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We study the covariant version of the quark-parton model, in which the general rules of the angular momentum composition are accurately taken into account. We demonstrate how these rules affect the relativistic interplay between the quark…

High Energy Physics - Phenomenology · Physics 2015-06-23 Petr Zavada

We identify quark and gluon helicity-flip distributions defined between nucleon states of unequal momenta. The evolution of these distributions with change of renormalization scale is calculated in the leading-logarithmic approximation. The…

High Energy Physics - Phenomenology · Physics 2009-10-31 Pervez Hoodbhoy , Xiangdong Ji

We briefly recall the main physical features of the parton distributions in the quantum statistical picture of the nucleon. Some predictions from a next-to-leading order QCD analysis are compared to recent experimental results.

High Energy Physics - Phenomenology · Physics 2009-12-03 Jacques Soffer

Determination of the orbital angular momentum of the proton is a difficult but important part of understanding fundamental structure. Insight can be gained from suitable models of the gluon asymmetry applied to the Jz = 1/2 sum rule. We…

High Energy Physics - Phenomenology · Physics 2008-01-09 Gordon P. Ramsey , Yev Binder , Dennis Sivers

We study the covariant version of the quark-parton model, in which the general rules of the angular momentum composition are accurately taken into account. We demonstrate how these rules affect the relativistic interplay between the quark…

High Energy Physics - Phenomenology · Physics 2014-04-07 Petr Zavada

This study proposes a theoretical model for studying the spin characteristics and angular correlations of fission fragments of heavy nuclei. The mechanisms of spin formation, including the influence of transverse vibrations, are considered…

Nuclear Theory · Physics 2025-03-13 D. E. Lyubashevsky , A. A. Pisklyukov , S. V. Klyuchnikov , P. V. Kostryukov

Status, open questions, and future prospects of the physics of excited nucleons are discussed. Emphasis is on the study of the structure of nucleons via measurements of their electromagnetic transition form factors, the search for "missing"…

Nuclear Theory · Physics 2009-09-25 Volker D. Burkert

This talk summarises the discussions during the conference on the spin structure of the nucleon held at Erice; July 1995. The summary focuses on where we have come, where we are now, and the emerging questions that direct where we go next…

High Energy Physics - Phenomenology · Physics 2007-05-23 Frank Close

Spin is commonly thought to reflect the true quantum nature of microphysics. We show that spin is related to intrinsic and field-like properties of single particles. These properties change continuously in external magnetic fields.…

Quantum Physics · Physics 2007-05-23 W. A. Hofer

More than three decades has passed since the European Muon Collaboration published the first surprising result on the spin structure of the proton. Much theoretical and experimental progress has been made in understanding the origins of the…

High Energy Physics - Phenomenology · Physics 2020-09-04 Xiangdong Ji , Feng Yuan , Yong Zhao

The spin structure of parity violating and time reversal invariance violating effects in neutron scattering is discussed. The explicit relations between these effects are presented in terms of functions nuclear spins and neutron partial…

Nuclear Theory · Physics 2018-06-20 Vladimir Gudkov , Hirohiko M. Shimizu

We present an extensive study on generalized parton distributions of pions. In particular, we present the results for the pion-photon transition distribution amplitudes in the Nambu - Jona-Lasinio model. We discuss the phenomenology of such…

High Energy Physics - Phenomenology · Physics 2010-10-15 A. Courtoy

The recent series of experiments on polarized lepton-nucleon scattering have provided a strange new twist in the story of the nucleon, some of whose aspects are reviewed in these lectures. In the first lecture, we review some issues arising…

High Energy Physics - Phenomenology · Physics 2007-05-23 John Ellis , Marek Karliner

We calculate the spin dependent structure functions g_{1}(x) and g_{2}(x) of the proton and neutron. Our calculation uses the meson cloud model of nucleon structure, which has previously given a good description of the HERMES data on…

High Energy Physics - Phenomenology · Physics 2008-11-26 F. Bissey , F. G. Cao , A. I. Signal

The leading chiral contributions to the quark and gluon components of the proton spin are calculated using heavy-baryon chiral perturbation theory. Similar calculations are done for the moments of the generalized parton distributions…

High Energy Physics - Phenomenology · Physics 2009-11-07 Jiunn-Wei Chen , Xiangdong Ji

In this talk, I review the status of theoretical understanding of nuclear structure functions and parton distributions and discuss the constraints on nuclear parton distributions from existing data and the global QCD analysis.

Nuclear Theory · Physics 2009-11-07 Jianwei Qiu

We argue that due to Parity constraints, the helicity combination of the purely momentum space counterparts of the Wigner distributions -- the generalized transverse momentum distributions -- that describes the configuration of an…

High Energy Physics - Phenomenology · Physics 2015-06-17 Aurore Courtoy , Gary R. Goldstein , J. Osvaldo Gonzalez Hernandez , Simonetta Liuti , Abha Rajan

We derive new positivity constraints on the spin-dependent structure functions of the nucleon. These model independent results reduce conside\-rably their domain of allowed values, in particular for the chiral-odd parton distribution $h_1…

High Energy Physics - Phenomenology · Physics 2010-11-01 J. Soffer

A fit to proton, neutron and deuteron spin asymmetries is presented and polarized parton distributions in nucleon are given. These densities have their roots in the MRS fit for unpolarized case. The integrals of polarized distributions are…

High Energy Physics - Phenomenology · Physics 2008-02-03 Jan Bartelski , Stanisław Tatur

We have used recent polarized deep-inelastic scattering data from CERN and SLAC to extract information about nucleon spin structure. We find that the SMC proton data, the E142 neutron data and the deuteron data from SMC and E143 give…

High Energy Physics - Phenomenology · Physics 2009-10-28 M. Goshtasbpour , Gordon P. Ramsey