scholarly journals Associated production of χc pairs with a gluon in the collinear-factorization approach

2019 ◽  
Vol 99 (7) ◽  
Author(s):  
Izabela Babiarz ◽  
Wolfgang Schäfer ◽  
Antoni Szczurek
Keyword(s):  
Collinear Factorization ◽  
Factorization Approach ◽  
Associated Production

scholarly journals Production of prompt photons associated with jets at LHC in kT-factorization

2019 ◽  
Vol 222 ◽  
pp. 03015
Author(s):  
Maxim Malyshev ◽  
Artem Lipatov ◽  
Hannes Jung
Keyword(s):  
Monte Carlo ◽  
Cross Sections ◽  
Parton Shower ◽  
Gluon Fusion ◽  
Monte Carlo Generator ◽  
Hadronic Jets ◽  
Factorization Approach ◽  
Associated Production ◽  
Parton Showering ◽  
Collinear Limit

We use the kT–factorization approach to calculate total and differential cross sections of associated production of prompt photons and hadronic jets at the LHC energies. Our consideration relies on the pegasus Monte-Carlo generator with implemented ℴ(αα2s) off-shell gluon–gluon fusion subprocess g*g* → γqq− and several subleading quark-initiated contributions from ℴ(ααs) and ℴ(αα2s) subprocesses, taken into account in the collinear limit. Using Monte-Carlo generators CASCADE and PYTHIA, we investigate parton showering effects and compare our predictions with the data, taken by CMS and ATLAS collaborations at the LHC. We demostrate reasonabledescription of the data and the importance of parton shower effects in the kT–factorization.

scholarly journals Introduction to the Transverse-Momentum-Weighted Technique in the Twist-3 Collinear Factorization Approach

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Hongxi Xing ◽  
Shinsuke Yoshida
Keyword(s):  
Transverse Momentum ◽  
Leading Order ◽  
Precise Description ◽  
Collinear Factorization ◽  
Factorization Approach ◽  
Hard Part ◽  
Spin Asymmetries ◽  
Single Spin ◽  
Single Spin Asymmetries ◽  
Successful Approach

The twist-3 collinear factorization framework has drawn much attention in recent decades as a successful approach in describing the data for single spin asymmetries (SSAs). Many SSAs data have been experimentally accumulated in a variety of energies since the first measurement was done in the late 1970s and it is expected that the future experiments like Electron-Ion-Collider will provide us with more data. In order to perform a consistent and precise description of the data taken in different kinematic regimes, the scale evolution of the collinear twist-3 functions and the perturbative higher-order hard part coefficients are mandatory. In this paper, we introduce the techniques for next-to-leading order (NLO) calculation of transverse-momentum-weighted SSAs, which can be served as a useful tool to derive the QCD evolution equation for twist-3 functions and to verify the QCD collinear factorization for twist-3 observables at NLO, as well as obtain the finite NLO hard part coefficients.

scholarly journals Intrinsic charm in the nucleon and charm production at large rapidities in collinear, hybrid and kT-factorization approaches

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Rafał Maciuła ◽  
Antoni Szczurek
Keyword(s):  
Transverse Momentum ◽  
High Energy ◽  
Charm Production ◽  
Leading Order ◽  
Collinear Factorization ◽  
Factorization Approach ◽  
High Energies ◽  
Neutrino Production ◽  
Intrinsic Charm ◽  
Gluon Distributions

Abstract We discuss the role of intrinsic charm (IC) in the nucleon for forward production of c-quark (or $$ \overline{c} $$ c ¯ -antiquark) in proton-proton collisions for low and high energies. The calculations are performed in collinear-factorization approach with on-shell partons, kT-factorization approach with off-shell partons as well as in a hybrid approach using collinear charm distributions and unintegrated (transverse momentum dependent) gluon distributions. For the collinear-factorization approach we use matrix elements for both massless and massive charm quarks/antiquarks. The distributions in rapidity and transverse momentum of charm quark/antiquark are shown for a few different models of IC. Forward charm production is dominated by gc-fusion processes. The IC contribution dominates over the standard pQCD (extrinsic) gg-fusion mechanism of $$ c\overline{c} $$ c c ¯ -pair production at large rapidities or Feynman-xF. We perform similar calculations within leading-order and next-to-leading order kT-factorization approach. The kT-factorization approach leads to much larger cross sections than the LO collinear approach. At high energies and large rapidities of c-quark or $$ \overline{c} $$ c ¯ -antiquark one tests gluon distributions at extremely small x. The IC contribution has important consequences for high-energy neutrino production in the Ice-Cube experiment and can be, to some extent, tested at the LHC by the SHIP and FASER experiments by studies of the ντ neutrino production.

Facing the challenge of 2017: beet juice and ion exchange based softening technologies

2014 ◽  
pp. 745-749 ◽  
Author(s):  
Marlene Beyerle ◽  
François Rousset ◽  
Nicolas-Julian Hilbold
Keyword(s):  
Ion Exchange ◽  
Critical Role ◽  
Regeneration System ◽  
Associated Production ◽  
Combined Use ◽  
Common Ion

This article will review common ion exchange-based softening technologies, describing how the most popular of them, the New Regeneration System (NRS) process, might be a key answer in facing the changes coming in 2017. The process’s principles and advantages will be explained, as well as the associated production-regeneration sequence. The combined use of additional technologies can play a critical role as well, and this article will demonstrate how the integration of additional technologies – in this case chromatography – can increase competitiveness.

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