scholarly journals QUARK ORBITAL ANGULAR MOMENTUM AND FINAL STATE INTERACTIONS

2014 ◽  
Vol 25 ◽  
pp. 1460029 ◽  
Author(s):  
MATTHIAS BURKARDT
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Final State ◽  
Spin Asymmetries ◽  
Single Spin ◽  
Wigner Distributions ◽  
Single Spin Asymmetries ◽  
Quark Orbital Angular Momentum ◽  
The Difference ◽  
Definition Of

Definitions of orbital angular momentum based on Wigner distributions are used to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. The difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering.

scholarly journals Quark Orbital Angular Momentum and Final State Interactions

2015 ◽  
Vol 37 ◽  
pp. 1560035 ◽  
Author(s):  
Matthias Burkardt
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Final State ◽  
Spin Asymmetries ◽  
Single Spin ◽  
Wigner Distributions ◽  
Single Spin Asymmetries ◽  
Quark Orbital Angular Momentum ◽  
The Difference ◽  
Definition Of

Definitions of orbital angular momentum based on Wigner distributions are used to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. The difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering.

GPDs AND TMDs

2012 ◽  
Vol 20 ◽  
pp. 75-83
Author(s):  
MATTHIAS BURKARDT
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Transverse Plane ◽  
Final State ◽  
Parton Distributions ◽  
Generalized Parton Distributions ◽  
Wigner Distributions ◽  
Quark Orbital Angular Momentum ◽  
Final State Interactions ◽  
The Difference

For transversely polarized nucleons the distribution of quarks in the transverse plane is transversely shifted and that shift can be described in terms of Generalized Parton Distributions (GPDs). This observation provides a 'partonic' derivation of the Ji-relation for the quark angular momentum in terms of GPDs. Wigner distributions are used to show that the difference between the Jaffe-Manohar definiton of quark orbital angular momentum and that of Ji is equal to the change of orbital angular momentum due to the final state interactions as the struck quark leaves the target in a DIS experiment.

scholarly journals MEASUREMENT OF FORWARD JETS AT RHIC

2014 ◽  
Vol 25 ◽  
pp. 1460022 ◽  
Author(s):  
◽  
L. C. BLAND
Keyword(s):  
Angular Momentum ◽  
Transverse Momentum ◽  
Orbital Angular Momentum ◽  
Initial State ◽  
Spin Asymmetries ◽  
Jet Production ◽  
Single Spin ◽  
Single Spin Asymmetries ◽  
Forward Jets

We present first measurements of forward jet production from p↑ + p collisions at [Formula: see text] GeV, including transverse single spin asymmetries. These asymmetries are expected to be sensitive to spin-correlated transverse momentum in the initial state, which is particularly interesting because it is related to orbital angular momentum in the proton.

scholarly journals Transverse Single Spin Asymmetries of Forward π0 and Jet-like Events in s = 500 GeV Polarized Proton Collisions at STAR

2016 ◽  
Vol 40 ◽  
pp. 1660037 ◽  
Author(s):  
Yuxi Pan
Keyword(s):  
Final States ◽  
High Transverse Momentum ◽  
Initial State ◽  
Final State ◽  
Spin Asymmetries ◽  
Proton Collisions ◽  
Single Spin ◽  
Single Spin Asymmetries ◽  
Polarized Proton ◽  
State Models

The large transverse single spin asymmetries (SSA) of high [Formula: see text] inclusive hadrons produced in polarized proton collisions are usually explained by means of collinear twist-3 multi-parton correlations. In this picture these asymmetries can originate from initial-state twist-3 parton distributions in the polarized proton and/or through the coupling between proton transversity and twist-3 fragmentation functions. The measurement of SSA for forward inclusive hadrons produced in [Formula: see text] collisions out to high transverse momentum helps to examine the validity and interplay of these initial- and final-state models. These models can be further explored by investigating the dependence of the SSA on event topologies. We present our latest status on the measurement of SSA for forward inclusive [Formula: see text] detected within [Formula: see text] in [Formula: see text] = 500 GeV [Formula: see text] collisions as well as its dependence on event topologies. We will also present our analysis of Sivers and Collins asymmetries for forward jet-like events consisting of multi-photon final states. The measurements are based on the data taken in 2011 with integrated luminosity [Formula: see text] 22 [Formula: see text].

