Landau-Pomeranchuk-Midgal effect and charm production in pp collisions at energies available at the CERN Large Hadron Collider using the parton cascade model

Abstract

We study the impact of the Landau Pomeranchuk Midgal (LPM) effect on the dynamics of parton interactions in proton proton collisions at the Large Hadron Collider energies. For our investigation we utilize a microscopic kinetic theory based on the Boltzmann equation. The calculation traces the space-time evolution of the cascading partons interacting via semihard pQCD scatterings and fragmentations. We focus on the impact of the LPM effect on the production of charm quarks, since their production is exclusively governed by processes well described in our kinetic theory. The LPM effect is found to become more prominent as the collision energy rises and at central rapidities and may significantly affect the model's predicted charm distributions at low momenta.

Bottom Production in $pp$ Collisions at Large Hadron Collider Energies using Parton Cascade Model

“…These results taken along with our earlier findings about charm quarks [13] elevate bottom quarks to a preeminent position to study medium modification of heavy quark production in AA collisions by comparing the same to that for pp collisions, while the charm quarks are elevated to a pre-eminent position for confirming the advent of an interacting medium in pp collisions at LHC energies, where multiple semi-hard partonic collisions take place even when LPM effects are accounted for.…”

“…This suggests that the inclusion of multiple scatterings does not lead to additional production of bottom quarks for reasonable values of m b . The deviations seen for m b = 4.00 GeV are similar in nature, though much smaller than that for the production of charm quarks reported earlier [13] The corresponding results for pp collisions at 13 TeV are given in Figs. 3 and 4.…”

“…If the results for the later two calculations differ significantly, it would indicate that the bottom quark production is affected by multiple scatterings in realistic situations after LPM effect is accounted for. We recall that there are indications [13] that the results for charm production are quite sensitive to these differing scenarios for lower transverse momenta and central rapidities.…”

“…A recent theoretical study of pp collisions at LHC energies [12] within Parton Cascade Model (PCM) suggested onset of a substantial multiple scattering, necessary for the formation of an interacting system. A further support for this was provided by the study of charm production which gave indications of deviations in results for calculations performed with and without multiple scatterings, already in minimum bias events for pp collisions at LHC energies [13]. The experimental data were found to indicate a preference for results of the calculations obtained with the inclusion of Landau Pomeranchuk Midgal (LPM) effect and multiple scatterings for low transverse momenta and central rapidities.…”

“…The radiating parton, however, is allowed to interact, and if that happens during the formation time, the radiated particle is removed from the list of partons forming the system. It has been reported [13,17] that the dependence of the results obtained in the parton cascade model on µ 0 is rather modest once the LPM effect is accounted for.…”