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Alexey Vladimirov

Publications and source records attributed to Alexey Vladimirov.

At least 19 recordsLinked to original sources
arXiv2026

Extraction of genuine twist-3 distribution from data

The report on an extraction of genuine twist-three parton distributions, obtained from a joint fit of the deep-inelastic scattering (DIS) structure function $g_2$, its moment $d_2$, and the Sivers and worm-gear-T asymmetries measured in semi-inclusive DIS (SIDIS). These four observables probe different sections of the same twist-three distributions, and thus their joint analysis makes a precision extraction of this two-variable function possible. Considering a sub-set of observables does not constrain the twist-three distribution in all its parts. Nonetheless, such consideration places a sufficient amount of restrictions to sufficiently accurately estimate eliminated observables, explicitly demonstrating the universality of twist-three distributions.

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arXiv2026

Phenomenology of genuine twist-three distributions from a global QCD analysis

We present an extraction and phenomenological study of genuine twist-three parton distribution functions (PDFs) through a global QCD analysis of the structure function $g_2$ in deep-inelastic scattering (DIS), its moment $d_2$, and single-/double-spin asymmetries in semi-inclusive DIS (SIDIS). The unified description of these processes clearly confirms the universality of genuine twist-three PDFs and the validity of QCD factorization theorems at this subleading level. The extraction is accompanied by several validation tests, tests of sum rules, comparisons with earlier literature, computation forces and average transverse momentum of partons. As a by-product, we also obtain Sivers and worm-gear-T transverse momentum dependent (TMD) distributions, which allows us to construct a tomographic picture of the proton based on substantially broader data.

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arXiv2026

Factorization theorem for quasi-TMD distributions with kinematic power corrections

We derive the factorization theorem for the quasi-transverse-momentum-dependent (quasi-TMD) correlator, including kinematic power corrections to all orders. The resulting expression involves only twist-two TMD distributions and is frame invariant. As in the leading-power approximation, the reduced soft factor factorizes multiplicatively; however, in contrast, the TMD evolution factor is not multiplicative but enters as a convolution with the nonperturbative TMD distribution. We present a numerical estimate of the difference between the derived expression and the leading-power approximation, finding it to be of the order of tens of percent for current lattice simulations. We also demonstrate that the inclusion of these corrections improves the agreement between phenomenological extractions of the Collins-Soper kernel and lattice results.

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arXiv2025

Determination of quark-gluon-quark interference within the proton

Quarks and gluon, as quantum particles, are subjects to various effects that go beyond the naive parton picture and are not captured by ordinary parton densities. In this work, we investigate the twist-three parton distribution functions, which encode quantum interference between quark-gluon-quark states, and for the first time, determine them directly from experimental data. The analysis combines observables described by collinear and transverse-momentum-dependent factorization theorems within a unified global fit, incorporating a complete leading-order QCD evolution at the twist-three level. The extracted distributions reveal a clear flavor-dependent patterns and distinct from zero at a statistically significant level ($2-3σ$). These findings provide the first quantitative evidence for quark-gluon-quark correlations within the proton, revealing its genuinely quantum nature and opening a new direction for precision studies of partonic correlations.

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arXiv2025

Kinematic power corrections for TMD factorization theorem of semi-inclusive deep-inelastic scattering

We evaluate the complete set of kinematic power corrections (KPCs) to the leading power (LP) term of the transverse momentum dependent (TMD) factorization theorem for semi-inclusive deep-inelastic scattering (SIDIS) with a polarized target. This formulation restores the contributions of twist-two TMD distributions to all structure functions, including those that vanish at leading power, such as contributions of longitudinal photons. The resulting expressions are explicitly gauge- and frame-invariant, and inherit all key features of the standard TMD factorization framework, including the coefficient functions and the evolution equations. Numerical estimations show that KPCs contribute only a few percent at $Q\sim10$GeV, but can reach several tens of percents when $Q\sim 2$GeV. Consequently, accounting for kinematic power corrections can be vital for an accurate theoretical description of current SIDIS measurements.

