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A new combined NLO QCD analysis of the polarized inclusive and semi-inclusive DIS data is presented. In contrast to previous combined analyses, the 1/Q^2 terms (kinematic - target mass corrections, and dynamic - higher twist corrections) in…

High Energy Physics - Phenomenology · Physics 2010-12-23 Elliot Leader , Alexander V. Sidorov , Dimiter B. Stamenov

We rederive the small-$x$ evolution equations governing quark helicity distribution in a proton using solely an operator-based approach. In our previous works on the subject, the evolution equations were derived using a mix of diagrammatic…

High Energy Physics - Phenomenology · Physics 2019-04-03 Yuri V. Kovchegov , Matthew D. Sievert

Semi-inclusive deep inelastic Scattering (SIDIS) has been a very successful tool to investigate the partonic structure of the nucleon over the last decade. Compared to inclusive DIS, information about the quantum numbers of the struck quark…

High Energy Physics - Experiment · Physics 2018-10-09 Anselm Vossen

We perform the first simultaneous global QCD analysis of spin-averaged and spin-dependent parton distribution functions (PDFs), including single jet production data from unpolarized and polarized hadron collisions. We critically assess the…

High Energy Physics - Phenomenology · Physics 2022-04-27 Y. Zhou , N. Sato , W. Melnitchouk

We construct a numerical solution of the small-$x$ evolution equations recently derived in \cite{Kovchegov:2015pbl} for the (anti)quark helicity TMDs and PDFs as well as the $g_1$ structure function. We focus on the case of large $N_c$…

High Energy Physics - Phenomenology · Physics 2017-02-08 Yuri V. Kovchegov , Daniel Pitonyak , Matthew D. Sievert

We investigate the polarized parton distribution functions (PDFs) and their uncertainties by using the world data on the spin asymmetry A_1. The uncertainties of the polarized PDFs are estimated by the Hessian method. The up and down…

High Energy Physics - Phenomenology · Physics 2008-11-26 M. Hirai , S. Kumano , N. Saito

We present a first global determination of spin-dependent parton distribution functions (PDFs) and their uncertainties using the NNPDF methodology: NNPDFpol1.1. Longitudinally polarized deep-inelastic scattering data, already used for the…

High Energy Physics - Phenomenology · Physics 2015-06-22 Emanuele R. Nocera , Richard D. Ball , Stefano Forte , Giovanni Ridolfi , Juan Rojo

We present a comprehensive new global QCD analysis of unpolarized parton distribution functions (PDFs) based upon proton, deuteron and $A\!=\!3$ data, including the latest inclusive deep-inelastic scattering (DIS) measurements from…

High Energy Physics - Phenomenology · Physics 2026-05-04 C. Cocuzza , W. Melnitchouk , N. Sato , A. W. Thomas

We present the first-ever description the world data on the $g_1^{p,n}$ structure function at small Bjorken $x$ using evolution equations in $x$ derived from first principles QCD. This is a Monte-Carlo analysis within the JAM global…

High Energy Physics - Phenomenology · Physics 2021-08-10 Daniel Adamiak

The impact of the recent very precise CLAS and COMPASS g1/F1 data on polarized parton densities and higher twist effects is discussed. It is demonstrated that the low Q^2 CLAS data improve essentially our knowledge of higher twist…

High Energy Physics - Phenomenology · Physics 2007-12-13 Elliot Leader , Alexander V. Sidorov , Dimiter B. Stamenov

The helicity dependent parton distributions describe the number density of partons with given longitudinal momentum x and given polarization in a hadron polarized longitudinally with respect to its motion. After the discovery, more than 70…

High Energy Physics - Phenomenology · Physics 2011-11-01 Sergio Scopetta , Vicente Vento

We present a quantitative assessment of the impact a future electron-ion collider will have on determinations of helicity quark and gluon densities and their contributions to the proton spin. Our results are obtained by performing a series…

High Energy Physics - Phenomenology · Physics 2013-05-30 Elke C. Aschenauer , Rodolfo Sassot , Marco Stratmann

We present the first unbiased determination of spin-dependent, or polarized, Parton Distribution Functions (PDFs) of the proton. A statistically sound representation of the corresponding uncertainties is achieved by means of the NNPDF…

High Energy Physics - Phenomenology · Physics 2014-03-04 Emanuele Roberto Nocera

We present MAPPDFpol1.0, a new determination of the helicity-dependent parton distribution functions (PDFs) of the proton from a set of longitudinally polarised inclusive and semi-inclusive deep-inelastic scattering data. The determination…

High Energy Physics - Phenomenology · Physics 2025-04-23 MAP , Collaboration , : , Valerio Bertone , Amedeo Chiefa , Emanuele R. Nocera

We present an updated global analysis of collinearly factorized nuclear parton distribution functions (PDFs) at next-to-leading order in perturbative QCD. In comparison to our previous fit, EPPS16, the present analysis includes more data…

High Energy Physics - Phenomenology · Physics 2022-05-25 Kari J. Eskola , Petja Paakkinen , Hannu Paukkunen , Carlos A. Salgado

The proton spin puzzle is a longstanding problem in high-energy nuclear physics: how the proton spin distributes among the spin and orbital angular momenta of the quarks and gluons inside. Two of the unresolved pieces of the puzzle are the…

High Energy Physics - Phenomenology · Physics 2023-06-29 Yossathorn Tawabutr

We study polarized Semi-Inclusive Deep Inelastic Scattering (SIDIS) processes, within the QCD parton model and a factorization scheme, taking into account all transverse motions, of partons inside the initial proton and of hadrons inside…

High Energy Physics - Phenomenology · Physics 2015-03-17 M. Anselmino , M. Boglione , U. D'Alesio , S. Melis , F. Murgia , E. R. Nocera , A. Prokudin

This article introduces {\tt AAK24}, a Next-to-Leading Order (NLO) QCD analysis of polarized data from both polarized Deep Inelastic Scattering (DIS) and Semi-Inclusive Deep Inelastic Scattering (SIDIS) experiments on the nucleon. The {\tt…

High Energy Physics - Phenomenology · Physics 2024-09-24 Fatemeh Arbabifar , Shahin Atashbar Tehrani , Hamzeh Khanpour

The combined analysis of polarized DIS and SIDIS data is performed in NLO QCD. The new parametrization on polarized PDFs is constructed. The uncertainties on PDFs and their first moments are estimated applying the modified Hessian method.…

High Energy Physics - Phenomenology · Physics 2010-02-11 A. Sissakian , O. Shevchenko , O. Ivanov

We include the quark to gluon and gluon to quark shock-wave transition operators into the small Bjorken-$x$ evolution equations for helicity in the flavor-singlet channel derived earlier. While such transitions do not affect the large-$N_c$…

High Energy Physics - Phenomenology · Physics 2024-06-18 Jeremy Borden , Yuri V. Kovchegov , Ming Li