Forward-Backward Drell-Yan Asymmetry and PDF Determination

A Glazov; A Luszczak; E Accomando; F Giuli; F Hautmann; F Olness; H Abdolmaleki; I Novikov; J Fiaschi; O Zenaiev

arxiv: 1907.08301 · v1 · pith:C3VQC7AJnew · submitted 2019-07-18 · ✦ hep-ph

Forward-Backward Drell-Yan Asymmetry and PDF Determination

H Abdolmaleki , E Accomando , V Bertone , J Fiaschi , F Giuli , A Glazov , F Hautmann , A Luszczak

show 4 more authors

S Moretti I Novikov F Olness O Zenaiev

This is my paper

Pith reviewed 2026-05-24 19:32 UTC · model grok-4.3

classification ✦ hep-ph

keywords Drell-Yan processforward-backward asymmetryparton distribution functionsPDF determinationLHC measurementsneutral currentprofiling analysis

0 comments

The pith

Neutral-current Drell-Yan forward-backward asymmetry supplies independent constraints on parton distribution functions.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper examines how high-statistics measurements of the forward-backward asymmetry in neutral-current Drell-Yan production at the LHC can improve the determination of parton distribution functions. It performs a profiling analysis to assess the impact on non-perturbative QCD effects. A sympathetic reader would care because accurate PDFs are essential for making reliable predictions in high-energy physics experiments at colliders. The analysis shows that this observable can supply useful new information in global PDF fits.

Core claim

High-statistics Drell-Yan measurements at the LHC impact the study of non-perturbative QCD effects from parton distribution functions via the neutral-current forward-backward asymmetry, as demonstrated by the results of a PDF profiling analysis.

What carries the argument

The neutral-current forward-backward asymmetry in Drell-Yan production, serving as input to a PDF profiling analysis.

If this is right

High-statistics LHC data on the asymmetry can reduce uncertainties in PDF determinations.
The asymmetry observable adds independent information to existing global fits.
Non-perturbative QCD effects can be studied more effectively through this channel.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Improved PDFs from this method would tighten predictions for other LHC processes that rely on the same distributions.
The same profiling technique could be applied to charged-current Drell-Yan data for cross-checks.
Consistency between asymmetry-derived constraints and those from other observables would strengthen in the independence assumption.

Load-bearing premise

The forward-backward asymmetry supplies PDF information independent enough from other observables in global fits to add meaningful new constraints.

What would settle it

A fit result in which including the asymmetry data produces no reduction in PDF uncertainties or shift in central values would show the information is redundant.

read the original abstract

We investigate the impact of high-statistics Drell-Yan (DY) measurements at the LHC on the study of non-perturbative QCD effects from parton distribution functions (PDF). We present the results of a PDF profiling analysis based on the neutral-current DY forward-backward asymmetry, using the open source fit platform xFitter.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

Standard xFitter profiling of A_FB shows modest PDF pulls but leaves the independence from existing DY data untested.

read the letter

This paper runs a PDF profiling exercise inside xFitter on the neutral-current forward-backward asymmetry measured in high-statistics Drell-Yan data at the LHC. The goal is to see what the asymmetry adds to constraints on non-perturbative effects in the parton distributions. They set up the fit in a straightforward way with an open tool and real LHC measurements, which is the main thing the work delivers. The presentation is clean and the choice of observable is reasonable because A_FB has some sensitivity to u-d differences. That part is done competently and the code being public helps anyone who wants to reproduce or extend it. The citation list covers the usual xFitter papers and relevant LHC results without obvious omissions. The soft spot is exactly the one the stress-test flagged: A_FB is extracted from the same underlying quark scattering as the inclusive DY cross sections already in global fits. The paper does not show a quantitative test that the asymmetry supplies constraints orthogonal to those other observables or to the parameterization choices already made. Without that comparison, any reported improvement could be redundant rather than additive. The abstract and setup give no numbers on how much the uncertainty bands actually shrink beyond what the baseline fit already achieves. This is the sort of incremental application note that PDF groups sometimes circulate internally when they are updating fits. A reader already working on LHC precision or PDF updates might want to glance at the profiled results for completeness, but it is not required reading for most people. It is coherent on its own terms and the authors engage honestly with the tool and the data they have. I would send it to peer review so a referee can ask for the missing orthogonality check and see whether the full tables change the picture. It does not need to be rejected outright.