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arXiv2025

Determination of unpolarized TMD distributions from the fit of Drell-Yan and SIDIS data at N$^4$LL

We present a fit of the transverse momentum spectrum for Drell-Yan and semi-inclusive deep inelastic scattering data, based on transverse momentum dependent (TMD) factorization at N$^4$LL accuracy. Our analysis shows good agreement with the data and confirms the findings of previous studies. Based on this, we extract the unpolarized TMD parton distribution functions, the TMD fragmentation functions, and the Collins-Soper kernel. Compared to earlier works, our study incorporates several improvements, including large-$x$ resummation, flavor and fragmentation function dependence, among others. Additionally, we supplement our extraction with an analysis of the transverse momentum moments of the extracted distributions.

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arXiv2025

Assessing the sensitivity of Energy-Energy Correlations in $e^+e^-$ annihilation to TMD dynamics

We critically examine the back-to-back limit of the energy-energy correlation (EEC) in $e^+e^-$ annihilation as a potential source of information on the Collins-Soper kernel and the strong coupling constant. The analysis is performed within the framework of transverse momentum dependent (TMD) factorization at next-to-next-to-next-to-next-to-leading logarithmic (N$^4$LL) accuracy, using a global fit to all available experimental data. Contrary to previous claims, we demonstrate that the current data do not provide meaningful constraints on either the Collins-Soper kernel or $α_s$.

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arXiv2025

Angular structure of Drell-Yan reaction in the TMD factorization approach

We study angular distributions in the Drell-Yan process using an extended transverse momentum dependent (TMD) factorization framework that includes kinematic power corrections. This approach allows the description of observables previously considered power-suppressed. The results show good agreement with experimental data and provide the first LHC-based indication of the Boer-Mulders function, highlighting the value of power corrections in TMD phenomenology.

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arXiv2025

Leading qT/Q correction for Drell-Yan in TMD factorization

The transverse momentum dependent (TMD) factorization theorem accommodates various types of power corrections. Among them, the least studied are qT/Q corrections, which become significant at large values of transverse momentum. These corrections partially originate from higher-twist TMD distributions, which exhibit singularity at small transverse distances. We propose a decomposition that reveals this singularity explicitly, and makes the qT/Q correction manifest. As a concrete application, we consider the next-to-leading power correction for the angular distributions in Drell-Yan, and determine the leading qT/Q corrections. These corrections are significant for the angular distributions A1 and A3, in complete agreement with the data.

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arXiv2025

Transverse momentum distributions at large-$x$

We investigate the collinear matching of transverse momentum dependent (TMD) distributions at large values of $x$, computing and resumming the leading large-$x$ asymptotics for matching coefficients. The large-$x$ resummation is done directly within TMD distributions, ensuring the process-independence of the result. The derived resummation formulas are valid for all TMD distributions (except the pretzelosity). Their application improves perturbative convergence, provides practical estimation for unknown higher-order contributions, and sets restrictions for the nonperturbative part of models. Using the known anomalous dimensions, resummation can reach N$^3$LL, often exceeding the accuracy of known coefficient functions.

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arXiv2025

Transverse momentum moments

We establish robust relations between Transverse Momentum Dependent distributions (TMDs) and collinear distributions. We define weighted integrals of TMDs that we call Transverse Momentum Moments (TMMs) and prove that TMMs are equal to collinear distributions evaluated in some minimal subtraction scheme. The conversion to the modified minimal subtraction ($\bar{MS}$) scheme, can be done by a calculable factor, which we derive up to three loops for some cases. We discuss in detail the zeroth, the first, and the second TMMs and provide phenomenological results for them based on the current extractions of TMDs. The results of this paper open new avenues for theoretical and phenomenological investigation of the three-dimensional and collinear hadron structures.

