Balitsky-Kovchegov equation
In high-energy particle physics the energy evolution of various quantities can be calculated from the Balitsky-Kovchegov (BK) equation. Depending on the frame that is used to describe the process, the BK equation can be seen to describe either the energy evolution of the virtual photon wave function or the gluon distribution function of a hadron.
In this work the BK equation is derived at leading logarithm accuracy from QCD and solved analytically in some special cases. In order to derive it the quantum field theory on the light cone is introduced. Part of the higher order corrections to the BK equation, namely the running strong coupling constant and the kinematical constraint effects, are studied numerically.
As a result it is shown that the running coupling slows down the evolution significantly compared with the evolution obtained with a fixed coupling constant. The different running coupling prescriptions used in the literature also cause significantly different evolution speeds. In addition the running coupling changes the asymptotical shape of the solution. On the other hand the kinematical constraint effects are shown to affect mainly the evolution speed while leaving the shape of the solution intact.
The numerical codes developed in this work can be used when studying the phenomenology of high-energy QCD.
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Finite Nc corrections in the Balitsky-Kovchegov equation at next-to-leading order
Lappi, T.; Mäntysaari, H.; Ramnath, A. (Sissa Medialab, 2021)We study the finite-Nc corrections to the next-to-leading order (NLO) Balitsky--Kovchegov (BK) equation. This contains correlators of six Wilson lines, which we express in terms of the two-point function using the Gaussian ... -
Inferring the initial condition for the Balitsky-Kovchegov equation
Casuga, Carlisle; Karhunen, Mikko; Mäntysaari, Heikki (American Physical Society (APS), 2024)We apply Bayesian inference to determine the posterior likelihood distribution for the parameters describing the initial condition of the small-x Balitsky-Kovchegov evolution equation at leading logarithmic accuracy. The ... -
Next-to-leading order Balitsky-Kovchegov equation beyond large Nc
Lappi, Tuomas; Mäntysaari, Heikki; Ramnath, Andrecia (American Physical Society (APS), 2020)We calculate finite-Nc corrections to the next-to-leading order (NLO) Balitsky-Kovchegov (BK) equation. We find analytical expressions for the necessary correlators of six Wilson lines in terms of the two-point function ... -
Balitsky-Kovchegov equation at next-to-leading order accuracy with a resummation of large logarithms
Lappi, Tuomas; Mäntysaari, H. (Sissa, 2016)We include resummation of large transverse logarithms into the next-to-leading order BalitskyKovchegov equation. The resummed NLO evolution equation is shown to be stable, the evolution speed being significantly reduced ... -
Charged-particle production as a function of multiplicity and transverse spherocity in pp collisions at √s = 5.02 and 13 TeV
ALICE Collaboration (Springer, 2019)We present a study of the inclusive chargedparticle transverse momentum (pT) spectra as a function of charged-particle multiplicity density at mid-pseudorapidity, dNch/dη, in pp collisions at √s = 5.02 and 13 TeV covering ...
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