QCD Reggeon field theory for every day: Pomeron loops included

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Abstract:We analyze the range of applicability of the high energy Reggeon Field Theory H RFT derived in [1]. We show that this theory is valid as long as at any intermediate value of rapidity η throughout the evolution at least one of the colliding objects is dilute. Importantly, at some values of η the dilute object could be the projectile, while at others it could be the target, so that H RFT does not reduce to either H JIM W LK or H KLW M IJ . When both objects are dense, corrections to the evolution not accounted for in [1] become important. The same limitation applies to other approaches to high energy evolution available today, such as for example [2,3] and [4][5][6]. We also show that, in its regime of applicability H RFT can be simplified. We derive the simpler version of H RFT and in the large N c limit rewrite it in terms of the Reggeon creation and annihilation operators. The resulting H RFT is explicitly self dual and provides the generalization of the Pomeron calculus developed in [4-6] by including higher Reggeons in the evolution. It is applicable for description of 'large' Pomeron loops, namely Reggeon graphs where all the splittings occur close in rapidity to one dilute object (projectile), while all the merging close to the other one (target). Additionally we derive, in the same regime expressions for single and double inclusive gluon production (where the gluons are not separated by a large rapidity interval) in terms of the Reggeon degrees of freedom.

“…[1] provided the most detailed derivation of the high energy evolution, starting from the fundamental QCD Hamiltonian, and considering the construction of the soft gluon…”

Section: Jhep04(2014)075mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

See 3 more Smart Citations

Reggeon field theory for large Pomeron loops

Altinoluk

Kovner

Levin

et al. 2014

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When does the gluon reggeize?

Caron-Huot

2015

133

346

Abstract:We propose the eikonal approximation as a simple and reliable tool to analyze relativistic high-energy processes, provided that the necessary subtleties are accounted for. An important subtlety is the need to include eikonal phases for a rapidity-dependent collection of particles, as embodied by the Balitsky-JIMWLK rapidity evolution equation. In the first part of this paper, we review how the phenomenon of gluon reggeization and the BFKL equations can be understood simply (but not too simply) in the eikonal approach. We also work out some previously overlooked implications of BFKL dynamics, including the observation that starting from four loops it is incompatible with a recent conjecture regarding the structure of infrared divergences. In the second part of this paper, we propose that in the strict planar limit the theory can be developed to all orders in the coupling with no reference at all to the concept of "reggeized gluon." Rather, one can work directly with a finite, process-dependent, number of Wilson lines. We demonstrate consistency of this proposal by an exact computation in N=4 super Yang-Mills, which shows that in processes mediated with two Wilson lines the reggeized gluon appears in the weak coupling limit as a resonance whose width is proportional to the coupling. We also provide a precise operator definition of Lipatov's integrable spin chain, which is manifestly integrable at any value of the coupling as a result of the duality between scattering amplitudes and Wilson loops in this theory.

High energy QCD at NLO: from light-cone wave function to JIMWLK evolution

Lublinsky

Mulian

2017

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Soft components of the light cone wave-function of a fast moving projectile hadron is computed in perturbation theory to the third order in QCD coupling constant. At this order, the Fock space of the soft modes consists of one-gluon, two-gluon, and a quark-antiquark states. The hard component of the wave-function acts as a non-Abelian background field for the soft modes and is represented by a valence charge distribution that accounts for non-linear density effects in the projectile. When scattered off a dense target, the diagonal element of the S-matrix reveals the Hamiltonian of high energy evolution, the JIMWLK Hamiltonian. This way we provide a new direct derivation of the JIMWLK Hamiltonian at the Next-to-Leading Order.