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arXiv2025

Transverse momentum dependent factorization for SIDIS at next-to-leading power

The semi-inclusive deep-inelastic scattering (SIDIS) is the golden process for investigating the nucleon's transverse momentum-dependent (TMD) structure. We present the complete expression for SIDIS structure functions in the TMD factorization formalism at the next-to-leading power. All perturbative elements of the factorization theorem -- coefficient functions and evolution kernels -- are presented at one-loop accuracy. We found several differences with earlier derivations, which are due to accounting for nontrivial kinematics of the quark-gluon interference terms. As a side result, we present the definition and evolution of twist-three TMD fragmentation functions, including the leading-order evolution kernel.

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arXiv2025

Definition and evolution of transverse momentum dependent distribution of twist-three

We present an in-depth analysis of transverse momentum dependent (TMD) distributions of twist-three. In particular, we focus on evolution equations, symmetry relations, parameterization, interpretation, small-b asymptotic behaviour and the structure of singularities. The starting point of discussion are the correlators with the definite TMD-twist. By considering suitable combinations of these correlators, we introduce physical TMD distribution of twist-three that can be used for practical applications. We also establish relations with generic TMD distribution of twist-three, and demonstrate that their evolution equations are autonomous in the large-$N_c$ limit.

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arXiv2024

Numerical implementation of evolution equations for twist-3 collinear PDFs

Twist-3 collinear parton distribution functions (PDFs) are matrix elements of quark-gluon-quark or three-gluons light-cone operators. They depend on three momentum fraction variables, which are restricted to a hexagon region, and the evolution kernels are defined via two-dimensional convolution in these variables. We present the numerical realisation of the twist-3 evolution equations at leading order in the strong coupling for all kinds of twist-3 PDF (quark, gluon, chiral-even/odd, etc). We provide two independent codes (in C and Fortran) that have been extensively cross-checked, and are ready-to-use. We supplement the paper with a review of known properties of twist-3 PDFs.

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arXiv2024

Angular distributions of Drell-Yan leptons in the TMD factorization approach

We present a comprehensive study of the angular structure functions for Drell-Yan leptons in $Z/γ$-boson production within the framework of the transverse momentum dependent (TMD) factorization theorem, including kinematic power corrections (KPCs). We find good agreement with the data in the applicability region of the TMD factorization theorem. The inclusion of KPCs allows us to describe all angular coefficients in a frame-independent manner using only the leading-twist TMD distributions: the unpolarized and the Boer-Mulders functions. The value of the Boer-Mulders function is determined using the ATLAS measurement of the $A_2$ angular coefficient. The analysis is performed at N$^4$LL perturbative order. Additionally, we discuss the technical implementation and impact of KPCs on the phenomenology of TMD distributions.

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arXiv2024

Extraction of unpolarized transverse momentum distributions from fit of Drell-Yan data at N$^4$LL

We present the extraction of unpolarized transverse momentum dependent parton distributions functions (TMDPDFs) and Collins-Soper kernel from the fit of Drell-Yan and weak-vector boson production data. The TMDPDF are parameterized, as commonly done, using their (large transverse momentum) asymptotic matching to PDF. The analysis is done at the next-to-next-to-next-to-next-to leading logarithmic accuracy (N$^4$LL) (performed only approximately because PDF evolution is known so far at next-to-next-to leading order (NNLO)). The non-perturbative model used for TMDPDF is flavor dependent to reduce the colllinear PDF bias. The estimation of uncertainties is done with the replica method and, for the first time, it includes the propagation of uncertainties due to the collinear distributions.

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arXiv2023

Quasi Transverse Momentum Dependent Distributions at Next-to-Next-to-Leading order

The partons' transverse momentum can be explored with QCD lattice simulations by studying the quasi-transverse-momentum-dependent parton distribution functions (qTMDPDFs), which are factorized in terms of physical TMDPDFs and soft factors in the limit of the large hadron's momentum. We present the next-to-next-to-leading order (NNLO) calculation of the coefficient function for this factorization. Together with already known expressions for anomalous dimensions, this result allows analysis of lattice data at NNLO perturbative accuracy.

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