Parton distributions with small-x resummation: evidence for BFKL dynamics in HERA data

Richard D. Ball, Valerio Bertone, Marco Bonvini, Simone Marzani, Juan Rojo, Luca Rottoli

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

We present a determination of the parton distribution functions of the proton in which NLO and NNLO fixed-order calculations are supplemented by NLLx small-x resummation. Deep-inelastic structure functions are computed consistently at NLO+NLL x or NNLO+NLL x, while for hadronic processes small-x resummation is included only in the PDF evolution, with kinematic cuts introduced to ensure the fitted data lie in a region where the fixed-order calculation of the hard cross-sections is reliable. In all other respects, the fits use the same methodology and are based on the same global dataset as the recent NNPDF3.1 analysis. We demonstrate that the inclusion of small-x resummation leads to a quantitative improvement in the perturbative description of the HERA inclusive and charm-production reduced cross-sections in the small x region. The impact of the resummation in our fits is greater at NNLO than at NLO, because fixed-order calculations have a perturbative instability at small x due to large logarithms that can be cured by resummation. We explore the phenomenological implications of PDF sets with small-x resummation for the longitudinal structure function FL at HERA, for parton luminosities and LHC benchmark cross-sections, for ultra-high-energy neutrino–nucleus cross-sections, and for future high-energy lepton–proton colliders such as the LHeC.

Original languageEnglish
Article number321
JournalEuropean Physical Journal C
Volume78
Issue number4
DOIs
Publication statusPublished - 1 Apr 2018

Fingerprint

partons
cross sections
Colliding beam accelerators
Distribution functions
Luminance
Protons
Kinematics
logarithms
kinematics
distribution functions
luminosity
inclusions
methodology
protons
energy

Cite this

Ball, Richard D. ; Bertone, Valerio ; Bonvini, Marco ; Marzani, Simone ; Rojo, Juan ; Rottoli, Luca. / Parton distributions with small-x resummation : evidence for BFKL dynamics in HERA data. In: European Physical Journal C. 2018 ; Vol. 78, No. 4.
@article{94c22a5d958a4ec3aa086d6c8dfcb970,
title = "Parton distributions with small-x resummation: evidence for BFKL dynamics in HERA data",
abstract = "We present a determination of the parton distribution functions of the proton in which NLO and NNLO fixed-order calculations are supplemented by NLLx small-x resummation. Deep-inelastic structure functions are computed consistently at NLO+NLL x or NNLO+NLL x, while for hadronic processes small-x resummation is included only in the PDF evolution, with kinematic cuts introduced to ensure the fitted data lie in a region where the fixed-order calculation of the hard cross-sections is reliable. In all other respects, the fits use the same methodology and are based on the same global dataset as the recent NNPDF3.1 analysis. We demonstrate that the inclusion of small-x resummation leads to a quantitative improvement in the perturbative description of the HERA inclusive and charm-production reduced cross-sections in the small x region. The impact of the resummation in our fits is greater at NNLO than at NLO, because fixed-order calculations have a perturbative instability at small x due to large logarithms that can be cured by resummation. We explore the phenomenological implications of PDF sets with small-x resummation for the longitudinal structure function FL at HERA, for parton luminosities and LHC benchmark cross-sections, for ultra-high-energy neutrino–nucleus cross-sections, and for future high-energy lepton–proton colliders such as the LHeC.",
author = "Ball, {Richard D.} and Valerio Bertone and Marco Bonvini and Simone Marzani and Juan Rojo and Luca Rottoli",
year = "2018",
month = "4",
day = "1",
doi = "10.1140/epjc/s10052-018-5774-4",
language = "English",
volume = "78",
journal = "European Physical Journal C. Particles and Fields",
issn = "1434-6044",
publisher = "Springer New York",
number = "4",

}

Parton distributions with small-x resummation : evidence for BFKL dynamics in HERA data. / Ball, Richard D.; Bertone, Valerio; Bonvini, Marco; Marzani, Simone; Rojo, Juan; Rottoli, Luca.

In: European Physical Journal C, Vol. 78, No. 4, 321, 01.04.2018.

Research output: Contribution to JournalArticleAcademicpeer-review

TY - JOUR

T1 - Parton distributions with small-x resummation

T2 - evidence for BFKL dynamics in HERA data

AU - Ball, Richard D.

AU - Bertone, Valerio

AU - Bonvini, Marco

AU - Marzani, Simone

AU - Rojo, Juan

AU - Rottoli, Luca

PY - 2018/4/1

Y1 - 2018/4/1

N2 - We present a determination of the parton distribution functions of the proton in which NLO and NNLO fixed-order calculations are supplemented by NLLx small-x resummation. Deep-inelastic structure functions are computed consistently at NLO+NLL x or NNLO+NLL x, while for hadronic processes small-x resummation is included only in the PDF evolution, with kinematic cuts introduced to ensure the fitted data lie in a region where the fixed-order calculation of the hard cross-sections is reliable. In all other respects, the fits use the same methodology and are based on the same global dataset as the recent NNPDF3.1 analysis. We demonstrate that the inclusion of small-x resummation leads to a quantitative improvement in the perturbative description of the HERA inclusive and charm-production reduced cross-sections in the small x region. The impact of the resummation in our fits is greater at NNLO than at NLO, because fixed-order calculations have a perturbative instability at small x due to large logarithms that can be cured by resummation. We explore the phenomenological implications of PDF sets with small-x resummation for the longitudinal structure function FL at HERA, for parton luminosities and LHC benchmark cross-sections, for ultra-high-energy neutrino–nucleus cross-sections, and for future high-energy lepton–proton colliders such as the LHeC.

AB - We present a determination of the parton distribution functions of the proton in which NLO and NNLO fixed-order calculations are supplemented by NLLx small-x resummation. Deep-inelastic structure functions are computed consistently at NLO+NLL x or NNLO+NLL x, while for hadronic processes small-x resummation is included only in the PDF evolution, with kinematic cuts introduced to ensure the fitted data lie in a region where the fixed-order calculation of the hard cross-sections is reliable. In all other respects, the fits use the same methodology and are based on the same global dataset as the recent NNPDF3.1 analysis. We demonstrate that the inclusion of small-x resummation leads to a quantitative improvement in the perturbative description of the HERA inclusive and charm-production reduced cross-sections in the small x region. The impact of the resummation in our fits is greater at NNLO than at NLO, because fixed-order calculations have a perturbative instability at small x due to large logarithms that can be cured by resummation. We explore the phenomenological implications of PDF sets with small-x resummation for the longitudinal structure function FL at HERA, for parton luminosities and LHC benchmark cross-sections, for ultra-high-energy neutrino–nucleus cross-sections, and for future high-energy lepton–proton colliders such as the LHeC.

UR - http://www.scopus.com/inward/record.url?scp=85046436061&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85046436061&partnerID=8YFLogxK

U2 - 10.1140/epjc/s10052-018-5774-4

DO - 10.1140/epjc/s10052-018-5774-4

M3 - Article

VL - 78

JO - European Physical Journal C. Particles and Fields

JF - European Physical Journal C. Particles and Fields

SN - 1434-6044

IS - 4

M1 - 321

ER -