Referee Report

2 major / 2 minor

Summary. The manuscript presents a PDF profiling analysis in the xFitter framework that incorporates high-statistics neutral-current Drell-Yan forward-backward asymmetry measurements from the LHC to constrain non-perturbative effects in parton distribution functions.

Significance. If the forward-backward asymmetry supplies PDF information that is demonstrably independent of the inclusive DY cross sections and other asymmetries already entering global fits, the profiling exercise could tighten constraints on quark distributions at moderate x and improve the treatment of non-perturbative QCD contributions.

major comments (2)

[PDF profiling analysis (results section)] The central claim that A_FB supplies additional PDF information rests on the assumption of orthogonality to existing DY observables, yet the manuscript provides no quantitative test (e.g., comparison of profiled uncertainties with and without A_FB, or correlation matrices between A_FB and inclusive DY data sets) that would establish this independence; without such a test the reported impact on non-perturbative effects cannot be assessed.
[Introduction and methodology] Because A_FB is extracted from the same partonic process as the inclusive DY cross sections already used in global fits, any shared higher-order corrections, acceptance cuts, or parameterization choices in xFitter could render the additional constraints redundant; the paper does not address this potential overlap explicitly.

minor comments (2)

Clarify the precise data sets (experiment, luminosity, kinematic cuts) entering the profiling exercise and state whether they overlap with the baseline PDF fit.
Specify the treatment of experimental systematic uncertainties and their correlation with those in the baseline DY measurements.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading of our manuscript and the constructive comments. We address each major comment below and indicate planned revisions to strengthen the presentation of the A_FB profiling analysis.

read point-by-point responses

Referee: [PDF profiling analysis (results section)] The central claim that A_FB supplies additional PDF information rests on the assumption of orthogonality to existing DY observables, yet the manuscript provides no quantitative test (e.g., comparison of profiled uncertainties with and without A_FB, or correlation matrices between A_FB and inclusive DY data sets) that would establish this independence; without such a test the reported impact on non-perturbative effects cannot be assessed.

Authors: We agree that a direct quantitative test would strengthen the central claim. In the revised manuscript we will add a side-by-side comparison of the profiled PDF uncertainties obtained with and without the A_FB data sets, together with the relevant correlation matrices between A_FB and the inclusive DY measurements already present in the fit. These additions will allow readers to assess the degree of independence and the resulting impact on non-perturbative effects. revision: yes
Referee: [Introduction and methodology] Because A_FB is extracted from the same partonic process as the inclusive DY cross sections already used in global fits, any shared higher-order corrections, acceptance cuts, or parameterization choices in xFitter could render the additional constraints redundant; the paper does not address this potential overlap explicitly.

Authors: While A_FB and the inclusive cross section share the same underlying partonic process, the asymmetry is constructed from the difference of forward and backward cross sections and is therefore sensitive to the ratio of quark to antiquark distributions in a manner orthogonal to the sum probed by the symmetric cross section. We will expand the introduction and methodology sections to discuss this complementarity explicitly, including the treatment of higher-order corrections and acceptance cuts within xFitter, and will reference prior literature that has used A_FB to obtain independent PDF constraints. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The paper describes a standard PDF profiling analysis in xFitter that adds neutral-current DY forward-backward asymmetry data to existing global fits. No load-bearing steps reduce by construction to inputs: the profiling procedure treats A_FB as an independent observable whose constraints are quantified by the change relative to the baseline PDFs. No self-definitional equations, fitted parameters renamed as predictions, or self-citation chains that substitute for external verification appear in the provided description. The result is therefore self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract only; no information on free parameters, axioms, or invented entities is available.

pith-pipeline@v0.9.0 · 5611 in / 931 out tokens · 18313 ms · 2026-05-24T19:32:17.793395+00:00 · methodology

discussion (0)

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

IndisputableMonolith/Cost/FunctionalEquation.lean washburn_uniqueness_aczel unclear

?

unclear
Relation between the paper passage and the cited Recognition theorem.

We present the results of a PDF profiling analysis based on the neutral-current DY forward-backward asymmetry, using the open source fit platform xFitter.
IndisputableMonolith/Foundation/AbsoluteFloorClosure.lean reality_from_one_distinction unclear

?

unclear
Relation between the paper passage and the cited Recognition theorem.

