scholarly journals Understanding the large-distance behavior of transverse-momentum-dependent parton densities and the Collins-Soper evolution kernel

2015 ◽  
Vol 91 (7) ◽  
Author(s):  
John Collins ◽  
Ted Rogers
Keyword(s):  
Transverse Momentum ◽  
Large Distance ◽  
Transverse Momentum Dependent ◽  
Evolution Kernel ◽  
Distance Behavior

scholarly journals Phenomenology of TMDs Using SCET

2015 ◽  
Vol 37 ◽  
pp. 1560026
Author(s):  
Stefano Melis ◽  
Umberto D'Alesio ◽  
Miguel G. Echevarria ◽  
Ignazio Scimemi
Keyword(s):  
Transverse Momentum ◽  
Z Boson ◽  
Nucleon Structure ◽  
Boson Production ◽  
Transverse Momentum Dependent ◽  
Evolution Kernel ◽  
Global Fit ◽  
Logarithmic Accuracy ◽  
Perturbative Corrections

We present a global fit of current available data for Drell-Yan and Z-boson production using the Transverse Momentum Dependent evolution formalism of Refs. [1–4]. We performed our analysis including perturbative calculable contributions up to next-to-next-to-leading-logarithmic accuracy. We took into account non-perturbative corrections both to the intrinsic nucleon structure and to the evolution kernel.

scholarly journals Factorization of e+e− → H X cross section, differential in zh, PT and thrust, in the 2-jet limit

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
M. Boglione ◽  
A. Simonelli
Keyword(s):  
Transverse Momentum ◽  
Cross Section ◽  
Belle Collaboration ◽  
Hadron Production ◽  
Leading Order ◽  
Transverse Momentum Dependent ◽  
Factorization Scheme ◽  
Phenomenological Studies ◽  
Cross Section Differential ◽  
Perturbative Part

Abstract Factorizing the cross section for single hadron production in e+e− annihilations is a highly non trivial task when the transverse momentum of the outgoing hadron with respect to the thrust axis is taken into account. We work in a scheme that allows to factorize the e+e−→ H X cross section as a convolution of a calculable hard coefficient and a Transverse Momentum Dependent (TMD) fragmentation function. The result, differential in zh, PT and thrust, will be given to all orders in perturbation theory and explicitly computed to Next to Leading Order (NLO) and Next to Leading Log (NLL) accuracy. The predictions obtained from our computation, applying the simplest and most natural ansatz to model the non-perturbative part of the TMD, are in exceptional agreement with the experimental measurements of the BELLE Collaboration. The factorization scheme we propose relates the TMD parton densities defined in 1-hadron and 2-hadron processes, restoring the possi- bility to perform global phenomenological studies of TMD physics including experimental data from semi-inclusive deep inelastic scattering, Drell-Yan processes, e+e−→ H1H2X and e+e−→ H X annihilations.

scholarly journals PHENOMENOLOGY OF THE SIVERS EFFECT WITH TMD EVOLUTION

2012 ◽  
Vol 20 ◽  
pp. 145-152
Author(s):  
M. ANSELMINO ◽  
M. BOGLIONE ◽  
S. MELIS
Keyword(s):  
Transverse Momentum ◽  
Evolution Equations ◽  
Distribution Functions ◽  
Dependent Data ◽  
Clear Indication ◽  
Transverse Momentum Dependent ◽  
Sidis Data ◽  
Sivers Function ◽  
Theoretical Developments

Recently, theoretical developments have led to the QCD evolution equations for the unpolarized Transverse Momentum Dependent (TMD) distribution functions and for the Sivers function (TMD-evolution). We tested whether the proposed TMD-evolution can already be observed in the SIDIS data on the Sivers asymmetry. Although very preliminary, our analysis shows that data are compatible with such an evolution with a clear indication of evolution in the x-dependent data subsets.

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

BESSEL-WEIGHTED ASYMMETRIES AND TRANSVERSE SPIN EFFECTS

2012 ◽  
Vol 20 ◽  
pp. 168-176
Author(s):  
LEONARD GAMBERG
Keyword(s):  
Transverse Momentum ◽  
Cross Section ◽  
Parton Distribution ◽  
Evolution Equations ◽  
Distribution Functions ◽  
Transverse Spin ◽  
High Transverse Momentum ◽  
Transverse Momentum Dependent ◽  
Fragmentation Functions ◽  
The Cross

We consider the cross section for semi-inclusive deep inelastic scattering in Fourier space, conjugate to the outgoing hadron's transverse momentum, where convolutions of transverse momentum dependent parton distribution functions and fragmentation functions become simple products. Individual asymmetric terms in the cross section can be projected out by means of a generalized set of weights involving Bessel functions. Advantages of employing these Bessel weights are that they suppress (divergent) contributions from high transverse momentum and that soft factors cancel in (Bessel-) weighted asymmetries. Also, the resulting compact expressions immediately connect to previous work on evolution equations for transverse momentum dependent parton distribution and fragmentation functions and to quantities accessible in lattice QCD. Bessel-weighted asymmetries are thus model independent observables that augment the description and our understanding of correlations of spin and momentum in nucleon structure.

Color Entanglement in Hadronic Processes for Transverse Momentum Dependent Parton Distribution Functions

2015 ◽  
Vol 37 ◽  
pp. 1560022
Author(s):  
M. G. A. Buffing ◽  
P. J. Mulders
Keyword(s):  
Transverse Momentum ◽  
Parton Distribution ◽  
Distribution Functions ◽  
Parton Distribution Functions ◽  
Initial State ◽  
Color Flow ◽  
Transverse Momentum Dependent ◽  
Gauge Link ◽  
Azimuthal Asymmetries ◽  
Different Parts

In the description of protons, we go beyond the ordinary collinear parton distribution functions (PDFs), by including transverse momentum dependent PDFs (TMDs). As such, we become sensitive to polarization modes of the partons and protons that one cannot probe without accounting for transverse momenta of partons, in particular when looking at azimuthal asymmetries. Hadronic processes require the inclusion of gluon contributions forming the gauge links, which are path-ordered exponentials tracing the color flow. In processes with two hadrons in the initial state, such as Drell-Yan (DY), the gauge links from different parts of the process get entangled. We show that in color disentangling this gauge link structure, one becomes sensitive to this color flow. After disentanglement, particular combinations of TMDs will require a different numerical color factor than one naively might have expected. Such color factors will even play a role for azimuthal asymmetries in the simplest hadronic processes such as DY.

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