scholarly journals TRANSVERSE-MOMENTUM-DEPENDENT PARTON DISTRIBUTIONS AT THE EDGE OF THE LIGHTCONE

2011 ◽  
Vol 04 ◽  
pp. 135-145 ◽  
Author(s):  
I. O. CHEREDNIKOV ◽  
N. G. STEFANIS
Keyword(s):  
Transverse Momentum ◽  
Invariant Operator ◽  
Parton Distributions ◽  
Gauge Invariant ◽  
Transverse Momentum Dependent ◽  
Tree Approximation ◽  
Definition Of ◽  
Consistent Treatment ◽  
Operator Definition ◽  
Soft Factors

We present a completely gauge-invariant operator definition of transverse-momentum-dependent parton densities (TMD), supplied with longitudinal lightlike gauge links as well as transverse gauge links at lightcone infinity. Within this framework, we consider the consistent treatment of specific divergences, emerging in the "unsubtracted" TMD beyond the tree approximation, and construct the soft factors to cancel unphysical singularities. We confront this approach with factorization schemes, which make use of covariant gauges with off-the-lightcone gauge links, and discuss their mutual connection.

scholarly journals The Boer-Mulders Transverse Momentum Distribution in the Pion and its Evolution in Lattice QCD

2015 ◽  
Vol 37 ◽  
pp. 1560034 ◽  
Author(s):  
M. Engelhardt ◽  
B. Musch ◽  
P. Hägler ◽  
A. Schäfer ◽  
J. Negele
Keyword(s):  
Transverse Momentum ◽  
Lattice Qcd ◽  
Momentum Distribution ◽  
Transverse Momentum Distribution ◽  
Matrix Elements ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
Gauge Link ◽  
Definition Of ◽  
Type Parameter

Starting from a definition of transverse momentum-dependent parton distributions (TMDs) in terms of hadronic matrix elements of a quark bilocal operator containing a staple-shaped gauge link, selected TMD observables can be evaluated within Lattice QCD. A TMD ratio describing the Boer-Mulders effect in the pion is investigated, with a particular emphasis on its evolution as a function of a Collins-Soper-type parameter which quantifies the proximity of the staple-shaped gauge links to the light cone.

TRANSVERSE MOMENTUM-DEPENDENT PARTON DISTRIBUTIONS FROM LATTICE QCD

2012 ◽  
Vol 20 ◽  
pp. 153-161
Author(s):  
M. ENGELHARDT ◽  
B. MUSCH ◽  
P. HÄGLER ◽  
J. NEGELE ◽  
A. SCHÄFER
Keyword(s):  
Transverse Momentum ◽  
Inelastic Scattering ◽  
Lattice Qcd ◽  
Lorentz Frame ◽  
Matrix Elements ◽  
Lattice Calculation ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
Calculation Results ◽  
Definition Of

Starting from a definition of transverse momentum-dependent parton distributions for semi-inclusive deep inelastic scattering and the Drell-Yan process, given in terms of matrix elements of a quark bilocal operator containing a staple-shaped Wilson connection, a scheme to determine such observables in lattice QCD is developed and explored. Parametrizing the aforementioned matrix elements in terms of invariant amplitudes permits a simple transformation of the problem to a Lorentz frame suited for the lattice calculation. Results for the Sivers and Boer-Mulders transverse momentum shifts are presented, focusing in particular on their dependence on the staple extent and the Collins-Soper evolution parameter.

scholarly journals Transverse-momentum-dependent parton distributions up to N3LL from Drell-Yan data

2020 ◽  
Vol 2020 (7) ◽  
Author(s):  
Alessandro Bacchetta ◽  
Valerio Bertone ◽  
Chiara Bissolotti ◽  
Giuseppe Bozzi ◽  
Filippo Delcarro ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Parton Distributions ◽  
Transverse Momentum Dependent

scholarly journals DEFINITION AND EVOLUTION OF TRANSVERSE MOMENTUM DISTRIBUTIONS

2012 ◽  
Vol 20 ◽  
pp. 92-108 ◽  
Author(s):  
MIGUEL G. ECHEVARRÍA ◽  
AHMAD IDILBI ◽  
IGNAZIO SCIMEMI
Keyword(s):  
Transverse Momentum ◽  
Evolution Equation ◽  
Gauge Invariance ◽  
Parton Distribution ◽  
Ultra Violet ◽  
Distribution Functions ◽  
Parton Distribution Functions ◽  
Transverse Momentum Dependent ◽  
Momentum Distributions ◽  
Definition Of

