scholarly journals Matching of fracture functions for SIDIS in target fragmentation region

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
K.B. Chen ◽  
J.P. Ma ◽  
X.B. Tong
Keyword(s):  
Transverse Momentum ◽  
Cross Sections ◽  
Virtual Photon ◽  
Fragmentation Region ◽  
Collinear Factorization ◽  
Parton Distributions ◽  
Gauge Invariant ◽  
Target Fragmentation ◽  
Modeling Fracture ◽  
Fragmentation Functions

Abstract In the target fragmentation region of Semi-Inclusive Deep Inelastic Scattering, the diffractively produced hadron has small transverse momentum. If it is at order of ΛQCD, it prevents to make predictions with the standard collinear factorization. However, in this case, differential cross-sections can be predicted by the factorization with fracture functions, diffractive parton distributions. If the transverse momentum is much larger than ΛQCD but much smaller than Q which is the virtuality of the virtual photon, both factorizations apply. In this case, fracture functions can be factorized with collinear parton distributions and fragmentation functions. We study the factorization up to twist-3 level and obtain gauge invariant results. They will be helpful for modeling fracture functions and useful for resummation of large logarithm of the transverse momentum appearing in collinear factorization.

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 DIRECT PHOTON PRODUCTION IN pp AND $p {\bar p}$ COLLISIONS AT HIGH ENERGIES

2007 ◽  
Vol 22 (02n03) ◽  
pp. 541-545
Author(s):  
TOMASZ PIETRYCKI ◽  
ANTONI SZCZUREK
Keyword(s):  
Transverse Momentum ◽  
Cross Sections ◽  
Good Description ◽  
Photon Production ◽  
Low Energy ◽  
Direct Photon ◽  
Parton Distributions ◽  
High Energies ◽  
Direct Photon Production ◽  
Standing Problem

The invariant cross sections for direct photon production in hadron-hadron collisions are calculated for several initial energies (SPS, ISR, [Formula: see text], RHIC, Tevatron, LHC) including initial parton transverse momenta within the formalism of unintegrated parton distributions (UPDF). Kwieciński UPDFs provide very good description of all world data, especially at SPS and ISR energies. Inclusion of the QCD evolution effects and especially their effect on initial parton transverse momenta allowed to solve the long-standing problem of understanding the low energy and low transverse momentum data.

scholarly journals Higgs-boson production in top-quark fragmentation

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Colomba Brancaccio ◽  
Michał Czakon ◽  
Terry Generet ◽  
Michael Krämer
Keyword(s):  
Higgs Boson ◽  
Transverse Momentum ◽  
Cross Sections ◽  
Differential Cross ◽  
Top Quark ◽  
Boson Production ◽  
Large Transverse Momentum ◽  
Quark Fragmentation ◽  
Fragmentation Functions ◽  
Logarithmic Accuracy

Abstract We compute the fragmentation functions for the production of a Higgs boson at $$ \mathcal{O} $$ O ($$ {y}_t^2 $$ y t 2 αs). As part of this calculation, the relevant splitting functions are also derived at the same perturbative order. Our results can be used to compute differential cross sections with arbitrary top-quark and Higgs-boson masses from massless calculations. They can also be used to resum logarithms of the form ln(pT/m) at large transverse momentum pT to next-to-leading-logarithmic accuracy by solving the DGLAP equations.

Exploring the Flavor Dependence of Partonic Transverse Momentum

2015 ◽  
Vol 37 ◽  
pp. 1560024 ◽  
Author(s):  
Marco Radici ◽  
Alessandro Bacchetta ◽  
Andrea Signori ◽  
Gunar Schnell
Keyword(s):  
Transverse Momentum ◽  
Inelastic Scattering ◽  
Deep Inelastic Scattering ◽  
Momentum Dependence ◽  
Parton Distributions ◽  
Average Transverse Momentum ◽  
Transverse Momentum Dependent ◽  
Transverse Momentum Dependence ◽  
Hermes Data ◽  
Fragmentation Functions

Using recently published HERMES data on multiplicities in semi-inclusive deep-inelastic scattering, we discuss the flavor dependence of unpolarized transverse-momentum dependent distribution and fragmentation functions. We find convincing indications that favored fragmentation into pions have smaller average transverse momentum than unfavored ones and fragmentation into kaons. We find weaker indications of flavor dependence in the transverse-momentum dependence of parton distributions.

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.

