Short path length pQCD corrections to energy loss in the quark gluon plasma

Isobel Kolbe,W A Horowitz

doi:10.1088/1742-6596/668/1/012107

Abstract

The twin identifications of high-pT enhancement and low-pT collective behaviour in the shockingly small systems of interacting particles created in pA collisions calls for a detailed theoretical energy loss analysis. We study the way in which energy is dissipated in the QGP created in pA collisions by calculating the short path length corrections to the DGLV energy loss formulae that have produced excellent predictions for AA collisions. We find that, shockingly, because of the large formation time assumption (used in the DGLV calculation), a highly non-trivial cancellation of correction terms results in a null short path length correction to the DGLV energy loss formula. We investigate the effect of relaxing the large formation time assumption in the final stages of the calculation and find, because of the separation distance between production and scattering centre is integrated over from 0 to ∞, ≳ 100% corrections, even in the large path length approximation employed by DGLV.

Highlights

1.1 MotivationWhile the SKA will soon be pushing the boundaries of South African physics, particle physics rivals cosmology on the global stage as one of the most fruitful fields of discovery physics, and it is truly the heavy ion particle physicists that are pulling down the veil of obscurity surrounding the underlying structure of the universe humanity finds itself in
The heavy ion community has all but universally accepted that a new state of matter is routinely created in colossal particle colliders such as the Large Hadron Collider (LHC) at CERN in Geneva [10], Switzerland and the Relativistic Heavy Ion Collider (RHIC) [11] at Brookhaven National Labratory (BNL) in the United States
Our naıve approach was to equate the concept of a small system to the idea of small separation distances, justified by the intuition that if energy loss occurs in a short, thin medium, the distance between production and scattering of the hard parton must necessarily be small as well

Summary

Introduction

1.1 MotivationWhile the SKA will soon be pushing the boundaries of South African physics, particle physics rivals cosmology on the global stage as one of the most fruitful fields of discovery physics, and it is truly the heavy ion particle physicists that are pulling down the veil of obscurity surrounding the underlying structure of the universe humanity finds itself in. The heavy ion community has all but universally accepted that a new state of matter is routinely created in colossal particle colliders such as the Large Hadron Collider (LHC) at CERN in Geneva [10], Switzerland and the Relativistic Heavy Ion Collider (RHIC) [11] at Brookhaven National Labratory (BNL) in the United States. This new state of matter, called the Quark Gluon Plasma (QGP), is thought to be a deconfined state of the most fundamental constituents of matter, quarks and gluons, that is brought about by the extreme temperatures and energy densities created by colliding heavy nuclei like gold at RHIC and lead at LHC at ultra-relativistic energies. The dual phenomena of elliptic (and higher order) flow of soft (or low transverse momentum, pT ) observables and the quenching of hard (or high pT ) observables are expected wherever a hot medium is created [10]

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Conclusion