arXiv subjects

R. M. Whitehill

Publications and source records attributed to R. M. Whitehill.

5 recordsLinked to original sources

arXiv2026

First simultaneous analysis of transverse momentum dependent and collinear parton distributions in the proton

We present the first simultaneous global QCD analysis of unpolarized transverse momentum dependent (TMD) and collinear parton distribution functions (PDFs) in the proton. Our study incorporates data from deep-inelastic scattering, Drell-Yan, inclusive weak boson, $W$+\,charm, and jet production involving PDFs, as well as TMD Drell-Yan and $Z$-boson production data from fixed target and collider experiments sensitive to both TMD and collinear distributions. The analysis is performed at next-to-next-to-leading logarithmic accuracy for QCD resummation in TMD observables and next-to-leading order for observables described in collinear factorization. The combined analysis improves knowledge of both TMD and collinear PDFs, particularly in the sea-quark sector, providing a consistent simultaneous description of the aforementioned observables.

hep-ph↗

arXiv2026

What are the consequences of independent factorization and renormalization scales?

It is common for separate factorization and renormalization scales to be discussed in connection with phenomenological applications of QCD factorization theorems. We observe that simultaneously preserving renormalization group invariance, Ward identities, and the basic sum rules in the definitions of parton densities forces these scales to be equal. The statement applies to generalized pole subtraction schemes that use dimensional regularization and to collinear factorization theorems for basic processes like deep inelastic scattering. We discuss implications for estimating the effects of scale sensitivity in phenomenological calculations, consistent extractions of Standard Model parameters alongside parton densities in global QCD analyses, and generally connecting phenomenologically extracted parton densities to first principles non-perturbative techniques like lattice QCD.

hep-ph↗

arXiv2026

Accessing gluon polarization with high-$P_T$ hadrons in SIDIS

A recent global QCD analysis of jet production and other polarized scattering data has found the presence of negative solutions for the gluon helicity distribution in the proton, $Δg$, along with the traditional $Δg > 0$ solutions. We consider polarized semi-inclusive deep-inelastic scattering for hadrons produced with large transverse momentum as a means of constraining the dependence of $Δg$ on the parton momentum fraction, $x$. Focusing on the double longitudinal spin asymmetry, we identify the kinematics relevant for future experiments at Jefferson Lab and the Electron-Ion Collider which are particularly sensitive to the polarized gluon channel and could discriminate between the different $Δg$ behaviors.

hep-ph↗

arXiv2026

Impact of parity-violating deep-inelastic scattering on the weak mixing angle and high-$x$ parton distributions

We discuss the impact of neutral current parity-violating deep-inelastic scattering (PVDIS) of electrons from protons and deuterons on the determination of the weak mixing angle, $\sin^{2}{θ_{\rm W}}$, and parton distribution functions (PDFs) at large parton momentum fractions $x$. Using the JAM global QCD analysis framework, we study the effect of incorporating pseudodata simulated for 11 GeV and 22 GeV Jefferson Lab kinematics, accounting for radiative corrections in a factorized QED+QCD approach and uncertainties from higher twist corrections in $γZ$ exchange. We find that including future PVDIS pseudodata could yield important constraints on the value of $\sin^{2}{θ_{\rm W}}$ at low $Q^2$ and on the high-$x$ behavior of the strange quark and $d/u$ PDF ratio. The strong correlation between $\sin^{2}{θ_{\rm W}}$ and the $x$ dependence of the PDFs demonstrates the necessity for simultaneous analysis of QCD and electroweak quantities to ensure an unbiased determination of the weak mixing angle from PVDIS data.

hep-ph↗

arXiv2023

Gluon helicity from global analysis of experimental data and lattice QCD Ioffe time distributions

We perform a new global analysis of spin-dependent parton distribution functions with the inclusion of Ioffe time pseudo-distributions computed in lattice QCD (LQCD), which are directly sensitive to the gluon helicity distribution, $Δg$. These lattice data have an analogous relationship to parton distributions as do experimental cross sections, and can be readily included in global analyses. We focus in particular on the constraining capability of current LQCD data on the sign of $Δg$ at intermediate parton momentum fractions $x$, which was recently brought into question by analysis of data in the absence of parton positivity constraints. We find that present LQCD data cannot discriminate between positive and negative $Δg$ solutions, although significant changes in the solutions for both the gluon and quark sectors are observed.

hep-ph↗