Title: Parton distribution function uncertainties in theoretical predictions for far-forward tau neutrinos at the Large Hadron Collider

Abstract

New experiments dealing with neutrinos in the far-forward region at the Large Hadron Collider (LHC) are under design or already in preparation. Two of them, FASERν and SND@LHC, are expected to be active during Run 3 and have the potential to detect the interactions of ν and $$\bar {v}$$ that come from high-energy collisions in one of the LHC interaction points, extracted along the direction tangent to the beam line. Tau neutrinos and antineutrinos come predominantly from $$D^{±}_{s}$$ production in pp collisions, followed by the leptonic decay of these mesons. Neutrino pseudorapidities in the range of η > 6.9 and η > 8.9 are relevant to these future experiments. At such pseudorapidities at high energies, QCD theoretical predictions for the flux of ν_τ plus $$\bar {v}_τ$$ rely on parton distribution functions (PDFs) in a combination of very small and large parton–x values. We evaluate PDF un certainties affecting the flux of ν_τ + $$\bar {v}_τ$$ produced by $$D^{±}_{s}$$ decay in the far forward region at the LHC. Next-to-leading order (NLO) QCD uncertainties are included in the calculation of $$D^{±}_{s}$$ production and NLO PDF sets are used for consistency. The theoretical uncertainty associated with the 40 PDF sets of the PROSA19 group amounts to ±(20 – 30)% for the (ν_τ + $$\bar {v}_τ$$) number of charged-current (CC) events. Scale uncertainties are much larger, resulting in a range of CC event predictions from ~70% lower to ~90% higher than the central prediction. A comparison of the predictions with those obtained using as input the central PDFs from the 3-flavour NLO PDF sets of the CT14, ABMP16 and NNPDF3.1 collaborations show that far-forward neutrino energy distributions vary by as much as a factor of ~2 – 4 relative to the PROSA19 predictions at TeV neutrino energies. The Forward Physics Facility in the high luminosity LHC era will provide data capable of constraining NLO QCD evaluations with these PDF sets.

Authors:

Bai, Weidong ^[1]; Diwan, Milind ^[2]; Garzelli, Maria Vittoria ^[3]; Jeong, Yu Seon  ^[4];

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Kumar, Karan ^[5]; Reno, Mary Hall ^[6]

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+ Show Author Affiliations

1. Sun Yat-Sen Univ., Guangzhou (China)
2. Brookhaven National Lab. (BNL), Upton, NY (United States)
3. Univ. of Hamburg (Germany)
4. Chung-Ang Univ., Seoul (Korea, Republic of)
5. Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States)
6. Univ. of Iowa, Iowa City, IA (United States)

Publication Date:

Mon Jun 27 00:00:00 EDT 2022

Research Org.:

Brookhaven National Laboratory (BNL), Upton, NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP); German Federal Ministry of Education and Research (BMBF); Korea government (MSIT2)

Contributing Org.:

PROSA Collaboration

OSTI Identifier:

1875468

Report Number(s):

BNL-223115-2022-JAAM
Journal ID: ISSN 1029-8479; TRN: US2307213

Grant/Contract Number:  

SC0012704; SC0010113; 05H21GUCCA; 2021R1A2C1009296; 2017R1A2B4004308

Resource Type:

Accepted Manuscript

Journal Name:

Journal of High Energy Physics (Online)

Additional Journal Information:

Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2022; Journal Issue: 6; Journal ID: ISSN 1029-8479

Publisher:

Springer Nature

Country of Publication:

United States

Language:

English

Subject:

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; higher-order perturbative calculations; neutrino interactions; patron distributions