PARTONIC PICTURE OF GTMDS

2014 ◽  
Vol 25 ◽  
pp. 1460009 ◽  
Author(s):  
SIMONETTA LIUTI ◽  
ABHA RAJAN ◽  
AURORE COURTOY ◽  
GARY R. GOLDSTEIN ◽  
J. OSVALDO GONZALEZ HERNANDEZ
Keyword(s):  
Angular Momentum ◽  
Compton Scattering ◽  
Orbital Angular Momentum ◽  
Scattering Amplitude ◽  
Final State Interaction ◽  
Deeply Virtual Compton Scattering ◽  
Virtual Compton Scattering ◽  
Matrix Elements ◽  
Final State ◽  
Wigner Distributions

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 unpolarized quark in a longitudinally polarized nucleon, can enter the deeply virtual Compton scattering amplitude only through matrix elements involving a final state interaction. The relevant matrix elements in turn involve light cone operators projections in the transverse direction, or they appear in the deeply virtual Compton scattering amplitude at twist three. Orbital angular momentum or the spin structure of the nucleon was a major reason for these various distributions and amplitudes to have been introduced. We show that twist three contributions to deeply virtual Compton scattering provide observables related to orbital angular momentum.

scholarly journals FINAL-STATE INTERACTIONS AND SINGLE-SPIN ASYMMETRIES IN SEMI-INCLUSIVE DEEP INELASTIC SCATTERING

2003 ◽  
Vol 18 (08) ◽  
pp. 1327-1334 ◽  
Author(s):  
STANLEY J. BRODSKY ◽  
DAE SUNG HWANG ◽  
IVAN SCHMIDT
Keyword(s):  
Spin Asymmetry ◽  
Proton Spin ◽  
Final State ◽  
Complex Phase ◽  
Target Nucleon ◽  
Spin Asymmetries ◽  
Single Spin ◽  
Polarized Target ◽  
Single Spin Asymmetries ◽  
Final State Interactions

Recent measurements from the HERMES and SMC collaborations show a remarkably large azimuthal single-spin asymmetries AUL and AUT of the proton in semi-inclusive pion leptoproduction γ*(q) p → π X. We show that final-state interactions from gluon exchange between the outgoing quark and the target spectator system leads to single-spin asymmetries in deep inelastic lepton-proton scattering at leading twist in perturbative QCD; i.e., the rescattering corrections are not power-law suppressed at large photon virtuality q2 at fixed xbj. The existence of such single-spin asymmetries requires a phase difference between two amplitudes coupling the proton target with [Formula: see text] to the same final-state, the same amplitudes which are necessary to produce a nonzero proton anomalous magnetic moment. We show that the exchange of gauge particles between the outgoing quark and the proton spectators produces a Coulomb-like complex phase which depends on the angular momentum Lz of the proton's constituents and thus is distinct for different proton spin amplitudes. The single-spin asymmetry which arises from such final-state interactions does not factorize into a product of structure function and fragmentation function, and it is not related to the transversity distribution δq(x,Q) which correlates transversely polarized quarks with the spin of the transversely polarized target nucleon.

scholarly journals WIGNER DISTRIBUTIONS AND QUARK ORBITAL ANGULAR MOMENTUM

2012 ◽  
Vol 20 ◽  
pp. 84-91 ◽  
Author(s):  
CÉDRIC LORCÉ ◽  
BARBARA PASQUINI
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Constituent Quark ◽  
Constituent Quark Model ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
Generalized Parton Distributions ◽  
Wigner Distributions ◽  
Quark Orbital Angular Momentum ◽  
Quark Phase

We discuss the quark phase-space or Wigner distributions of the nucleon which combine in a single picture all the information contained in the generalized parton distributions and the transverse-momentum dependent parton distributions. In particular, we present results for the distribution of unpolarized quarks in a longitudinally polarized nucleon obtained in a light-front constituent quark model. We show how the quark orbital angular momentum can be extracted from the Wigner distributions and compare it with alternative definitions.

scholarly journals Potential linear and angular momentum in the scalar diquark model

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
David Arturo Amor-Quiroz ◽  
Matthias Burkardt ◽  
William Focillon ◽  
Cédric Lorcé
Keyword(s):  
Angular Momentum ◽  
Transverse Momentum ◽  
Direct Calculation ◽  
Final State ◽  
Diquark Model ◽  
Scalar Diquark ◽  
Angular Momenta ◽  
The Difference ◽  
Definition Of ◽  
Quark Transverse Momentum

AbstractWe present an analytic two-loop calculation within the scalar diquark model of the potential linear and angular momenta, defined as the difference between the Jaffe-Manohar and Ji notions of linear and angular momenta. As expected by parity and time-reversal symmetries, a direct calculation confirms that the potential transverse momentum coincides with the Jaffe-Manohar (or canonical) definition of average quark transverse momentum, also known as the quark Sivers shift. We examine whether initial/final-state interactions at the origin of the Sivers asymmetry can also generate a potential angular momentum in the scalar diquark model.

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