Transverse-momentum-dependent fragmentation functions in e+e- annihilation

2016 ◽  
Vol 52 (6) ◽  
Author(s):  
Isabella Garzia ◽  
Francesca Giordano
Keyword(s):  
Transverse Momentum ◽  
Transverse Momentum Dependent ◽  
Fragmentation Functions

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.

scholarly journals General helicity formalism for two-hadron production in e+e− annihilation within a TMD approach

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Umberto D’Alesio ◽  
Francesco Murgia ◽  
Marco Zaccheddu
Keyword(s):  
Transverse Momentum ◽  
Hadron Production ◽  
Probabilistic Interpretation ◽  
Leading Order ◽  
Transverse Momentum Dependent ◽  
Factorization Scheme ◽  
Helicity Formalism ◽  
Double Polarization ◽  
Fragmentation Functions ◽  
Polarization Observables

Abstract We present the complete leading-order results for the azimuthal dependences and polarization observables in e+e−→ h1h2 + X processes, where the two hadrons are produced almost back-to-back, within a transverse momentum dependent (TMD) factorization scheme. We consider spinless (or unpolarized) and spin-1/2 hadron production and give the full set of the corresponding quark and gluon TMD fragmentation functions (TMD-FFs). By adopting the helicity formalism, which allows for a more direct probabilistic interpretation, single- and double-polarization cases are discussed in detail. Simplified expressions, useful for phenomenological analyses, are obtained by assuming a factorized Gaussian-like dependence on intrinsic transverse momenta for the TMD-FFs.

scholarly journals Transverse Momentum Dependent Hadron Multiplicities at COMPASS

2016 ◽  
Vol 40 ◽  
pp. 1660031
Author(s):  
Nour Makke
Keyword(s):  
Transverse Momentum ◽  
Inelastic Scattering ◽  
Deep Inelastic Scattering ◽  
Spin Structure ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
Compass Experiment ◽  
Fragmentation Functions

Unpolarised semi-inclusive deep inelastic scattering is receiving a growing interest as a powerful tool to access poorly known transverse momentum dependent parton distributions and fragmentation functions that play a key role in many processes, in particular in the study of the spin structure of the nucleon. These functions can be investigated through experimental observables. New results on these observables by the COMPASS experiment at CERN will be shown and discussed.

scholarly journals PHENOMENOLOGY OF TRANSVERSE MOMENTUM DEPENDENT PARTON DENSITIES

2014 ◽  
Vol 25 ◽  
pp. 1460017
Author(s):  
MARIAELENA BOGLIONE
Keyword(s):  
Transverse Momentum ◽  
Energy Dependence ◽  
Transverse Momentum Dependent ◽  
Short Overview ◽  
Fragmentation Functions

This talk provides a short overview of the phenomenology of transverse momentum dependent distribution and fragmentation functions, focussing on the most recent phenomenological developments in the study of their Q2 evolution and energy dependence.

scholarly journals TMD THEORY, FACTORIZATION AND EVOLUTION

2014 ◽  
Vol 25 ◽  
pp. 1460001 ◽  
Author(s):  
JOHN COLLINS
Keyword(s):  
Transverse Momentum ◽  
Transverse Momentum Dependent ◽  
Fragmentation Functions

The concepts and methods of factorization using transverse-momentum-dependent (TMD) parton densities and/or fragmentation functions are summarized.

scholarly journals Quarkonium TMD fragmentation functions in NRQCD

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Miguel G. Echevarria ◽  
Yiannis Makris ◽  
Ignazio Scimemi
Keyword(s):  
Transverse Momentum ◽  
Phenomenological Study ◽  
Light Quark ◽  
Distance Matrix ◽  
Gluon Fusion ◽  
Coupling Constant ◽  
Long Distance ◽  
Transverse Momentum Dependent ◽  
Quarkonium Production ◽  
Fragmentation Functions

Abstract We study the transverse-momentum spectrum of quarkonium production from single light-parton fragmentation mechanism. In the case of semi-inclusive deep inelastic scattering, we observe that there are two possible initiating processes, namely photon-gluon fusion and light-quark fragmentation. For the second case we derive the factorization theorem, which involves a new hadronic quantity: the quarkonium transverse-momentum-dependent fragmentation functions in NRQCD. We calculate their matching onto the non-perturbative long distance matrix elements at the lowest order in the strong-coupling constant, $$ \mathcal{O}\left({\alpha}_s^2\right) $$ O α s 2 . Focusing on the case of the electron-ion collider, we make a comparative phenomenological study of the two production mechanisms and find the regions of the phase space where one is dominant over the other.

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