The AFB is dominated by the Z/γ interference cos θ term... primarily sensitive to the charge-weighted PDF linear combination (2/3)u + (1/3)d.

What do these tags mean?

matches: The paper's claim is directly supported by a theorem in the formal canon.
supports: The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends: The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses: The paper appears to rely on the theorem as machinery.
contradicts: The paper's claim conflicts with a theorem or certificate in the canon.
unclear: Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

28 extracted references · 28 canonical work pages · 1 internal anchor

[1]

QCD and High Energy Interactions: MORIOND 2019 Theory Summary

D. Wackeroth, arXiv:1906.09138 [hep-ph]

work page internal anchor Pith review Pith/arXiv arXiv 1906
[2]

Aaboud et al

M. Aaboud et al. (ATLAS), Eur. Phys. J. C77, 367 (2017)

work page 2017
[3]

Dulat et al., Phys

S. Dulat et al., Phys. Rev. D93, 033006 (2016)

work page 2016
[4]

R. D. Ball et al. (NNPDF), Eur. Phys. J. C77, 663 (2017)

work page 2017
[5]

Alekhin, J

S. Alekhin, J. Bluemlein, S. Moch and R. Placakyte, Phys. R ev. D96, 014011 (2017)

work page 2017
[6]

L. A. Harland-Lang et al., Eur. Phys. J. C75, 204 (2015)

work page 2015
[7]

Abramowicz et al

H. Abramowicz et al. (ZEUS, H1), Eur. Phys. J. C75, 580 (201 5)

work page
[8]

CMS Coll., Eur. Phys. J. C78, 701 (2018)

work page 2018
[9]

ATLAS Coll., ATL-CONF-2018 037

work page 2018
[10]

Bodek, J

A. Bodek, J. Han, A. Khukhunaishvili and W. Sakumoto, Eur . Phys. J. C76, 115 (2016)

work page 2016
[11]

Aad et al

G. Aad et al. (ATLAS), JHEP 09, 049 (2015)

work page 2015
[12]

Chatrchyan et al

S. Chatrchyan et al. (CMS), Phys. Rev. D84, 112002 (2011)

work page 2011
[13]

Aaij et al

R. Aaij et al. (LHCb), JHEP 11, 190 (2015)

work page 2015
[14]

Accomando, J

E. Accomando, J. Fiaschi, F. Hautmann and S. Moretti, Eur . Phys. J. C78, 663 (2018)

work page 2018
[15]

Accomando, J

E. Accomando, J. Fiaschi, F. Hautmann and S. Moretti, Phy s. Rev. D98, 013003 (2018)

work page 2018
[16]

Accomando et al., preprint CERN-TH-2019-110, DESY 19 -127

E. Accomando et al., preprint CERN-TH-2019-110, DESY 19 -127

work page 2019
[17]

Alekhin et al., Eur

S. Alekhin et al., Eur. Phys. J. C75, 304 (2015)

work page 2015
[18]

Azzi et al

P. Azzi et al. (HL-LHC, HE-LHC Working Group), arXiv:190 2.04070 [hep-ph]

work page
[19]

Alwall et al., JHEP 07, 079 (2014)

J. Alwall et al., JHEP 07, 079 (2014)

work page 2014
[20]

Carli et al., Eur

T. Carli et al., Eur. Phys. J. C66, 503 (2010)

work page 2010
[21]

Bertone et al., JHEP 08, 166 (2014)

V. Bertone et al., JHEP 08, 166 (2014)

work page 2014
[22]

Dittmar, Phys

M. Dittmar, Phys. Rev. D55, 161 (1997)

work page 1997
[23]

T. G. Rizzo, JHEP 08, 082 (2009)

work page 2009
[24]

Accomando et al., Phys

E. Accomando et al., Phys. Rev. D95, 035014 (2017)

work page 2017
[25]

Accomando et al., Phys

E. Accomando et al., Phys. Lett. B770, 1 (2017)

work page 2017
[26]

Accomando et al., JHEP 01, 127 (2016)

E. Accomando et al., JHEP 01, 127 (2016)

work page 2016
[27]

