ELLIPTIC FLOW IN pp-COLLISIONS AT THE LHC

Abstract

We consider collective effects in pp-collisions at the LHC energies related to presence of the large orbital angular momentum in the initial state and role of this orbital momentum in the elliptic flow behavior.

Observation of a Ridge Correlation Structure in High Multiplicity Proton–proton Collisions: A Brief Review

“…More discussions of possible elliptic and higher-order flow effects in pp can be found in a series of literatures in Refs. 44,45,46,47,48,49,50. Motivated by the concept of gluon saturation at very small x in QCD, the theory of color glass condensate (CGC) describes the initial state of nuclear matter at very high energy 51,52 .…”

Some Intensive and Extensive Quantities in High-Energy Collisions

“…Furthermore, none of available microscopic Monte Carlo (MC) models describes the development of anisotropic flow in elementary hadron-hadron interactions yet [40]. Particular non-perturbative approach was suggested as a mechanism of anisotropic flow might be a leading one in hadron collisions, since those have smaller geometrical extension and the probability of hydrodynamical generation of elliptic flow is lower compared to the collisions of nuclei [41].…”

ON THE POSSIBLE DECOHERENCE OBSERVED AT $\sqrt{s} = 7~{\rm TeV}$

“…Due to strong interaction between quarks mediated by pions this results in the coherent rotation of the quark system located in the overlap region as a whole in the xz-plane. This mechansim allows to explain, at least qualitatively, several experimental findings at the LHC energies and among them an appearance of the ridge and anisotropic flows in pp-collisions [5,6]. It also allowed to get quantitave description of the energy dependence of the average transverse momentum [4].…”

“…In the papers [4,5,6] the mechanism of hadron interactions based on collective properties of the transient matter has been proposed. This mechanism uses the geometrical picture of hadron collision at non-zero impact parameters which implies that the generated massive virtual quarks in overlap region obtain large orbital angular momentum at high energies.…”