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We determine the properties of generalised parton distributions (GPDs) from a lattice QCD calculation of the off-forward Compton amplitude (OFCA). By extending the Feynman-Hellmann relation to second-order matrix elements at off-forward…

In the large momentum transfer limit, generalized parton distributions can be calculated through a QCD factorization theorem which involves perturbatively-calculable hard kernels and light-cone parton distribution amplitudes of hadrons. We…

High Energy Physics - Phenomenology · Physics 2009-11-10 Pervez Hoodbhoy , Xiangdong Ji , Feng Yuan

Generalized parton distributions (GPDs) are studied at the hadronic (nonperturbative) scale within different assumptions based on a relativistic constituent quark model. In particular, by means of a meson-cloud model we investigate the role…

High Energy Physics - Phenomenology · Physics 2009-11-11 S. Boffi , B. Pasquini , M. Traini

In these proceedings, we summarize the main results from the first-ever calculations of the chiral-even and chiral-odd twist-3 parton distributions, $g_T(x)$ and $h_L(x)$, of the proton from lattice QCD. We use an $N_f=2+1+1$ ensemble of…

High Energy Physics - Lattice · Physics 2021-11-02 Shohini Bhattacharya , Krzysztof Cichy , Martha Constantinou , Andreas Metz , Aurora Scapellato , Fernanda Steffens

In recent years, there has been a breakthrough in lattice calculations of $x$-dependent partonic distributions. This encompasses also distributions describing the 3D structure of the nucleon, such as generalized parton distributions (GPDs).…

We present an initiatory study of quark helicity flip generalized parton distributions (GPDs) in n_f=2 lattice QCD, based on clover-improved Wilson fermions for a large number of coupling constants and pion masses. Quark helicity flip GPDs…

High Energy Physics - Lattice · Physics 2008-11-26 M. Gockeler , Ph. Hagler , R. Horsley , D. Pleiter , P. E. L. Rakow , A. Schafer , G. Schierholz , J. M. Zanotti

It is often taken for granted that Generalized Parton Distributions (GPDs) are defined in the "symmetric" frame, where the transferred momentum is symmetrically distributed between the incoming/outgoing hadrons. However, such frames pose…

For the first time, we present a lattice QCD determination of Mellin moments of unpolarized generalized parton distributions (GPDs) of the proton from an analysis of the quasi-GPD matrix elements within the short-distance factorization…

We present a determination of the structure functions of the off-forward Compton amplitude $\mathcal{H}_1$ and $\mathcal{E}_1$ from the Feynman-Hellmann method in lattice QCD. At leading twist, these structure functions give access to the…

High Energy Physics - Lattice · Physics 2024-07-11 A. Hannaford-Gunn , K. U. Can , J. A. Crawford , R. Horsley , P. E. L. Rakow , G. Schierholz , H. Stüben , R. D. Young , J. M. Zanotti

We compute the generalized parton distributions (GPDs) of valence quarks, sea quarks, and gluons in the proton using light-front wave functions obtained within the basis light-front quantization (BLFQ) framework, providing a realistic…

High Energy Physics - Phenomenology · Physics 2026-04-21 Yiping Liu , Siqi Xu , Chandan Mondal , Xingbo Zhao , James P. Vary

We extend the formalism of asymmetric frames of reference for generalized parton distributions (GPDs) to the case of nonzero skewness, i.e., including longitudinal momentum transfer. The framework, based on Lorentz-invariant amplitudes and…

We review the latest progress in lattice QCD calculations of the partonic structure of hadrons. This structure is, in particular, described in terms of $x$-dependent distributions, the simplest of which are the standard parton distribution…

High Energy Physics - Lattice · Physics 2021-10-18 Krzysztof Cichy

The generalized parton distributions, introduced nearly a decade ago, have emerged as a universal tool to describe hadrons in terms of quark and gluonic degrees of freedom. They combine the features of form factors, parton densities and…

High Energy Physics - Phenomenology · Physics 2009-09-29 A. V. Belitsky , A. V. Radyushkin

A method is described for calculating the Generalized Parton Distributions (GPDs) of spin 1/2 hadrons made of composite constituents, in an Impulse Approximation framework. GPDs are obtained from the convolution between the light cone…

High Energy Physics - Phenomenology · Physics 2008-11-26 Sergio Scopetta

The internal structure of hadrons is important for a variety of topics, including the hadron form factors, proton spin and spin asymmetry in polarized proton scattering. For a systematic study generalized parton distributions (GPDs) encode…

An approach is proposed to calculate Generalized Parton Distributions (GPDs) in a Constituent Quark Model (CQM) scenario. These off-diagonal distributions are obtained from momentum space wave functions to be evaluated in a given non…

High Energy Physics - Phenomenology · Physics 2007-05-23 Sergio Scopetta , Vicente Vento

We argue that generalized parton distributions (GPDs), accessible in hard exclusive processes, carry information about the spatial distribution of forces experienced by quarks and gluons inside hadrons. This way the measurements of hard…

High Energy Physics - Phenomenology · Physics 2009-11-07 M. V. Polyakov

We report the first-ever calculation of the isovector flavor combination of the chiral-odd twist-3 parton distribution $h_L(x)$ for the proton from lattice QCD. We employ gauge configurations with two degenerate light, a strange and a charm…

High Energy Physics - Lattice · Physics 2022-01-05 Shohini Bhattacharya , Krzysztof Cichy , Martha Constantinou , Andreas Metz , Aurora Scapellato , Fernanda Steffens

We report on our lattice calculations of the nucleon's generalized parton distributions (GPDs), concentrating on their first moments for the case of N_f=2. Due to recent progress on the numerical side we are able to present results for the…

High Energy Physics - Lattice · Physics 2012-03-30 A. Sternbeck , M. Göckeler , Ph. Hägler , R. Horsley , Y. Nakamura , A. Nobile , D. Pleiter , P. E. L. Rakow , A. Schäfer , G. Schierholz , J. Zanotti

Generalized parton distributions (GPDs) characterize the 3-dimensional structure of hadrons, combining information about their internal quark and gluon longitudinal momentum distributions and transverse position within the hadron. The…

High Energy Physics - Phenomenology · Physics 2024-12-25 A. Freese , D. Adamiak , I. Cloët , W. Melnitchouk , J. -W. Qiu , N. Sato , M. Zaccheddu