Leading order analysis of twist-3 space- and time-like cut vertices in QCD

2017 ◽  
Vol 32 (22) ◽  
pp. 1730018 ◽  
Author(s):  
A. V. Belitsky
Keyword(s):  
Evolution Equations ◽  
Scale Dependence ◽  
Leading Order ◽  
Order Analysis ◽  
Space And Time ◽  
Theoretical Progress ◽  
Fragmentation Functions

We review the recent theoretical progress in the construction and solution of the evolution equations which govern the scale dependence for the twist-3 structure and fragmentation functions of the nucleon.

SCALE DEPENDENCE OF TWIST-3 CORRELATION FUNCTIONS

2011 ◽  
Vol 04 ◽  
pp. 146-156
Author(s):  
Zhong-Bo Kang ◽  
Jian-Wei Qiu
Keyword(s):  
Correlation Functions ◽  
Evolution Equations ◽  
Scale Dependence ◽  
Leading Order ◽  
Coupling Constant ◽  
Parton Distributions ◽  
Spin Asymmetries ◽  
Single Spin ◽  
Single Spin Asymmetries ◽  
Similarities And Differences

In this talk, we introduce two sets of twist-3 quark-gluon correlation functions that are relevant to transverse single spin asymmetries, and present corresponding evolution equations at the leading order in strong coupling constant, αs. The similarities and differences between the evolution of the leading power parton distributions and that of the twist-3 multiparton correlation functions are also discussed.

scholarly journals SUSY-like relation of the splitting functions in evolution of gluon and quark jet multiplicities

2018 ◽  
Vol 191 ◽  
pp. 04006
Author(s):  
Anatoly Kotikov
Keyword(s):  
Evolution Equations ◽  
Dglap Evolution ◽  
Leading Order ◽  
Logarithmic Order ◽  
World Data ◽  
Charged Hadrons ◽  
Anomalous Dimensions ◽  
The World ◽  
Fragmentation Functions ◽  
Gluon Fragmentation

We show the new relationship [1] between the anomalous dimensions, resummed through next-to-next-to-leading-logarithmic order, in the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equations for the first Mellin moments Dq,g(μ2) of the quark and gluon fragmentation functions, which correspond to the average hadron multiplicities in jets initiated by quarks and gluons, respectively. So far, such relationships have only been known from supersymmetric (SUSY) QCD. Exploiting available next-to-nextto- next-to-leading-order (NNNLO) information on the ratio D+g (μ2)=D+q (μ2) of the dominant plus components, the fit of the world data of Dq,g(μ2) for charged hadrons measured in e+e- annihilation leads to α(5)s (MZ) = 0:1205 +0:0016 -0:0020.

scholarly journals Vector meson fragmentation using a model with broken SU(3) at the next-to-leading order

2014 ◽  
Vol 29 (07) ◽  
pp. 1450049 ◽  
Author(s):  
H. Saveetha ◽  
D. Indumathi ◽  
Subhadip Mitra
Keyword(s):  
Vector Meson ◽  
Cross Section ◽  
Evolution Equations ◽  
Light Quark ◽  
Energy Scale ◽  
Dglap Evolution ◽  
Leading Order ◽  
Quark Fragmentation ◽  
Fragmentation Functions ◽  
The Cross

A detailed study of fragmentation of vector mesons at the next-to-leading order (NLO) in QCD is given for e+e- scattering. A model with broken SU(3) symmetry using three input fragmentation functions α(x, Q2), β(x, Q2) and γ(x, Q2) and a strangeness suppression parameter λ describes all the light quark fragmentation functions for the entire vector meson octet. At a starting low energy scale of [Formula: see text] for three light quarks (u, d, s) along with initial parametrization, the fragmentation functions are evolved through DGLAP evolution equations at NLO and the cross-section is calculated. The heavy quarks contribution are added in appropriate thresholds during evolution. The results obtained are fitted at the momentum scale of [Formula: see text] for LEP and SLD data. Good-quality fits are obtained for ρ, K*, ω and ϕ mesons, implying the consistency and efficiency of this model. Strangeness suppression in this model is understood both in terms of ratios of quark fragmentation functions alone as well as in terms of observables; the latter yield a suppression through the K*/ρ multiplicity ratio of about 0.23 while the x dependence of this suppression is also parametrized through the cross-section ratios.

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 COMPASS Measurement of Pion and Kaon Multiplicities and Extraction of Quark Fragmentation Functions into Pions

2016 ◽  
Vol 40 ◽  
pp. 1660027
Author(s):  
Fabienne Kunne
Keyword(s):  
Inelastic Scattering ◽  
Deep Inelastic Scattering ◽  
Leading Order ◽  
Data Set ◽  
Quark Fragmentation ◽  
Z Domain ◽  
Fragmentation Functions

We present preliminary COMPASS results on pion and kaon multiplicities produced in semi inclusive deep inelastic scattering of 160[Formula: see text]GeV muons off an isoscalar ([Formula: see text]LiD) target. The results constitute an impressive data set of more than 400 points in p and 400 in K, covering a large x,Q[Formula: see text] and z domain in a fine binning, which will be used in future QCD fits at next to leading order to extract quark fragmentation functions. We show results of a first leading order fit performed to extract the favored and unfavored quark fragmentation functions into pions D[Formula: see text] and D[Formula: see text].

scholarly journals NLO Hierarchy of Wilson Lines Evolution

2015 ◽  
Vol 37 ◽  
pp. 1560056
Author(s):  
I. Balitsky
Keyword(s):  
Evolution Equations ◽  
High Energy ◽  
Leading Order ◽  
High Energy Behavior ◽  
Energy Behavior

The high-energy behavior of QCD amplitudes can be described in terms of the rapidity evolution of Wilson lines. I present the hierarchy of evolution equations for Wilson lines in the next-to-leading order.

An inverse problem for space and time fractional evolution equations with an involution perturbation

2017 ◽  
Vol 40 (2) ◽  
pp. 151-160 ◽  
Author(s):  
Bashir Ahmad ◽  
Ahmed Alsaedi ◽  
Mokhtar Kirane ◽  
Ramiz G. Tapdigoglu
Keyword(s):  
Inverse Problem ◽  
Evolution Equations ◽  
Fractional Evolution Equations ◽  
Space And Time

scholarly journals DOUBLE PARTON FRAGMENTATION FUNCTION AND ITS EVOLUTION IN QUARKONIUM PRODUCTION

2014 ◽  
Vol 25 ◽  
pp. 1460040
Author(s):  
ZHONG-BO KANG
Keyword(s):  
Fragmentation Function ◽  
Evolution Equations ◽  
Heavy Quarkonia ◽  
Large Transverse Momentum ◽  
Heavy Quark Mass ◽  
Qcd Factorization ◽  
Factorization Formalism ◽  
Quarkonium Production ◽  
Large Enhancement ◽  
Fragmentation Functions

We summarize the results of a recent study on a new perturbative QCD factorization formalism for the production of heavy quarkonia of large transverse momentum pT at collider energies. Such a new factorization formalism includes both the leading power (LP) and next-to-leading power (NLP) contributions to the cross section in the [Formula: see text] expansion for heavy quark mass mQ. For the NLP contribution, the so-called double parton fragmentation functions are involved, whose evolution equations have been derived. We estimate fragmentation functions in the non-relativistic QCD formalism, and found that their contribution reproduce the bulk of the large enhancement found in explicit NLO calculations in the color singlet model. Heavy quarkonia produced from NLP channels prefer longitudinal polarization, in contrast to the single parton fragmentation function. This might shed some light on the heavy quarkonium polarization puzzle.

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