scholarly journals Diffractive $$\gamma \gamma $$ production in pp collisions at the LHC

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
V. P. Gonçalves ◽  
D. E. Martins ◽  
M. S. Rangel
Keyword(s):  
Transverse Momentum ◽  
Large Hadron Collider ◽  
Invariant Mass ◽  
Parton Distribution ◽  
Hadron Collider ◽  
Distribution Functions ◽  
Pp Collisions ◽  
Parton Distribution Functions ◽  
Momentum Distributions

AbstractIn this letter we estimate the contribution of the double diffractive processes for the diphoton production in pp collisions at the large hadron collider (LHC). The acceptance of the central and forward LHC detectors is taken into account and predictions for the invariant mass, rapidity and, transverse momentum distributions are presented. A comparison with the predictions for the light-by-light (LbL) scattering and exclusive diphoton production is performed. We demonstrate that the events associated to double diffractive processes can be separated and its study can be used to constrain the behavior of the diffractive parton distribution functions.

scholarly journals DEFINITION AND EVOLUTION OF TRANSVERSE MOMENTUM DISTRIBUTIONS

2012 ◽  
Vol 20 ◽  
pp. 92-108 ◽  
Author(s):  
MIGUEL G. ECHEVARRÍA ◽  
AHMAD IDILBI ◽  
IGNAZIO SCIMEMI
Keyword(s):  
Transverse Momentum ◽  
Evolution Equation ◽  
Gauge Invariance ◽  
Parton Distribution ◽  
Ultra Violet ◽  
Distribution Functions ◽  
Parton Distribution Functions ◽  
Transverse Momentum Dependent ◽  
Momentum Distributions ◽  
Definition Of

We consider the definition of unpolarized transverse-momentum-dependent parton distribution functions while staying on-the-light-cone. By imposing a requirement of identical treatment of two collinear sectors, our approach, compatible with a generic factorization theorem with the soft function included, is valid for all non-ultra-violet regulators (as it should), an issue which causes much confusion in the whole field. We explain how large logarithms can be resummed in a way which can be considered as an alternative to the use of Collins-Soper evolution equation. The evolution properties are also discussed and the gauge-invariance, in both classes of gauges, regular and singular, is emphasized.

QCD EVOLUTION OF HELICITY AND TRANSVERSITY TMDs

2014 ◽  
Vol 25 ◽  
pp. 1460016
Author(s):  
ALEXEI PROKUDIN
Keyword(s):  
Transverse Momentum ◽  
Parton Distribution ◽  
Distribution Functions ◽  
Parton Distribution Functions ◽  
Momentum Distributions ◽  
Definition Of

We examine the QCD evolution of the helicity and transversity parton distribution functions when including also their dependence on transverse momentum. Using an appropriate definition of these polarized transverse momentum distributions (TMDs), we describe their dependence on the factorization scale and rapidity cutoff, which is essential for phenomenological applications.

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.

Sphericity distribution in pp collisions and the gluon Parton Distribution Functions

2011 ◽  
Author(s):  
Antonio Ortiz ◽  
Eleazar Cuautle ◽  
Guy Paić ◽  
Alejandro Ayala ◽  
Guillermo Contreras ◽  
...  
Keyword(s):  
Parton Distribution ◽  
Distribution Functions ◽  
Pp Collisions ◽  
Parton Distribution Functions

scholarly journals RENORMALIZATION-GROUP ANATOMY OF TRANSVERSE-MOMENTUM DEPENDENT PARTON DISTRIBUTION FUNCTIONS IN QCD

2009 ◽  
Vol 24 (35n37) ◽  
pp. 2913-2923 ◽  
Author(s):  
N. G. STEFANIS ◽  
I. O. CHEREDNIKOV
Keyword(s):  
Transverse Momentum ◽  
Parton Distribution ◽  
Anomalous Dimension ◽  
Distribution Functions ◽  
Divergent Part ◽  
Parton Distribution Functions ◽  
Transverse Momentum Dependent ◽  
Light Cone Gauge ◽  
Soft Factor ◽  
First Case

The ultraviolet and rapidity divergences of transverse-momentum dependent parton distribution functions with lightlike and transverse gauge links is studied, also incorporating a soft eikonal factor. We find that in the light-cone gauge with q--independent pole prescriptions extra divergences appear which amount, at one-loop, to a cusp-like anomalous-dimension. We show that such contributions are absent when the Mandelstam-Leibbrandt prescription is used. In the first case, the soft factor cancels the anomalous dimension defect, while in the second case its ultraviolet-divergent part reduces to unity.

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