J. C. Collins and D. E. Soper, Phys. Rev. D 16, 2219 (1977)

work page 1977
[28]

Aaboud et al

M. Aaboud et al. (ATLAS), JHEP 12, 059 (2017)

work page 2017

[1] [1]

QCD and High Energy Interactions: MORIOND 2019 Theory Summary

D. Wackeroth, arXiv:1906.09138 [hep-ph]

work page internal anchor Pith review Pith/arXiv arXiv 1906

[2] [2]

Aaboud et al

M. Aaboud et al. (ATLAS), Eur. Phys. J. C77, 367 (2017)

work page 2017

[3] [3]

Dulat et al., Phys

S. Dulat et al., Phys. Rev. D93, 033006 (2016)

work page 2016

[4] [4]

R. D. Ball et al. (NNPDF), Eur. Phys. J. C77, 663 (2017)

work page 2017

[5] [5]

Alekhin, J

S. Alekhin, J. Bluemlein, S. Moch and R. Placakyte, Phys. R ev. D96, 014011 (2017)

work page 2017

[6] [6]

L. A. Harland-Lang et al., Eur. Phys. J. C75, 204 (2015)

work page 2015

[7] [7]

Abramowicz et al

H. Abramowicz et al. (ZEUS, H1), Eur. Phys. J. C75, 580 (201 5)

work page

[8] [8]

CMS Coll., Eur. Phys. J. C78, 701 (2018)

work page 2018

[9] [9]

ATLAS Coll., ATL-CONF-2018 037

work page 2018

[10] [10]

Bodek, J

A. Bodek, J. Han, A. Khukhunaishvili and W. Sakumoto, Eur . Phys. J. C76, 115 (2016)

work page 2016

[11] [11]

Aad et al

G. Aad et al. (ATLAS), JHEP 09, 049 (2015)

work page 2015

[12] [12]

Chatrchyan et al

S. Chatrchyan et al. (CMS), Phys. Rev. D84, 112002 (2011)

work page 2011

[13] [13]

Aaij et al

R. Aaij et al. (LHCb), JHEP 11, 190 (2015)

work page 2015

[14] [14]

Accomando, J

E. Accomando, J. Fiaschi, F. Hautmann and S. Moretti, Eur . Phys. J. C78, 663 (2018)

work page 2018

[15] [15]

Accomando, J

E. Accomando, J. Fiaschi, F. Hautmann and S. Moretti, Phy s. Rev. D98, 013003 (2018)

work page 2018

[16] [16]

Accomando et al., preprint CERN-TH-2019-110, DESY 19 -127

E. Accomando et al., preprint CERN-TH-2019-110, DESY 19 -127

work page 2019

[17] [17]

Alekhin et al., Eur

S. Alekhin et al., Eur. Phys. J. C75, 304 (2015)

work page 2015

[18] [18]

Azzi et al

P. Azzi et al. (HL-LHC, HE-LHC Working Group), arXiv:190 2.04070 [hep-ph]

work page

[19] [19]

Alwall et al., JHEP 07, 079 (2014)

J. Alwall et al., JHEP 07, 079 (2014)

work page 2014

[20] [20]

Carli et al., Eur

T. Carli et al., Eur. Phys. J. C66, 503 (2010)

work page 2010

[21] [21]

Bertone et al., JHEP 08, 166 (2014)

V. Bertone et al., JHEP 08, 166 (2014)

work page 2014

[22] [22]

Dittmar, Phys

M. Dittmar, Phys. Rev. D55, 161 (1997)

work page 1997

[23] [23]

T. G. Rizzo, JHEP 08, 082 (2009)

work page 2009

[24] [24]

Accomando et al., Phys

E. Accomando et al., Phys. Rev. D95, 035014 (2017)

work page 2017

[25] [25]

Accomando et al., Phys

E. Accomando et al., Phys. Lett. B770, 1 (2017)

work page 2017

[26] [26]

Accomando et al., JHEP 01, 127 (2016)

E. Accomando et al., JHEP 01, 127 (2016)

work page 2016

[27] [27]

J. C. Collins and D. E. Soper, Phys. Rev. D 16, 2219 (1977)

work page 1977

[28] [28]

Aaboud et al

M. Aaboud et al. (ATLAS), JHEP 12, 059 (2017)

work page 2017