We consider the definition of unpolarized transverse-momentum-dependent parton distribution functions while staying on-the-light-cone. By imposing a requirement of identical treatment of two collinear sectors, our approach, compatible with a generic factorization theorem with the soft function included, is valid for all non-ultra-violet regulators (as it should), an issue which causes much confusion in the whole field. We explain how large logarithms can be resummed in a way which can be considered as an alternative to the use of Collins-Soper evolution equation. The evolution properties are also discussed and the gauge-invariance, in both classes of gauges, regular and singular, is emphasized.

scholarly journals Nucleon transverse momentum-dependent parton distributions from domain wall fermion calculations at 297 MeV pion mass

2015 ◽  
Author(s):  
Michael Engelhardt ◽  
Bernhard Musch ◽  
Tanmoy Bhattacharya ◽  
Rajan Gupta ◽  
Ph. Hagler ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Domain Wall ◽  
Pion Mass ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
Domain Wall Fermion

scholarly journals TMDlib and TMDplotter: library and plotting tools for transverse-momentum-dependent parton distributions

2014 ◽  
Vol 74 (12) ◽  
Author(s):  
F. Hautmann ◽  
H. Jung ◽  
M. Krämer ◽  
P. J. Mulders ◽  
E. R. Nocera ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Parton Distributions ◽  
Transverse Momentum Dependent

NONTRIVIAL RELATIONS BETWEEN GPDs AND TMDs>

2009 ◽  
Vol 24 (35n37) ◽  
pp. 2973-2983 ◽  
Author(s):  
ANDREAS METZ ◽  
STEPHAN MEISSNER ◽  
MARC SCHLEGEL
Keyword(s):  
Transverse Momentum ◽  
Present Knowledge ◽  
The Other ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
Generalized Parton Distributions ◽  
Model Independent ◽  
The One

The present knowledge about nontrivial relations between generalized parton distributions for a spin-1/2 hadron on the one hand and transverse momentum dependent distributions on the other is reviewed. While various relations can be found in the framework of simple spectator models, so far no model-independent nontrivial relations have been established. In fact, by relating the two types of parton distributions to the fully unintegrated, off-diagonal quark-quark correlator for a spin-1/2 hadron, we argue that none of the nontrivial relations can be promoted to a model-independent status.

scholarly journals Flavor decomposition of transverse momentum dependent parton distributions

2014 ◽  
Vol 73 ◽  
pp. 02019 ◽  
Author(s):  
Alessio Del Dotto ◽  
Leonid Kaptari ◽  
Emanuele Pace ◽  
Giovanni Salmè ◽  
Sergio Scopetta ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Parton Distributions ◽  
Transverse Momentum Dependent

scholarly journals THE SPIN STRUCTURE OF THE NUCLEON IN LIGHT-CONE QUARK MODELS

2009 ◽  
Vol 24 (35n37) ◽  
pp. 2903-2912 ◽  
Author(s):  
B. PASQUINI ◽  
S. BOFFI ◽  
P. SCHWEITZER
Keyword(s):  
Transverse Momentum ◽  
Light Cone ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
Spin Asymmetries ◽  
Generalized Parton Distributions ◽  
Quark Spin ◽  
Quark Models ◽  
Impact Parameter Space

The quark spin densities related to generalized parton distributions in impact-parameter space and to transverse-momentum dependent parton distributions are reviewed within a light-cone quark model, with focus on the role of the different spin-spin and spin-orbit correlations of quarks. Results for azimuthal spin asymmetries in semi-inclusive deep inelastic scattering due to T -even transverse-momentum dependent parton distributions are also discussed.

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