of variables: leptonic, hadronic, mixed, Jaquet-Blondel, double angle etc. Besides the leading logarithmic approximation up to order O(alpha^2), exact order O(alpha) corrections and inclusive soft photon exponentiation are taken into account. The photoproduction region is also covered.

Paper Structure

This paper contains 31 sections, 76 equations, 10 figures, 5 tables.

Table of Contents

  1. Introduction
  2. Basic notations
  3. Born cross sections
  4. Input parameters
  5. The running electromagnetic coupling $\alpha(Q^2)$
  6. Structure functions
  7. Generalized structure functions
  8. Structure functions
  9. Generalized structure functions for improved Born cross sections
  10. Parton distributions and QCD corrections to structure functions
  11. The strong coupling constant
  12. Parton distributions in the $\overline{\rm MS}$ factorization scheme
  13. Parton distributions in the DIS factorization scheme
  14. Structure functions in different schemes
  15. Low $Q^2$ modifications of structure functions and parton distributions
  16. ...and 16 more sections

Figures (10)

  • Figure 1: Low $Q^2$ interpolation for the structure function $F_2(x,Q^2)$ between $F_2 = F_2^{LO}(CTEQ3)$ for $Q^2 \geq 5 {\mathrm GeV^2}$ ( ISCH = 0, ISSE =1), and the low $Q^2$ extension seleced by the flag IVAR=2 for $Q^2 \leq 3 {\mathrm GeV^2}$.
  • Figure 2: Basic HECTOR flowchart. Shown are subdirectories.
  • Figure 3: Logical structure of GENSTF
  • Figure 4: Building structure functions in HECTOR
  • Figure 5: The branches of HECTOR. Different treatments of QED corrections are chosen by settings of flags IMEA and IDSP.
  • ...and 5 more figures