arXiv subjects

Alim Ablat

Publications and source records attributed to Alim Ablat.

8 recordsLinked to original sources

arXiv2026

Nucleon electromagnetic form factors in nonlocal chiral effective theory

In this paper, we calculate the pion one-loop corrections to the electromagnetic form factors of the nucleon up to $\mathcal{O}(p^4)$ order in the nonlocal framework. To systematically investigate the role of vector-meson dominance in the model, we also include the leading-order nucleon-vector-meson coupling. Owing to the renormalization-scheme dependence of chiral low-energy coupling constants (LECs), we refit these constants to the nucleon magnetic moments, electromagnetic radii, and the $Q^2$-dependence of the electromagnetic form factors. Compared with the previous local analysis, the model results show that, in the nonlocal framework, the $Q^2$-dependence of the electromagnetic form factors in the large-$Q^2$ region is significantly improved and are consistent with experimental data.

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arXiv2025

Strong Coupling Constant Determination from the new CTEQ-TEA Global QCD Analysis

We present a new determination of the strong coupling constant $\alpha_s$ from a global QCD analysis CT25 of parton distribution functions (PDFs) that incorporates high-precision experimental measurements from the Run-2 of the Large Hadron Collider together with a large sample of other measurements over a wide interval of energies. This work addresses two objectives: providing an up-to-date determination of $\alpha_s$ using NNLO calculations and a sensitive nucleon data set within a self-consistent framework, and critically assessing the robustness of the $\alpha_s(M_Z)$ extraction in light of systematic uncertainties as well as correlations of $\alpha_s(M_Z)$ with the functional forms of PDFs and other model parameters. In regard to the uncertainty assessment, we demonstrate that some commonly used criteria, including the dynamical tolerance and Bayesian hierarchical models, may produce significantly different or even unstable estimates for the net $\alpha_s$ uncertainty, and we introduce a concept of \textit{data-clustering safety} that the replicable uncertainty estimates must satisfy. Based on this in-depth examination of the CT25 global hadronic data set using a combination of analysis methods, and after demonstrating a weak correlation between $\alpha_s$ and the functional forms of CT25 PDF parametrizations, we find $\alpha_s(M_Z)=0.1183^{+0.0023}_{-0.0020}$ at the 68\% credibility level.

hep-ph↗

arXiv2025

Impact of lattice gluon dataset on CTEQ-TEA global PDFs

We investigate the impact of the latest gluon parton results from lattice QCD on the global parton distribution function (PDF) analysis within the CTEQ-TEA framework. The dependence on PDF parameterization is explored using the CT18As variant, incorporating the ATLAS 7 TeV precision $W,Z$ dataset and introducing more flexible parameters to allow strangeness asymmetry at the starting scale $Q_0$. The interplay between lattice input and collider inclusive jet datasets is examined by including the post-CT18 inclusive jet datasets from recent LHC measurements and/or removing all collider inclusive jet datasets. Finally, we demonstrate several phenomenological implications at the LHC, focusing on gluon-gluon parton luminosity and related processes, such as the production of a Higgs-like scalar, top-quark pairs, and their associated production with an additional jet, Higgs, or $Z$ boson.

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arXiv2024

The impact of LHC precision measurements of inclusive jet and dijet production on the CTEQ-TEA global PDF fit

In this study, we investigate the impact of new LHC inclusive jet and dijet measurements on parton distribution functions (PDFs) that describe the proton structure, with a particular focus on the gluon distribution at large momentum fraction, $x$, and the corresponding partonic luminosities. We assess constraints from these datasets using next-to-next-to-leading-order (NNLO) theoretical predictions, accounting for a range of uncertainties from scale dependence and numerical integration. From the scale choices available for the calculations, our analysis shows that the central predictions for inclusive jet production show a smaller scale dependence than dijet production. We examine the relative constraints on the gluon distribution provided by the inclusive jet and dijet distributions and also explore the phenomenological implications for inclusive $H$, $t\bar{t}$, and $t\bar{t}H$ production at the LHC at 14 TeV.

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arXiv2024

Progress in top-quark pair production cross section calculations and impact on parton distribution functions of the proton

We discuss the impact of eligible top-quark pair production differential cross-section measurements at the LHC with a collision energy of 13 TeV on the parton distribution functions (PDFs) of the proton as well as the impact of approximate next-to-next-to-next-to-leading order (aN$^3$LO) QCD corrections combined with next-to-leading order (NLO) electroweak (EW) corrections on $t\bar t$ observables. We illustrate the effects on the gluon PDF at large $x$ from an optimal baseline selection of data in NNLO global fits, and show comparisons between the theory prediction for $t\bar t$ total and differential cross sections at aN$^3$LO QCD combined with NLO EW and recent measurements from the ATLAS and CMS collaborations at the LHC.

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arXiv2024

Exploring the impact of high-precision top-quark pair production data on the structure of the proton at the LHC

The impact of recent LHC top-quark pair production single differential cross section measurements at 13 TeV collision energy on the structure of the proton is explored. In particular, the impact of these high-precision data on the gluon and other parton distribution functions (PDFs) of the proton at intermediate and large partonic momentum fraction $x$ is analyzed. This study extends the CT18 global analysis framework to include these new data. The interplay between top-quark pair and inclusive jet production as well as other processes at the LHC, is studied. In addition, a study of the impact of scale choice on the theory description of the new 13 TeV $t\bar t$ measurements is performed.

hep-ph↗

arXiv2023

Precision studies of the post-CT18 LHC Drell-Yan data in the CTEQ-TEA global analysis

In this study, we examine closely the impact of the post-CT18 LHC Drell-Yan data on parton distribution functions (PDFs) in the general CTEQ-TEA global analysis framework. We compare the two main theoretical predictions, the MCFM fixed order calculations at next-to-next-to-leading order (NNLO) and the ResBos2 NNLO matched to $q_T$ resummation up to next-to-next-to-next-to-leading logarithmic (N3LL) level. We find that the overall inclusive cross sections agree well but the fiducial distributions can differ at a percent level. We mainly discuss the result of the ResBos2 resummation calculation which yields a smaller Monte-Carlo uncertainty, and a better description to the post-CT18 LHC Drell-Yan data. We find that the majority of post-CT18 LHC Drell-Yan data are consistent with the ATLAS 7 TeV $W,Z$ data, which were included in the CT18A, but not CT18, fit and increases the strange quark distribution at the small $x$ region. The noticeable exception is that the ATLAS and LHCb 8 TeV $W$ data pull $d(\bar{d})$ quark PDFs to the opposite direction with respect to the ATLAS 7 TeV $W,Z$ data. The inclusion of these post-CT18 LHC Drell-Yan data sets in the CTEQ-TEA global analysis is to update the CT18 PDFs following similar trends as CT18Z PDFs. The parton luminosities and a few phenomenological implications with the fiducial $W^\pm,Z$ and inclusive $H,t\bar{t},t\bar{t}H$ productions at the 14 TeV LHC, as examples, are presented.

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arXiv2022

Heavy-flavor impact on CTEQ-TEA global QCD analyses

We discuss heavy-flavor production at hadron colliders in recent global QCD analyses to determine parton distribution functions (PDFs) in the proton. We discuss heavy-flavor treatments in precision theory predictions at the LHC. In particular, we discuss factorization schemes in presence of heavy flavors in proton-proton collisions, as well as the impact of heavy-flavor production at the LHC on PDFs. We show results of recent updates beyond CT18, the latest global QCD analysis from the CTEQ-TEA group.

hep-ph↗