EXPERIMENTAL DATA ON TRANSVERSE-MOMENTUM DISTRIBUTIONS FROM SEMI-INCLUSIVE DEEP-INELASTIC SCATTERING

2014 ◽  
Vol 25 ◽  
pp. 1460013
Author(s):  
GUNAR SCHNELL
Keyword(s):  
Transverse Momentum ◽  
Inelastic Scattering ◽  
Deep Inelastic Scattering ◽  
The Novel ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
Quark Spin ◽  
Momentum Distributions ◽  
Sivers Function ◽  
Fragmentation Functions

The exploration of the structure of the nucleon reaches a new level of sophistication when explicit dependences on transverse momenta of partons in both parton distributions and fragmentation functions are included. These dependences lead to a manifold of new correlations between the nucleon and quark spin as well as their momenta and thus a wealth of experimental observables. A particular example is the novel Sivers function that—according to firm QCD predictions—has to change sign when going from the Drell-Yan process to semi-inclusive deep-inelastic scattering. Here a review is given on which knowledge has been gathered about transverse-momentum-dependent (TMD) distribution and fragmentation functions from semi-inclusive deep-inelastic scattering experiments.

scholarly journals Exclusive photoproduction of a γ ρ pair with a large invariant mass

2017 ◽  
Vol 2017 (2) ◽  
Author(s):  
R. Boussarie ◽  
B. Pire ◽  
L. Szymanowski ◽  
S. Wallon
Keyword(s):  
Transverse Momentum ◽  
Invariant Mass ◽  
Cross Sections ◽  
Differential Cross ◽  
Scattering Amplitude ◽  
Differential Cross Sections ◽  
Leading Order ◽  
Collinear Factorization

Abstract Exclusive photoproduction of a γ ρ pair in the kinematics where the pair has a large invariant mass and the final nucleon has a small transverse momentum is described in the collinear factorization framework. The scattering amplitude is calculated at leading order in α s and the differential cross sections for the process where the ρ−meson is either longitudinally or transversely polarized are estimated in the kinematics of the JLab 12-GeV experiments.

scholarly journals Saturation effects in SIDIS at very forward rapidities

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
E. Iancu ◽  
A. H. Mueller ◽  
D. N. Triantafyllopoulos ◽  
S. Y. Wei
Keyword(s):  
Inelastic Scattering ◽  
Cross Section ◽  
Cross Sections ◽  
Virtual Photon ◽  
Large Fraction ◽  
Quark Distribution ◽  
High Energy ◽  
Longitudinal Momentum ◽  
Black Disk ◽  
Gluon Saturation

Abstract Using the dipole picture for electron-nucleus deep inelastic scattering at small Bjorken x, we study the effects of gluon saturation in the nuclear target on the cross-section for SIDIS (single inclusive hadron, or jet, production). We argue that the sensitivity of this process to gluon saturation can be enhanced by tagging on a hadron (or jet) which carries a large fraction z ≃ 1 of the longitudinal momentum of the virtual photon. This opens the possibility to study gluon saturation in relatively hard processes, where the virtuality Q2 is (much) larger than the target saturation momentum $$ {Q}_s^2 $$ Q s 2 , but such that z(1 − z)Q2 ≲ $$ {Q}_s^2 $$ Q s 2 . Working in the limit z(1 − z)Q2 ≪ $$ {Q}_s^2 $$ Q s 2 , we predict new phenomena which would signal saturation in the SIDIS cross-section. For sufficiently low transverse momenta k⊥ ≪ Qs of the produced particle, the dominant contribution comes from elastic scattering in the black disk limit, which exposes the unintegrated quark distribution in the virtual photon. For larger momenta k⊥ ≳ Qs, inelastic collisions take the leading role. They explore gluon saturation via multiple scattering, leading to a Gaussian distribution in k⊥ centred around Qs. When z(1 − z)Q2 ≪ Q2, this results in a Cronin peak in the nuclear modification factor (the RpA ratio) at moderate values of x. With decreasing x, this peak is washed out by the high-energy evolution and replaced by nuclear suppression (RpA< 1) up to large momenta k⊥ ≫ Qs. Still for z(1 − z)Q2 ≪ $$ {Q}_s^2 $$ Q s 2 , we also compute SIDIS cross-sections integrated over k⊥. We find that both elastic and inelastic scattering are controlled by the black disk limit, so they yield similar contributions, of zeroth order in the QCD coupling.

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
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