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Screening effects in the ultrahigh energy neutrino interactions

Krzysztof Kutak, Jan Kwiecinski

TL;DR

The authors address how saturation and non-linear QCD dynamics affect ultrahigh-energy neutrino interactions with nucleons. They compare a phenomenological GBW dipole saturation model with a more complete unified BFKL/DGLAP framework augmented by BK-type nonlinear screening, both constrained by HERA data. Their results show that saturation reduces neutrino-nucleon cross-sections by roughly a factor of two at E_nu ~ 10^12 GeV, with nuclear shadowing further suppressing neutrino-nucleus cross sections. The study emphasizes that subleading ln(1/x) effects and full QCD evolution are crucial alongside saturation for reliable extrapolations to ultra-small x, informing neutrino astrophysics and Earth-attenuation studies.

Abstract

We study possible saturation effects in the total cross-section describing interaction of ultrahigh energy neutrinos with nucleons. This analysis is performed within the two approaches, i.e. within the Golec-Biernat Wüsthoff saturation model and within the scheme unifying the DGLAP and BFKL dynamics incorporating non-linear screening effects which follow from the Balitzki-Kovchegov equation. The structure functions in both approaches are constrained by HERA data. It is found that screening effects affect extrapolation of the neutrino-nucleon total cross-sections to ultrahigh neutrino energies $E_ν$ and reduce their magnitude by a factor equal to about 2 at $E_ν \sim 10^{12}GeV$. This reduction becomes amplified by nuclear shadowing in the case of the neutrino-nucleus cross-sections and approximate estimate of this effect is performed.

Screening effects in the ultrahigh energy neutrino interactions

TL;DR

The authors address how saturation and non-linear QCD dynamics affect ultrahigh-energy neutrino interactions with nucleons. They compare a phenomenological GBW dipole saturation model with a more complete unified BFKL/DGLAP framework augmented by BK-type nonlinear screening, both constrained by HERA data. Their results show that saturation reduces neutrino-nucleon cross-sections by roughly a factor of two at E_nu ~ 10^12 GeV, with nuclear shadowing further suppressing neutrino-nucleus cross sections. The study emphasizes that subleading ln(1/x) effects and full QCD evolution are crucial alongside saturation for reliable extrapolations to ultra-small x, informing neutrino astrophysics and Earth-attenuation studies.

Abstract

We study possible saturation effects in the total cross-section describing interaction of ultrahigh energy neutrinos with nucleons. This analysis is performed within the two approaches, i.e. within the Golec-Biernat Wüsthoff saturation model and within the scheme unifying the DGLAP and BFKL dynamics incorporating non-linear screening effects which follow from the Balitzki-Kovchegov equation. The structure functions in both approaches are constrained by HERA data. It is found that screening effects affect extrapolation of the neutrino-nucleon total cross-sections to ultrahigh neutrino energies and reduce their magnitude by a factor equal to about 2 at . This reduction becomes amplified by nuclear shadowing in the case of the neutrino-nucleus cross-sections and approximate estimate of this effect is performed.

Paper Structure

This paper contains 5 sections, 65 equations, 9 figures.

Table of Contents

  1. Introduction
  2. Basic formulas describing the deep inelastic neutrino scattering.
  3. DIS in the dipole picture and ultrahigh energy neutrino interactions
  4. Unified BFKL/DGLAP evolution with nonlinear screening effects and ultrahigh neutrino cross-sections
  5. Summary and conclusions.

Figures (9)

  • Figure 1: Deep inelastic scattering.
  • Figure 2: Schematic representation of the dipole picture GBW.
  • Figure 3: The prediction for the neutrino nucleon CC cross section obtained from the GBW saturation model. For comparison we also show results based on the (linear) unified BFKL/DGLAP evolution.
  • Figure 4: As for Fig. 2, but for the NC interactions.
  • Figure 5: The prediction for the neutrino nucleon CC cross section obtained from unified BFKL/DGLAP equation supplemented by screening effects. For comparison we also present results based on the GBW saturation model and the linear unified BFKL/DGLAP evolutions
  • ...and 4 more figures